# White LED lumen testing



## jtr1962

Having acquired quite a few different types of white LEDs over the last two years I've long wanted to see how they stacked up against each other. To that end, and since summer is traditionally my season for indoor projects, I ran a slew of tests. Besides the usual intensity and Vf measurements, I also built a device to enable me to estimate lumen output:






 

I made a cradle to hold my light meter out of silicon rubber for consistency of measurements. An old CD serves as the dial to rotate the LED. Starting at 0°, I first position the LED so that the light meter reading is as high as I can get it in order to obtain a hot spot reading. This is important because the relative value of all the other measurements to the highest reading is what will ultimately determine the accuracy. I record the reading, and then rotate the dial in 5° increments all the way to 180°, recording all the light meter readings. A few times during the test I block off the LED in order to obtain a background reading which needs to be subtracted from all the readings. The value is usually 0.1 to 0.2 lux, and while it may not sound like much, at the 17.5" distance between the LED and light meter it can affect the final result by as much as half a lumen.

After I obtain my results on the test jig running the LED at 20 mA I then take lux readings of the LED at one meter at different currents using the constant current source with the thumbwheel switches to change the current. I also record the LED's Vf. I then plug all the data into an Excel spreadsheet made for that particular LED and come up with the final results. Here is a .zip file containing all my spreadsheets so far for anyone who wants to see how I do my calculations.

This post contains my results for low-power LEDs. For those interested in power LEDs, I collected all of my power LED test results in this post.

*Although I have tested many LEDs in this thread, I am not in a position to recommend specific LEDs for use in flashlights or other devices to people. I feel the need to mention this because I have received quite a few PMs asking me which LED would be good for such and such project. I feel it would be best to start a new thread asking for LED recommendations rather than asking me. I just don't have the time or desire or ability to help people determine which LED to use in any given project.*

Before showing graphs of the results here is a list and short description of the LEDs I tested so far in order of date of purchase (all are from eBay with the exception of the Hebei LED and the old Nichia):

*Nichia(?) 5600 mcd 20° 5mm white (purchased 2001 from Hosfelt Electronics)*
A bought a pair of these for $3 each back in 2001 when white LEDs were something of a novelty. In fact, until I started buying on eBay I only had a handful of white and blue LEDs as they were just too pricey to buy in quantity. Anyway, based on the tapered shape and the warm color this LED is probably a Nichia. It actually greatly outperformed the 5600 mcd spec, and did surprising well for a 4-year old white LED, coming in at 28 lm/W efficiency at 20 mA. The tapered shape seems to avoid the ring of light at 60° off-axis as is the case with straight narrow viewing angle 5mm LEDs. As a result, the hot spot is brighter for a given lumen output, and very little light comes out the back.

*SpectrumLEDs (noshankyhank at time of purchase) 6,000 mcd, 30° 5mm white (purchased May 2003)*
The first white LED I purchased on eBay. Very blue tint.

*ChiWing 5,000 mcd 3mm white (purchased July 2003)*
Bluish color, wide angle beam.

*ChiWing 8,000 mcd 20° 5mm white (purchased July 2003)*
Slightly bluish-green, outperformed specs, fairly long-lived based on the one used in my PC as a power indicator. Very low Vf in the 3.00 volt area.

*BestHongKong 10,000 mcd 20° 5mm white (purchased February 2004)*
Slightly purple, outperformed specs, degrades almost instantly at drive currents above 60 mA.

*SpectrumLEDs 8,000 mcd 20° 5 mm white (purchased November 2004)*
Decent color but very dim for a late 2004 LED, seemed to degrade rapidly even at 20 mA.

*warden_jp2002 26,000 mcd 20° white (purchased February 2005)*
Slightly bluish tint, the highest output LED tested by me to date due to a slight wider beam for a 20° LED, no longer available on eBay.

*Hebei L5B47VW5C 60° 5mm white (purchased March 2005)*
Nice color, wide angle beam, purchased for testing for use in my taxi lighting project. Ultimately rejected for that purpose due to costs and output but still a quality LED, and probably very-long lived.

*LCK 12,000 mcd 20° 5 mm white (purchased July 2005)*
White with just a hint of blue, greatly outperformed specs, maybe these are LCK's 26,000 mcd LEDs which were put into a 12,000 mcd bag by accident.

*BestHongKong 25,000 mcd 20° 5mm UWLC series white (purchased July 2005)*
The UWLC series is designed for better color rendering and purer white. These LEDs excel on both counts, especially when rendering reds, and are neither too blue nor too yellow, coming in at a color temp of around 5000K. A slightly wider beam than most 20° LEDs, these come in near the low end of their 14,000 to 25,000 mcd range spec, average in the 16,000 to 17,000 mcd range. The wider beam gives them more output than would be expected for an LED with their intensity.

*Light of Victory 35,000 mcd 20° 5mm white (purchased July 2005)*
The second best color of any LED I've tested so far. Intensity is a close match to the warden_jp2002 26,000 mcd whites but slightly less in lumen output. These seem a match for the Nichia CS in terms of both lumens and intensity. Low Vf compared to most other white LEDs.

*LCK 12,000 mcd 20° 5mm warm white (purchased July 2005)*
The first warm white LED I've purchased. Color temp looks like 3200K to 3300K. As with the LCK 12,000 mcd white, it outperformed specs.

*Jeled 40,000 mcd 20° 5mm white (purchased December 2005)*
Very similar color to the Light of Victory 35,000 mcd, and identical lead frame design. Intensity is nearly 31,000 mcd at 20 mA, a new record for 5mm, 20° white LEDs. Vf is middle of the pack at 3.3V at 20 mA. I also managed to reach over 70,000 mcd at 80 mA, well above my previous records. These intensity records seem to be mostly because the beam is a bit more tightly focused rather than from increased output. Efficiency at 20 mA is a solid 70 lm/W, still less than the warden_jp2002 from early 2005.

*BestHongKong 40,000 mcd 20° 5mm white (purchased January 2006)*
Note that these are NOT the UWLC series pure white but are optimized for intensity instead. Part number is BEB1000003-100. They are slightly bluish white rather than pure white, maybe about 8000K, but with a very even beam. They are also not anywhere near 40,000 mcd at 20 mA due to a much wider than usual beam. A few of the ones with tighter beams were in the 25,000 mcd area but most were about 20,000 mcd. Vf is a bit on the high side at 3.4V to 3.45V at 20 mA. Thanks to the wide beam, output and efficiency are close to the best I've measured so far. In fact, at 5 mA these set a new efficiency record of nearly 97 lm/W. Although I didn't test at lower currents, they may well break 100 lm/W at 2 or 3 mA. Given the results of this test and the Jeled 40,000 mcd, there hasn't been that much improvement in overall white LED efficiency since early last year, although LEDs of top efficiency are now more widely available (remember that the record setting warden_jp2002 26,000 mcd LEDs last year were a very limited run, and it took until late in the year before comparable LEDs were widely available).

*Jeled 50,000 mcd 20° 5mm white (purchased January 2006)*
Identical to their 40,000 mcd LED in design, except the color is slightly whiter. I tested three samples and averaged the results. In short, I broke all my previous records by a good margin. Intensity averages around 41,000 mcd at 20 mA and 55,000 mcd at 30 mA. I also reached average intensities over 90,000 mcd at 80 mA. One of the three with a somewhat tighter beam managed over 100,000 mcd at 80 mA. Vf is tending to the high side at 3.4V at 20 mA. Efficiency at 20 mA averaged 82 lm/W, well above previous records. At 5 mA all three samples were well above 100 lm/W, with an average of 110 lm/W. Just for kicks I tested at lower currents to see if efficiency improved further. It did, averaging nearly 125 lm/W at 1 mA, which is well into HID and HPS territory. Assuming a luminous efficacy of 330 lm/W, typical for white LEDs, energy to light conversion efficiency at 1 mA is around 40%. I also noticed an interesting phenomenom. After I test intensity versus current, I measure the intensity and Vf again at 20 mA just to see if the LED's characteristics changed from the excursion to 80 mA. Usually I find little if any change, and it's usually just a slight decrease in intensity from being abused. In this case, I not only found that intensity was _higher_ after the test, but also that Vf was lower! This is very much what happens with a Luxeon. Because of this I redid the entire intensity versus current tests for all three LEDs after the initial "burn-in", for lack of a better word. Overall the changes bumped the average efficiency from about 75 lm/W at 20 mA to the 82 lm/W figure mentioned earlier. The changes also occurred in an LED that was run at 20 mA overnight.

*Peak Snow 29 5mm white (acquired February 2006)*
CPF member *Pinter *was kind enough to send me 5 samples of the Peak Snow 29 LEDs for testing. These LEDs have a wider than usual beam and a very even color. Color temperature on one sample looked like about 5500K with the rest falling around 6500K. Efficiency on these was impressive, averaging nearly 80 lm/W at 20 mA for the 5 samples. Even more interesting was that the samples ranged from 70 lm/W all the way up to a bit over 90 lm/W at the nominal 20 mA. Average intensity was 21,260 mcd and average output was 5.11 lumens, both figures about equal to the Nichia CS. This verifies the claim Peak makes which states that the Snow 29 LEDs match the Nichia.

*Nichia CS bin B1U 15° 5mm white (acquired February 2006)*
Along with the Peak Snow 29 LEDs Pinter also sent me 4 samples of the Nichia CS LEDs. At the nominal 20 mA operating current these came in at close to 75 lm/W, 4.83 lumens output, and 24,100 mcd intensity. The consistency between samples was very impressive as well-the worst measured 70.6 lm/W while the best was 76.0 lm/w, a variation of less than 8%. Where the Nichias really shined (pun intended) was at higher currents. The majority of LEDs I've tested increased little in output beyond about 70 or 80 mA, and so I usually stopped the testing at 80 mA. The 80 mA output was typically about 2.2 to 2.5 times the 20 mA output. On the other hand, the Nichias gave about 2.75 times their 20 mA output at 80 mA, and the curve showed no signs of flattening out. Therefore, I tested up to 100 mA, which is as high as my test jig goes (and the absolute maximum limit for 5mm LEDs). At 100 mA the Nichias were giving nearly 3.1 times the 20 mA output, or on average nearly 15 lumens! To put this into perspective remember that this isn't much less than Luxeons were giving a few years ago, and at 350 mA. Furthermore, the Nichias showed no signs of stress following their brief excursion to 100 mA. Their output at 20 mA once they cooled down was exactly the same as before. If you really need to overdrive a 5mm LED, then the Nichia is the best candidate.

*MPJA 15,000 mcd 10mm white (acquired July 2006)*
This is one of four different types of LEDs sent to me by CPF member *milkyspit* for testing. I wasn't expecting much based on the 15,000 mcd rating since this is way under the ratings for similar very narrow beam 10mm LEDs from other manufacturers. The five samples all exceeded their ratings by a large margin, coming in at 41.4, 47.8, 60.0, 62.9, and 81.9 cd at 20 mA. I tested the lumens on the best and worst ones, and averaged the results. Of course the intensity far exceeds anything I've tested to date, but this was expected given the tight focus. The efficiency averages a respectable 60.9 lm/W at 20 mA. Color is somewhat blue, with a color temperature of roughly 9000K. The beam is as smooth as can be expected from an LED with as tight a focus as these, but the bond wires and die are clearly visible. Measured beam angle is only about 8.5° but alot of light falls outside the main beam.

*unknown 26,000 mcd 5mm white (acquired July 2006)*
This is the second of four different types of LEDs sent to me by CPF member milkyspit for testing. After testing I'm reasonably sure that this _isn't_ one of the warden_jp2002 26K LEDs which milkyspit thought it might be. Rather, the tapered shape causes me to think this is a Nichia. Based on the color and intensity, I'd say it's a Nichia CS 1BU rank T, and this is what I labeled the results as. The three samples came in at 15.5, 16.8, and 17.9 cd at 20 mA. I tested the middle one for lumens. Efficiency is 61.6 lm/W at 20 mA. Unlike the othe Nichia CS LEDs I tested, these don't do as well at higher currents. The output is more or less maxed out at 80 mA. These may in fact _not_ be Nichias, but if so I have no idea what they are.

*LS Diodes THC3 4-die 5mm white (acquired July 2006)*
This is the third of four different types of LEDs sent to me by CPF member milkyspit for testing. This is the first quad-die LED I've ever tested so the results are quite interesting. The beam is very smooth and white, coming in at about 6000K. Half-intensity beam angle is fairly wide at 27.4° so the intensity is nothing to write home about, reaching only 8,300 mcd at 20 mA. Efficiency at 20 mA is 72.8 lm/W which is very respectable. Note though that since each die is only receiving 5 mA this number isn't as good as it appears at first glance. Where this LED shines is at higher currents. Once you exceed 40 mA it surpasses every 5mm white LED tested to date in efficiency. Even at 100 mA efficiency is still a very decent 50.1 lm/W. As expected, forward voltage is very low compared to other 5mm whites since each die is only getting 1/4 of the current.

*SMJLED 4-die 5mm white (acquired July 2006)*
This is the fourth of four different types of LEDs sent to me by CPF member milkyspit for testing. As with the LS Diodes THC3, the beam is very smooth and white. Color temperature is about 6500K to 7000K. Beam angle is fairly wide (31.6°) so the intensity is low, reaching only 7,100 mcd at 20 mA. Efficiency at 20 mA is 87.8 lm/W which is a new record. Once again, note that since each die is only receiving 5 mA this number isn't as good as it appears at first glance. Again, this LED shines at higher currents. Once past 20 mA it surpasses every 5mm white LED tested to date in efficiency. At 100 mA efficiency is 57.2 lm/W. As expected, forward voltage is very low compared to other 5mm whites since each die is only getting 1/4 of the current. Lumen output far exceeds any 5mm LED tested to date, reaching 17.67 lumens at 100 mA. While these numbers are great, remember that at 100 mA each die is only getting 25 mA. Just for comparison purposes four Jeled 50,000 mcd whites each running at 25 mA would output 26.5 lumens at an efficiency of 76.7 lm/W. Basically, this means that the dies used in the SMJLED (and the LS Diodes THC3) are decent, but not the best available.

*Nichia NSPW310BS-E 60° 3mm white (purchased August 2006)*
I purchased 200 of these on eBay to be used for lighting projects requiring very small LEDs. The beam is bluer in the middle, and most of the LEDs seem to have a color temperature in the 6500K to 7500K range. A few are significantly more blue or yellow than this however. Since these are wide angle LEDs intensity wasn't very high, coming in at around 2,600 mcd at 20 mA. Half-intensity beam angle measured 51°. As with the other Nichias I've tested, these do well at higher currents, giving nearly 3 times their 20 mA output when driven at 100 mA. They might do even better soldered to a PC board with heavy traces. Efficiency was low for a white LED these days, coming in at 36.2 lm/W at 20 mA but peaking in the 50 lm/W area when driven at 2 to 5 mA. Nevertheless, 36 lm/W is still 4 to 10 times higher than the efficiencies of the grain of wheat incandescents which LEDs like this might be used to replace. The NSPW310CS, which is the newer, brighter version of this LED, would do about 65 lm/W based on the relative typical intensities given by Nichia.

*Jeled PLCC-2 2000 mcd white (purchased August 2006)*
I purchased 100 of these PLCC2 surface mount LEDs on eBay to be used for small scale area lighting projects. I also purchased 50 each of the 4 available colored PLCC-2 LEDs (blue, green, red, orange). The beam is very even and color temperature seems to be in the 7000K to 7500K range. Since these are very wide angle LEDs intensity wasn't very high, coming in at around 950 mcd at 20 mA. Half-intensity beam angle measured 112°. Efficiency was unspectacular for a white LED these days, coming in at 43.4 lm/W at 20 mA but breaking 60 lm/W area when driven at 1 to 5 mA. I'll admit to being underwhelmed by these since they are speced at 2000 mcd typical. Had they done so with the same light distribution pattern they would have had efficiencies around 90 lm/W. Nevertheless, the mid 40s isn't horrible, and since I would mainly use these on something non-battery powered like a train layout efficiency isn't terribly important. These would make great miniature imitation metal halide parking lot lights, for example. Had they lived up to spec they would have been almost as efficient as the real ones! The orange ones would do a fair job simulating sodium vapor streetlights. As to why these aren't in the same league as the Jeled 50Ks, my guess is they're not using their best dice, and also the PLCC-2 package basically blocks any light past 90° which might be reflected off the sides or front of the encapsulant. This can be as much as an additional half a lumen, and that would have brought the efficiency up to the low 50s.

*BestHongKong 20° 5mm warm white (purchased June 2006)*
These are my second purchase of warm white LEDs. They have a hotspot with a color temp in the 3300K to 3500K range and a corona of somewhat lower color temp resembling the light from a sodium vapor street lamp. Overall I’d say the average color temperature is around 3000K. The intensity is around 14,500 mcd at 20 mA, Vf is a low 3.12V, beam angle is 11.9°, and overall efficiency is an unspectacular for these days 37 lm/W. Remember though that warm white LEDs tend to have somewhat lower efficiencies than their cool white cousins. Overall the output of this LED is much closer to the incandescent it seeks to replace than the greenish hued LCK warm whites I tested last year.

*LCK 40,000 mcd 15° 5mm white (acquired January 2007)*
This is one of four different types of LEDs sent to me by CPF member *TMorita* for testing. The three samples came in at 30.2, 30.9, and 31.3 cd at 20 mA. The average output at 20 mA was 4.91 lumens, average Vf was 3.26V, and average efficiency was a very respectable 75.2 lm/W. There wasn't much variation between samples in any of the parameters. The beam was somewhat blue, perhaps 8000K, but very smooth. Measured beam angle was 15.1°. These seemed to have less efficiency loss at higher currents than most other eBay LEDs I've tested so far. Even at 80 mA they managed 46.6 lm/W.

*Jeled 50,000 mcd 25° 5mm white test #2 (acquired January 2007)*
This is the second of four different types of LEDs sent to me by CPF member TMorita for testing. The three samples came in at 32.6, 36.2, and 30.1 cd at 20 mA. The average output at 20 mA was 5.01 lumens, average Vf was a very low 3.07V, and average efficiency was a very respectable 81.5 lm/W. There was a little more variation between samples than with the LCK 40Ks in terms of beam angle and intensity but overall output and Vf were close for all the samples. The beam was a little blue but somewhat blothy. Average color temperature looked around 6500K to 7000K. Measured beam angle was 13.5°. As with the LCK 40Ks, these seemed to have less efficiency loss at higher currents than most other eBay LEDs I've tested so far. At 80 mA they managed an even better 49.4 lm/W. It seems plausible that these and the LCK 40Ks may be using the same chip since the test results are similar. Since this is my second test of the Jeled 50Ks there appear to be some notable differences from my first test a year ago. Efficiency is about the same but Vf is much lower so total output is about half a lumen less. Efficiency at higher currents is much improved, as is total output. The original Jeled 50Ks only managed about 2.3 times their 20 mA output at 80 mA, or roughly 13 lumens. The newest batch manages about 2.8 times and 14 lumens while having about 21% greater efficiency. The only downside is that the efficiency of the newer Jeled 50Ks peaks at around 5 to 10 mA in the 90 lm/W area while the older ones averaged as high as 125 lm/W at 1 mA and close to 100 lm/W at 10 mA. You can see the differences below with a side-by-side comparison on the same chart (new in white, old in red). If I had to guess what the change was, I'd say a larger physical size, less efficient chip was used. This would account for the lower Vf and lower peak efficiency. However, by virtue of lower current density efficiency is actually better from about 20 mA and up. This is actually a very sensible decision since if anything 5mm white LEDs tend to be overdriven, not underdriven. Perhaps the larger chip was also used to help lumen maintenance. Lumen maintenance is probably getting more important for inexpensive Chinese LEDs since many are being used in Christmas lights where short lifetime would be very apparent. On another note, based on this test and the LCK 40Ks I'm somewhat disappointed that in a year 5mm LED efficiency has been stagnant. I was expecting 100+ lm/W at 20 mA by summer 2006.








*LCK 35,000 mcd 2-die 30° 5mm white (acquired January 2007)*
This is the third of four different types of LEDs sent to me by CPF member TMorita for testing. The three samples came in at 8.8, 8.0, and 9.0 cd at 20 mA. The average output at 20 mA was 3.50 lumens, average Vf was a very low 3.02V, and average efficiency was a decent 58.0 lm/W. There wasn't much variation between samples in any of the parameters. The beam was a pure white similar to the BestHongKong UWLC series with a color temperature of around 5000K, and very smooth. Measured beam angle was 21.3°. Even though these are two-chip LEDs they didn't do as well at higher currents as the LCK 40K and the second batch of Jeled 50Ks in terms of output. However, because they are dual die they will probably last longer at higher currents. Note that even at their rated 40 mA these don't come anywhere near their ratings of 35,000 mcd and 30° beam angle. However, this isn't unusual for eBay LEDs. The only way to know what you're getting is to buy it and test it. For what these cost they are still a decent value even if they don't live up to their billing.

*Jeled 15,000 mcd 140° superflux white (acquired January 2007)*
This is the fourth of four different types of LEDs sent to me by CPF member TMorita for testing. I only tested one of the three samples since the other two appeared very similar in output. The result was 2.9 cd and 3.46 lumens at 20 mA. Beam angle was 60.6°. Vf was 3.26V and overall efficiency was 53.1 lm/W. Color was very blue, perhaps as high as 9000K, and the beam was very smooth. Of course, these figures are nowhere near the claimed output of 15,000 mcd and a 140° beam angle. However, consider that an LED with those specs would have a total output of around 70 lumens so I wasn't expecting this part to meet specs. If it did, it would have had an efficiency in the 1000 lm/W area which would be physically impossible! Overall this is a decent LED which should give long life owing to the superior heat dissipation of the superflux or pirahna package.

*New LS Diodes THC3 4-die 5mm white (acquired February 2007)*
CPF member *milkyspit* sent me a new THC3 and a Quickar 5m100w for comparison testing. The beam is very smooth and white, coming in at about 6500K. Half-intensity beam angle is fairly wide at 29.4° so the intensity is only 6,400 mcd at 20 mA. Efficiency at 20 mA is 65.5 lm/W, a little lower than the original THC3 which was 72.8 lm/W. As with other 4-die LEDs this one does well at higher currents. Even at 100 mA efficiency is still a very decent 47.6 lm/W. As expected, forward voltage is very low compared to other 5mm whites since each die is only getting 1/4 of the current.

*Quickar 5m100w 4-die 5mm white (acquired February 2007)*
This LED is similar to, but less expensive than, the LS Diodes THC3. In a head-to-head comparison with the new THC3 it did very well. The beam is very smooth and white, quite similar to the THC3, and with a similar color temperature of roughly 6500K. Half-intensity beam angle is fairly wide at 33.9° so the intensity is a mere 5,600 mcd at 20 mA. Efficiency at 20 mA is 63.2 lm/W, a little lower than the new THC3. At 100 mA efficiency is a very decent 46.4 lm/W, just a hair under what the new THC3 does. Once again, forward voltage is very low compared to other 5mm whites since each die is only getting 1/4 of the current.

*SuperbrightLEDs 7,500 mcd 90° superflux (acquired February 2007)*
CPF member *TMorita* sent me this LED along with a bunch of others for testing. The result was 2,600 mcd and 3.83 lumens at 20 mA. Beam angle was 72.0°. Vf was a very low 3.04V and overall efficiency was a decent 63.0 lm/W. Color was pure white, about 6500K, and the beam was very smooth. This is a decent LED which should give long life owing to the superior heat dissipation of the superflux or pirahna package.

*LVEHK 10,000 mcd 20° 3mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 3.0, 3.0, and 3.6 cd at 20 mA, way less than spec. Average beam angle was 29.7°, somewhat wider than claimed, which explains the lower intensity. Color was somewhat blue, around 8000K. Average efficiency of the three samples was only 25.9 lm/W, average output was 1.67 lumens, and average Vf was 3.22V. Although efficiency of these isn't that great, it is much better than the 2 to 4 lm/W of the tiny incandescents which they might be used to replace.

*SpectrumLEDs 2,000 to 4,000 mcd 180° 4.8mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. These are the 4.8mm "top hat" package which is designed for area lighting applications. The results were 1.75, 1.84, and 1.81 cd at 20 mA, around the low end of the spec. Average beam angle was 105.6°. Color temperature was 6500K, which is pure white to most people. Even though the intensity was low because of the wide beam angle average efficiency of the three samples was an excellent 79.2 lm/W. Average output was 5.10 lumens, and average Vf was 3.22V. Consistency between samples was impressive-outputs were 5.06, 5.15, and 5.10 lumens. Overall these are great LEDs for any application required flood lighting, or perhaps to focus with a reflector.

*SuperbrightLEDs 18,000 mcd 15° 5mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 24.6, 23.3, and 24.2 cd at 20 mA, higher than spec. Average beam angle was 15.3°. Color temperature was a slightly but not offensively blue 7000K. The beam was smooth. Average efficiency of the three samples was a decent 66.0 lm/W. Average output was 3.99 lumens, and average Vf was a very low 3.02V. Consistency between samples was impressive-outputs were 4.12, 3.76, and 4.09 lumens. Overall these LEDs are solid performers.

*SuperbrightLEDs 18,000 mcd 30° 5mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 13.1, 13.2, and 12.3 cd at 20 mA, way less than spec. Average beam angle was 20.2°, also less than spec. Color temperature was a match to the 15° version of this LED, coming in at 7000K. The beam was smooth. Average efficiency of the three samples was a solid but not overly impressive for these days 50.7 lm/W. Average output was 3.19 lumens, and average Vf was 3.14V. Consistency between samples was even more impressive than the 15° version-outputs were 3.10, 3.24, and 3.22 lumens. Overall these LEDs are decent even though they didn't meet their specs.

*BestHongKong 35,000 mcd 20° 5mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 29.0, 29.1, and 29.5 cd at 20 mA, slightly less than spec. Average beam angle was 14.7°. Color temperature averaged around 7000K but the beam was a little blotchy, with a blue center and yellowish corona. Average efficiency of the three samples was a decent 65.8 lm/W. Average output was 4.53 lumens, and average Vf was a somewhat high 3.44V which hurt the efficiency numbers. Consistency between samples was quite impressive-outputs were 4.53, 4.64, and 4.41 lumens. The high Vf and poor scaling of output with current (output at 80 mA was only 2.06 times the output at 20 mA) indicates that these LEDs likely use small but efficient dice.

*LVEHK 55,000 mcd 20° 5mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 28.6, 28.4, and 29.7 cd at 20 mA. Note however that the 55,000 mcd spec is at 25 mA. Average intensity of the three samples at 25 mA was 34.6 cd, still somewhat below spec. Average beam angle was 14.0°. Color temperature averaged around 7000K but the beam was a little blotchy, with a blue center and yellowish corona. Average efficiency of the three samples was a decent 64.1 lm/W. Average output was 4.15 lumens, and average Vf was 3.23V. Consistency between samples was decent-outputs were 4.30, 4.20, and 3.94 lumens. Output scales very well with current (output at 80 mA is 2.53 times the output at 20 mA), and efficiency numbers increase by only about 25% at lower currents compared to at 20 mA, indicating that these LEDs use large dice. While these LEDs are decent, and comparable in performance to the BestHongKong 35,000 mcd, I was disappointed that they didn't even come close to their brightness and beam angle specs.

*LVEHK 65,000 mcd 40° 8mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The beam pattern was somewhat unusual with a slightly darker spot in the center, and the brightest part of the beam around the dark spot. The results (dead center of the beam) were 6.8, 5.2, and 7.5 cd at 20 mA, way less than spec. About 5° off-axis these numbers were around 15% higher. Average beam angle was 31.1°. Color temperature was quite blue, about 9000K. Average efficiency of the three samples was a not too impressive 43.2 lm/W. Average output was 3.06 lumens, and average Vf was a very high 3.55V which definitely hurt the efficiency numbers. Consistency between samples was good-outputs were 3.16, 2.91, and 3.13 lumens. Despite the high Vf indicating a small die output scales very well with current (output at 80 mA was 2.65 times the output at 20 mA), perhaps because the larger lead frame of the 8mm package conducts away heat better.

*LVEHK 140,000 mcd 12° 10mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 63.5, 59.8, and 59.8 cd at 20 mA, well below spec. Average beam angle was 7.5°. Color temperature averaged around 7000K to 7500K but the beam was reasonably smooth, at least as smooth as can be expected from LEDs as tightly focused as these. Average efficiency of the three samples was a decent 67.6 lm/W. Average output was 4.44 lumens, and average Vf was 3.29V. Consistency between samples was decent-outputs were 4.59, 4.39, and 4.35 lumens. Output scales very well with current (output at 80 mA is 2.57 times the output at 20 mA), and efficiency numbers increase by only about 25% at lower currents compared to at 20 mA, indicating that these LEDs use large dice. These are decently performing LEDs overall.

*BestHongKong 135,000 mcd 12° 10mm white (acquired February 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 166.2, 129.0, and 144.9 cd at 20 mA, all over or very close to spec. Average beam angle was an extremely narrow 6.5°, almost all hotspot with virtually no sidespill. Color temperature averaged a blotchy, slightly yellow 5000K but the blotchy beam quality is to be expected from LEDs as tightly focused as these. Average efficiency of the three samples was an excellent 79.6 lm/W. Average output was 5.14 lumens, and average Vf was 3.23V. Consistency between samples wasn't that great-outputs were 5.54, 4.67, and 5.18 lumens. Output scales very poorly with current (output at 80 mA was only 2.16 times the output at 20 mA), indicating that these LEDs likely use very small but very efficient dice. The much higher efficiency numbers at low currents (in the 115 lm/W area at 1 to 2 mA) further support this conclusion. A single one of these LEDs can make a very impressive flashlight with plenty of throw.

*Nichia NFSW036L, bin T, tint C1 white (acquired February 2007)*
CPF member TMorita sent me this LED along with a bunch of others for testing. The result was 3,340 mcd and 4.02 lumens at 20 mA. Beam angle was 51.3°. Vf was an extremely low 2.72V and overall efficiency was a decent 73.9 lm/W. Color was similar to a cool-white fluorescent, about 4500K, and the beam was very smooth. The LED's output scaled very well with current, giving 3.57 times the output at 100 mA as it did at 20 mA. Efficiency at 100 mA was a decent 49.7 lm/W. However, all this is to be expected since this LED is designed to operate at 150 mA with a heat sink. This is also why the Vf was very low. Although my tester couldn't go above 100 mA by looking at the relative outputs in the spec sheet for this LED I estimated output at 150 mA to be around 20 lumens. This is right on spec.

*SuperbrightLEDs RL5-W45-360 360° 5mm white (acquired February 2007)*
CPF member TMorita sent me this LED along with a bunch of others for testing. The very wide but very low output presented special measurement difficulties. Even at 17.5" distance of my testing jig the intensity hitting my light meter was only in the 2 lux area, and the scattered background light accounted for about one-third of this. Measuring the intensity at 1 meter proved impossible at 20 mA so I did it at 100 mA and used the intensity ratio measured at 17.5" to calculate my results. The result was a mere 280 mcd. Calculated output was 4.18 lumens at 20 mA, close enough to the 4500 mlm (4.5 lm) spec. 50% beam angle was nonexistent since the LED more or less emitted in a complete 360° circle. Vf was 3.16V and overall efficiency was a decent 66.2 lm/W. Color was slightly blue, about 7000K. These are very unusual LEDs in that it appears they have their phosphor deposited on the outer surface of the package. They appear yellow unlit but once lit they are white. Any application where an LED seeks to mimic a light bulb in terms of intensity distribution would be a good one for these.

*SuperbrightLEDs RL8-W110-360 360° 8mm white (acquired February 2007)*
CPF member TMorita sent me this LED along with a bunch of others for testing. This is an 8mm version of the 360° LED described above. Again, the very wide but very low output presented special measurement difficulties as described for the RL5-W45-360. The intensity at 20 mA was only 280 mcd. Calculated output was 4.48 lumens at 20 mA. At 60 mA, which is what these LEDs are speced at, output is 10.54 lumens, slightly above the 9000 mlm (9.0 lm) spec. 50% beam angle was nonexistent since the LED more or less emitted in a complete 360° circle. At 20 mA Vf was a very low 2.85V and overall efficiency was an excellent 78.6.2 lm/W. Corresponding numbers at 60 mA were 3.12V and 56.3 lm/W. Color was cool-white fluorescent white, about 4500K. These are very unusual LEDs in that it appears they have their phosphor deposited on the outer surface of the package. They appear yellow unlit but once lit they are white. Any application where an LED seeks to mimic a light bulb in terms of intensity distribution would be a good one for these.

*ISP 22,000 mcd 25° 5mm white (acquired March 2007)*
Three of these were sent to me by CPF member *TMorita* for testing, and are special order using one large single die for operation at 100 mA. They are not the stock 2-die ones rated at 40 mA. The three samples came in at 6.4, 6.6, and 7.1 cd at 20 mA. The average output at 20 mA was 3.37 lumens, average Vf was a very low 2.94V, and average efficiency was a decent 57.3 lm/W. There wasn't much variation between samples in any of the parameters, especially the forward voltage. The beam was slightly blue, with a color temperature of around 7000K, and very smooth. Measured beam angle was 25.7°, which slightly exceeds the advertised 25°. At higher currents these did very well, giving slightly over 13 lumens at 100 mA. At their rated 100 mA these manage 25,900 mcd, exceeding their 22,000 mcd rating. Overall these are decent LEDs, and probably quite long lasting at higher currents due to their large-die construction.

*LCK 55,000 mcd 15° 5mm white (acquired March 2007)*
TMorita sent me 3 samples of this LED for testing. The results were 27.4, 27.4, and 27.9 cd at 20 mA. Average beam angle was only 10.6°, so the less than rated intensity wasn't due to a wider beam angle as is sometimes the case. Color temperature averaged around 7000K but the beam was a little blotchy, with a blue center and yellowish corona. Average efficiency of the three samples was a decent 59.8 lm/W. Average output was 3.79 lumens, and average Vf was 3.17V. Consistency between samples was quite good-outputs were 3.80, 3.73, and 3.84 lumens. Output scales very well with current (output at 80 mA is 2.65 times the output at 20 mA), and efficiency numbers increase by only about 25% at lower currents compared to at 20 mA, indicating that these LEDs use large dice. These LEDs are decent but I was disappointed that they didn't even come close to their brightness and beam angle specs.

*Jeled 55,000 mcd 15° 5mm white (acquired March 2007)*
CPF member *Minjin* sent me two of these for testing. The two samples came in at 35.2 and 32.4 cd at 20 mA. The average output at 20 mA was 5.11 lumens, average Vf was a very low 3.05V, and average efficiency was a very respectable 83.9 lm/W. This means that the Jeled 55Ks squeak by for a new efficiency record for 5mm single die LEDs at 20 mA. The beam was a little blue but somewhat blothy. Average color temperature looked around 6500K. Measured beam angle was 14.1°. These have less efficiency loss at higher currents than most other eBay LEDs I've tested so far. At 80 mA they managed 50.9 lm/W. Even at 100 mA they are a decent 42.1 lm/W (and over 15 lumens!). Peak efficiency numbers increase by only about 20% at lower currents compared to at 20 mA, indicating that these LEDs use large dice. While I'm glad to have finally measured a new efficiency record, I remain disappointed that in over a year 5mm LED efficiency has more or less been stagnant. Since 5mm LED efficiency usually precedes the next jump in power LED efficiency by up to a year, and there are planned increases in power LED efficiency for 2008, I remain hopeful that we'll have 5mm LEDs of 100+ lm/W at 20 mA within the next few months.

*Hebei 520MW7C 20° 5mm white (acquired June 2007)*
CPF member *LEDude* sent me 10 samples of this LED for testing. I picked three of the ten at random to test. The results were 15.6, 14.1, and 15.9 cd at 20 mA. Average beam angle was 19.3°, very close to spec. Color temperature averaged around 7000K-7500K and the beam was a very smooth. Average efficiency of the three samples was a decent 65.1 lm/W. Average output was 3.98 lumens, and average Vf was a low 3.06V. Consistency between samples was quite good-outputs were 4.04, 4.01, and 3.88 lumens. Output scales fairly well with current (output at 80 mA is 2.42 times the output at 20 mA). It's been over two years since I last tested Hebei LEDs. These LEDs are quite an improvement in efficiency over their previous offerings.

*Hebei 530MW7C 30° 5mm white (acquired June 2007)*
CPF member LEDude sent me 10 samples of this LED for testing. I picked three of the ten at random to test. The results were 12.0, 12.3, and 11.4 cd at 20 mA. Average beam angle was 22.1°, somewhat under spec. Color temperature averaged around 7000K with a very smooth beam. Average efficiency of the three samples was a decent 58.9 lm/W. Average output was 3.55 lumens, and average Vf was a very low 3.01V. Consistency between samples was quite good-outputs were 3.57, 3.49, and 3.60 lumens. Output scales fairly well with current (output at 80 mA is 2.41 times the output at 20 mA). Overall, performance is very similar to the 520MW7C but that's to be expected since they likely use the same die, but moved further towards the front of the epoxy package for a wider beam angle.

*Hebei 550MW7C 50° 5mm white (acquired June 2007)*
CPF member LEDude sent me 10 samples of this LED for testing. I picked three of the ten at random to test. The results were 5.1, 4.5, and 4.9 cd at 20 mA. Average beam angle was 47.9°,very close to spec. Color temperature averaged around 6500K with a very smooth beam. Average efficiency of the three samples was a decent 66.5 lm/W. Average output was 4.14 lumens, and average Vf was a low 3.12V. Consistency between samples was quite good-outputs were 4.36, 4.07, and 4.00 lumens. Output scales fairly well with current (output at 80 mA is 2.51 times the output at 20 mA). Performance is very similar to the 520MW7C and 5307C as expected. All three of these LEDs are quite decent performers given the low cost, and quite well made.

*Jeled 210000 mcd 10mm warm white (acquired December 2007)*
CPF member *knabsol *sent me 3 samples of this LED for testing. The results were 5.1, 5.5, and 5.6 cd at 20 mA. Average beam angle was 26.7°, less than the specified 40°. Color temperature was very low, perhaps 2500K, and with a very smooth beam. In all honesty these looked more like sodium vapor lamps than anything else. Average efficiency of the three samples was only 38.1 lm/W. Average output was 2.20 lumens, and average Vf was a low 2.88V (expected due to the 5-die construction). Consistency between samples was not so good-outputs were 1.81, 2.27, and 2.53 lumens. Output scales very well with current as expected (output at 100 mA is 3.47 times the output at 20 mA). Even at 100 mA the intensity of these averages only 18.7 cd, well below the spec of 210 cd. Not sure what to make of these really. The large case size seems to make the beam smoother rather than focus it.

*Jeled 255000 mcd 10mm white (acquired December 2007)*
CPF member knabsol sent me 3 samples of this LED for testing. The results were 8.9, 9.9, and 11.3 cd at 20 mA. Average beam angle was 24.2°, less than the specified 30°. Color temperature was around 7500K, and the beam was very smooth. Average efficiency of the three samples was a decent 60.6 lm/W. Average output was 3.48 lumens, and average Vf was a low 2.87V (expected due to the 5-die construction). Consistency between samples was OK-outputs were 3.30, 3.31, and 3.84 lumens. Output scales very well with current as expected (output at 100 mA is 3.70 times the output at 20 mA). At 100 mA the intensity of these averages only 37.2 cd, well below the spec of 255 cd. As with their warm white cousins, the large case size seems to make the beam smoother rather than focus it. In both cases performance seemed disappointing given the 5-die construction.

*Oatley Electronics 80000 mcd 10mm white (acquired December 2007)*
CPF member *lctorana* sent me 3 samples of this LED for testing. The results were 5.7, 6.1, and 7.1 cd at 20 mA. Average beam angle was 38.8°. Color temperature was around 7500K, and the beam was very smooth. Average efficiency of the three samples was a very decent 72.4 lm/W. Average output was 4.26 lumens, and average Vf was a low 2.94V. (expected due to the multi-die construction). Consistency between samples was excellent-outputs were 4.06, 4.31, and 4.41 lumens. Output scales very well with current as expected (output at 100 mA is 3.60 times the output at 20 mA). At 100 mA the intensity of these averages only 22.7 cd, well below the spec of 80 cd. These are supposed to be able to output 25 lumens at 150 mA. My test jig only went to 100 mA, and the average output at that current was 15.34 lumens. At 150 mA output would probably be around 20 or 21 lumens, not much below the 25 lumen spec. Overall, these are pretty decent LEDs. It seems in all cases that the large 10 mm case size seems to make the beam smoother rather than focus it. For maximum focusing it appears that the 8mm case is best based on my tests so far.

*Deal Extreme 20mm white (acquired March 2008)*
CPF member *nein166* loaned me one of these for testing. This thing is huge! The die area and leads are much larger than on normal indicator type LEDs. Results at 20 mA are 6.6 cd, 4.23 lumens, and 70.7 lm/W. Beam angle is 39.1°, and Vf is a very low 2.99V. Output scales well with current, and at 100 mA is nearly 3 times that of 20 mA. Beam is extremely smooth and around 7000K. These make great area lights. I would imagine that they would have a very long lifetime even at 100 mA due to the superior thermal path.

*BestHongKong 25000 mcd 5mm 5-die white (acquired March 2008)*
CPF member *TMorita* sent me 3 samples of this LED for testing. These are BestHongKong's 5-die whites which have 5 dies and a larger lead frame to allow operation at 100 mA. The results were 6.0, 6.5, and 6.9 cd at 20 mA. I assume the 25,000 mcd rating is at 100 mA, so the corresponding results at 100 mA are 24.3, 25.8, and 28.1. The average is 26.1 cd, slightly above spec. Average beam angle was 34.7°, less than the specified 50°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a decent 72.8 lm/W at 20 mA and 52.9 lm/W at 100 mA. I was expecting somewhat better than that due to the 5-die construction. Apparently they're not using the most efficient dies for these. Average output was 4.07 lumens at 20 mA, and average Vf was a low 2.87V (expected due to the 5-die construction). Corresponding figures at 100 mA were 16.41 lumens and 3.10V. The 16.41 lumens comes reasonably close to the specified 20 lumens at 100 mA. Consistency between samples was excellent-outputs were 3.91, 4.14, and 4.16 lumens at 20 mA. Output scales very well with current as expected (output at 100 mA is 4.03 times the output at 20 mA). Overall these appear to be a decent, well-constructed LED capable of sustained operation at higher currents.


*LED Tech 14000 mcd 5mm 100 mA white (acquired March 2008)*
CPF member TMorita sent me 3 samples of this LED for testing. These are LED Tech's 100 mA whites which have a larger lead frame to allow operation at 100 mA, and probably also multiple dies. The results were 2.8, 2.8, and 3.2 cd at 20 mA. I assume the 14,000 mcd rating is at 100 mA, so the corresponding results at 100 mA are 11.0, 11.2, and 12.3. The average is 11.5 cd, somewhat below spec. Average beam angle was 77.1°, nearly equal to the specified 80°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a very decent 86.8 lm/W at 20 mA and an excellent 63.8 lm/W at 100 mA. These are better numbers than the very similar BestHongKong LEDs because they're apparently using better dies. Average output was 5.12 lumens at 20 mA, and average Vf was a low 2.95V (expected due to the multi-die construction). Corresponding figures at 100 mA were 20.06 lumens and 3.15V. Consistency between samples was OK-outputs were 4.71, 5.05, and 5.60 lumens at 20 mA. Output scales very well with current as expected (output at 100 mA is 3.92 times the output at 20 mA). Overall these appear to be a decent, well-constructed LED capable of sustained operation at higher currents.


*Nichia NSPS500GS-K1 5mm white (acquired March 2008)*
CPF member TMorita sent me 3 samples of this LED for testing. These are Nichia's latest and greatest 5mm whites. The results were 36.0, 39.2, and 39.8 cd at 20 mA. I think these are speced for 44,000 mcd, so the average of 38.3 cd is only slightly out of spec. Average beam angle was 13.4°, a little less than the specified 15°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a excellent 96.7 lm/W at 20 mA, so these take the new efficiency crown. Even at 100 mA efficiency manages to remain at nearly 50 lm/W. Average output was 6.15 lumens at 20 mA, and average Vf was 3.18V. Corresponding figures at 100 mA were 21.43 lumens and 4.34V. Given the rather steep increase in Vf with current, these don't appear to be multi-die as some here have speculated. Consistency between samples was OK-outputs were 5.75, 6.19, and 6.52 lumens at 20 mA. Output scales very well with current despite the apparent single-die construction (output at 100 mA is 3.48 times the output at 20 mA). This isn't much worse than the two types of multidie LEDs just tested. It looks like Nichia has another winner here, and we have a new efficiency champ.


*Cree C503B-WAN-CCACB231 5mm white (acquired January 2009)* *NEW!*
CPF member *Holepuncher* sent me 3 samples of this LED for testing. These are Cree's brightest commercially available 5mm whites. The results were 26.9, 26.2, and 25.4 cd at 20 mA. These are speced for 23,500 to 32,900 mcd according to the datasheet, so the average of 26.17 cd is well within spec, although on the low side. Average beam angle was 15.1°, dead on the specified value of 15°. Color temperature was around 6500K, and the beam was extremely smooth. Average efficiency of the three samples was an excellent 79.2 lm/W at 20 mA. At 100 mA efficiency drops to 31.5 lm/W. Average output was 4.93 lumens at 20 mA, and average Vf was a low 3.11V. Corresponding figures at 100 mA were 12.36 lumens and 3.92V. Consistency between samples was great-outputs were 4.67, 5.16, and 4.97 lumens at 20 mA. Output doesn't scale as well with current as some other recent 5mm LEDs I've seen, but it's not horrible, either. Overall these appear to be great LEDs, and could be even better if they used Cree's best dice. Just doing some rough assumptions regarding phosphor conversion efficiency of 80% and package efficiency of 80%, I've calculated that these are using blue dice with an output of about 24 mW @ 20 mA. Cree's best dice produce 33 to 35 mW. This would produce a white LED of 110 to 115 lm/W, perhaps even as high as 125 lm/W in a wide-angle package.


*cece718 6000 mcd flat top 3mm white (acquired January 2009)* 
I purchased 100 of these for use in model railroading lighting applications. These are the flat top 3mm LEDs sold on eBay by seller cece718. Color temperature is around 7000K, and the beam is very smooth. I knew these couldn't come anywhere close to their 6000 mcd spec given their wide angle. I measured 800 mcd at 20 mA. Output was 3.49 lumens and efficiency was an OK for nowadays 54.1 lm/W. Beam angle was a very wide 129°. Output doesn't increase much with current, and levels off at 5.91 lumens at 60 mA. This isn't surprising given the poorer thermal properties of the 3mm package, and in service I doubt I would run these LEDs over 10 mA. Overall, these LEDs aren't bad given their price. In fact, I was pleasantly surprised they performed as well as they did. It was only a few years ago that only the best LEDs managed 50 or 60 lm/W. Nowadays most commodity LEDs seem to reach that mark.



*Osram LW E6SG PLCC4 white (acquired May 2009)* *NEW!*
I purchased 200 of these for use in model railroading lighting and LED night light applications. These are surface mount PLCC-4 style LEDs. Color temperature is around 5500K, somewhat warmer than usual for small LEDs and the beam is very smooth. Intensity was 1010 mcd at 20 mA. Output was 3.15 lumens and efficiency was an OK for nowadays 48.8 lm/W. Beam angle was a very wide 119°. Output scales well with current, and was 8.07 lumens at 100 mA. The claim to fame of these LEDs is a special silicon encapsulant which gives a lifetime of 50,000 hours at 25 mA and 25°C. I put them in 9 LED night lights so far in order to attempt to validate this claim. The LEDs which were previously in these night lights faded to practically nothing after 3 years of continuous use. 

I'll be adding to this list as I acquire more white LEDs...

Here are the graphs for efficiency versus current:
















































































































































































































































[/SIZE]
Here is a series of head-to-head comparisons of all the LEDs for a number of different parameters:


















Note how there is more or less (with the exception of the SpectrumLEDs 8000 mcd white) a steady improvement in efficiency from 2003 until the present. Most of the LEDs clustered together in the efficiency graphs were purchased at roughly the same time.

Here is a chart summarizing the results at 20 mA test current:






As to the accuracy of my results, for a sanity check the Light of Victory 35,000 mcd seem a close match to the Nichia CS in terms of intensity and lumens, and the Nichias are supposed to have efficiencies in the 60 lm/W area at 20 mA. This is exactly where the Light of Victory 35,000 mcd falls. The warden_jp2002 actually is around 74 lm/W at 20 mA. I'm guessing someone got a supply a Cree's XT-24 chips for those. Nothing else could give efficiencies that high. Also note how these same LEDs break 90 lm/W at 5 mA. (Nothing thus far has beat these LEDs, which were available for a fairly short time on eBay.) - Note: _The warden_jp2002 LEDs were finally beaten by the Jeled 50000 mcd ones, but they held the record for nearly a year._

_*Update 04/10/2008: The Nichia NSPW500GS-K1 takes the crown now at 96.7 lm/W-tantalizingly close to the magic 100 lm/W mark.*_


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## chimo

jtr1962, great work! I d/l'd the zip file but I got errors in it. Could you check it out? I would like to compare you data to mine. Thanks,

Pual


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## jtr1962

Yeah, were right about the error Paul. I fixed it so just download it again.


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## chimo

Got the new copy. Thanks!

Paul


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## tvodrd

Wow! /ubbthreads/images/graemlins/thumbsup.gif and thanks!

Larry


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## evan9162

How are you generating a lumens value from the set of lux measurements? Are you doing a series of spherical caps, and summing up the intensity/area for each cap to get a total lumen output?

I was thinking of doing this a while ago, but never got around to it - I wanted to see how accurate my lumens coefficient was, and how close the lumileds datasheet was in reagards to the beam pattern of a luxeon high done.


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## jtr1962

Yes evan9162, that's exactly how I'm doing it. For example, I take the relative lux readings for 0° and 5°, average them, multiply by the area in steradians, and then multiply by the intensity in candelas. After that, I'll do the same with the 5° and 10° values, etc, and add this to my running total. It's interesting that for narrow viewing angle (i.e. 15° or 20°) LEDs the traditional methods of calculating lumens in the main beam grossly underestimates the output. One can see why by examining the radiation pattern of one of these LEDs. Some light falls outside the main beam but this decreases in intensity rather quickly. Still, since the spherical area is larger as the angle increases, this spill still makes significant contributions to the output. After that you usually have a bright ring about 60° off axis. This shows up clearly in the graphs in my spreadsheets. While the intensity might only be 2% or 3% of the maximum intensity, it is spread over a large area and contributes a good 15% to 20% of the total output. Finally, a great deal of light actually makes it out the back because of reflection off the front lens. This could easily add another 10% to 15% to total output. I was honestly amazed by this myself although it makes sense. For example, using the usual way of figuring lumens, and assuming a 20° beam angle, I might have guestimated about 2.3 lumens for the Light of Victory 35,000 mcd LED based on it's peak intensity reading of ~24,000 mcd at 20 mA (the 35,000 mcd spec is at 30 mA according to the manufacturer). I usually multiplied this by 1.25 to account for spill outside the main beam, giving me a final estimate of 2.9 lumens. The actual measurements come out to 3.75 to 3.9 based on a few samples, or over 30% more. I guess I'll revise my adhoc mutliplier to about 1.65 to give a more realistic estimate.

I'll also add that since the dial is just screwed to the tester and easily removeable, I might make another one up complete with a heat sink and mounting area to test Luxeons, Lamina BL-2000s, and other power LEDs. My constant current source can supply up to 2 amps if need be. I can verify my methodology if I get lumen measurements in the mid 30s with my Q-bin Luxeons.


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## PeterB

Great data collection! 
And the warden_jp2002 data fits quite well to my old measurements with a completely different method (I had also these warden LEDs).

Lumen vs. current and Power


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## evan9162

jtr,

Sounds cool. I think I may finally do this myself someday. In another thread, I used the method, combined with the typical beam distribution from the luxeon data sheet to come up with a "Lumen coefficient". You would simply take a 0-degree lux measurement of a HD luxeon at 1m, and multiply by the coefficient to get a lumens estimate. I'm hoping to both a) verify that this coefficient is usable and b) see how well the beam distribution in the datasheet holds true.


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## jtr1962

I remember that thread, Peter. It looks like you're getting a little less output than I did because the light coming out the back of the LED didn't make it to the fraen lens. Still, it looks like we're reasonably close which makes me feel better. I did a double take after I entered the data for the warden LEDs. I was saying no way can they be this good but I guess they are.


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## idleprocess

Nice!

I've often thought about doing something like that, but lack the math background (and mesurement apparatus) to do something like that.

The calculations in the LEDDB are rather lacking for accurate mcd * beam angle : lumens calculations.

I'll have to look over your spreadsheets. Most manufacturers include radiation patterns, so maybe I can borrow your work for more accurate numbers from spec sheets...


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## NewBie

A fella should also consider de-rating the lumens due to heat produced in real life. Especially if using as a "calibration" source.

jtr1962- Have you thought about running a luxeon at 20/40/60mA to see where they fall?


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## idleprocess

Hm. Looks like I'm going to have to take a different route - but at least I got off my butt and have a somewhat better understanding of optics.

So deviously simple-_(sounding)_!

1 lm == 1 cd / steridian

65.542173315° = 1.0000000000116693 sr _(got tired of monkeying with digits in the beam angle calulator here)_

4Pi steridians (sr) / sphere


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## jtr1962

I made a jig for testing power LEDs. Here are my results for a Q3J Luxeon, a Lamina BL-2000, a Seoul Semiconductor W32182 bin RSX0I star, and a Cree 7090 XR-E bin P4:






















Here are the relevant spreadsheets.

I have 5 Q bin Luxeons. Four of them seem about equal in brightness and the fifth is about 10% dimmer. Assuming then that the dim one is at the low end of the Q-bin (say 31 lumens), then the other ones should test in the mid 30s. My results give me 37.1 lumens, a little past the middle of the Q-bin. I think this more or less verifies the accuracy of my methods. At worst my results are less than 10% too high.


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## ViReN

Wow .. Amazing Data /ubbthreads/images/graemlins/smile.gif Thanks for doing the test jtr1962

Any Chance you will test the Nichia NSPW500CS ... C0 / A0 Tint, U Bins...

Also, It would be interesting to see the BS LED's too...


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## jtr1962

I'll probably get 5 of the Nichia CS to test from Grumpy's group buy if he has any more. Other than that I don't have any Nichias except possibly two really old ones from around 2001. I purchased them from Hosfelt Electronics but they have the tapered shape typical of Nichias. At the time they were rated at 5600 mcd, 20° viewing angle, which goes to show how old they are. Assuming a similar light distribution pattern to other 20° white LEDs I've tested so far I would imagine they would put out roughly 0.9 to 1.0 lumens at 20 mA, for an overall efficiency in the 15 lm/W area. Maybe I'll run a test on them just to verify my estimates.

If anyone wants to send me LEDs for testing PM me for my address and send a stamped, self-addressed envelope if you want the LEDs returned. For now I'm sticking to testing white LEDs. I've tested a few colored ones, but finding a true hotspot reading at 1 meter is somewhat difficult thanks to the splotchy beam patterns. Also, because of these beam patterns I'm not sure how accurate my methodology would be. Most white LEDs have a fairly even beam, making the results more valid.


----------



## jtr1962

I added the LCK 12,000 mcd warm white, which arrived today, to my list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs.


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## jtr1962

I added an old (c.2001) white LED, probably a Nichia, to the first post and updated the graphs. I also made the comparison charts easier to read by using heavier lines.


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## jtr1962

I've finished testing any colored LEDs I have worth testing (the dim indicator LEDs would be pointless). Here are the results in the order in which they were purchased:















































The blue LEDs are surprisingly efficient in terms of lumens per watt, especially the Hebei blue LED. The likely reason for this is that the dominant wavelength is probably somewhat higher than 470 nm. The rest of the colored LEDs fall more or less where one would expect. Except for blues and reds, colored LED efficiency has not been advancing as fast as white LED efficiency, especially for amber, orange, and yellow green.

The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## jtr1962

I added the BestHongKong 40,000 mcd and Jeled 40,000 mcd to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## ViReN

jtr1962 .... Great plots in deed... its valuable data when it comes to designing a light considering the Lumen/Watt & total Lumen output for a 5 mm LED

I wonder if you could help me for a project, if you have any Luxeon I (Q/R Bin's H/J Vf) and Luxeon III (S/T Bin's J/K Vf) LED's is it possible for you to have similar charts. i.e. Lumens V/S Current & Vf

i have been looking for this over the forum here and there... but could not find such a chart. i do not have the equipment to do the testing either 

your help is highly appreciated.


----------



## jtr1962

ViReN said:


> I wonder if you could help me for a project, if you have any Luxeon I (Q/R Bin's H/J Vf) and Luxeon III (S/T Bin's J/K Vf) LED's is it possible for you to have similar charts. i.e. Lumens V/S Current & Vf


Hi Viren,

Thanks for the compliments, and I hope this data is useful to people. If you look a few posts up you'll see that I did indeed plot a Luxeon Q3J in the same manner as my 5mm LEDs, and included a link for the relevant spreadsheets which have the Vf versus current data. I don't have any Luxeon IIIs on hand to do plots, but I imagine they wouldn't be much different. Maybe now that Future Electronics finally lowered their prices for these to something I consider reasonable I'll pick up a few LIIIs in various colors and play around.


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## winny

Good job jr1962!

I didn't read it all but as you used the word steradian so I'm quite confident that you know how it works. Very good. Welcome to the higher intelligence club! ;-p

From the picture it looked like you where using the same light meter as I am. I'll give you a warning on them. They are cheap and in my manual it said "the spectral response _almost_ corresponds with the CIE curve". When you measure non 2860 K light sources, like LEDs, the error margin is big and comparing LEDs with different shades of white or with incans is, ..., questionable.


----------



## jtr1962

winny said:


> From the picture it looked like you where using the same light meter as I am. I'll give you a warning on them. They are cheap and in my manual it said "the spectral response _almost_ corresponds with the CIE curve". When you measure non 2860 K light sources, like LEDs, the error margin is big and comparing LEDs with different shades of white or with incans is well, questionable.


The light meter is a CEM DT-1300. I took part in the light meter tests as described here. For LED-type white light my meter only seems to read a few percent above the averages of everyone elses. It does read quite high for blue LED light which explains my ridiculously high results in tests of blue LEDs (about twice as high as they should be).

Note that I did sanity check my results. The brightest 5mm LEDs nowadays are in the 60 to 70 lm/W range so if I had gotten results much different I would have been suspicious. Also, my Q bin Luxeon came in at 37 lumens, solidly in the middle of the Q bin. Again, if I had gotten results of 45 or 50 lumens, I might have been suspicious. Overall, I'd say for white LEDs my results might be about 5% or so high, if that. I'm more interested in relative measurements anyway so as to tell which LEDs are better. In the future I may adjust my data once the CPF standard LED test lights are professionally checked but for now the relative measurements are a good guide for everyone.


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## winny

You obviously have thought of everything! Very good.  

I hope I didn't offend you, but I just had to warn you as my light meter can be waaay of when it comes to LEDs sometimes. I'll send mine to SilverFox for testing when he get the lamps back.

Anyway, how much did you get out of that MR16 in the background of the picture?


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## jtr1962

winny said:


> Anyway, how much did you get out of that MR16 in the background of the picture?


I never tested it but now that you mentioned it I think I will. BTW, it's a standard 50W halogen MR-16 so I figure it should be good for ~1000 lumens.


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## jtr1962

I added the Jeled 50,000 mcd to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## winny

Any progress on the MR16?


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## jtr1962

winny said:


> Any progress on the MR16?


Unfortunately, that picture was taken before I cleaned the room and now I can't remember where I put the MR16. :green: If/when it turns up I'll be sure to test it and post the results. I did actually look for it for a while when you first mentioned testing it but had no luck.


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## Pinter

jtr1962 said:


> For LED-type white light my meter only seems to read a few percent above the averages of everyone elses. It does read quite high for blue LED light which explains my ridiculously high results in tests of blue LEDs (about twice as high as they should be).


That means that leds with blue hotspot are resulting in higher Lux reading in your test than real white ones?


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## hotbeam

jtr, fantastic set of results. you must be a very persistent fellow


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## jtr1962

Pinter said:


> That means that leds with blue hotspot are resulting in higher Lux reading in your test than real white ones?


Maybe except that the greatest errors with my meter occur with narrowband blue light such as from a blue LED, rather than the bluish-white hotspots present in some white LEDs. As a reality check on the accuracy of my light meter I compare my intensity results to ratings. If anything, most eBay sellers overrate their LEDs so I should be getting lower intensities. In fact, that is almost always the case. Only a few sellers, such as BestHongKong and ChiWing, usually live up to their ratings, or occasionally even exceed them. The only time I get intensity readings well above ratings across many manufacturers is with blue LEDs. The CPF light meter test verified that my meter is indeed reading very high for blue light but pretty much on the mark for white light (both incandescent and LED).


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## jtr1962

hotbeam said:


> jtr, fantastic set of results. you must be a very persistent fellow


Obsessive-compulsive is sometimes a better description of me.


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## vortechs

Hi jtr1962, 

I was really happy to find this thread reviewing the 50k white LED's from jeled. Thanks for all your work to compare the real statistics and output from all of these different LED types. 

Are you still running new tests on white LED's and, if so, what LED's are you planning to test next? 

I've been thinking about getting the 3mm white 18,000mcd LED's available from jeledhk on eBay (link). Their published stats show 15,000 to 18,000mcd with a 30 degree viewing angle, but I'm wondering how close to this they actually are. I've been considering getting some to modify one of KevinL's picolights that use 3mm LED's and possibly for a solitare or 2AA maglite mod without needing the reflector modification that using a 5mm LED would require. 

If you've already tested these 18k 3mm white LED's or are planning to test them, please let me know. Alternatively, if you are interested, I could get some and send you a few to test (I don't know what I'd do with 50 of them anyway).


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## jtr1962

vortechs said:


> Are you still running new tests on white LED's and, if so, what LED's are you planning to test next?


These tests are ongoing, and I just updated the first post with the Peak Snow 29 and Nichia CS B1U LEDs sent to me by CPF member Pinter. I'm accepting LEDs for testing, and also will continue testing any new ones I acquire for my own personal use.



> If you've already tested these 18k 3mm white LED's or are planning to test them, please let me know. Alternatively, if you are interested, I could get some and send you a few to test (I don't know what I'd do with 50 of them anyway).


If you've gotten the 18K 3mm LEDs and have some left I'll be happy to test them. Just PM me for a mailing address.


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## jtr1962

I also tested the Seoul Semiconductor W32182 1 watt stars. The results are in this post. Interestingly, I got an luminous flux of almost exactly the 52 lumens claimed as typical at 350 mA for this part.


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## winny

Have you found that MR16 yet?


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## jtr1962

winny said:


> Have you found that MR16 yet?


Not yet, but I think I have a good idea where I put it. Stay tuned....


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## Pinter

Hi jtr1962,

Thank you for testing the Nichias and Peak Snow, I did not think you measure all 9 samples.
Nichia performance was a real surprise over 60mA. This is in good correlation with another thread in which Nichia has shown better lumen maintenance at 60mA than others at 30mA.

I have some questions about the methodology:
- what is the sensor diameter 
- (whether if I understood correctly) you measure the beam profile from 17.5" then you read the peak lux readings from 1m on different currents and weight this data with the relative intensity that came from the profile?


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## jtr1962

Pinter said:


> I have some questions about the methodology:
> - what is the sensor diameter
> - (whether if I understood correctly) you measure the beam profile from 17.5" then you read the peak lux readings from 1m on different currents and weight this data with the relative intensity that came from the profile?


Sensor diameter is 1.5". I chose 17.5" as the measuring distance because the sensor diameter at that distance covers exactly 5° of the beam, and I measure output in 5° increments. When I'm done I weight the beam profile data with my lux readings from exactly one meter, and use a spreadsheet to do the calculations. The end result is of course the total output in lumens. Yes, I do all the lux readings at different currents at one meter, although since they're all relative anyway I could just as easily do them at 17.5", and only do the 1 meter lux reading at one current just to weight all my data. The method works surprising well. The main source of error seems to be the absolute value of my lux readings at 1 meter. The meter is supposed to be within 10%, so I assume this is the upper bounds of my error. In practice, based on my relative measurements in Silverfox's light meter benchmark testing, my light meter is reading maybe 5% high for white LED type light compared to the average (although the average isn't necessarily dead accurate).

In any case, my results aren't horribly off. The U bin Nichias are supposed to be in the vicinity of 60 lm/W efficiency at 20 mA but Vf is typically about 3.4 volts. The samples you sent me had a lower Vf in the 3.2V area which would put efficiency into the mid 60s. Furthermore, all seemed to be at the upper end of the U bin, probably pushing them into the 70 to 75 lm/W area. Since 75 lm/W is what I measured, my errors are likely 5% or less. This also explains why V bin Nichias are very rare. They need to have efficiencies of 80 lm/W or higher, and this represents the present upper limit of production white LEDs these days.


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## NewBie

jtr1962 said:


> The meter is supposed to be within 10%, so I assume this is the upper bounds of my error. In practice, based on my relative measurements in Silverfox's light meter benchmark testing, my light meter is reading maybe 5% high for white LED type light compared to the average (although the average isn't necessarily dead accurate).



Unfortuately, the majority of the error is in the spectral response. These meters are "calibrated" for incandescent, sodium vapor, fluorescent, and such. Some have correction tables built in you select the type of light source, to adjust for the error, others have the correction factor in the manual that you have to apply manually. Read your manual, if it worth beans at all, they will mention those correction factors (the LM631 is only accurate for tungsten lamps as I recall).

An example is one of the higher end, unfortunately more expensive light meter (though it is not accurate for LEDs):
http://www.extech.com/instrument/products/400_450/407026manualregist.html

Unfortunately, nobody I know of has created a spectral correction factor for white LEDs, and that would be somewhat futile, since the white led spectrum varies from white LED to white LED, even from the same manufacturer.

One of the few instruments that can remove this *very* significant source of error is a spectroradiometer, and they are darned expensive.


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## NewBie

Results of the certified testing of a batch of lights, as compared to various folks light meters can be found here:
http://candlepowerforums.com/vb/showpost.php?p=1462364&postcount=461

Note the large error, especially for the Red Green and Blue.

Hopefully, some day, someone will have a chance to test "white" LEDs from several bins the same way, vs. light meter reported results.


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## LumenHound

Newbie, I would like to know how these leds would test out on your light meter using the identical testing procedure jtr1962 used. 

Jeled 40K, 50K
BestHongKong 40K
Light of Victory 35K
Peak Snow 29
Nichia CS B1U white

I think it would be very interesting and informative to see what variations there are from one consumer level light meter to the next.

Anxiously awaiting your results...


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## NewBie

LumenHound said:


> Newbie, I would like to know how these leds would test out on your light meter using the identical testing procedure jtr1962 used.
> 
> Jeled 40K, 50K
> BestHongKong 40K
> Light of Victory 35K
> Peak Snow 29
> Nichia CS B1U white
> 
> I think it would be very interesting and informative to see what variations there are from one consumer level light meter to the next.
> 
> Anxiously awaiting your results...




Variation testing has been done, along with Certified Lab Testing, see this thread:
http://candlepowerforums.com/vb/showthread.php?p=1461977


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## LumenHound

Excellent thread. Thanks for the link.
Looks like I'm going to need to get a fresh cup of coffee before I get comfortable and start to wade through it all.


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## jtr1962

I haven't been keeping up much on things around here since my father died on March 28 but this thread being bumped caught my attention. Three or so months ago Pinter analyzed my testing procedure and found that in theory my reported results would be higher than the actual results due to my using 5° increments instead of smaller ones. The difference between actual and reported would be higher for narrower beam LEDs than for wide-beam ones, but for most 15° to 20° LEDs it was on the order of 10%. By sheer coincidence my light meter reads about 10% low compared to the lab standard so the errors more or less cancel. Of course, the spectra of the white LEDs I test is different from the spectra of A1 white but nevertheless it gives some idea of the typical errors of my meter when measuring white LEDs. Anyway, while I certainly won't say my lumen measurements are dead accurate, I think it's reasonable to say they're within 10%. As for the color LED measurements, after seeing how much my meter is off, and also how a slight shift in center wavelength can make any "corrections" based on the standard meaningless, I've decided to refrain from testing any more colored LEDs. The results, other than for relative light intensity versus beam angle, are utterly worthless since I don't possess the equipment to accurately measure the spectral distribution.

I plan to eventually add to this thread but for now there don't seem to be any new white LEDs worth testing and I'm still grieving over my father. Perhaps when the 85 lm/W and 100 lm/W Nichias are in circulation later this year I'll continue. I'd also love to test one of Cree's new 131 lm/W LEDs as it represents a good 50% increase over my best efficiency measures so far.


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## jtr1962

NewBie said:


> Unfortunately, nobody I know of has created a spectral correction factor for white LEDs, and that would be somewhat futile, since the white led spectrum varies from white LED to white LED, even from the same manufacturer.


True, but in much the same way corrections for fluorescent sources are somewhat futile as well. While many light meters may have a correction for old-school halophosphor cool-whites there are so many types and color temps of fluorescents available now which differ markedly in their spectra from the "standard" fluorescent used in the corrections.


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## milkyspit

Jtr, you rule!!! This is some GREAT information. Certainly is a Godsend for me!
:bow: :bow: :bow:

BTW, check your PM Inbox... PM sent!


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## jtr1962

milkyspit said:


> Jtr, you rule!!! This is some GREAT information. Certainly is a Godsend for me!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> BTW, check your PM Inbox... PM sent!


PM read and answered.





Thanks for the praise!



I'm certainly glad many are finding this info useful. Now if I could only get my hands on some of those 131 lm/W Crees soon for some testing...


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## Xe54

NewBie said:


> Unfortuately, the majority of the error is in the spectral response. These meters are "calibrated" for incandescent, sodium vapor, fluorescent, and such. Some have correction tables built in you select the type of light source, to adjust for the error, others have the correction factor in the manual that you have to apply manually. Read your manual, if it worth beans at all, they will mention those correction factors (the LM631 is only accurate for tungsten lamps as I recall).
> 
> An example is one of the higher end, unfortunately more expensive light meter (though it is not accurate for LEDs):
> http://www.extech.com/instrument/products/400_450/407026manualregist.html
> 
> Unfortunately, nobody I know of has created a spectral correction factor for white LEDs, and that would be somewhat futile, since the white led spectrum varies from white LED to white LED, even from the same manufacturer.
> 
> One of the few instruments that can remove this *very* significant source of error is a spectroradiometer, and they are darned expensive.



Theoretically speaking, IF a highly accurate photopic filter could be achieved to cause a transducer such as a photodiode to be accurately matched in response to the human eye (according to the current standard response curve) then that detector would exhibit accurate lux measurements for any color temperature of white light and even for monochromatic sources.

I believe I have found the most accurate photopic photodiodes available in the marketplace. One is the OSI Optoelectronics (used to be UDT Sensors) PIN10AP device in the datasheet below:

http://www.osioptoelectronics.com/products/35-36_DetecFiltComb_OSIOpto.pdf

Note however that the $275 device (with 6 month lead time) is specified as having 4% max error in area vs. CIE rather than error at any particular wavelength. Unfortunately the error at some specific wavelengths in the 470-520nm region is very large. This still precludes the use of the device for highly accurate photometric measurements of monochromatic sources near the blue, and perhaps could lead to significant errors even with white LEDs with a large blue spectral peak. I do expect however that a device such as this is considerably more accurate than a typical lux meter sensor.

When searching for this device, I found devices from two other manufacturers. A Hamamatsu device in BNC package was ridiculously expensive, more than $1000, though I think around $60 but unobtanium in small quantity for the TO-5 package.

http://sales.hamamatsu.com/assets/pdf/parts_S/S9219_series.pdf

The other device was from Advanced Photonix, PDV-C406, but which is no longer shown on their website (I have a datasheet and 4 samples if anyone's interested). Actually was from a company they recently acquired, though they told me in an email that the product would still be available. They also said the response was never calibrated.

http://www.advancedphotonix.com/index.asp

Hmm, now I need to consider whether to cancel my backordered PIN10/AP device...


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## jtr1962

I added four samples (MPJA 15,000mcd 10mm, unknown 26,000 mcd, LS Diodes THC3, SMJLED) sent to me by CPF member milkyspit to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## jtr1962

I added the Nichia NSPW310BS wide angle 3mm white LED to the list. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## milkyspit

Jtr, this is admittedly a VERY picky little request... but if it's not overly difficult, could you post your charts as separate images rather than a single big, long, continuous image? I love your research and like to save a copy of this thread locally for quick reference purposes... even turn it into a PDF for convenience... but those ultra-long images are giving me fits! No matter what I do, they get cutoff at page bottom. (As in a physical page... piece of paper.) I would need to cut them apart by hand in Photoshop then recreate a hacked version of the thread to fix the problem... if you can generate them as separate images to begin with, it would be a BIG help!

:bow: :bow: :bow:


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## SemiMan

GREAT TEST!


"It's interesting that for narrow viewing angle (i.e. 15° or 20°) LEDs the traditional methods of calculating lumens in the main beam grossly underestimates the output. One can see why by examining the radiation pattern of one of these LEDs. Some light falls outside the main beam but this decreases in intensity rather quickly."

When reading your post, I got the impression that you used different distances depending on the LED? If true, this would effect your measurements somewhat. 

If possible, it is best to place the LED as far from the meter as possible given the resolution of the meter. This ensures the most homogenous output on the light meter. At those short distances the cosine correction may come into play assume the meter is corrected.

Interesting that your blue output is higher than normal. Most low cost light meters (i.e. less than $2,000) are very inaccurate at the wavelength of blue LEDs used for white LEDs often reading 50% low or more. This changes rapidly around that spot as well making things worse. This can effect the measurements by about 10-15% overall (low), but not the end of the world.

Overall, great experiment and nice set setup.

One way to improve things would be to put a length of 2" PVC pipe painted inside with a very flat black paint in front of your light meter. This will get rid of a lot of the side reflections from the LED hitting other things plus general ambient light.You may need to be careful with this given how close your LED is though.


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## jtr1962

milkyspit said:


> Jtr, this is admittedly a VERY picky little request... but if it's not overly difficult, could you post your charts as separate images rather than a single big, long, continuous image? I love your research and like to save a copy of this thread locally for quick reference purposes... even turn it into a PDF for convenience... but those ultra-long images are giving me fits! No matter what I do, they get cutoff at page bottom. (As in a physical page... piece of paper.) I would need to cut them apart by hand in Photoshop then recreate a hacked version of the thread to fix the problem... if you can generate them as separate images to begin with, it would be a BIG help!


I'm actually thinking of doing that because that long image is getting unwieldy. I simply have to see how much web space separate images versus one large one would take up as Roadrunner only gives me 5 MB of web space. It would make my life easier in that I wouldn't have to edit that huge picture every time I test a new LED.


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## jtr1962

SemiMan said:


> When reading your post, I got the impression that you used different distances depending on the LED? If true, this would effect your measurements somewhat.


When doing the beam profile the LED is 17.5" inches from the light meter in all cases. My test apparatus sees to that. This is the distance at which one 5° increment is the same size as the diameter of my light meter sensor. Another reason for using the shorter distance to measure the beam profile is that the background light represents a smaller percentage of my reading. As I mentioned it's at most 0.3 lux with the brighter LEDs. If I took the beam profile at 1 meter instead then once I got off center axis my readings might differ from the background reading by less than 0.1 lux, which is the resolution of my light meter. If I had a light meter with an extra digit then I might be able to do this but 4.5 digit light meters seem very rare and expensive. Of course, I do measure the actual intensity in mcd of the LED at 1 meter. One interesting thing to note is that since my background readings are limited in resolution to 0.1 lux increments then the final lumen values technically have a granularity of roughly (17.5/39.3)² x 0.1 x 4pi or 0.25 lumens. This is generally way less than 10% of the total lumen output at 20 mA of most LEDs these days. Doing the beam profile at a higher test current than this would reduce the contibution of the finite meter resolution to the final calculation.



> Interesting that your blue output is higher than normal. Most low cost light meters (i.e. less than $2,000) are very inaccurate at the wavelength of blue LEDs used for white LEDs often reading 50% low or more. This changes rapidly around that spot as well making things worse. This can effect the measurements by about 10-15% overall (low), but not the end of the world.


Yes, for colored and especially blue LEDs my readings are way off which is why I decided to refrain from further testing of colored LEDs. While the blue component can undoubtedly affect the reading from white LEDs somewhat, I have yet to find any white LED which gives significantly more than its rated mcd (with the exception of the MPJA 10 mm). In fact, most of the eBay LEDs I've tested thus far read _under_ their rated mcd. The Nichias seem to be very close to what they're supposed to be so I suppose that tells me my light meter isn't terribly off.

Another sanity check are the tests done for wide angle power LEDs like Luxeons. Q-bin Luxeons test right in the mid-range of the Q bin. A Seoul Semiconductor LED tested right at the 52 lumen typical value shown in the data sheet. Wide angle LEDs are less prone to the sorts of errors which might affect more narrow beam LEDs. It might be interesting to one day check how some of my tested LEDs do in a calibrated integrating sphere. My guess is they probably wouldn't be more that 10% to 15% off except possibly in the case of 10 mm LEDs with very narrow beams.



> One way to improve things would be to put a length of 2" PVC pipe painted inside with a very flat black paint in front of your light meter. This will get rid of a lot of the side reflections from the LED hitting other things plus general ambient light.You may need to be careful with this given how close your LED is though.


I may one day build a new test apparatus with some of these improvements, including detents on the angle wheel to make the testing yet more consistent. I do place the apparatus on top of a narrow cardboard box now so as to minimize the stray reflections. I plan to paint the top of the box and the rest of my apparatus flat black. One thing to note is that the stray reflections mainly make the readings in the main beam higher although hopefully subtracting out the background reading reduces most of this error. Since all the readings in the beam profile are relative, this tends to give the readings outside the main beam smaller relative values than they would otherwise have. The end result is actually a lower total lumen value. It would be interesting to retest a few LEDs if I modify my apparatus to see if I actually end up with higher lumen values.


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## milkyspit

jtr1962 said:


> I'm actually thinking of doing that because that long image is getting unwieldy. I simply have to see how much web space separate images versus one large one would take up as Roadrunner only gives me 5 MB of web space. It would make my life easier in that I wouldn't have to edit that huge picture every time I test a new LED.



If it gets down to it, maybe I could give you some space on my hosting account, or at least point you to a hosting provider where $10 per month would buy you something along the lines of 150-300MB of space. Let me know if you need the help... glad to assist!


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## jtr1962

milkyspit said:


> If it gets down to it, maybe I could give you some space on my hosting account, or at least point you to a hosting provider where $10 per month would buy you something along the lines of 150-300MB of space. Let me know if you need the help... glad to assist!


So far so good-the separate files for the white LEDs were only about 15K more than the one big file. The white LED efficiency charts are now separate pictures. Stay tuned for the colored LEDs...

Update: The colored LED efficiency charts are now separate files. They actually use less space than the one big file since I was able to convert most of them to 16 colors.

Second Update: LED comparison charts are now separate images.

Third Update: Power white LED charts now separate images. I think that takes care of everything.


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## jtr1962

I adding the following chart summarizing my results at 20 mA to the first post:


----------



## jtr1962

I added the Jeled PLCC-2 2000 mcd surface mount white LED to the list. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## bizzybody

jtr1962 said:


> Update: The colored LED efficiency charts are now separate files. They actually use less space than the one big file since I was able to convert most of them to 16 colors.


 
If the graphics app* you're using has a feature to convert to Indexed Color with Exact pallete, saving to .PNG or .GIF can make really small files of huge graphics.

Fer instance, I've been doing some texture maps for 3D models at a 2048x2048 pixels, in 2 colors. Saving to GIF with an exact pallet crunches the 12 megabyte image down to around 47-67 kilobytes with no loss of quality.  More colors would of course increase that, but with the lossless compression on chart and graph type images with large areas of the same color, it wouldn't be much.

*Photoshop 7.01 and/or Photoshop CS2 (9.01) is my tool of choice.


----------



## jtr1962

I added the BestHongKong 5mm warm white LEDs to the list. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


----------



## jtr1962

Cree 7090 XR-E bin P4 (purchased November 2006)

I purchased these from CPF member Erasmus. These are tint bin WH and flux bin P4 (80.6 to 87.4 lumens at 350 mA). The color temp of these seems a close match for my 5000K fluorescents which makes the WH bin perfect for interior lighting although perhaps a bit warm for flashlights. I measured the 50% beam angle at 95.3° which is somewhat wider than the 75° given on the spec sheet. Despite the out of spec beam angle, the overall flux at 350 mA is 85.67 lumens which is within the range of the P4 bin (and also a verification of the accuracy of my methodology). Vf at 350 mA is 3.25V and overall efficiency is a very impressive 75.37 lm/W. Even at 700 mA efficiency remains above 60 lm/W. Luminous flux at 500 mA is about equal to the Lamina Ceramics BL-2000 arrays but the power input is only around 1.7 watts instead of the 4.7 or so watts used by the Lamina array. Although these obviously aren’t a 20 mA part if they were they would break previous records by a huge margin, coming in at nearly 112 lm/W. There’s really nothing more to say about these than hasn’t already been said by me and many others. They represent a huge step forwards in LED technology.

Here is the efficiency versus current chart:


----------



## EngrPaul

Great information, Joseph. WOW the Cree can be run efficiently down at 25mA !

Thanks for your one-of-a-kind comprehensive testing!


----------



## Erasmus

Great results JTR!


----------



## frenzee

Thank you very much for this info. I wish all manufacturers would provide this data on their data sheets. Hopefully one of these days you will find the time and patience to do the same kind of testing on red and amber LEDs.


----------



## ViReN

Now That's Impressive


----------



## jtr1962

frenzee said:


> Thank you very much for this info. I wish all manufacturers would provide this data on their data sheets. Hopefully one of these days you will find the time and patience to do the same kind of testing on red and amber LEDs.


I did test some colored LEDs (results in post #19 of this thread). I decided to discontinue doing so after finding out how inaccurate my light meter was with colored LEDs in the Light Meter Benchmark Test. If I ever have suitable equipment available to accurately test colored LEDs I would certainly reconsider doing so.


----------



## milkyspit

Hey Joe, :wave:

Great data as always. You know I'm a big fan of your work! :bow: :bow:

Question: for the Cree, was 25mA the lowest current you tested, or did performance really fall off a cliff below that as shown in your graph?


----------



## jtr1962

milkyspit said:


> Hey Joe, :wave:
> 
> Great data as always. You know I'm a big fan of your work! :bow: :bow:
> 
> Question: for the Cree, was 25mA the lowest current you tested, or did performance really fall off a cliff below that as shown in your graph?


Many thanks for the compliments!  I'm just glad this data is useful to so many people.

Actually 20 mA was the lowest current I tested at. It looks like 25 mA on the graph thanks to the way Excel plots the data. For the same reason the performance also looks like it falls off a cliff.

I didn't bother testing under 20 mA because of the difficulties of measuring the intensity. The Cree is a wide angle LED. At 20 mA I was only getting 2.8 lux at 1 meter. Since my light meter only resolves to 0.1 lux on the lowest scale this meant at 20 mA my granularity was already close to 4%. Also, NewBie tested these at lower currents and from his data it seemed that efficiency more or less peaked at 20 mA and then dropped off at lower currents. 20 mA is a little under 6% of rated current. I've found that with 5mm LEDs I get similar results where the efficiency peaks at 5% or so of rated current although in this case rated is 20 mA. So for 5mm LEDs I usually test down to 1 mA but for power LEDs like the Cree I usually go down to around 5% of rated.

BTW, you can access the spreadsheets containing the raw data for my power LED tests here.


----------



## EngrPaul

I'm sitting here visually comparing the beam patterns of "BestHongKong 25,000 mcd 20° 5mm UWLC series white" BUWLC333W24BA25 against the "Jeled 50,000 mcd 20° 5mm white"

All I have to say is the BestHongKong has excellent distribution and overall color. If you are going to upgrade a 1-LED light, this would be a very good candidate. 

On the other end of the spectrum is the JELED. It's splotchy, with regions of pi$$ yellow and ocean blue. The only place I found for them were behind the frosted bezel of LED nightlights and all mixed together in multiple-LED cheapie lights.

Neither of them have tapered heads, which prevents them from being a drop-in for many applications.


----------



## 3rd_shift

Is there a way that you can remove the lense and retaining ring from a cree xre to measure how much light is getting out without those on it?


----------



## Pinter

JTR, thank you for the XR-E test. Overall lumen value is fitting great in the given bin range.



jtr1962 said:


> I measured the 50% beam angle at 95.3° which is somewhat wider than the 75° given on the spec sheet.


Just wondering that this huge difference is general issue, or just an individual misalignment of the embedded optic?

Do you have other Crees from this batch?


----------



## Erasmus

Here's another table belonging to the Cree XR-E tests : 




Once I can get my hands on Q-bins, these will to straight to Jtr1962 so he can measure the output! Thanks Jtr!


----------



## Opto-King

Hmm, according to your testing and to SSC's datasheets for their P4 LEDs the P4 LED in U binning is better than the Cree LED.


How is this possible if they are both using the same die?


----------



## SpeedEvil

The die is a very important component - it's hardly the only one though.

You've then got the thermal connection to the heatsink, so it doesn't heat up too much, and stop working.
The electrical connections, which are a compromise in some ways between light output, ease of manufacture, and resistance.
The refractive index, and design of the bits just around the die, to optimise on extraction of light from the die.
Manufacturability (hence cost).
The phosphor coating formulation, thickness and evenness of that coating.
Then you've got the lens, and how it all ages over time, which is probably the hardest bit.


----------



## NewBie

Opto-King said:


> Hmm, according to your testing and to SSC's datasheets for their P4 LEDs the P4 LED in U binning is better than the Cree LED.
> 
> 
> How is this possible if they are both using the same die?




You will notice the CREE hit the lm/W target even with actual derating for temperature.

In other words, the test was conducted on the part with the die heated, as it would be in a flashlight.


It will be interesting to see how the Seoul Semiconductor part actually does, when ran at actual temperatures.

The LumiLEDs parts, you have to de-rate from their datasheet/binned numbers due to die heating to get to the actual real life lm/W.


----------



## NewBie

jtr1962 said:


> Cree 7090 XR-E bin P4 (purchased November 2006)
> 
> I purchased these from CPF member Erasmus. These are tint bin WH and flux bin P4 (80.6 to 87.4 lumens at 350 mA). The color temp of these seems a close match for my 5000K fluorescents which makes the WH bin perfect for interior lighting although perhaps a bit warm for flashlights. I measured the 50% beam angle at 95.3° which is somewhat wider than the 75° given on the spec sheet. Despite the out of spec beam angle, the overall flux at 350 mA is 85.67 lumens which is within the range of the P4 bin (and also a verification of the accuracy of my methodology). Vf at 350 mA is 3.25V and overall efficiency is a very impressive 75.37 lm/W. Even at 700 mA efficiency remains above 60 lm/W. Luminous flux at 500 mA is about equal to the Lamina Ceramics BL-2000 arrays but the power input is only around 1.7 watts instead of the 4.7 or so watts used by the Lamina array. Although these obviously aren’t a 20 mA part if they were they would break previous records by a huge margin, coming in at nearly 112 lm/W. There’s really nothing more to say about these than hasn’t already been said by me and many others. They represent a huge step forwards in LED technology.
> 
> Here is the efficiency versus current chart:



Your testing on an actual part is still hitting CREE's claims even with the die not at 25C, very impressive. 


Very nice, your P4 did even better than my P3:







My peak lm/W on the XR-E was 20mA.


----------



## NewBie

.


----------



## jtr1962

3rd_shift said:


> Is there a way that you can remove the lense and retaining ring from a cree xre to measure how much light is getting out without those on it?


Unfortunately I need all 6 pieces I purchased for projects (and I don't want to risk destroying one by removing the lens). However, if anyone wants to send me one without the lens I'll be happy to test it.



Pinter said:


> Just wondering that this huge difference is general issue, or just an individual misalignment of the embedded optic?
> 
> Do you have other Crees from this batch?


I haven't tested the other 5 I have. I can maybe do a rough check on the beam angle to see if the others are out of spec. In the end I don't think it matters much as far as total lumen output goes. These are factory tested, presumably in a small integrating sphere, so the lumen output will be within the bin specification regardless of beam angle.



Opto-King said:


> Hmm, according to your testing and to SSC's datasheets for their P4 LEDs the P4 LED in U binning is better than the Cree LED.
> 
> How is this possible if they are both using the same die?


The P4 U bin isn't a whole lot different than the XR-E Q2/Q3 bins. Neither are out yet so I don't think SSC has accomplished something Cree hasn't. By the time P4 U bins are out we'll also have comparable XR-E Q2/Q3 bins.


----------



## jtr1962

NewBie said:


> Your testing on an actual part is still hitting CREE's claims even with the die not at 25C, very impressive.
> 
> Very nice, your P4 did even better than my P3:


My power LED test jig uses a ~7"x3"x2" U-channel of aluminum as a heatsink. As a result, slug temperature is probably fairly close to room temperature. Also, the room was at about 65°F when I tested. Given that, the die may well have been not much over 25°C at 350 mA. Using 8°C/W for the junction to solder point interface, and allowing perhaps 2°C/W for the thermal grease interface to my heat sink, I'm calculating a junction temperature of perhaps 30°C given a heat sink temperature of ~65°F. This means the output is only derated by 1 or 2% relative to a junction temperature of 25°C.

I found it interesting that our efficiency numbers are close because Vf on your sample was less than on mine. I wonder if the higher binned XR-Es will have output which scales with Vf? If so, then they won't be substantially more efficient than the regular binned ones.

Another interesting thing here is that according to the light meter benchmark testing my meter reads about 10% low for an LED-type spectrum. Granted that the error will be different for different types of LEDs, but this could mean that my test sample was putting out as much as 8.5 lumens more than my test results show. Or perhaps the error in my meter just about cancels any errors resulting from my test methodology. I'm really surprised that _all_ my tests of power LEDs have given the results they were supposed to. A SSC came out at almost exactly the typical 52 lumens it was supposed to. A Q-bin Luxeon was also practically dead center of where it should have been.


----------



## NewBie

I sure would be handy if someone had a certified lab for testing lumens.

Since high power LEDs, that are not abused, have such long lifetimes, I've often considered building up a very well regulated (light feedback mechanism), grossly over heatsinked, and sending it off to a certified lab for testing. I've also considered purchasing a certified reference bulb, but as you mention, the spectrums are different.


----------



## Doug S

jtr: This is one of the true great threads on the CPF. I'm sure many here appreciate your hard work. 
I've read your first thread carefully but still have a question about your test setup. 
Is any special or at least consistant provision made to remove heat from the cathode [negative] lead of the LED tested? The cathode lead is the primary path for heat extraction from a white 5MM LED. If you are not making any special provision to heatsink the cathode lead, a very interesting comparision would be a comparison with and without the cathode lead heat sinked to a few square inches of copper.


----------



## jtr1962

I added four samples (LCK 40,000mcd, Jeled 50,000 mcd, LCK 35,000 mcd 2-die 5mm, Jeled 15,000 mcd superflux) sent to me by CPF member TMorita to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


----------



## jtr1962

Doug S said:


> jtr: This is one of the true great threads on the CPF. I'm sure many here appreciate your hard work.
> I've read your first thread carefully but still have a question about your test setup.
> Is any special or at least consistant provision made to remove heat from the cathode [negative] lead of the LED tested? The cathode lead is the primary path for heat extraction from a white 5MM LED. If you are not making any special provision to heatsink the cathode lead, a very interesting comparision would be a comparison with and without the cathode lead heat sinked to a few square inches of copper.


Thanks for the praise, Doug. 

To answer your question, I haven't made any provision to remove heat from the LED because I'm interested in how the LED performs in a typical application where it might have poor thermal coupling. I'll try your suggestion out of curiosity on a few LEDs just to see if it makes much difference. I would guess offhand that it wouldn't because LED output doesn't vary as dramatically with temperature for whites as it does for reds or especially ambers. I've noted that when I test at higher currents the output will drop somewhat as the LED heats up but the drop doesn't seem to be more than maybe 10% at most, usually under 5%. Heatsinking 5mm LEDs with heavy copper planes is usually done for lifetime purposes rather than to increase output.

A couple of quick calculations might shed some light as to how much there is to be gained. A 5mm LED in air has a thermal impedance in the 300°C/W area (junction to ambient). Since the socket I mount the LED in helps a little let's say it's closer to 200°C/W. I usually test at 80 mA maximum since that's around where output levels off. At a Vf of around 3.7V (typical at 80 mA) power dissipation would be about 0.3 watts. Junction temperature rise would therefore be roughly 0.3x200 or 60°C. Looking at some output versus temperature charts and we end up derating the output by around 15%. Even if a heatsink cut the junction temperature rise by two-thirds we would be looking at only a 10% increase in output at 80 mA (less at lower currents).


----------



## 3rd_shift

I just finally found this.


> However, if anyone wants to send me one without the lens I'll be happy to test it.



Can you email me your shipping address?
I can send over one without and one with the lense, both with the same binning to show the difference.


----------



## NewBie

It would be *much* more accurate to measure one, then pull it's lens off. Otherwise, you don't really know for sure.


----------



## 3rd_shift

That could be tried with the one with the lense still on it.
After measuring, then an attemp can be made to carefully remove the lense and ring.
Then re-measure it.

My offer is still good.


----------



## jtr1962

3rd_shift said:


> That could be tried with the one with the lense still on it.
> After measuring, then an attemp can be made to carefully remove the lense and ring.
> Then re-measure it.
> 
> My offer is still good.


I sent my shipping address yesterday to the email in your signature. I look forward to doing the testing.


----------



## 3rd_shift

Got the email.
Weather permitting, I'll get them out tomorrow.
These are the ones I got from Nitroz a couple months back.
I forgot the binning already. 
But I think I can look it up.
PS;
Go ahead and keep the leds when and if you are done with them. :santa:

One more thing.
Be very careful with the domeless one.
It's kinda fragile.
I just killed another one trying to take it's dome off. 
I ended up successfully removing and testing a working one from a maglite mod I did last month.
Unpack it carefully in case the gel stuck to the plastic baggie it is in.


----------



## jtr1962

3rd_shift said:


> One more thing.
> Be very careful with the domeless one.
> It's kinda fragile.
> I just killed another one trying to take it's dome off.
> I ended up successfully removing and testing a working one from a maglite mod I did last month.
> Unpack it carefully in case the gel stuck to the plastic baggie it is in.


Thanks for the warning. I'll try not to kill it before I have a chance to test it. :huh:


----------



## jtr1962

Doug S said:


> If you are not making any special provision to heatsink the cathode lead, a very interesting comparision would be a comparison with and without the cathode lead heat sinked to a few square inches of copper.


I ran a few tests of both the old and new Jeleds with and without a heat sink. The heat sink consisted of a ~0.75" square of copper soldered on the cathode lead as close as possible to the epoxy body. Here is the relative output for the older Jeleds (red is without heat sink, blue is with heat sink):







Here is the same thing for the newer Jeleds (again red is without heat sink, blue is with heat sink):






Based on my tests of these a few days ago they already do substantially better at higher currents than the older Jeleds. There is some improvement with a heat sink but not as much as the older style.

Here is the percentage improvement versus current for both LEDs (older Jeled is in blue, newer one in red):






My tests are telling me that the way the LED is made is probably way more important than any external heatsinking. The newer Jeled probably uses a larger die with more contact area with the cathode "cup". It may even be attached with more thermally conductive material. The heat sink still helps, but only to the tune of about 10% at 80 mA.


----------



## Doug S

jtr1962 said:


> I ran a few tests of both the old and new Jeleds with and without a heat sink. The heat sink consisted of a ~0.75" square of copper soldered on the cathode lead as close as possible to the epoxy body.
> 
> My tests are telling me that the way the LED is made is probably way more important than any external heatsinking. The newer Jeled probably uses a larger die with more contact area with the cathode "cup". It may even be attached with more thermally conductive material. The heat sink still helps, but only to the tune of about 10% at 80 mA.



Thanks for doing this. The differences are in line with what I had expected. I agree with your general analysis. Heatsinking becomes a consideration for those who are inclined to drive the **** out of 5mm leds. While 10% may not be much, it is better than a poke in the eye. 10% is about the span of one cree flux bin and folks have been known to pay a premium for a single bin step. With the 5mm leds, sometimes it is possible to get that 10% for free with a little attention to the thermal paths. BTW, back in the dark ages before Nichia introduced white LEDs, it was not uncommon for LED datasheets to specify a thermal resistance from the junction to a point 3mm down the cathode lead. I remember that for some of the Hewlett Packard products this value was given as 220 C/W. The practice of providing this thermal resistance seems to be uncommon with the current 5mm white products.


----------



## Pinter

The older Jeled 50k leds were in drawer for a long time, got humidity from the air. Just wondering if their re-measured brightness were the same as in your original tests or were affected somehow?


----------



## jtr1962

Pinter said:


> The older Jeled 50k leds were in drawer for a long time, got humidity from the air. Just wondering if their re-measured brightness were the same as in your original tests or were affected somehow?


Actually they were still in the antistatic bag they came in which in turn was in the shipping envelope and then in a small box with my other white LEDs. It wouldn't matter if they had lost brightness anyway since my heat sink tests were solely to measure relative increases in brightness of the same LED by adding a heat sink.

I don't think humidity would affect the LED all that much anyhow since the epoxy case is designed to protect against that. I have a BestHongKong UWLC white LED sitting in my tester all the time it's not in use. It's therefore exposed to the ambient humidity all the time. It measured around 14 lux at one meter when new. It still does whenever I check it. It's over 18 months old.


----------



## 3rd_shift

My apologies for the delay, I finally mailed the leds to you today.
The icy weather here has been a nightmare all week long.
Enjoy.


----------



## NewBie

Doug S said:


> Thanks for doing this. The differences are in line with what I had expected. I agree with your general analysis. Heatsinking becomes a consideration for those who are inclined to drive the **** out of 5mm leds. While 10% may not be much, it is better than a poke in the eye. 10% is about the span of one cree flux bin and folks have been known to pay a premium for a single bin step. With the 5mm leds, sometimes it is possible to get that 10% for free with a little attention to the thermal paths. BTW, back in the dark ages before Nichia introduced white LEDs, it was not uncommon for LED datasheets to specify a thermal resistance from the junction to a point 3mm down the cathode lead. I remember that for some of the Hewlett Packard products this value was given as 220 C/W. The practice of providing this thermal resistance seems to be uncommon with the current 5mm white products.




I specifically asked Nichia this about a year ago, on their various leaded parts, and they replied with 200-300 C/W, depending on the part.

It would be interesting to remove the thermal resistance from the base of the package to the cup (grind away the clear epoxy). I know I see considerable differences between these two points when I heatsink the lead. About a month ago, I wound up on a website somewhere, where they had not necked down the lead to the normal size, but brought it out full width- can't recall who it was though. It was also a very high current part for a 5mm LED...


----------



## Doug S

NewBie said:


> I specifically asked Nichia this about a year ago, on their various leaded parts, and they replied with 200-300 C/W, depending on the part.
> 
> It would be interesting to remove the thermal resistance from the base of the package to the cup (grind away the clear epoxy). I know I see considerable differences between these two points when I heatsink the lead. About a month ago, I wound up on a website somewhere, where they had not necked down the lead to the normal size, but brought it out full width- can't recall who it was though. It was also a very high current part for a 5mm LED...



Since the geometry is simple, this is a straight forward calculation. I just grabbed a random 5MM white LED off of the litter on my workbench. Measuring from where the relatively massive die cup structure necks down to the square lead crossection I get 6mm to the point 3mm outside the package. The lead crossection is 0.55mmX0.55mm. Using the 3.8W/cm-K conductivity of high purity copper would give a thermal resistance of 52C/W for this 6mm distance. This shows that the bulk of the thermal resistance from the junction to 3mm outside the package lies in the die attachment. I feel pretty confident that we can generalize that conclusion to the larger power LEDs. The high die attachment thermal resistance of the 5mm products is a function of their small area. As a reality check, lets assume that all of the Cree XR-E 8C/W thermal resistance is at the die interface. Cree uses a 1mmX1mm die. IIRC, the typical 5mm LED uses a 0.2mmX0.2mm die so it has an area of 25th that of the Cree. At best, we would expect the die interface resistance to thus be 25 times higher or 25X8C/W=200 C/W. Add this to the 52C/W for the lead as I calculated above and you have 252 C/W which is pretty near the middle of the range that was given to you by your Nichia contact.


----------



## Pinter

Interestingly, at 5mm leds heat exits not only through the leads; if you hold the "dome" with your fingers, the Vf will start decreasing slowly. Within 10-20 seconds I saw -0,02 V change in Vf, while the current went up by 0,2mA (simple resistored setup from NiMH batteries).


----------



## 3rd_shift

I almost forgot to mention that these are P2 binned Cree XRE's that I sent over.


----------



## evan9162

Pinter said:


> Interestingly, at 5mm leds heat exits not only through the leads; if you hold the "dome" with your fingers, the Vf will start decreasing slowly. Within 10-20 seconds I saw -0,02 V change in Vf, while the current went up by 0,2mA (simple resistored setup from NiMH batteries).



With 250C/W through the leads, it's not surpising that a considerable percentage of the heat is being dissipated through the epoxy encapsulent. This will not hold true for power LEDs - heat dissipation through the dome/lens of a power LED will be negligable - the dome does not prodivide an appreciable thermal path.

FYI - when you held the dome, you were actually causing the LED to heat up, reducing the amount of heat dissipated by the epoxy. The Vf of LEDs drop when they heat up.


----------



## jtr1962

I finally got around to testing the two Cree XR-E emitters 3rd_shift sent me. The purpose of this test was to determine the difference between an emitter with and without the dome. The unmodified Cree XR-E bin P2 emitter tested as follows:







Output was 70.67 lumens at 350 mA. This is right in the middle of the P2 bin (67.2 to 73.9 lumens). The same bin emitter with the dome removed only had an output of 54.35 lumens at 350 mA. The beam angle was wider as well (122° versus 83.3° for the unmodified emitter). The relative intensity versus angle for the two emitters is shown below (domeless emitter in magenta):






Apparently the silicon encapsulant combined with the dome helps to extract a considerable amount of light from the die. The output of the domeless emitter is 24% less than the stock emitter.


----------



## jtr1962

Seoul Semiconductor W42180 bin U (tested February 2007)

I purchased a U bin Seoul Semiconductor emitter from milkyspit recently. The results of the test are shown below:






I believe the results speak for themselves. The efficiency at 350 mA is a very impressive 82.1 lm/W and the output is 96 lumens. This is a new record for power LEDs and also matches my best results for single die 5mm LEDs. Beam angle is close to 130° which means these have a light distribution similar to a Luxeon emitter. Since the emitter is rated for 1000 mA I felt comfortable going to 1500 mA, at which point output more or less leveled off. The output scales with current almost identically to the Cree XR-E bin P4 which I tested in December but this is no surprise since both emitters use the same die. Note that the U bin has a range of 91 to 118.5 lumens so these are at the low end (which I expected). I anticipate that the Cree XR-E Q3 bins will offer similar results. Shown below is a chart of Vf, power, and lumens at various currents.


----------



## Erasmus

Great job Jtr!!!!


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## milkyspit

Erasmus said:


> Great job Jtr!!!!



+1! :bow:

This is terrific data. Speaking very selfishly, this will help me a great deal in my builds to get good estimates of the outputs of various configurations... but beyond that, you've done and continue to do a great service to the entire community. Hat's off to you, JTR! (but there's no hat's off icon, well, here ya go...)

 :thumbsup: :naughty:


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## chimo

+2 Great data! Thanks for continuing to do these! :goodjob: 

Paul


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## ViReN

+3 :bow: very very valuable information


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## EngrPaul

:twothumbs :bow:


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## MattK

Awesome job!
:bow:


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## bombelman

Nice, very nice...


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## jtr1962

I added 2 samples (New LS Diodes THC3 4-die 5mm white, Quickar 5m100w 4-die 5mm white ) sent to me by CPF member milkyspit to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## jtr1962

I added 13 samples (SuperbrightLEDs 7,500 mcd superflux white, LVEHK 10,000 mcd 3mm white, SpectrumLEDs 2,000 to 4,000 mcd 4.8mm white , SuperbrightLEDs 18,000 mcd 15° 5mm white, SuperbrightLEDs 18,000 mcd 30° 5mm white, BestHongKong 35,000 mcd 5mm white, LVEHK 55,000 mcd 5mm white, LVEHK 65,000 mcd 8mm white, LVEHK 140,000 mcd 10mm white, BestHongKong 135,000 mcd 10mm white, Nichia NFSW036L, SuperbrightLEDs RL5-W45-360 5mm white, SuperbrightLEDs RL8-W110-3608mm white) sent to me by CPF member TMorita to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


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## jtr1962

I did a chart of efficiency versus time of manufacture for the LEDs I've tested:






While it's difficult to draw many conclusions, three things are apparent. One, the trend is towards increasing efficiencies. Two, the spread between best and worst LEDs is increasing. The worst are no better than similar ones of five years ago while the best are perhaps 4 times better. Three, the majority of the LEDs made today fall in the 60 to 70 lm/W area.


----------



## TMorita

Lots of good data!

By the way, I think the new THC3 LEDs might be single-die rather than 4-die.

If you look at the die, you'll probably only see two bond wires. I'm not sure if this means this is single-die, but I would expect four bond wires for a 4-die.

Toshi


----------



## milkyspit

TMorita said:


> Lots of good data!
> 
> By the way, I think the new THC3 LEDs might be single-die rather than 4-die.
> 
> If you look at the die, you'll probably only see two bond wires. I'm not sure if this means this is single-die, but I would expect four bond wires for a 4-die.
> 
> Toshi




+1... although the Quickar 5m100ma performance is virtually identical and that one DOES have four bond wires... go figure...
:thinking:


----------



## NewBie

jtr1962 said:


> Seoul Semiconductor W42180 bin U (tested February 2007)
> 
> I purchased a U bin Seoul Semiconductor emitter from milkyspit recently. The results of the test are shown below:



It is interesting comparing the differences between the three of them.

Do you happen to know the tint bins of each one?

How were these mounted in each case, and what were they heatsinked with for the testing?

Were these all bare LEDs mounted on the channel aluminum, or were any of them on MCPCB or other mounting methods?

Which meter model do you use for your testing?


Thank you *very* much for taking the time to do the testing and putting the results here on cpf for everyone!


.


----------



## jtr1962

NewBie said:


> It is interesting comparing the differences between the three of them.
> 
> Do you happen to know the tint bins of each one?


The P4 Cree is tint WH, the P2 is tint WC. I don't know about the SSC. It looks similar in tint to the Cree WC so maybe it's XO.


----------



## jtr1962

NewBie said:


> How were these mounted in each case, and what were they heatsinked with for the testing?
> 
> Were these all bare LEDs mounted on the channel aluminum, or were any of them on MCPCB or other mounting methods?
> 
> Which meter model do you use for your testing?
> 
> Thank you *very* much for taking the time to do the testing and putting the results here on cpf for everyone!


To answer your questions in order:

1) Here's my power LED testing apparatus:






I soldered the LED to be tested directed to the PCB, making sure it sat on the piece of copper bar shown covered in thermal grease. I didn't bother cooling the heatsink with a fan, although it did get a little warm when I cranked the current up to 1.5 amps.

When I test stars I can screw them directly to the aluminum channel.

2) My light meter is a CEM model DT-1300.

3) You're quite welcome-I'm glad the results are useful and the work is appreciated.


----------



## NewBie

I thought you might be interested in this, a spectral scan of a Seoul P4 USXOI bin and a CREE P3 WC bin. I originally did it for another thread, but thought you might find it useful:







There will be an un-marked up one which I'll put in my Seoul thread.

I noticed the Seoul has a slightly deeper blue, significantly less "cyan-green", and a bit less red. It does have more of a peak in yellow. The blue human eye has a hard time telling the differences at the 460-470nm wavelength range anyhow.

Both parts had 700mA passing thru them in this view here.


----------



## TMorita

I don't think the LVEHK 140ks were rated at 80ma.

Here's a link to the specs:

http://cgi.ebay.com/100p-10mm-SUPER...hZ002QQcategoryZ66952QQtcZphotoQQcmdZViewItem

The DC forward current is 20ma.

Toshi


----------



## jtr1962

I added 2 samples (ISP 2-die 22,000 mcd 25° 5mm white, LCK 55,000 mcd 15° 5mm white) sent to me by CPF member TMorita to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


----------



## jtr1962

I added the Jeled 55,000 mcd 15° 5mm whites sent to me by CPF member Minjin to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


----------



## jtr1962

TMorita said:


> I don't think the LVEHK 140ks were rated at 80ma.
> 
> Here's a link to the specs:
> 
> http://cgi.ebay.com/100p-10mm-SUPER-BRIGHT-WHITE-LED-LAMP-140Kmcd-Resistor_W0QQitemZ120065723300QQihZ002QQcategoryZ66952QQtcZphotoQQcmdZViewItem
> 
> The DC forward current is 20ma.
> 
> Toshi


Corrected-Thanks!


----------



## TMorita

One note:

The ISP 22ks are actually rated for 100ma AFAIK. They are not the 40ma ones on the website. I had to special order them.

The 40ma ones on the ISP website are dual-die:

http://www.powerleds.com/

However, if you look at the ISP 22K LEDs, you'll see there is only a two bond wires visible - one from the cathode, one from the anode. So it appears to be a single large die, and not two small dies.

Toshi


----------



## jtr1962

TMorita said:


> One note:
> 
> The ISP 22ks are actually rated for 100ma AFAIK. They are not the 40ma ones on the website. I had to special order them.
> 
> The 40ma ones on the ISP website are dual-die:
> 
> http://www.powerleds.com/
> 
> However, if you look at the ISP 22K LEDs, you'll see there is only a two bond wires visible - one from the cathode, one from the anode. So it appears to be a single large die, and not two small dies.
> 
> Toshi


Thanks again, I corrected the write-up to match the new info you gave me. :thumbsup:


----------



## jtr1962

I added 3 samples ( Hebei 520MW7C 20° 5mm white, Hebei 530MW7C 30° 5mm white, Hebei 550MW7C 50° 5mm white ) sent to me by CPF member LEDude to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs. The relevant spreadsheets were added to the .zip file linked to in the first post of this thread.


----------



## jtr1962

*Lumileds Rebel White LXML-PWC1-0100 (acquired July 2007)*

*Note: Earlier results multiplied by correction factor of 1.116 and post edited accordingly (See post #138 for explanation).*

I purchased a pair of these from Future Electronics for evaluation. I only tested one of the two samples. Color bin was not specified, but these are similar in color to the WH Crees, so I'd guess that they are V0s. I soldered the Rebel to a small length of brass bar with two holes drilled in the ends. I screwed the bar to my heat sinked power LED test jig with some thermal grease at the interface for better heat transfer. Beam angle measured 100.1°, a bit narrower than Luxeon IIIs, and the beam pattern is close to, but not exactly, lambertian. In the course of testing I learned how important it is to keep the lens of these LEDs clean. My initial test results gave roughly 91 lumens at 350 mA. I tried cleaning the lens with alcohol and then rerunning the tests. The final results were 96.7 lumens at 350 mA, but I later determined that I needed to apply the correction factor for my light meter. This revised the results to 107.9 lumens which is within spec. At 700 mA the Rebel put out 183.1 lumens, just about dead on the specified 180 lumens. Output continued to increase with current, reaching over 290 lumens at 1500 mA, which is as high as my current source goes. Moreover, the output curve wasn't entirely flattened out, even at 1500 mA. I would guess that output would continue to increase to 2 amps, albeit not very much over the output at 1.5 amps. Vf was extremely low and didn't rise very fast with current. It was 3.14V at 350 mA but only 3.43V at 1500 mA. Efficiency at 350 mA was 98.2 lm/W, a new record for power LEDs, and tantalizingly close to the magic 100 lm/W. Interestingly, with the apparent stagnation in small LED efficiency since early 2006, power LEDs are now actually more efficient than indicator-type LEDs. Moreover, efficiency at 1000 mA, the maximum specified operating current, was still a very decent 69.4 lm/W, about on par with CFLs, and stayed above 56 lm/W even at 1500 mA. Maximum efficiency was reached at 20 mA, and it was an incredible 150.7 lm/W. This translates into a conversion efficiency of over 45%. Efficiency remained above 100 lm/W until around 325 mA. Overall the Rebels have broken all previous records, but I suspect their time on top will be short-lived as I have yet to acquire the Cree XR-E Q5s for testing.


Original post:

_I purchased a pair of these from Future Electronics for evaluation. I only tested one of the two samples. Color bin was not specified, but these are similar in color to the WH Crees, so I'd guess that they are V0s. I soldered the Rebel to a small length of brass bar with two holes drilled in the ends. I screwed the bar to my heat sinked power LED test jig with some thermal grease at the interface for better heat transfer. Beam angle measured 100.1°, a bit narrower than Luxeon IIIs, and the beam pattern is close to, but not exactly, lambertian. In the course of testing I learned how important it is to keep the lens of these LEDs clean. My initial test results gave roughly 91 lumens at 350 mA. I tried cleaning the lens with alcohol and then rerunning the tests. The final results were 96.7 lumens at 350 mA. Since this is less than Lumiled's tolerance for lumen measurement this is still within spec. More importantly, at 700 mA the Rebel put out 179.63 lumens, just about dead on the specified 180 lumens. Output continued to increase with current, reaching over 260 lumens at 1500 mA, which is as high as my current source goes. Moreover, the output curve wasn't entirely flattened out, even at 1500 mA. I would guess that output would continue to increase to 2 amps, albeit not very much over the output at 1.5 amps. Vf was extremely low and didn't rise very fast with current. It was 3.14V at 350 mA but only 3.43V at 1500 mA. Efficiency at 350 mA was 88.0 lm/W, a new record for power LEDs. Interestingly, with the apparent stagnation in small LED efficiency since early 2006, power LEDs are now actually more efficient than indicator-type LEDs. Moreover, efficiency at 1000 mA, the maximum specified operating current, was still a very decent 62.2 lm/W, about on par with CFLs, and stayed above 50 lm/W even at 1500 mA. Maximum efficiency was reached at 20 mA, and it was an incredible 135 lm/W. This translates into a conversion efficiency of over 40%. Efficiency remained above 100 lm/W until 200 mA. Overall the Rebels have broken all previous records, but I suspect their time on top will be short-lived as I have yet to acquire the Cree XR-E Q5s for testing.
_


----------



## RonM

Wow! This is awesome work you are doing jtr1962!

Can you recommend a 5mm LED to upgrade my eternaLights with? My last mod replaced the originals with the 25kmcd's.


----------



## Codeman

RonM said:


> Wow! This is awesome work you are doing jtr1962!
> 
> Can you recommend a 5mm LED to upgrade my eternaLights with? My last mod replaced the originals with the 25kmcd's.



I put the 20x40k's in mine when I order the blaster kit from EternaLight.


----------



## jtr1962

RonM said:


> Wow! This is awesome work you are doing jtr1962!


Thanks! :thumbsup:



> Can you recommend a 5mm LED to upgrade my eternaLights with? My last mod replaced the originals with the 25kmcd's.


Based on what I've tested, the Jeled 55Ks are about the best available 5mm LED right now.


----------



## Codeman

jtr1962 said:


> ...Based on what I've tested, the Jeled 55Ks are about the best available 5mm LED right now.



Yikes at those shipping costs, though!


----------



## LED_Thrift

Thanks for all this good work JTR.
That Rebel looks like a great LED for a well designed light.


----------



## ViReN

jtr1962 ... it clears up a lot of miss-information that i was having.....

great work.


----------



## Erasmus

Good results on the Rebel! However I think the Q5 will beat it. Waiting for that test...


----------



## lctorana

Hi jtr1962,

It seems that every 5mm LED has a peak lm/W at a round 4-5 mA-ish.

Is this peak the optimum current to run 5mm LEDs at?

For example, I have a 128-LED shower head torch that drives each LED at 4mA. It works very, very well.

But although this seems to be the optimum for power consumption, will it also maximise LED life?

Any thoughts?

(I am thinking of low-power solar lighting, etc.)


----------



## ViReN

Erasmus said:


> Good results on the Rebel! However I think the Q5 will beat it. Waiting for that test...



:twothumbs


----------



## jtr1962

lctorana said:


> Hi jtr1962,
> 
> It seems that every 5mm LED has a peak lm/W at a round 4-5 mA-ish.
> 
> Is this peak the optimum current to run 5mm LEDs at?


For any LED the lower the current the longer the lifetime. Lifetime is probably maximized by running at 1 mA but of course you end up needing a lot more LEDs. 5 to 10 mA seems to be a good balance between lifetime, efficiency, and cost. Also, the majority of 5mm LEDs seem to have their best efficiency around 4 or 5 mA, but there are a few which do a little better as low as 1 mA.

I made some LED train lights recently which run the LEDs at 10 mA. This combined with wide PC board traces to dissipate the heat should result in reasonable lifetime (hopefully 10,000 to 20,000 hours) before noticeable dimming occurs. This is more than sufficient in this application. You may be able to get a few hundred thousand hours by dropping down to 1 mA. However, for most applications this is overkill. Remember that at 6 hours a night a 100,000 hour lifetime equates to nearly 46 years. The item being lit will most likely either be obsolete or lost or broken long before then.


----------



## jtr1962

I changed my setup somewhat immediately before the tests of the Rebel 100 and the Hebei LEDs. I set up a series of baffles and totally enclosed them to block out any ambient light:






I even put a removeable cover to block ambient light near the light meter:











The purpose of these modifications was to eliminate guestimating the background light which needed to be subtracted from the light meter reading. For 5mm LEDs this was at most about 0.5 lux, but for power LEDs it was considerably more. Prior to this, I would block out the direct portion of the beam with a piece of cardboard, note the reading, then subtract it from the unblocked reading. This method always bothered me because it introduced another variable. While the background reading was fairly steady, it did vary enough depending upon the placement of the cardboard to cause concern. Hence my use of the term guestimating at the start of this paragraph. The modified setup introduces consistency. When I block off the small hole where light enters from the LED, the reading is at most 0.1 lux, even in a undarkened room. I still do my testing in a darkened room, but with the new setup I don't have to!

Now this is all good and well except that when I tested the Rebel 100 I was getting somewhat less than the minimum of 100 lumens (96.7 lumens @ 350 mA to be exact). However, according to the results of the CPF light meter testing which I had participated in my light meter was reading low for white LED light. The correction factor was 1.116. I applied the correction factor to my Rebel 100 results in post #127 and the numbers are more in line with what I should have gotten.

The only question remaining was whether or not I could reliably compare my earlier results with my new ones. To answer this question I decided to retest the P4 bin Cree XR-E which I had tested last November. The original results were 85.67 lumens at 350 mA. The _uncorrected_ results using the modified tester were 80.24 lumens at the same 350 mA. This was about 6.4% low. The corrected result was 89.55 lumens, within 4.5% of my original results. I also ended up with a somewhat narrower beam angle (new results in red, old in blue):






It seems then that although I did not apply any correction factors to my earlier results the inherent methodology resulted in slightly wider beam angles which more or less compensated for the lower absolute lux readings. Remember that all of my earlier power LED test results pretty much fell within the ballpark of where they were supposed to for a given bin. The only problem is that LEDs obviously come in different tints, and I suspect I would need different correction factors depending upon the tint. Based on the fact that my light meter was nearly dead-on with incandescent light, the correction factor would increase with increasing color temperature. However, since guestimating correction factors would make this testing more art than science, I'll stick to using the official correction factor of 1.116. The fact that my corrected result for the P4 Cree is a little high probably has to do with that LED being a warmer (WH) tint bin.


----------



## jtr1962

*Cree 7090 XR-E Warm White bin P4 (acquired September 2007)*

I ordered some Q5 Cree XR-Es from CPF member *Erasmus*. Along with the Q5s Erasmus sent me a Cree XR-E warm white bin P4 for testing. The P4 bin is specified at 80.6 to 87.4 lumens at 350 mA. The color temperature looked like roughly 3300K, so I would say the tint bin was 7A. Since the color temperature was in the incandescent range, I didn't need to apply a correction factor. The output of 83.0 lumens at 350 mA is solidly within the P4 flux bin.

Results are shown below:


----------



## ViReN

jtr1962, great work. many thanks.

just wondering why the Vf is on higher side in warm Cree XR-E P4's...


----------



## jtr1962

*Cree 7090 XR-E bin Q5 (acquired September 2007)*

I ordered 10 Q5 Cree XR-Es, bin WG, from CPF member *Erasmus*. The Q5 bin is specified at 107 to 114 lumens at 350 mA. The color temperature of the WG bin is roughly 6000K. The results are a little low (105 lumens at 350 mA), but remember that this is a cooler bin. My correction factor is probably a little too low for such a cool tint, and this is what accounts for the discrepancy. In any case, the difference between the actual measurement and the manufacturer's specification is less than 2%, and my setup is far from 100% accurate anyway. Even if this difference is real, it is well outside what would be noticeable with the eye.

Vf is 3.20V @ 350 mA, efficiency is a very impressive 93.7 lm/W. Note that this is a little less than the corrected results for the Rebel 100 (98.2 lm/W @ 350 mA). However, the Rebel's higher efficiency is nearly all due to its lower Vf (3.14V @ 350 mA), and the fact that it is a warmer tint (and hence reads a little higher on my light meter). Also note that despite the slightly lower output at 350 mA the Cree bests the Rebel in terms of raw output at higher currents (298.5 versus 290.5 lumens at 1500 mA). The Rebel 100 still has a slight edge in efficiency at 1500 mA (56.5 versus 54.7 lm/W) due to its Vf increasing less with current than the Cree Q5. I took the Cree all the way to 2000 mA and it managed 334 lumens.

Results below:


----------



## jtr1962

ViReN said:


> jtr1962, great work. many thanks.
> 
> just wondering why the Vf is on higher side in warm Cree XR-E P4's...


The P4s have 3 bond wires instead of 4. This and variation among chips probably account for it. I also noticed that the Cree warm white has a different colored phosphor (slightly more orange in color), although this has nothing to do with Vf.


----------



## jtr1962

Erasmus said:


> Good results on the Rebel! However I think the Q5 will beat it. Waiting for that test...


The Q5 actually does beat the Rebel at higher currents in raw output, and comes very close in terms of efficiency. Also, due to the way my light meter responds I think my results would have been a little higher if it had been a WH tint instead of WG. I think a WH tint Q5 hand selected for low Vf could easily crack 100 lm/W at 350 mA.


----------



## evan9162

The warm white XR-E has an interesting beam profile. Is the "step" visibly noticable? Is the warm white using the conformal phosphor coating like the cool whites?

My Q4 XR-E has a higher Vf than my P4 did, even though it had 4 bond wires vs. 3 - Vf is influenced more by the individual die than by the number of bond wires. Some have noticed a trend that the Q4s and Q5s tend to have a higher Vf than lower binned XR-Es.


----------



## Erasmus

jtr1962 said:


> The Q5 actually does beat the Rebel at higher currents in raw output, and comes very close in terms of efficiency. Also, due to the way my light meter responds I think my results would have been a little higher if it had been a WH tint instead of WG. I think a WH tint Q5 hand selected for low Vf could easily crack 100 lm/W at 350 mA.


Does the lightmeter respond better to lower color temperatures? There should be a correction factor for the high color temperatures, because these Q5's put out at least 107 lumen at 350 mA. From the LEDs from my group buy I tested 5 of my own LEDs and none of them comes above 3.26V @ 350 mA, while most people say their Vf is higher than lower binned XR-E's. Maybe these are from a different production with a lower Vf? Anyway I also have tested 2 with around 3V @ 350 mA, one only 2.98V! They put out at least 107 lumen and the power consumption for this particular one is 1.043W which results in an efficacy of *103.48lm/W @ 350 mA*! Woohoo!

Jtr1962, thanks for these great tests!


----------



## evan9162

Remember:

http://www.cree.com/products/pdf/XLamp7090XR-E.pdf

Page 2:

"Cree maintains a tolerance of +/- 7% on flux and power measurements"

Thus, that 107-114 lumens bin could still contain samples in the range of 100-120 lumens.


----------



## Ron Schroeder

Is the blue only (no phospher) LED version of any of the better 5mm white LEDs available.


----------



## jtr1962

evan9162 said:


> The warm white XR-E has an interesting beam profile. Is the "step" visibly noticable? Is the warm white using the conformal phosphor coating like the cool whites?


The step is slightly noticeable (it looks like a faint ring). The phosphor coating method looks very similar to the cool-whites, so yes, I would say it's conformally coated. I also noticed that my P4 warm white does have four bond wires, same as the Q5s.



> My Q4 XR-E has a higher Vf than my P4 did, even though it had 4 bond wires vs. 3 - Vf is influenced more by the individual die than by the number of bond wires. Some have noticed a trend that the Q4s and Q5s tend to have a higher Vf than lower binned XR-Es.


Possibly true. Another one of my Q5s tested slightly lower than the first one (103.77 lumens) but Vf was also lower (3.16V versus 3.20V), making efficiency nearly the same.


----------



## Gryloc

jtr1962,

I had a chance to test the WG Q5's ordered from Erasmus by a friend that I was doing a mod for, and I was rather bothered by a few things. I also noticed that the Vfs were unusually higher than older XR-Es. Out of two Q5s that were next to each other on the cut section of reel, I measured 3.48V for LED A and 3.38V for LED B. LED A had an annoying overly blue-purple tint, while LED B had an annoyingly overly green-ish tint. LED B was actually noticeably brighter than LED A when able to compare them side by side using a special paper shade that blocked the light (casted a shadow) that allowed me to directly compare the two on my ceiling or wall. Finally, the beam from both (with or without an optic) shows a distinctive checker pattern on the wall. Have you noticed such oddities as this?

All things were not negative. Both oddly colored LED A and B (Q5s) were easily noticeably brighter than a perfectly white Q2 LED that had a lower Vf. So my friend got what he paid for: a brighter LED. It is too bad you have to sacrifice color an efficiency for brightness nowadays.

Well, thanks for presenting this updated test rig to us. It is great to see that you are willing to improve the quality of our tests. How does these new numbers (from the fully enclosed box) compare to the results from evan9162 or Newbie? Are you willing to pass around a few LEDs, such as the XR-E P4, the XR-E Q5, and the new Rebel 0100, to evan9162 and Newbie? This is not to dis-prove your own results, but instead to allow us other hobbyists to get the most accurate information from the only three persons that are willing to measure the Lumens of the high power LEDs that we use often. This is for more consistent numbers between testers (which inconsistency seems to come from the two variables: color and Vf). Thanks again!

-Tony


----------



## jtr1962

Gryloc said:


> jtr1962,
> 
> I had a chance to test the WG Q5's ordered from Erasmus by a friend that I was doing a mod for, and I was rather bothered by a few things. I also noticed that the Vfs were unusually higher than older XR-Es. Out of two Q5s that were next to each other on the cut section of reel, I measured 3.48V for LED A and 3.38V for LED B. LED A had an annoying overly blue-purple tint, while LED B had an annoyingly overly green-ish tint. LED B was actually noticeably brighter than LED A when able to compare them side by side using a special paper shade that blocked the light (casted a shadow) that allowed me to directly compare the two on my ceiling or wall. Finally, the beam from both (with or without an optic) shows a distinctive checker pattern on the wall. Have you noticed such oddities as this?


So far I haven't noticed such radical tint variations or poor beam patterns, but given that the Q5 bin is cutting edge this wouldn't surprise me. All my Q5s so far seem to be similar in tint. The only beam irregularities are the usual rings which the Crees have. As for Vf, one of my Q5s tested at 3.20V at 350 mA, two others at 3.16V. I haven't tested the others yet.



> Well, thanks for presenting this updated test rig to us. It is great to see that you are willing to improve the quality of our tests. How does these new numbers (from the fully enclosed box) compare to the results from evan9162 or Newbie? Are you willing to pass around a few LEDs, such as the XR-E P4, the XR-E Q5, and the new Rebel 0100, to evan9162 and Newbie? This is not to dis-prove your own results, but instead to allow us other hobbyists to get the most accurate information from the only three persons that are willing to measure the Lumens of the high power LEDs that we use often. This is for more consistent numbers between testers (which inconsistency seems to come from the two variables: color and Vf). Thanks again!


My numbers compare fairly well to evan9162 and Newbie's numbers. I think my corrected Rebel 100 results were within 2% of evan9162s. Newbie's were somewhat lower, but not horribly so.

Yes, I would be willing to make some sort of test rig with a few sample LEDs to pass around. This is actually something I've been thinking about doing for a long time. I would include a power supply set to 350 mA (perhaps also with several other current settings) in order to eliminate that variable. The rig would allow a direct comparison of our results. All things considered, I'd say we're all within 10% of each other. However, it would be nice to determine empirically exactly how close our results are.


----------



## Pinter

jtr1962 said:


> It seems then that although I did not apply any correction factors to my earlier results the inherent methodology resulted in slightly wider beam angles which more or less compensated for the lower absolute lux readings.


jtr1962, great work as always.
Regarding the beam angles and profiles.
Finding out the center of a bare XR-E (or other) emitter is not an easy job as the beam center is not always in the real center. The beam profile gets somewhat inconsistent in the central regions, you can get different intensity curves from the estimated "0" angle, depending on the rotating direction or the orientation you attached the led to the heatsink.
I mean something like this (two thin lines are painting errors on my wall)



This can be a reason of the different beam profiles of the old and new XR-E P4 tests. 
The real zero angle position can easily be missed with 1-2 degrees. This can affect lumen calculation also. If the same intensity values are belonging to greater angles, this results in more cumulative lumens. 

For a quick test, you can try getting the profile towards the other rotating direction and average them.


----------



## lctorana

Pardon my ignorance, but WTF is that?


----------



## MattK

YES I CAN SEE THE DOLPHIN!!!



:nana:


----------



## Pinter

Dolphin? Not really.  Sorry for not explaining it.

This is a "beamshot" of a bare XR-E emitter on the wall that was taken with a Pana FZ50 digital camera in RAW format. Horizontal field of view is about 53 degrees so it shows the central 25-40 degrees of the beam.

Raw data from CCD (linear intensity values) went under image processing and the intensity falloff was false-colored with ten colors that are repeated.
The min and max intensity range found on the pic was divided into 100 units. 0-9%, 10-19%, ... 90-100% share the same set of ten color, thus showing the intensity change of the beam.

The central section does not consist of the ideal circles, still shows something from the shape of the chip.


----------



## lctorana

So...

...what is the age of the tree?


----------



## lctorana

Hi jtr1962,

I've just found something exciting:

http://secure.oatleyelectronics.com...d=696&osCsid=533886c830ad6644d0c0a203da904333

The thought of 25 lumens without a heatsink is very exciting.

Have you seen these? If so, are they any good?

If not, would you like me to send you some for testing? If so, how many?

Cheers,

Bruce.


----------



## jtr1962

I added 2 samples ( Jeled 210000 mcd 10mm warm white, Jeled 255000 mcd 10mm white) sent to me by CPF member *knabsol*, 1 sample ( Oatley Electronics 80000 mcd 10mm white ) sent to me by CPF member *lctorana*, and 1 sample ( Deal Extreme 20mm white ) sent to me by CPF member *nein166* to the list in the first post and updated the graphs accordingly. You might need to refresh your browser to see the updated graphs.


----------



## jtr1962

*Cree 7090 XR-E bin R2 (acquired March 2008)*

I borrowed an R2 Cree XR-E, bin WG, from CPF member *nein166* for testing. The R2 bin is specified at 114 to 122 lumens at 350 mA. The color temperature of the WG bin is roughly 6000K. The results are as show below:



















These results are nothing short of amazing! The output at 350 mA is nearly 122 lumens, well above any previous results for power LEDs at that current. Despite the middle of the road Vf of 3.31V, efficiency at 350 mA is still 105.3 lm/W. It remains above 100 lm/W past 400 mA. Even at 1000 mA, efficiency is nearly 75 lm/W. Things get even more interesting at low currents. Under 50 mA, efficiency hovers around 145 lm/W. This represents a wall-plug, or power-to-light conversion efficiency, of around 45%.

Output scales with current in pretty much the same manner as other XR-Es I've tested. At 1000 mA output is over 270 lumens. It approaches 400 lumens at 2000 mA. Cree has continued to raise the bar for LED performance. While we won't see as dramatic improvements as in the past, Cree has continued to squeeze every last ounce of perfomance from its XR-E line of LEDs. I expect we'll have R4 bins and beyond by this time next year.


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## MattK

Awesome work as always!


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## IsaacHayes

Granted 2amp is 2x max current, but 390lm from a single normal sized die is awesome!


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## Photon_Whisperer

jtr1962 said:


> Yes evan9162, that's exactly how I'm doing it. For example, I take the relative lux readings for 0° and 5°, average them, multiply by the area in steradians, and then multiply by the intensity in candelas. After that, I'll do the same with the 5° and 10° values, etc, and add this to my running total. It's interesting that for narrow viewing angle (i.e. 15° or 20°) LEDs the traditional methods of calculating lumens in the main beam grossly underestimates the output. One can see why by examining the radiation pattern of one of these LEDs. Some light falls outside the main beam but this decreases in intensity rather quickly. Still, since the spherical area is larger as the angle increases, this spill still makes significant contributions to the output. After that you usually have a bright ring about 60° off axis. This shows up clearly in the graphs in my spreadsheets. While the intensity might only be 2% or 3% of the maximum intensity, it is spread over a large area and contributes a good 15% to 20% of the total output. Finally, a great deal of light actually makes it out the back because of reflection off the front lens. This could easily add another 10% to 15% to total output. I was honestly amazed by this myself although it makes sense. For example, using the usual way of figuring lumens, and assuming a 20° beam angle, I might have guestimated about 2.3 lumens for the Light of Victory 35,000 mcd LED based on it's peak intensity reading of ~24,000 mcd at 20 mA (the 35,000 mcd spec is at 30 mA according to the manufacturer). I usually multiplied this by 1.25 to account for spill outside the main beam, giving me a final estimate of 2.9 lumens. The actual measurements come out to 3.75 to 3.9 based on a few samples, or over 30% more. I guess I'll revise my adhoc mutliplier to about 1.65 to give a more realistic estimate.
> 
> I'll also add that since the dial is just screwed to the tester and easily removeable, I might make another one up complete with a heat sink and mounting area to test Luxeons, Lamina BL-2000s, and other power LEDs. My constant current source can supply up to 2 amps if need be. I can verify my methodology if I get lumen measurements in the mid 30s with my Q-bin Luxeons.



Nice work but may I ask why not just build an integrating sphere? You'll get much better precision & accuracy (especially with focused emitters), and it's much faster.


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## jtr1962

Photon_Whisperer said:


> Nice work but may I ask why not just build an integrating sphere? You'll get much better precision & accuracy (especially with focused emitters), and it's much faster.


The method I'm using takes under 30 minutes and is very repeatable. For the very low volume of testing I do it suits me fine. And as a bonus I get beam profile information.

Calibrating an integrating sphere is the real problem. Besides that, all my attempts to build a practical device have been very sensitive to emitter placement. Move the emitter a few degrees, or a fraction of a inch in or out, and the reading changes by over 10%. Even worse, results aren't consistent between different types of emitters. A narrow angle emitter of x lumens will give a wildly different reading than a wide angle emitter of the same lumens. I'll agree if I'm interested in sorting a batch of the same type of LEDs for relative (not absolute) lumens then a simple milk-container type integrating sphere is the only practical way to do it. But building a home-made integrating sphere of reasonable (say 5%) accuracy which works for many different types of emitters is well beyond my capabilities.

If anyone has any ideas on how to make a decent integrating sphere to supplement my usual method I'm all ears. It needs to be accurate, repeatable, and more importantly able to deal with both narrow beam sources and those which emit over an entire sphere (i.e. many indicator LEDs have a significant amount of back scatter).


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## jtr1962

I added 3 samples ( BestHongKong 25000 mcd 5-die white, LED Tech 14000 mcd 100 mA white, and Nichia NSPS500GS-K1 white) sent to me by CPF member *TMorita*. You might need to refresh your browser to see the updated graphs. I'm also posting the results here:

*BestHongKong 25000 mcd 5mm 5-die white (acquired March 2008)*
These are BestHongKong's 5-die whites which have 5 dies and a larger lead frame to allow operation at 100 mA. The results were 6.0, 6.5, and 6.9 cd at 20 mA. I assume the 25,000 mcd rating is at 100 mA, so the corresponding results at 100 mA are 24.3, 25.8, and 28.1. The average is 26.1 cd, slightly above spec. Average beam angle was 34.7°, less than the specified 50°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a decent 72.8 lm/W at 20 mA and 52.9 lm/W at 100 mA. I was expecting somewhat better than that due to the 5-die construction. Apparently they're not using the most efficient dies for these. Average output was 4.07 lumens at 20 mA, and average Vf was a low 2.87V (expected due to the 5-die construction). Corresponding figures at 100 mA were 16.41 lumens and 3.10V. The 16.41 lumens comes reasonably close to the specified 20 lumens at 100 mA. Consistency between samples was excellent-outputs were 3.91, 4.14, and 4.16 lumens at 20 mA. Output scales very well with current as expected (output at 100 mA is 4.03 times the output at 20 mA). Overall these appear to be a decent, well-constructed LED capable of sustained operation at higher currents.








*LED Tech 14000 mcd 5mm 100 mA white (acquired March 2008)*
These are LED Tech's 100 mA whites which have a larger lead frame to allow operation at 100 mA, and probably also multiple dies. The results were 2.8, 2.8, and 3.2 cd at 20 mA. I assume the 14,000 mcd rating is at 100 mA, so the corresponding results at 100 mA are 11.0, 11.2, and 12.3. The average is 11.5 cd, somewhat below spec. Average beam angle was 77.1°, nearly equal to the specified 80°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a very decent 86.8 lm/W at 20 mA and an excellent 63.8 lm/W at 100 mA. These are better numbers than the very similar BestHongKong LEDs because they're apparently using better dies. Average output was 5.12 lumens at 20 mA, and average Vf was a low 2.95V (expected due to the multi-die construction). Corresponding figures at 100 mA were 20.06 lumens and 3.15V. Consistency between samples was OK-outputs were 4.71, 5.05, and 5.60 lumens at 20 mA. Output scales very well with current as expected (output at 100 mA is 3.92 times the output at 20 mA). Overall these appear to be a decent, well-constructed LED capable of sustained operation at higher currents.







*Nichia NSPS500GS-K1 5mm white (acquired March 2008)*
These are Nichia's latest and greatest 5mm whites. The results were 36.0, 39.2, and 39.8 cd at 20 mA. I think these are speced for 44,000 mcd, so the average of 38.3 cd is only slightly out of spec. Average beam angle was 13.4°, a little less than the specified 15°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a excellent 96.7 lm/W at 20 mA, so these take the new efficiency crown. Even at 100 mA efficiency manages to remain at nearly 50 lm/W. Average output was 6.15 lumens at 20 mA, and average Vf was 3.18V. Corresponding figures at 100 mA were 21.43 lumens and 4.34V. Given the rather steep increase in Vf with current, these don't appear to be multi-die as some here have speculated. Consistency between samples was OK-outputs were 5.75, 6.19, and 6.52 lumens at 20 mA. Output scales very well with current despite the apparent single-die construction (output at 100 mA is 3.48 times the output at 20 mA). This isn't much worse than the two types of multidie LEDs just tested. It looks like Nichia has another winner here, and we have a new efficiency champ.


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## saabluster

jtr1962 said:


>



Awesome job as usual! I'm really glad you test these all the way up to 2A instead of stopping at manufacturers specs. I would be willing to donate an R2 to test as well if you can push the test even further. I want to see just what these things can handle. PM me if you are interested.


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## jtr1962

saabluster said:


> Awesome job as usual! I'm really glad you test these all the way up to 2A instead of stopping at manufacturers specs. I would be willing to donate an R2 to test as well if you can push the test even further. I want to see just what these things can handle. PM me if you are interested.


The new current sources I made actually go all the way up to 10 amps. When I build a pair of them a few months ago I was thinking of the future, figuring that the 2 amp limit of my old tester eventually wouldn't be enough. Turns out with the release of the P7 I was right.

Anyway, I'll be happy to test your R2 if you want. I'll basically push until either the output stops increasing or the thing blows, whichever comes first. 

PM sent with my shipping address.


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## saabluster

jtr1962 said:


> The new current sources I made actually go all the way up to 10 amps. When I build a pair of them a few months ago I was thinking of the future, figuring that the 2 amp limit of my old tester eventually wouldn't be enough. Turns out with the release of the P7 I was right.
> 
> Anyway, I'll be happy to test your R2 if you want. I'll basically push until either the output stops increasing or the thing blows, whichever comes first.
> 
> PM sent with my shipping address.



I sent you a PM then realized others might like to know what is transpiring. So here is a copy of what I sent.

"Thanks for the quick response. My intent is to know the absolute limit of these things. This way there will be no guessing or wondering how much they can handle. Of course I understand this means I will not be getting the R2 back. I'm doing this in the interest of science. :naughty:
As part of this "pushing the limit" I would like to see how it does with the best heat-sink we can provide it, be that solid copper or a heat-pipe, and solder it down directly. I can't remember what you're protocol is exactly when it comes to heat-sinking endeavors so if this is above and beyond what you normally do I can mount it for you and send it that way. Let me know."


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## jtr1962

saabluster said:


> I sent you a PM then realized others might like to know what is transpiring. So here is a copy of what I sent.
> 
> "Thanks for the quick response. My intent is to know the absolute limit of these things. This way there will be no guessing or wondering how much they can handle. Of course I understand this means I will not be getting the R2 back. I'm doing this in the interest of science. :naughty:
> As part of this "pushing the limit" I would like to see how it does with the best heat-sink we can provide it, be that solid copper or a heat-pipe, and solder it down directly. I can't remember what you're protocol is exactly when it comes to heat-sinking endeavors so if this is above and beyond what you normally do I can mount it for you and send it that way. Let me know."


Rather than respond via PM since my inbox is almost full I'll answer here. I'm using a pretty large microprocessor heatsink for my testing. It should do fine here. Normally I use passive cooling (heat sink gets warm but not hot at 2 amps), but for this test I was planning to use forced air cooling just to see what the R2 is capable of under optimum conditions. We should break 400 lumens before 2 amps, and possible 500 or more lumens past that. Maybe I could go even crazier with this and try thermoelectrics if the R2 survives the initial round of forced air cooling. The real limits here will probably be how much current the bond wires can take. Decent cooling should make junction temperatures a non-issue, even at well over 2 amps.


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## saabluster

jtr1962 said:


> Rather than respond via PM since my inbox is almost full I'll answer here. I'm using a pretty large microprocessor heatsink for my testing. It should do fine here. Normally I use passive cooling (heat sink gets warm but not hot at 2 amps), but for this test I was planning to use forced air cooling just to see what the R2 is capable of under optimum conditions. We should break 400 lumens before 2 amps, and possible 500 or more lumens past that. Maybe I could go even crazier with this and try thermoelectrics if the R2 survives the initial round of forced air cooling. The real limits here will probably be how much current the bond wires can take. Decent cooling should make junction temperatures a non-issue, even at well over 2 amps.


I've got to get some work done so I will talk to you again Sunday or Monday about this in more detail. 
Anyone want to guess the amperage it blows at and the peak lumens? This is going to be real interesting.


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## jirik_cz




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## ViReN

Awesome work jtr1962


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## chimo

jtr1962 said:


> These are Nichia's latest and greatest 5mm whites. The results were 36.0, 39.2, and 39.8 cd at 20 mA. I think these are speced for 44,000 mcd, so the average of 38.3 cd is only slightly out of spec. Average beam angle was 13.4°, a little less than the specified 15°. Color temperature was around 7000K, and the beam was very smooth. Average efficiency of the three samples was a excellent 96.7 lm/W at 20 mA, so these take the new efficiency crown. Even at 100 mA efficiency manages to remain at nearly 50 lm/W. Average output was 6.15 lumens at 20 mA, and average Vf was 3.18V. Corresponding figures at 100 mA were 21.43 lumens and 4.34V. *Given the rather steep increase in Vf with current, these don't appear to be multi-die as some here have speculated*. Consistency between samples was OK-outputs were 5.75, 6.19, and 6.52 lumens at 20 mA. Output scales very well with current despite the apparent single-die construction (output at 100 mA is 3.48 times the output at 20 mA). This isn't much worse than the two types of multidie LEDs just tested. It looks like Nichia has another winner here, and we have a new efficiency champ.[/FONT]
> 
> 
> 
> [/FONT]



Nice work, as always. I have a question on the GS. The beam profile on this LED is asymmetric due to the rectangular die. Did you modify your testing to account for the different beam profile?

I think I put the two die question to bed here. Cheers,

Paul


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## jtr1962

chimo said:


> Nice work, as always. I have a question on the GS. The beam profile on this LED is asymmetric due to the rectangular die. Did you modify your testing to account for the different beam profile?


I just checked the beam profile. The asymmetry is barely noticeable to my eyes. As it turns out, I took beam profile readings on the short side of the rectangle. If anything this reduces the efficiency numbers. Also note that most of asymmetry is in the initial ±20° but this portion of the beam only accounts for a little more than half the lumens. In other words, my failure to account for the asymmetry probably affected the overall results by less than 10%. It's likely then that the lumens per watt of these are in the low 100s at 20 mA instead of around 97.



> I think I put the two die question to bed here. Cheers,


Yes, and increasing die size looks to be a good way to bump efficiency. Looking at the efficiency versus current chart, if Nichia used a normal size die then current density would be doubled, and efficiency at 20 mA would only be in the high 70s to low 80s. Conversely, as can be seen by the leveling off of efficiency under 10 mA, doubling the size of the present die would only result in an efficiency gain of around 10%.

Overall I'm just glad to finally see a jump in 5mm LED efficiency. The best ones were stagnating in the low 80s for the last two years. Now if all the lab improvements make it into production, we should see LEDs about 50% better than the Nichia GS fairly soon.


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## chimo

jtr1962 said:


> I just checked the beam profile. The asymmetry is barely noticeable to my eyes. As it turns out, I took beam profile readings on the short side of the rectangle. If anything this reduces the efficiency numbers. Also note that most of asymmetry is in the initial ±20° but this portion of the beam only accounts for a little more than half the lumens. In other words, my failure to account for the asymmetry probably affected the overall results by less than 10%. It's likely then that the lumens per watt of these are in the low 100s at 20 mA instead of around 97.
> 
> 
> Yes, and increasing die size looks to be a good way to bump efficiency. Looking at the efficiency versus current chart, if Nichia used a normal size die then current density would be doubled, and efficiency at 20 mA would only be in the high 70s to low 80s. Conversely, as can be seen by the leveling off of efficiency under 10 mA, doubling the size of the present die would only result in an efficiency gain of around 10%.
> 
> Overall I'm just glad to finally see a jump in 5mm LED efficiency. The best ones were stagnating in the low 80s for the last two years. Now if all the lab improvements make it into production, we should see LEDs about 50% better than the Nichia GS fairly soon.



Well that's good news (higher efficiency). I just checked an ArcAAA that I modded last night with a GS and an ArcMania 40mA converter. The hotspot rectangle was about a 2:3 ratio. Cheers,

Paul


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## saabluster

jtr1962 said:


> I'm using a pretty large microprocessor heatsink for my testing. It should do fine here. Normally I use passive cooling (heat sink gets warm but not hot at 2 amps), but for this test I was planning to use forced air cooling just to see what the R2 is capable of under optimum conditions. We should break 400 lumens before 2 amps, and possible 500 or more lumens past that. Maybe I could go even crazier with this and try thermoelectrics if the R2 survives the initial round of forced air cooling.


My main intent with this is to see what it can survive with a reasonably doable(could actually be used in a flashlight) heatsink setup. I can not think of a better way of keeping the junction temps down than soldering the Cree directly to a heat pipe. This is also, I feel, completely doable in a flashlight. Here is a picture of exactly what I would like to give you.
This heat-pipe is of the flat variety and will allow me to solder the Cree down easily. The Heatpipe will then be soldered to a 1/8" piece of copper that you can then attach to your heatsink setup.




I don't have to tell you how much better heatpipes are than even copper. It is of the utmost importance that the heat that comes through under the die be extracted as fast as possible. 
As I said I'm mainly interested with what we could actually do in a flashlight. As such I think that precludes active cooling. However it would be interesting to have the additional data just for our edification. 
So here is my proposal. Run the test as you normally do but with the heatsink I discused. When you reach 2A and for every additional 100mA or so take a measurement without the aid of active cooling and then cool the heatsink and take another measurement. So that at each increment above 2A your will have two lumens measurements. An easy way to do the cryo-cooling without having to change the rest of the setup would be to use a "can of air" upside down and spray it onto the heatsink. I don't know if this is what you had in mind already. I don't think a peltier would be as easy or as effective to use here.

Thats it. Let me know what you think.


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## nein166

saabluster said:


> ... I don't think a peltier would be as easy or as effective to use here.
> 
> Thats it. Let me know what you think.


 
jtr1962 tell him about your freezerator :nana:


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## saabluster

nein166 said:


> jtr1962 tell him about your freezerator :nana:


 Yes! Do tell!


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## jtr1962

saabluster said:


> My main intent with this is to see what it can survive with a reasonably doable(could actually be used in a flashlight) heatsink setup. I can not think of a better way of keeping the junction temps down than soldering the Cree directly to a heat pipe. This is also, I feel, completely doable in a flashlight. Here is a picture of exactly what I would like to give you.
> This heat-pipe is of the flat variety and will allow me to solder the Cree down easily. The Heatpipe will then be soldered to a 1/8" piece of copper that you can then attach to your heatsink setup.
> 
> I don't have to tell you how much better heatpipes are than even copper. It is of the utmost importance that the heat that comes through under the die be extracted as fast as possible.
> 
> As I said I'm mainly interested with what we could actually do in a flashlight. As such I think that precludes active cooling. However it would be interesting to have the additional data just for our edification.
> So here is my proposal. Run the test as you normally do but with the heatsink I discused. When you reach 2A and for every additional 100mA or so take a measurement without the aid of active cooling and then cool the heatsink and take another measurement. So that at each increment above 2A your will have two lumens measurements. An easy way to do the cryo-cooling without having to change the rest of the setup would be to use a "can of air" upside down and spray it onto the heatsink. I don't know if this is what you had in mind already. I don't think a peltier would be as easy or as effective to use here.
> 
> Thats it. Let me know what you think.


The main problem with doing it the way you pictured is that I can't put the LED on my test jig to get the beam profile. In other words, I won't be able to get lumen measurements, only intensity measurements. And while it's true the heat pipe has very low thermal resistance, the real controlling factor will ultimately be the heat sink. The heat pipe won't make the heat sink "better". In fact, the heat pipe will add a small amount of thermal resistance into the equation as opposed to just mounting the LED on the heat sink as I always do. Heat pipes are used mainly to carry heat from tight spaces where larger heat sinks don't fit to open areas where they do. A possible use might be to carry heat from a microprocessor to a large passive heat sink on back of a PC case. Or in the case of a flashlight, to carry heat from the LED to the body. However, the size of the flashlight body is ultimately the controlling factor in how hot things get.

Anyway, I think the best idea for now is to send an unmounted, never soldered LED. You can send the heat pipe and plate setup if you want. I can determine the thermal impedance of it and see how much it would raise operating temperatures as opposed to just mounting the LED directly on my heat sink.

I'll definitely be doing two sets of measurements as you said-one without forced cooling and one with.

Anyway, those are my thoughts for now. If anyone sees any flaws with my thinking please let me know.



> Yes! Do tell!


I'll upload some pictures of my "freezerator" later. I also wrote a description of it on another forum a few years ago, so I'll have to find my post and cut and paste the text here.


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## jtr1962

OK, here's the promised pictures of my thermoelectric temperature chamber (or the freezerator as nein166 calls it). These are from 2004. I've since added white LED interior lighting.

Overview of the entire chamber:






Here's the chamber part in case anyone is curious (inside measures 10"x10'x14"):











Multipaned plastic viewing window:






Cold sink (note temperature sensor IC on chamber ceiling):






These are copper heat sinks that I made. Altogether at full load they dissipate over 500W of TEC power plus up to 200W of pumped heat (much less as the temperature drops), for a total of over 700W. And they do so while keeping the hot side of the TEC only about 3° C higher than the tap water temperature. Since this is intermittantly used, I don't recirculate the water via an external air-to-air heat exchanger. Rather, I just throw it away, or send it to the garden in the warmer months. I only use about 30 gph, so it is more cost effective to do so.






Here's a picture of the control panel with unit in operation (note -55.63°F actual chamber temperature). The auxiliary display shows 47.6°F, which is the heat sink temperature (tap water in February is around 41°F). I use a two stage setup. 6 modules in the first stage cool the hot side of 3 modules running at lower current in the second stage. I had problems with condensation at one point, and some of my modules are performing a little less than optimally. Still, I can reach under -55°F in the winter months. I'm thinking of replacing the 70W first stage modules with 85W ones. This will probably let me reach roughly -65°F. 






Those two large main power supply transformers are cooled by the copper plates with water tubes. You can see some large filter caps right under the transformers.






Here's a top view:






The large toroids on top are inductors for the power supply. The tubes you barely see in the middle of the picture cool the power supply MOSFETs.






The fan is just to ensure a slight airflow over the large black voltage regulator heat sink and the aforementioned inductors. It only comes on when the chamber runs at or near full power. With these two exceptions, everything is water cooled. The MOSFET cooling tubes are more visible here.






Here's the display boards shown from a front view (sorry about the blurring):






Closeup of the control panel:






The chamber can also heat by running the second stage modules in reverse. I need to limit my temps in heating mode to about 200°F because the chamber fans and some of the plastics used to line the chamber can't take much more than that. BTW, when under no load the second stage cold plates get down to about -80°F, and that numbs your fingers in a few seconds (yes, I touched it). Just for kicks once when I was testing I put a TEC on the second stage cold plate, and a temperature probe on the TEC's cold side. I covered it with insulation and let the whole thing cool down to -80°F or so. I then powered the TEC. Of course, the aluminum cold plate it was sitting on heated up pretty fast (a relative term since it likely never got above -20°F during this whole procedure), so any temps I reached wouldn't be maintainable, but I did see the temperature probe reach about -110°F before it started creeping up again.

Besides testing electronics, I did this simply as a fun, long term project. I started the chamber in 1995. It took me over three years to get everything working right. It started out as air-cooled but I couldn't get much under 0°F. By small increments I made refinements and got lower temperatures. This included changes in both the heat sinks and also in making the chamber leak heat less. My first attempt at liquid cooling didn't go well-I used aluminum plates instead of copper. This meant using epoxy instead of solder to hold everything together. Epoxy and water don't mix long term. Hence, water-damaged TECs. Also, scaling developed inside the channels which compromised the efficiency of the heat sinks.

Besides changes in the physical setup I tried two makes of TECs. The second make was much better in terms of lower temperatures and durability. I also redid the power supply to get the efficiency up to about 95%. And then there was the problem of maintaining the set temperature. You can't get stable temperatures by just turning the TECs on and off. I designed a PID (proportional-integral-differential) controller which cut TEC power just enough to maintain temperature as the set point was reached. The unit can maintain stable temperatures within about 0.02°F of setpoint. While the chamber uses well over 500 watts at minimum temperature, it uses much less when set to maintain higher values. For example, to maintain 0°F I only need about 40 watts. To hold -20°F will use maybe 100 watts. Operating as a refrigerator (32°F) uses just a few watts. Of course at higher settings I can cut my water flow from 30 gph to 1 or 2 gph since I'm removing far less heat.

BTW, commercial temperature range is -40°C to 85°C (-40°F to 185°F). That's what I usually need to test over. I'd like to be able to get the chamber extemes to match the military range eventually, which is -55°C to 125°C (-67°F to 257°F).

It's a shame that no better thermoelectric materials than bismuth telluride have been commercialized in the 40+ years TECs have existed. I've heard researchers have found a few promising candidates. Since my chamber only requires about 25 watts of cooling power to maintain -67°F in theory if a TEC operating at Carnot efficiency existed I would only need about 10 watts of input power. I could make such a chamber using simple air cooling as the heatsink would only need to deal with 35 watts. I'd even be happy with TECs running at half the Carnot efficiency. I could hold -67°F with ~20 watts, and approach -200°F with less than 200 watts. There is plenty of incentive to make better TECs to eventually replace compressor-based cooling. I think we'll see a major breakthrough within the next decade


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## Gryloc

jtr1962,

Wonderful project! That is some amazing work; I see that it took plenty of time and dedication. Can I ask what sort of insulation you used? I am familiar with Zircar's Microsil, but that is used in extremely hot temperatures. I made a small furnace that could maintain 800C from around 150W. It is too bad that Peltiers aren't as efficient as removing heat as it is creating heat. I, too, would be thrilled to see the technology advance further. You wouldn't know off the top of your head what the efficiency is for the better Peltier devices compared to the average compressor-based coolers would you? I was just curious.

So, are you able to mount an LED in that chamber to test how the latest efficiency LEDs fare in low temperatures (to see the percentage increase in brightness). Though it would not be the most impressive as it would be with an older emitter, it would still be nifty to see a Q5 or R2 XR-E driven at 2A in your chamber. Maybe even a wildly overdriven Seoul P7 (ooh at 8A). I still dream of having access to some liquid nitrogen for casual experimentation. I heard from someone somewhere on the CPF years ago that someone stuck a standard 5mm high brightness red LED emitter in some liquid nitrogen and it supposedly lit up like a road flare. Maybe that experience was based on observations from non-flashaholic eyes. :huh: I do not know what the conditions were, however, and how the LED fared in the extreme environment.

I understand that heat pipes are configured to have certain operating ranges (where either above or below the range would cause the vapor to freeze or vaporize before returning), but could you find one that could work in your cold environment? What if you could mount an emitter right outside the insulation (with the heat pipe going through the insulation if you do not mind), and mount a heatsink to the inside of the chamber? You might be able to tilt everything so you can get lumen measurements, but it is not a huge deal. Actually, can you take lumen measurements before hand, then use the change in intensity due to the extreme cold to estimate the lumen output? I thought that was how you took lumen measurements to scale according to current input. I was just thinking...

Thank you for sharing your mighty cooling rig. I must have missed the first time that you presented this beast.  <(Brr, I'm cold!)


-Tony


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## jtr1962

Gryloc said:


> Wonderful project! That is some amazing work; I see that it took plenty of time and dedication. Can I ask what sort of insulation you used?


Thanks for the compliments. This really was an "endless" project. I may even upgrade it as I discussed when I have the time. It would be nice to see -65°F, perhaps even -70°F if I'm really lucky. Regarding the insulation, I used 2 layers of 2" thick Celotex insulation board. This is basically polyurethane foam. Probably better insulations exist these days, but not in 1995. Also, it was readily available at Home Depot, and cheap ($20 for a 4'x8' sheet). I think the insulating value is pretty similar to Microsil. I heard evacuated stainless steel panels filled with aerogel are nearly perfect insulators but well out of my price range. The chamber is pretty well insulated. I think I figured the thermal impedance is roughly 3.3°C/W. In other words, to maintain -55°F in a 65°F room only takes about 20 watts of cooling power (actually the cold sink fan adds another 1.5 watts to that total).



> It is too bad that Peltiers aren't as efficient as removing heat as it is creating heat. I, too, would be thrilled to see the technology advance further. You wouldn't know off the top of your head what the efficiency is for the better Peltier devices compared to the average compressor-based coolers would you? I was just curious.


I know there's a lot of R&D devoted to improving Peltiers but so far nothing has made it out of the lab. The efficiency of Peltiers relative to compressors depends upon the size of the system. For something like a room AC or a refrigerator compressors are probably 2 to 4 times more efficient at the temperature differentials involved. For small cooling applications like picnic coolers Peltiers are probably better because the the frictional losses in a compressor are a greater percentage of the total power input.



> So, are you able to mount an LED in that chamber to test how the latest efficiency LEDs fare in low temperatures (to see the percentage increase in brightness). Though it would not be the most impressive as it would be with an older emitter, it would still be nifty to see a Q5 or R2 XR-E driven at 2A in your chamber. Maybe even a wildly overdriven Seoul P7 (ooh at 8A).


For cooling LEDs it makes more sense just to mount them on a cold plate rather than put an LED-heatsink assembly in the chamber. I actually did a test a few years ago with an amber Luxeon. Link to thread. There probably wouldn't be as much gain with whites but even a 25% gain in efficiency with an R2 translates into ~130 lm/W at 350 mA.



> I still dream of having access to some liquid nitrogen for casual experimentation. I heard from someone somewhere on the CPF years ago that someone stuck a standard 5mm high brightness red LED emitter in some liquid nitrogen and it supposedly lit up like a road flare. Maybe that experience was based on observations from non-flashaholic eyes. :huh: I do not know what the conditions were, however, and how the LED fared in the extreme environment.


My guess is the thermal shock wouldn't be too good for it but I'm sure it could deal with the temperatures just fine if gradually cooled. There's probably limits on how much increase in efficiency you'll get at low temperatures. The amber Luxeon was already failing to show much improvement under -40°F.

If Peltiers improve significantly then we should be able to reach liquid nitrogen temperatures with a two-stage device. I'd be happy even to reach dry ice temperatures.



> I understand that heat pipes are configured to have certain operating ranges (where either above or below the range would cause the vapor to freeze or vaporize before returning), but could you find one that could work in your cold environment? What if you could mount an emitter right outside the insulation (with the heat pipe going through the insulation if you do not mind), and mount a heatsink to the inside of the chamber? You might be able to tilt everything so you can get lumen measurements, but it is not a huge deal. Actually, can you take lumen measurements before hand, then use the change in intensity due to the extreme cold to estimate the lumen output? I thought that was how you took lumen measurements to scale according to current input. I was just thinking...


No need to go through all that. I just mount the LED on my test jig, do a beam profile, and then get absolute lux readings from 1 meter to calculate lumens. Once that's done, I can just take relative lux readings at different currents/temperatures to see what effect that has on lumen output. I'm sure the heat pipe scenario you mentioned won't work well at all. Far better to just mount the LED right on a cold plate.



> Thank you for sharing your mighty cooling rig. I must have missed the first time that you presented this beast.  <(Brr, I'm cold!)


I never talked about it in detail here. I did on a few other forums I used to frequent but that was 3 or 4 years ago. Most of the description above was just a cut and paste of what I wrote on the other forums. Glad you enjoyed it! Now go get yourself some hot coffee. :devil:


----------



## saabluster

jtr1962 said:


> The main problem with doing it the way you pictured is that I can't put the LED on my test jig to get the beam profile.


Thats why i posted a picture. If you can give me a picture of your setup I'm sure I can make something that will fit.



jtr1962 said:


> The heat pipe won't make the heat sink "better".


I think i may not have been clear enough. My intent was that you still use your heatsink. I would not classify what I'm trying to do with the heatpipe as a "heatsink" per se. Consider it as a heatspreader which would still be in need of a good heatsink. 



jtr1962 said:


> In fact, the heat pipe will add a small amount of thermal resistance into the equation as opposed to just mounting the LED on the heat sink as I always do.


I have the utmost respect for your knowledge and methods but I have to disagree very strongly on this point. As our old buddy Newbie has on his site(and here too I'm sure) many heatpipes have thermal resistances 2,000 times lower than copper and 4,000 times lower than aluminum. When you consider that the vast majority of heat coming from the LED die is concentrated in a very small spot and is not significantly spread by the ceramic substrate thermal resistance(and the need for a heat-spreader) becomes a _very_ big deal. Heatpipes are in an entirely different league when it comes to spreading heat.

Love your "freezerator"! I can not imagine how many hours went into that. What do you use it for?


----------



## jtr1962

Here's three pictures:

















I need something where the LED is mounted to a plate with screw holes spaced 0.75" apart. Note the 5/8" aluminum spacer between the LED and the heat sink in the second picture. Originally I simply had the LED right on the heat sink, and I had the heat sink mounted such that the LED sat where it does now (right at the pivot point of the test jig). I later added the spacer and moved the heat sink back 5/8" because some light past 90° was being blocked. Not much, but it could affect the results by a few percent. I'll be removing the aluminum spacer for these tests. Basically if you make a plate with holes drilled for 4-40 screws, space 0.75" apart, solder a heat pipe to the plate, and then bend the heat pipe in such a manner that the LED is sitting roughly 5/8" off the plate, and centered between the screw holes, I should be OK. I can always bend the heat pipe to make any small final adjustments once it's in my test jig. And solder the LED the heat pipe such that the power contacts are oriented vertically when everything is mounted to the tester. This will make everything consistent with the way this test jig works.

Here's a rough drawing (side view) of something I think will work:











> Love your "freezerator"! I can not imagine how many hours went into that. What do you use it for?


Testing electronics devices mostly. I sometimes make things for the taxi industry which must function in temps as low as -40°F. I'd rather test them before the get into the field. Besides that it was just a fun project. Yes, literally months and perhaps $1500 went into this. Note that the housing for the power supply and controller is an old AT computer case I found! If I had to make another chamber I could do so much faster and better based on what I learned. Also, we have nice heat sinks available which I didn't at the time. I actually made the cold sink myself by soldering copper plates to a copper base. Now I would just use a couple of microprocessor heat sinks instead.


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## saabluster

Thanks for going through the trouble of posting those pictures. I have also rethought slightly where I would mount everything. I used your picture and tried to make a fairly accurate representation (layout+scale) of what it would look like. I based it on your cpu heatsink being 2" across. The thickness of the copper plate and heatpipe together is 1/4". My thought is ditch the aluminum spacer as you mentioned and replace it with some 1/4" thick aluminum that I have. This will have the LED die very close to the 5/8" you currently have. I think putting the LED over the area of the copper plate will allow even faster heat extraction than if the LED was mounted on the heatpipe far away from the copper plate.


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## jtr1962

That will definitely work so long as it's not too much trouble for you to make it. My only real concern here is will soldering the LED to the heat pipe cause any damage to it? I'm guessing you've already done this with good results. If so, then we're all set to go as soon as you have a chance to build what you envisioned.

Nice photoshop job on my picture! :twothumbs


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## saabluster

jtr1962 said:


> That will definitely work so long as it's not too much trouble for you to make it. My only real concern here is will soldering the LED to the heat pipe cause any damage to it? I'm guessing you've already done this with good results. If so, then we're all set to go as soon as you have a chance to build what you envisioned.
> 
> Nice photoshop job on my picture! :twothumbs


Great!:twothumbs I"ll get started on it. And yes I've figured out how to keep the LED from being damaged. I just need confirmation on the width I have to work with. I scaled it at 2" in width. Is this correct? Should I make my setup just under that maybe 1 3/4"- 1 7/8"?


----------



## jtr1962

saabluster said:


> Great!:twothumbs I"ll get started on it. And yes I've figured out how to keep the LED from being damaged. I just need confirmation on the width I have to work with. I scaled it at 2" in width. Is this correct? Should I make my setup just under that maybe 1 3/4"- 1 7/8"?


It's slightly more than 2" but making the plate about 1⅞" should work out fine. Just try to orient the LED so that the power contacts are vertical as in my drawing. It doesn't have to be perfect as long as it's close.

I look forward to doing these tests!


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## saabluster

saabluster said:


> Anyone want to guess the amperage it blows at and the peak lumens?


OK. Here is my official prediction. 

[email protected] with the heatpipe
[email protected] chilled


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## marschw

I'm definetly outclassed on the engineering involved here, but I thought heat pipes were only useful when they draw heat upwards, since they rely on gravity to let the condensed fluid fall back down to the hot end of the pipe. Thus an arch-shaped heat pipe, as in the drawing, would only be as effective as an equivalent mass of copper, since the fluid would condense on the cold side and just sit there?


----------



## jtr1962

marschw said:


> I'm definetly outclassed here on the engineering involved here, but I thought heat pipes were only useful when they draw heat upwards, since they rely on gravity to let the condensed fluid fall back down to the hot end of the pipe. Thus an arch-shaped heat pipe, as in the drawing, would only be as effective as an equivalent mass of copper, since the fluid would condense on the cold side and just sit there?


My understanding of the way heat pipes work is that the condensed fluid returns via a wick. Therefore, the pipe can be bent, and orientation is unimportant. See here and here


----------



## marschw

jtr1962 said:


> My understanding of the way heat pipes work is that the condensed fluid returns via a wick. Therefore, the pipe can be bent, and orientation is unimportant. See here and here


Ahh, that makes sense, didn't know about the wick.


----------



## saabluster

jtr1962 said:


> It's slightly more than 2" but making the plate about 1⅞" should work out fine. Just try to orient the LED so that the power contacts are vertical as in my drawing. It doesn't have to be perfect as long as it's close.
> 
> I look forward to doing these tests!



Well it's ready! All that I have left is to drill the holes. I need to know how big you want the holes drilled out to. Also, just to double check, is it exactly 3/4" center to center? Of note too I did not get the LED centered perfectly left/right. From the the center of the LED die to the right edge(as viewed from the front of your device) is 1". Since you said your heatsink is a little over 2" wide I figure this is still barely within spec. If not let me know.


----------



## jtr1962

saabluster said:


> Well it's ready! All that I have left is to drill the holes. I need to know how big you want the holes drilled out to. Also, just to double check, is it exactly 3/4" center to center? Of note too I did not get the LED centered perfectly left/right. From the the center of the LED die to the right edge(as viewed from the front of your device) is 1". Since you said your heatsink is a little over 2" wide I figure this is still barely within spec. If not let me know.


1/8" should be enough on the holes. It just needs to be large enough for a 4-40 screw and yes, it's exactly 0.75" center-to-center. It doesn't matter much if the LED is exactly on center. I can probably play around a bit to get everything lined up once it arrives.

Just letting you know also that I'll be busy with some work-related stuff for another week and change, so I won't have time to do the tests until I'm finished.


----------



## simple

:bow:


----------



## saabluster

jtr1962 said:


> Just letting you know also that I'll be busy with some work-related stuff for another week and change, so I won't have time to do the tests until I'm finished.


No problem.


----------



## saabluster

Well I finally got around to sending it to you jtr1962. I know you've been busy so I have not been in a hurry. However as I was driving down the road today, thinking about the fact that I sent it, it occurred to me that I forgot to drill the holes. Hope thats not a problem. If so, just let me know. Should be there by Friday so the mailman says. It was sent USPS.


----------



## jtr1962

Thanks for letting me know it's on the way. :thumbsup: Nothing in the mail today, it'll probably come tomorrow. Also, no problem drilling the holes myself. I have a drill press.


----------



## saabluster

jtr1962 said:


> Thanks for letting me know it's on the way. :thumbsup: Nothing in the mail today, it'll probably come tomorrow. Also, no problem drilling the holes myself. I have a drill press.


I'm sure you already know this but you will need to use a little oil and go fairly slowly to avoid the two layers(aluminum and copper) from delaminating. They are bonded with Artic Alumina epoxy. Can't wait!


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## saabluster

JTR have you received it yet? Looking forward to the results. Thought I would mention I bought a power supply a couple weeks ago and did a little test on one of my Q5s. I took it up to 3.2A for about 5 seconds. Did not appear to hurt it at all. The tint didn't even shift very much. The LED was soldered down to a solid piece of copper. I did not want to blow the LED just yet because I'm using it for some driver and run-time tests but as soon as that is over I WILL find that Q5's breaking point.:naughty:


----------



## jtr1962

saabluster said:


> JTR have you received it yet? Looking forward to the results. Thought I would mention I bought a power supply a couple weeks ago and did a little test on one of my Q5s. I took it up to 3.2A for about 5 seconds. Did not appear to hurt it at all. The tint didn't even shift very much. The LED was soldered down to a solid piece of copper. I did not want to blow the LED just yet because I'm using it for some driver and run-time tests but as soon as that is over I WILL find that Q5's breaking point.:naughty:


I received it a while ago. Unfortunately I had flooding in my basement on June 14 so it's taking a while for things in my "lab" to get back to normal. I'll probably finally be doing the tests sometime in the next few days.

Good to know a Q5 can handle 3.2A. My plan is to increase current until either the LED blows, or the brightness stops increasing (no point going further than that since ultimate maximum output is really what we're after here.).


----------



## jtr1962

I finally finished the testing. First order of business after drilling the holes and attaching the LED to my heat sink was to determine the nominal output the usual way. My results were 122.97 lumens at 350 mA, slightly above spec actually, but then again the margin of error for my testing is probably a few percent either way. Vf was a somewhat high 3.37V. Efficiency was 104.3 lm/W.

Next order of business was to begin increasing current until either the LED blew, or it didn't get any brighter. For this round of tests I used passive cooling. The heat pipe and copper plate spread the heat to the heat sink, which in turn dissipated it. The results were a little better than my usual setup. Apparently the heat pipe, or perhaps the combination of heat pipe and copper plate, did _something_. At 2 amps the output was 3.35 times the output at 350 mA, compared to 3.21 for the stock setup. The heatpipe provided a small (about 4%) advantage here. As I increased the current past 2 amps I was crossing my fingers for the LED to hold together. Finally at 2.5 amps the output stopped increasing. At 2.6 amps it was a little lower. Peak output was passive cooling was *436.7 lumens*. Vf at 2.5 amps was 4.22V, and total power input was 10.55 watts.

Obviously in the case of passive cooling you'll eventually reach a point of diminishing returns. However, it's a good indication of what a reasonably-sized flashlight body can do if you pump enough current into the LED. The next order of business was the ultimate output which the LED was capable of. To that end I set a large fan to actively cool the heat sink. Throughout the tests the temperature of the copper plate the LED was mounted on remained very close to room temperature. Once the temperature rise of the heat sink was factored out of the equation, I was able to get increasing output past 2.5 amps. The peak output was reached at 2.7 amps. At 2.8 amps it was a little less. The results at 2.7 amps were *453.9 lumens*, Vf was 4.32V, and a power input was 11.664 watts. This is the absolute maximum which this Cree R2 emitter can give under ideal cooling conditions.

Wanting to continue this "insanity", I bolted the copper plate and LED to the cold plate of one of my thermoelectric assemblies. By the time ice was starting to form on the plate, the LED was giving me *502 lumens* at 2.5 amps. Even though below ambient cooling was required, the 500 lumen barrier for a single emitter was finally broken. Even better, the emitter is none the worse for all the abuse it's been through. It didn't have to die in the name of science. :devil:

Here are some charts of the final results:

Lumen output using fan-cooled heatsink






Comparison of passive versus fan-cooled output


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## Erasmus

Haha this is total madness, but I like it  A single die emitter putting out 500 lumens, amazing! 

By the way, did you receive my R2's already?

Cheers!


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## Nitroz

Wow! Simply amazing!

Do you have any pictures of the LED powered at these currents?

If a single die can do this, imagine what the new well cooled MC-E could do.


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## jtr1962

Erasmus said:


> Haha this is total madness, but I like it  A single die emitter putting out 500 lumens, amazing!
> 
> By the way, did you receive my R2's already?
> 
> Cheers!


Yes, your LEDs safely arrived a few days ago. Thanks for the extra for testing purposes. :thumbsup: Results were 115.5 lumens at 350 mA and 347.2 lumens at 2 amps. Nice color as well. I also loved the label you put on the package! 

3 or 4 of the R2s you sent me will find a new home in a bike light I'm making.


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## Nitroz

jtr1962 said:


> Yes, your LEDs safely arrived a few days ago. Thanks for the extra for testing purposes. :thumbsup: Results were 115.5 lumens at 350 mA and 347.2 lumens at 2 amps. Nice color as well. I also loved the label you put on the package!
> 
> 3 or 4 of the R2s you sent me will find a new home in a bike light I'm making.



So in your testing it looks like the warmer WG bin LEDs do not put out as much light as the cooler LEDs. Would that be correct?


----------



## jtr1962

Nitroz said:


> Wow! Simply amazing!
> 
> Do you have any pictures of the LED powered at these currents?
> 
> If a single die can do this, imagine what the new well cooled MC-E could do.


I didn't take any pictures during the test, but I took pictures of something even better. I recently burned in 44 Rebels for milkyspit. Here are some pictures (all LEDs are running at 1 amp). We have here ~10000 lumens of light.


----------



## jtr1962

Nitroz said:


> So in your testing it looks like the warmer WG bin LEDs do not put out as much light as the cooler LEDs. Would that be correct?


It seems they put out marginally less light although they're still in spec. I think some of the cooler bin R2s may well be exceeding spec a bit at this point, but not by enough for Cree to warrant selling the R3 bin on its own. However, as the manufacturing process continues to be tweaked, I think we should see R3s before too long.

When I get my hands on an MC-E things are going to get really interesting. I have little doubt that overdriven slightly these things will exceed 1000 lumens by a wide margin. Of course, I'll be using strictly fan-forced cooling during such a test as passive cooling with a small heat sink just can't deal with well over 10 watts of power.


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## Nitroz

Cool!


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## Nitroz

jtr1962 said:


> It seems they put out marginally less light although they're still in spec. I think some of the cooler bin R2s may well be exceeding spec a bit at this point, but not by enough for Cree to warrant selling the R3 bin on its own. However, as the manufacturing process continues to be tweaked, I think we should see R3s before too long.
> 
> When I get my hands on an MC-E things are going to get really interesting. I have little doubt that overdriven slightly these things will exceed 1000 lumens by a wide margin. Of course, I'll be using strictly fan-forced cooling during such a test as passive cooling with a small heat sink just can't deal with well over 10 watts of power.




Thanks! And keep up the extreme testing!


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## Calina

Thank you for this fascinating test. I am truly amazed by the thoughness of these small dies.


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## saabluster

Wow! *502 lumens*!:twothumbs Excellent work JTR. I really appreciate your doing this for me. I don't think I did a very good job getting the led really close to the heatpipe but it still seems to make a difference. I have an even more extreme way of mounting the LED that should give it even more of a boost. It will be awhile before I can get it made but it should be incredible when I do. 

So are you going to try to unmount the LED from the heatpipe to use in one of your projects? I wonder how difficult that would be.

One other thing. What program do you use to make those graphs. I would like to use it to display run times and such. Thanks again for your hard work.




jtr1962 said:


> By the time ice was starting to form on the plate, the LED was giving me *502 lumens* at 2.5 amps. Even though below ambient cooling was required, the 500 lumen barrier for a single emitter was finally broken. Even better, the emitter is none the worse for all the abuse it's been through.
> 
> Comparison of passive versus fan-cooled output


----------



## Ron Schroeder

Hi jtr,

Can you get reliable measurements from a very wide angle LED that only puts out about 5 lumens? I have some of the JKL 5mm LED "condoms" that convert a blue LED to diffused white. I am very interested in comparing that technology to the phosphor on die technology.


----------



## Gunner12

This is amazing, 500 lumen from a single die commercially available LED. I'm surprised it didn't die at above 2 something amp.

From what you posted, I'm assuming the LED didn't loose much of it's performance even after this abuse?

A well cooled MC-E might even be able to break 2000 lumen, but that would be a lot of cooling.

Great job jtr!


----------



## jtr1962

Calina said:


> Thank you for this fascinating test. I am truly amazed by the thoughness of these small dies.


Me too. I thought for sure I would hear a pop by 2.5 amps but the emitter just kept on cooking!



Gunner12 said:


> This is amazing, 500 lumen from a single die commercially available LED. I'm surprised it didn't die at above 2 something amp.
> 
> From what you posted, I'm assuming the LED didn't loose much of it's performance even after this abuse?
> 
> A well cooled MC-E might even be able to break 2000 lumen, but that would be a lot of cooling.
> 
> Great job jtr!


When I remeasured the lux at 350 mA after the tests it was exactly the same as before. The LED went through all this abuse yet came back in pristine condition. While I have little doubt it wouldn't have survived long running continuously at those currents, brief excursions seem to be harmless.

Yes, it's entirely possible an MC-E may break 2000 lumens. I think the limiting factor there and even in the case of the XR-E is the thermal attachment resistance. For the XR-E it's listed as 8°C/W. That means when I was running the LED at 2.7 amps the temperature rise of the die was in excess of 80°C (accounting for the percentage of input power which exited the die as light rather than heat). An 80°C rise will degrade output by about 15%. In other words, with the fan-cooled tests had there been zero thermal impedance between the LED junction and the heat sink I probably would have obtained perhaps 530 lumens from the LED, and even more with below ambient cooling. I suspect the thermal attachment impedance will affect the MC-E even more. I believe it's listed as 3°C/W, which translates into 12°C/W for each die.



Ron Schroeder said:


> Hi jtr,
> 
> Can you get reliable measurements from a very wide angle LED that only puts out about 5 lumens? I have some of the JKL 5mm LED "condoms" that convert a blue LED to diffused white. I am very interested in comparing that technology to the phosphor on die technology.


Yes, I've measured many low-output, wide-angle LEDs as you can see here:


----------



## jtr1962

saabluster said:


> Wow! *502 lumens*!:twothumbs Excellent work JTR. I really appreciate your doing this for me. I don't think I did a very good job getting the led really close to the heatpipe but it still seems to make a difference. I have an even more extreme way of mounting the LED that should give it even more of a boost. It will be awhile before I can get it made but it should be incredible when I do.


I'll be happy to see if I can better my results with your new mounting method. I may also repeat the below ambient cooling part of the tests in the winter. The amount of humidity in the air was causing condensation which had to continually be wiped off the LED. In the winter these problems would be far less severe. Perhaps I could even try a liquid-cooled thermoelectric setup allowing me to bring the thermal pad well below 0°F. That might make breaking 600 lumens possible. 



> So are you going to try to unmount the LED from the heatpipe to use in one of your projects? I wonder how difficult that would be.


I'll leave it as is. Unmounting it would probably destroy the LED. I'm thinking of doing a long-term 350 mA lumen degradation test with it similar to the ongoing one I started with a Q bin Luxeon 4.5 years ago (yes, it's still going strong).



> One other thing. What program do you use to make those graphs. I would like to use it to display run times and such. Thanks again for your hard work.


I use Microsoft Excel '97. I believe the free Open Office has a spreadsheet as part of its suite which would work equally well here.


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## saabluster

JTR could you make a graph showing the original R2 tests you did with these new tests(including the active cooled) all together on one? I think it would help us visualize the differences better. Thanks!


----------



## jtr1962

saabluster said:


> JTR could you make a graph showing the original R2 tests you did with these new tests(including the active cooled) all together on one? I think it would help us visualize the differences better. Thanks!


Is this OK?

Yellow line is with my stock setup, purple line is your setup but passively cooled, and the dark blue line is your setup actively (fan) cooled.


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## saabluster

jtr1962 said:


> Is this OK?


I was hoping you also had the data points with it on the cold plate as well. If not I understand and thank you for posting that last graph.


----------



## PhantomPhoton

Ah, LED overclocking... brings back memories of me and my Athlons a few years ago. 

I'm surprised at the apparent robustness of those Crees. When will we see the first production of lights by some crazy modder attaching a heatpipe to the Emitter and running the heat down to the body (heatsink) of the light while thermally isolating the head? Running a Cree @ 2A+ in a _compact _handheld light would be pretty sweet.


----------



## jtr1962

saabluster said:


> I was hoping you also had the data points with it on the cold plate as well. If not I understand and thank you for posting that last graph.


With the constant condensation of moisture on the LED due to the humidity I wasn't really able to do a controlled test on the cold plate like I would have wanted to. My only data point is 2.5 amps, 502 lumens. At lower currents the LED dome froze over due to the lack of light energy to melt the ice, making measurements impossible. I'll probably try again when conditions for this sort of test are optimal. This is usually January or February when my workroom temps are in the mid 50s.


----------



## saabluster

jtr1962 said:


> With the constant condensation of moisture on the LED due to the humidity I wasn't really able to do a controlled test on the cold plate like I would have wanted to.


I kind of thought that to be the the case. Thanks.


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## curry__muncha

Excellent database!!

very useful!

really appreciate the effort that has been put into this, as many others have said.

=]

keep up the good stuff! ;]


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## MattK

Awesome work as always gents!

Is anyone planning to do some P7 testing?


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## ViReN

MattK said:


> Awesome work as always gents!
> 
> Is anyone planning to do some P7 testing?



WOW Matt :bow:, you have already sent the P7 to jtr1972 for testing.... 

we all look forward for amazing test results....:thumbsup:


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## MattK

LOL I haven't but I'd happily do so - or fund his testing if he wants to source it himself.


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## zzonbi

Marvelous, on par with Osram 500lm world record

http://www.osram-os.com/osram_os/EN/Press/Press_Releases/Light_Emitting_Diodes/LED-chip-record.jsp

This OC reminds me of those engine dyno charts. So basicaly we have max hp(450lm) at 2700rpm(mA) without phase-change cooling (normal fuel or natural aspiration) from 1l capacity (1mm^2).

I wonder if the other main chip (Philips die of the Luxeon K2 with TFFC) maxes out around the same 'rpm'.

Even if lm/W is limited, there is no clear limit for emittance (lm/m2).


----------



## Brlux

Do you know what the flux and tint bin was for your Nichia NSPW500GS-K1 led's?


----------



## Cemoi

Thanks and congratulations jtr for this excellent and impressive work.

Could you please kindly make your table available as a spreadsheet, which would allow us to sort it to our liking (e.g. by Vf, output, etc.)?

On the other hand, are you still interested in testing 5mm red LEDs? I have purchased some 25 cd 20 degree red LEDs from BestHongKong, so I could send you one for testing.


----------



## redlaw55

The table listing measurements of LEDs has me thinking of upgrading the 5mm leds in a Nite-Ize module for AA maglites. I wonder how the Nite-Ize leds would do against those listed.


----------



## jtr1962

*Seoul Semiconductor P7 Bin C (tested October 2008)*

I obtained a Seoul P7 of the highest brightness bin this week. The C bin is rated at between 740 and 900 lumens. For this test I epoxied the P7 to a 60mm heat sink. I tested the output with and without a fan cooling the heat sink. Here are the results:



























At the nominal current of 2800 mA the fan makes only a small difference. Output is 731 lumens without the fan, and 742 lumens with fan cooling. This is barely but still within ratings. Efficiency at nominal current is 70.7 lm/W, good but certainly not in the same league as the latest single-die Cree or Seoul LEDs running at a comparable current of 700 mA. However, that's to be expected since the thermal path per die for the P7 isn't as good as for the Seoul P4 or Cree XR-E. If you underdrive the P7 then you can get significantly greater efficiency. For example, at 1000 mA the efficiency is 97.9 lm/W, way better than even an R2 bin XR-E at that current, and output is 329 lumens, about 20% greater than the Cree at that current. At 350 mA the P7 can manage 115 lm/W and 125 lumens, both figures somewhat greater than the best single die LEDs. Efficiency peaks in the 125 lm/W area at currents under 100 mA. Output versus current actually remains linear to well under 10 mA, but with the slight drop in Vf you're only gaining a few percent efficiency compared to 100 mA.

The results when cranking up the current are interesting. Without the fan cooling the heat sink, the output levels off at 6 amps and 998 lumens. With the fan I was able to go to 7 amps and 1114 lumens, although the increase in output was flat from 6.8 to 7.0 amps. The increase from 6.5 to 6.8 amps barely registered on my light meter. Therefore, even with very good forced-air cooling there is no point taking the P7 past about 6.5 amps, and only then if you want to squeeze out every last lumen. In fact, if you consider that the eye can't detect brightness differences of 10%, then the absolute maximum current of the P7 should be no more than around 4.5 amps, even less with the heat sinking typically available in flashlight bodies. At 4.5 amps you will get about 1000 lumens with very good cooling. Note however that 1000 lumens is only 35% more than what the P7 will give you at its nominal current of 2.8 amps. The lumen increases from overdriving the P7 just aren't as dramatic as with single die LEDs. In a typical situation with less than stellar heat-sinking I doubt it even pays to go above the nominal 2.8 amp current.


----------



## jtr1962

Brlux said:


> Do you know what the flux and tint bin was for your Nichia NSPW500GS-K1 led's?


It looks to be rank W (the highest) based on my results.



Cemoi said:


> Thanks and congratulations jtr for this excellent and impressive work.
> 
> Could you please kindly make your table available as a spreadsheet, which would allow us to sort it to our liking (e.g. by Vf, output, etc.)?
> 
> On the other hand, are you still interested in testing 5mm red LEDs? I have purchased some 25 cd 20 degree red LEDs from BestHongKong, so I could send you one for testing.


The spreadsheet for the table is available in the zip file containing all my spreadsheets: Link (look for the file LED Comparison Chart.xls )

Regarding the BHK 5mm reds, I don't test colored LEDs because the results would be meaningless. When I participated in the CPF light meter testing I found that my meter was way off with colored LEDs.


----------



## Gryloc

jtr1962,

I just wanted to check. Could you give us the exact bin of SSC P7 emitter that you used? I remember that you said in a PM that the emitter that you tested was actually a D-bin. If you cannot be 100% certain there, then could you try to give us the forward voltage bin? I was curious if it was a J or I bin. According to their documentation, I believe that Seoul bins their Vf when the I = 2800mA. The I bin means a Vf of 3.25V - 3.50V, and the J bin means a Vf of 3.50V - 3.75V. Seeing your data, it seems to be a J bin. However, on my own Vf vs I tests on P7 emitters, the actual data seemed different than what the bin supposed to be (actual Vf is lower than what the bin states). Maybe the Vf drops a bit over time. Thanks! :twothumbs

-Tony


----------



## Holzleim

Hi jtr1962,

any plans testing CREE Mc-E?

I made a quick test with my MC-E (WG, K-bin) soldered to solid copper giving the feeling that output still increases till 2A. Between 2A and 2,1A output nearly stagnated so I stopped measuring at 2A in order not to destory my only MC-E.

But I have no equipment to measure real lumen output, the values shown below are just Lux-meter reading of the same optical system while increasing current. Temperature of the copper was nearly static.

Current Lux x100 
0,1 88 
0,3 188 
0,7 349 
1,0 455 
1,5 600 
1,8 670 
2,0 708


Thanks for your superior work,
Regrads,
Holzleim


----------



## jtr1962

Gryloc said:


> I just wanted to check. Could you give us the exact bin of SSC P7 emitter that you used? I remember that you said in a PM that the emitter that you tested was actually a D-bin. If you cannot be 100% certain there, then could you try to give us the forward voltage bin? I was curious if it was a J or I bin. According to their documentation, I believe that Seoul bins their Vf when the I = 2800mA. The I bin means a Vf of 3.25V - 3.50V, and the J bin means a Vf of 3.50V - 3.75V. Seeing your data, it seems to be a J bin. However, on my own Vf vs I tests on P7 emitters, the actual data seemed different than what the bin supposed to be (actual Vf is lower than what the bin states). Maybe the Vf drops a bit over time. Thanks! :twothumbs


The guy who gave it to me doesn't even know the Vf bin. Honestly, I don't put much value in Vf binning because I've seen Vf change over time, and it certainly changes with temperature. Binning by Vf ostensibly might be beneficial in that matched emitters should track with temperature, but they still might not track with time. And this isn't theoretical, either. I've carefully matched emitters by Vf when I made a few bike lights using 5mm LEDs only to find some months later some emitters were brighter than others. IMHO matching Vf is a lesson in futility. Now I design so that Vf doesn't matter.

I haven't yet tested the emitters you sent me. Last two weeks I've had to reorganize my work area as it was getting to the point I couldn't function. As soon as that's completed, I'll be resuming my lumens testing.


----------



## jtr1962

Holzleim said:


> Hi jtr1962,
> 
> any plans testing CREE Mc-E?


Tony (Gryloc) mentioned that he'll send me some samples to test as soon as I'm done with the P4s and P7s he sent me, assuming that Cutter sends them to him by then.


----------



## Gryloc

jtr1962 said:


> Tony (Gryloc) mentioned that he'll send me some samples to test as soon as I'm done with the P4s and P7s he sent me, assuming that Cutter sends them to him by then.



We all know that things are a little weird with Cutter. They have not shipped yet. I may order the M-binned MC-E from Kaidomain, but I fear the equally long wait. Is that a bad idea? DX has the 370lm version available, as does LEDsupply and Digikey (which would ship promptly), but I sort of wanted to send jtr1962 the best bin that is available. 

To all, :candle:

Does anybody have an MC-E currently available to lend to jtr1962 for lumen testing? I offer to pay for shipping charges or what ever as some aid to mail it. Thanks. :thumbsup:

-Tony


----------



## saabluster

I have an M bin that I could send him. I will even mount it to solid copper.



Gryloc said:


> We all know that things are a little weird with Cutter. They have not shipped yet. I may order the M-binned MC-E from Kaidomain, but I fear the equally long wait. Is that a bad idea? DX has the 370lm version available, as does LEDsupply and Digikey (which would ship promptly), but I sort of wanted to send jtr1962 the best bin that is available.
> 
> To all, :candle:
> 
> Does anybody have an MC-E currently available to lend to jtr1962 for lumen testing? I offer to pay for shipping charges or what ever as some aid to mail it. Thanks. :thumbsup:
> 
> -Tony


----------



## Paul Baldwin

Hi,
Very interesting info, I'm glad I stumbled across this thread  I had wondered if keeping an led properly cool would allow you to push it harder and you've well and truly confirmed that!
I'm now wanting to go and buy a peltier/heatsink and fix an led directly to the cold side and see what can be achieved.
Keep up the great work you are doing :twothumbs 

Paul.


----------



## Jarl

Holzleim said:


> Hi jtr1962,
> 
> any plans testing CREE Mc-E?
> 
> I made a quick test with my MC-E (WG, K-bin) soldered to solid copper giving the feeling that output still increases till 2A. Between 2A and 2,1A output nearly stagnated so I stopped measuring at 2A in order not to destory my only MC-E.
> 
> But I have no equipment to measure real lumen output, the values shown below are just Lux-meter reading of the same optical system while increasing current. Temperature of the copper was nearly static.
> 
> Current Lux x100
> 0,1 88
> 0,3 188
> 0,7 349
> 1,0 455
> 1,5 600
> 1,8 670
> 2,0 708
> 
> 
> Thanks for your superior work,
> Regrads,
> Holzleim



Do you have any idea of what the Vf was doing at such high currents?

Thanks!


----------



## saabluster

Holzleim said:


> Hi jtr1962,
> 
> any plans testing CREE Mc-E?
> 
> I made a quick test with my MC-E (WG, K-bin) soldered to solid copper giving the feeling that output still increases till 2A. Between 2A and 2,1A output nearly stagnated so I stopped measuring at 2A in order not to destory my only MC-E.
> 
> But I have no equipment to measure real lumen output, the values shown below are just Lux-meter reading of the same optical system while increasing current. Temperature of the copper was nearly static.
> 
> 
> 
> 
> Thanks for your superior work,
> Regrads,
> Holzleim


I missed this post somehow. You have done something *really* wrong if you can only get it to 2A before lumen output starts to go down. Especially considering the fact that you said the temperature of the copper remained static. That tells you the LED is not able to get the heat out of the package. It should still be gaining in output at twice that drive level.


----------



## thegeek

saabluster said:


> I missed this post somehow. You have done something *really* wrong if you can only get it to 2A before lumen output starts to go down. Especially considering the fact that you said the temperature of the copper remained static. That tells you the LED is not able to get the heat out of the package. It should still be gaining in output at twice that drive level.



Was it wired in series or parallel? Series I can see it peaking at 2A. Maybe it was a BIG piece of copper.


----------



## saabluster

thegeek said:


> Was it wired in series or parallel? Series I can see it peaking at 2A.


This is a very good point. I wasn't even thinking series as most people just run them parallel. Now we wait for his response.


----------



## Holzleim

@Jarl:
I turned it on again and measured 3,33V at 350mA and 4,25V at 2A. So not the very best Vf values I got with my sample.

@Saabluster:
Yes, in this case I should have mentioned the die where wired in series, and so the current was 2A per die.
Was a bit astonished when you mentioned output should increase till twice 2A


----------



## phantom23

Now it's clear. Everything is fine.


----------



## Jarl

phantom23 said:


> Now it's clear. Everything is fine.



When you say fine, it's 8.5W/die. That isn't fine, it's AWESOME 

Can't wait for some lumen figures to be attached to that.... by my calculations, it's about 1200 lumens at 2A (350ma=220 lux=370 lumens, factor =1.68, 708*1.68=1190). Admittedly also ~35 lumens/watt at this high current, but that's the point of having a squirt mode, isn't it?

Matches fairly well with the P7 as well.


----------



## nein166

Hey jtr1962 I have a few M Bin MC-E I recently got from Amilite with an individually addressable star included free, do you feel like a visit?
If not I can throw it in the mail box.
Brian


----------



## motymen

Hello i saw this post liked it and i want to contribute 

i should have a bounch of 55000 mcd (25 degrees) i got from jeledhk

could i send a couple for testing?
M


----------



## saabluster

motymen said:


> Hello i saw this post liked it and i want to contribute
> 
> i should have a bounch of 55000 mcd (25 degrees) i got from jeledhk
> 
> could i send a couple for testing?
> M



Thanks for posting in this thread. You just reminded me I forgot to send the MC-E to him. Sorry guys. I'll get right on it.


----------



## Jarl

lol, there I am seeing a post by you and thinking "yes! Finally some results!" 

Take as long as you like, it's the quality that's important


----------



## space

jtr1962 : How/Have you calibrated your measuring setup? Do you have a known good reference of some sort?

I've copied your setup for measuring some of my LED's. I've a power supply with CC-regulation and I use a digital voltmeter (quite expensive Agilent 34940A + 34901A) for monitoring the Vf and current (using a shunt resistor). So I get fairly reliable readings for Vf and current but I use the cheap DealExtreme light meter for lux-measurments witch I don't believe to be to accurate.

The measurements I've done so far, seem to indicate that my calculated light outputs is roughly 30% lower than expected. (Measured some SSC P4 U-bins and some CREE XR-E R2-bins all bought at DX.) I wonder if anyone has a good suggestion for a cheep, known good reference that I could use for calibration. Is there anyone here with a calibrated setup that I can send one/some LEDs to for accurate measurement of light output?

(Will ad some photos of my setup as soon as my newly registered web domain is up and running.)


space


----------



## kappa_ii

hi
i want to built a lcd projector - and for light , insted of normal bulb , to use leds.
i find on ebay some leds , but i don`t know what color temperatur will be best and what size , cmd etc.

an exemple = this leds are good ? 
and how many for equal a normal light bulb of 400-600w ?
http://cgi.ebay.com/50-PCs-10mm-0-5...hZ021QQcategoryZ66954QQtcZphotoQQcmdZViewItem

thanks anticipated for help !


----------



## LEDninja

What kind of projector are you building?

Short answer NO using LEDs are not a good idea especially the type you linked to.
They are 5 to 25 lumens each. A 400W bulb is 4000+ lumens. So you need 160 to 800 of those LEDs to match the brightness.
5mm/10mm LEDs have trouble getting rid of heat so some will die very fast if you drive them hard for maximum brightness.

SSC-P7 & Cree MCE can give you about 700-800 lumens if heatsinked properly and driven hard. But to avoid problems in long term use it might be advisable to run them no more than 350 mA per die or 1.4A at 3.6V (the MCE can also do 700 mA at 7.2V or 350 mA) giving you ~440 lumens. You still need 9 or 10 to match a 400W bulb. An 3x3 array of LEDs will not focus well from a projectors lens.
If you can live with a dimmer projector (darkened room, small screen) you can use a single P7 or MCE or even the single die P4 or XRE (dimmer still but easier to focus / less artifacts)
Here is a sample of a commercial LED projector.
https://www.candlepowerforums.com/threads/212691

The other problem with LEDs is colour rendition.
Normal LEDs are very strong in blue with green & yellow. Purple cyan orange and red are weak. This gives it a very strong blue tint.
An incandescent bulb is weak in blue more cyan and green and strong in yellow orange and red. This gives it a very strong warm (yellow through red) tint.
Sunlight is weak in blue more cyan and strong in green yellow orange and red. This gives a neutral white tint.
There are high CRI LEDs that more closely match sunlight. The Nichia 083 used in the Sundrop for example.
https://www.candlepowerforums.com/threads/199058
There are other threads in the McGizmo subforum about that LED. Also contact McGizmo about how to get the LED.
A less expensive LED is the Cree Q2/Q3 5A. Not as wide a spectrum as the high CRI LEDs but at least have the proper amount (less) of blue.
https://www.candlepowerforums.com/threads/211450


----------



## saabluster

kappa_ii said:


> hi
> i want to built a lcd projector - and for light , insted of normal bulb , to use leds.
> i find on ebay some leds , but i don`t know what color temperatur will be best and what size , cmd etc.
> 
> an exemple = this leds are good ?
> and how many for equal a normal light bulb of 400-600w ?
> http://cgi.ebay.com/50-PCs-10mm-0-5...hZ021QQcategoryZ66954QQtcZphotoQQcmdZViewItem
> 
> thanks anticipated for help !


This should have been in a different thread. Do some searching and you will find other threads that are talking about LEDs in projectors and post this in there as it really does not pertain to this thread. :welcome:


----------



## Gryloc

Hello, fellows! I just wanted to be a squeaky wheel and ask about progress. I finally got my MC-Es from Cutter just before Christmas. A super busyness, as well as laziness, took me over since the holidays and I have barely participated here on the CPF. Sadly, I barely experimented with these new LEDs either! I have a feeling that many others have been super busy in the past month to do much on the CPF as well.

So, how have you been, jtr1962? Have you had the opportunity to test those P7 and P4 emitters? I am excited to see the results. saabluster, have you had the chance to send those MC-Es? I have some to send now if you are interested, jtr. I have one M10 MC-E (very white) and two J6 MC-Es (kind of pink-ish orange neutral white). They have been fired up with care lately, but have less than ten minutes of use at low current levels on each. 

I plan on using one of the neutral whites in a light mod project, but I am having second thoughts after noticing the unique tint and the odd optical qualities of the MC-E (It required lots of modding to the LOP reflector and still does not have the most pleasant beam). Thanks!

Cheers,
-Tony


----------



## jtr1962

Gryloc said:


> So, how have you been, jtr1962? Have you had the opportunity to test those P7 and P4 emitters? I am excited to see the results. saabluster, have you had the chance to send those MC-Es? I have some to send now if you are interested, jtr. I have one M10 MC-E (very white) and two J6 MC-Es (kind of pink-ish orange neutral white). They have been fired up with care lately, but have less than ten minutes of use at low current levels on each.


Since you asked the last month has been horrible. In late November my mom got the flu. Sick in bed for a week and then symptomatic for the next three. On December 12 I got it.    I guess sooner or later it had to happen living in the same house. A week in bed for me, and only now are most of the symptoms past. Actually this is the sickest I've even been in my life. I still feel weak, and my first bike ride in 3 weeks yesterday showed how much conditioning I lost. The only good part is my mom and I weren't sick at the same time, so each was able to care for the sick party and do the shopping. But the bottom line is between taking care of my mom, then getting sick myself, the last month was a loss.

It's best to wait until I test what you already sent me before sending me anything else. Besides your LEDs, I'm also be testing some Cree 5mm's which Holepuncher sent me. It looks like rain tomorrow. Maybe I'll stay in and devote the day to testing. It'll be a nice change of pace to being sick in bed.


----------



## LED_Thrift

Glad to hear you're on the upswing. Thanks again for the great work you've done here. I hope you have a great year.


----------



## jtr1962

I added the Cree 503B and cece718 3mm flat top white to the first post. Here is a repost of the results:

*Cree C503B-WAN-CCACB231 5mm white (acquired January 2009)*

CPF member *Holepuncher* sent me 3 samples of this LED for testing. These are Cree's brightest commercially available 5mm whites. The results were 26.9, 26.2, and 25.4 cd at 20 mA. These are speced for 23,500 to 32,900 mcd according to the datasheet, so the average of 26.17 cd is well within spec, although on the low side. Average beam angle was 15.1°, dead on the specified value of 15°. Color temperature was around 6500K, and the beam was extremely smooth. Average efficiency of the three samples was an excellent 79.2 lm/W at 20 mA. At 100 mA efficiency drops to 31.5 lm/W. Average output was 4.93 lumens at 20 mA, and average Vf was a low 3.11V. Corresponding figures at 100 mA were 12.36 lumens and 3.92V. Consistency between samples was great-outputs were 4.67, 5.16, and 4.97 lumens at 20 mA. Output doesn't scale as well with current as some other recent 5mm LEDs I've seen, but it's not horrible, either. Overall these appear to be great LEDs, and could be even better if they used Cree's best dice. Just doing some rough assumptions regarding phosphor conversion efficiency of 80% and package efficiency of 80%, I've calculated that these are using blue dice with an output of about 24 mW @ 20 mA. Cree's best dice produce 33 to 35 mW. This would produce a white LED of 110 to 115 lm/W, perhaps even as high as 125 lm/W in a wide-angle package.







*cece718 6000 mcd flat top 3mm white (acquired January 2009)*

I purchased 100 of these for use in model railroading lighting applications. These are the flat top 3mm LEDs sold on eBay by seller cece718. Color temperature is around 7000K, and the beam is very smooth. I knew these couldn't come anywhere close to their 6000 mcd spec given their wide angle. I measured 800 mcd at 20 mA. Output was 3.49 lumens and efficiency was an OK for nowadays 54.1 lm/W. Beam angle was a very wide 129°. Output doesn't increase much with current, and levels off at 5.91 lumens at 60 mA. This isn't surprising given the poorer thermal properties of the 3mm package, and in service I doubt I would run these LEDs over 10 mA. Overall, these LEDs aren't bad given their price. In fact, I was pleasantly surprised they performed as well as they did. It was only a few years ago that only the best LEDs managed 50 or 60 lm/W. Nowadays most commodity LEDs seem to reach that mark.


----------



## jtr1962

Gryloc sent me a pair of DSW0J Seoul Semiconductor P7s and one each of U2SW0H and U2SV0H P4s. One of the P7s appeared defective (it didn't light up until driven at around 1 amp, and output was reduced compared to the good one). Here are the results of the good P7:
















Output at 2800 mA is only a little lower than the speced value of 800 to 900 lumens. Note that I was able to reach nearly 1200 lumens at 7 amps. Unlike the last P7 test, this time around I always had a fan cooling the heat sink in order to maximize output.

Here are the results of the U2SW0H:
















Here are the results of the U2SV0H:
















The U2 bin is speced for 100 to 118.5 lumens. Both samples met this spec, although on the low side. Although not quite in the same league as Cree's best XR-E bins, these are close enough that most couldn't tell the difference by eye. Note that the efficiency of these really falls off above 1500 mA, and not much past 1500 mA the output levels off. At 2000 mA the output is quite a bit less, and the LEDs also turn an angry blue color. Hence, I only drove them a few seconds at that level.


----------



## jtr1962

space said:


> jtr1962 : How/Have you calibrated your measuring setup? Do you have a known good reference of some sort?
> 
> I've copied your setup for measuring some of my LED's. I've a power supply with CC-regulation and I use a digital voltmeter (quite expensive Agilent 34940A + 34901A) for monitoring the Vf and current (using a shunt resistor). So I get fairly reliable readings for Vf and current but I use the cheap DealExtreme light meter for lux-measurments witch I don't believe to be to accurate.
> 
> The measurements I've done so far, seem to indicate that my calculated light outputs is roughly 30% lower than expected. (Measured some SSC P4 U-bins and some CREE XR-E R2-bins all bought at DX.) I wonder if anyone has a good suggestion for a cheep, known good reference that I could use for calibration. Is there anyone here with a calibrated setup that I can send one/some LEDs to for accurate measurement of light output?


I checked my lightmeter in Silverfox's lightmeter benchmark tests and now apply a correction factor (x1.116) to my calculations. Also, a while back I measured some samples sent to me by evan9162. My results agreed with his to within a few percent despite using different meters and setups. Your results are probably off due to your light meter not giving accurate absolute measurements. I don't know if the lightmeter benchmark testing is still ongoing, but that's as good a way as any to calibrate your meter against known standards. Here's the link to the thread.


----------



## jtr1962

LED_Thrift said:


> Glad to hear you're on the upswing. Thanks again for the great work you've done here. I hope you have a great year.


Thanks for the warm wishes. :thumbsup: I certainly hope 2009 is better than 2008 for everyone.


----------



## Holepuncher

Nice work jtr1962. Dont know how you manage it all. I guess my nichias are the 27,000 mcd ones. I was wondering if you could explain something about your test setup. It would seem to me, at a distance of 1 meter, much of the light from the led would miss the sensor of your light meter. I know it works because all your numbers are in the ballpark.


----------



## tebore

That's some interesting results for the U2 bins. Seems like after almost 2 years Seoul hasn't improved much. 

Would it be possible to test some S2 bin High-CRI SSC P4s in the future? That seems to be the gaining some popularity. I'd send one except it's hard to even get a supplier to ship to Canada that allows you to select the bin.


----------



## saabluster

tebore said:


> I'd send one except it's hard to even get a supplier to ship to Canada that allows you to select the bin.


Have you tried Mouser?


----------



## tebore

saabluster said:


> Have you tried Mouser?


I have. The shipping was more than the LEDs and they didn't specify the color bin.


----------



## Holepuncher

Deleted because of my stupidity


----------



## saabluster

Nothing to see here. LA LA LA LA LA


----------



## jtr1962

Holepuncher said:


> Simply amazing. jtr1962 asks for some led's to do his testing. I send them to him no charge and spend time going to the post office to mail them. He does his testing (exquisite job) and posts his results. I followup with a question and he cant even respond. Makes you wonder about the caliber of some people on this forum.


Sorry about that. The LED forum is usually so busy that this thread gets bumped down a few pages within a day. A lot of times I miss new posts as a result. Also, sometimes I post results and it might be a few days before I get any comments. As a result, I usually don't check what's happening in this thread very often. And on occasion my carpal tunnel syndrome gets bad and I just can't type in order to give responses. Again, I apologize.

Believe me, you're not the only one I've taken a long time to respond to. And there have also been times when I've taken a really long time to test LEDs people sent me. For example, the LEDs Gryloc sent me I didn't get to for about six or seven weeks. I feel really bad about that, but first my mom was sick, then I was sick.



> Nice work jtr1962. Dont know how you manage it all. I guess my nichias are the 27,000 mcd ones. I was wondering if you could explain something about your test setup. It would seem to me, at a distance of 1 meter, much of the light from the led would miss the sensor of your light meter. I know it works because all your numbers are in the ballpark.


The LED is about 17.5" from the light meter sensor for most of my testing. I specifically choose this distance because when getting the beam profile I was measuring the relative output in 5° increments. At a distance of 17.5" my light meter sensor covers an angle of exactly 5°, so I effectively get an average of the intensity over that entire 5° cone. The only time I need to measure the LED intensity at 1 meter is when I'm getting the absolute measurements to scale my results. Here I just need to take one measurement at dead center, namely the hotspot. I use that to scale my results.

I just noticed that the links to the .zip files containing my spreadsheets in my first post are dead because RoadRunner eliminated the web space. I'll have to find somewhere else to host them. My apologies to all for that.


----------



## jtr1962

tebore said:


> Would it be possible to test some S2 bin High-CRI SSC P4s in the future? That seems to be the gaining some popularity. I'd send one except it's hard to even get a supplier to ship to Canada that allows you to select the bin.


I might order one or two to test next time I place an order with Mouser.


----------



## jtr1962

saabluster said:


> He has been very busy over in this thread and probably just hasn't come up for air yet. Keep in mind this thread is in the busiest of the forums and it is easy to overlook things in here. In all honesty it *really *should be in the LED forum and not here.


Those are exactly the reasons. Also there are times I'm just busy with work, and don't visit CPF at all for a week or two. In addition, this thread holds interest for only a fairly limited number of people. Sometimes it won't get new posts for weeks. I usually try to check it once a week or so but sometimes I might miss a few weeks.

Thanks BTW for the support here and in the other thread. I really appreciate it.


----------



## Holepuncher

Ok I deleted my post. I had a bad day here yesterday with snow. My friend that usually plows me out had his truck break down. I get out my normally super reliable Toro snowblower and the belt breaks 5 minutes later. After running around for 2 hours trying to buy a belt with no success I just shoveled everything. After it was done, an hour later it started snowing again (4 more inches) At that point it was time to hit the bottle. 2 beers and a little scotch. Even so there is no exuse for my words. I apologize.


----------



## jtr1962

Holepuncher said:


> Ok I deleted my post. I had a bad day here yesterday with snow. My friend that usually plows me out had his truck break down. I get out my normally super reliable Toro snowblower and the belt breaks 5 minutes later. After running around for 2 hours trying to buy a belt with no success I just shoveled everything. After it was done, an hour later it started snowing again (4 more inches) At that point it was time to hit the bottle. 2 beers and a little scotch. Even so there is no exuse for my words. I apologize.


Thanks. Apology accepted. We all have bad days, and yesterday sounded like a doozy for you.


----------



## Holepuncher

jtr1962 said:


> I just noticed that the links to the .zip files containing my spreadsheets in my first post are dead because RoadRunner eliminated the web space. I'll have to find somewhere else to host them. My apologies to all for that.




If you want I can set up 5Mb of webspace on my verizon account that you can upload to with FTP software.


----------



## jtr1962

Holepuncher said:


> If you want I can set up 5Mb of webspace on my verizon account that you can upload to with FTP software.


I just checked and the reason for the dead links is because Road Runner changed servers. I do have 25 MB of web space according to them. I just need to set it up, upload my files, and change the urls. Thanks for the offer however. :twothumbs It's greatly appreciated.


----------



## Holepuncher

jtr1962 said:


> Thanks. Apology accepted. We all have bad days, and yesterday sounded like a doozy for you.



Thanks jtr. I feel like a dunce. Part of my doozy day was my own fault. During last weeks snow storm here I noticed that the snowblowers belt was slipping. But did I fix it then? I guess I'm a dunce all around.

I'll probably be doing a Digikey order this week and I'll get 10 of those 110 deg crees you mentioned and send 5 to you. And I'll send a few more of the other Cree's for the degradation test when you have time.


----------



## jtr1962

I uploaded the .zip files with my spreadsheets to my box.net account. Here are the new links:

New link for LED test spreadsheets

New link for power LED test spreadsheets

Links also fixed in first post of thread.


----------



## jtr1962

Holepuncher said:


> I'll probably be doing a Digikey order this week and I'll get 10 of those 110 deg crees you mentioned and send 5 to you. And I'll send a few more of the other Cree's for the degradation test when you have time.


Great! I look forward to doing the tests!


----------



## milkyspit

jtr1962 said:


> I might order one or two to test next time I place an order with Mouser.




Or you could ask your buddy milky for one! Got a couple things to discuss with ya anyway. If you place the call, I'll pledge to send you a SSCP4 S2-4000K-93CRI! 

BTW, on the web server thing... you might want to get something setup with Google Sites, where I'm pretty sure you'll get a LOT of space. If you register a domain (or already have one) then setup to point to Google, you can route your web services through there at no additional charge... so including domain registry at GoDaddy (for example), I'd guess you're looking around $10 per year. Not bad IMHO!


----------



## Holepuncher

saabluster said:


> Nothing to see here. LA LA LA LA LA


 

:thumbsup: I owe you one.


----------



## jtr1962

milkyspit said:


> Or you could ask your buddy milky for one! Got a couple things to discuss with ya anyway. If you place the call, I'll pledge to send you a SSCP4 S2-4000K-93CRI!


Good idea-it's been a while since we chatted anyway. I'll call sometime this week.



> BTW, on the web server thing... you might want to get something setup with Google Sites, where I'm pretty sure you'll get a LOT of space. If you register a domain (or already have one) then setup to point to Google, you can route your web services through there at no additional charge... so including domain registry at GoDaddy (for example), I'd guess you're looking around $10 per year. Not bad IMHO!


This sounds like a good idea also. $10 a year-even I can afford that. LOL


----------



## Gryloc

jtr,

How have you been? I have been meaning to reply to your testing (SSC P4s and P7s), but I have been super lazy the past couple months.  I know, it is quite a pathetic excuse. Actually it is quite sad because I worked with my flashlight mods and LEDs in the past month just as much as I posted here.

Thank you for testing those LEDs. It is nice seeing multiple tests of of the same emitter, and it really allows it to sink in how awesome the P7 really is. I love how the P7 is so efficient at 1400mA due to the parallel dies. The P4s are very nice as well, even if many around here believe that the XR-E R2s are supreme. I have grown used to my T-binned TFFC K2s (200lm min @1A -which are wonderful), so it is nice to see that the U2-binned SSC P4s perform better. I do have three nice R2s sitting in a bin, waiting for a project. I need better optics for XR-E emitters, and I am too cheap to purchase three of the nice McR-XXC series reflectors at the Shoppe. I just love the beam of a single die-lambertian emitter behind the good ol IMS SO20XA (I am old school I guess). Maybe I will have to get some R2 XP-E emitters...

You mentioned that the U2 binned P4s became angry blue at 2000mA, but how did they fare between 1000mA and 1500mA? It is too bad (even though somewhat expected) that the total flux started dropping befor current reached 2A. I wonder why it performs more poorly (as in hitting peak flux before decreasing with higher currents) than a Lumileds K2, considering the P4 has the die bonded directly to a copper slug. 1.5A is a comfortable current for a K2, and they are not bothered by 2A one bit. I noticed that my TFFC K2s never had problems with 2.5A in some tests (tested for only several minutes).

I still think that your work is amazing. It seems as though few at the CPF appreciate actual lumen measurements for these common emitters. Your figures are wonderful when I begin designing a new lighting device or preparing for a mod. Could a moderator please move this to the LED section where it belongs? How about making it a sticky in addition? I do not understand why such a thread as this was never made a sticky, at minimum, in the LED flashlights section. :thinking:

Just a thought: PhotonFanatic is selling TVOD TFFC K2 emitters (200 min lumens @ 1A), and TNC_Products is selling UWOE TFFC K2 emitters (220 min lumens @ 1A) over in the Marketplace. Could I send a couple your way for testing down the road? I use the TUME K2 emitters, and I love the creamy tint and the low Vf qualities, so I think that these would be just as nice. I believe that decent TFFC K2s can finally be had by all now (after many had a bad taste in their mouth from the TFFC K2's high Vfs in the past). 

Oh, did anyone have the chance to send jtr a MC-E emitter? I have a JE6 bin 320lm @350mA Warm White MC-E emitter on a star (I wired it in series) available for testing if you are interested. I bet there would be more interest in the 430lm cool white MC-Es, but you never know. Just PM if you are interested in some new TFFC K2s or a WW MC-E.

Again, thank you for your hard work and your time put into those Seoul P7 and P4 emitters! :thumbsup: :twothumbs


Cheers,
-Tony

EDIT: Thanks for providing xls spreadsheets showing all of your data. I will value these files like gold. They will be wonderful sources of info in case something tragic happens with CPF, or if we fail to pay the bill for our DSL.


----------



## jtr1962

Gryloc said:


> jtr,
> 
> How have you been? I have been meaning to reply to your testing (SSC P4s and P7s), but I have been super lazy the past couple months.  I know, it is quite a pathetic excuse. Actually it is quite sad because I worked with my flashlight mods and LEDs in the past month just as much as I posted here.


Better than in December but it seems lately I have a cold I just can't quite shake. No fever but I've been sleeping a lot more than usual. Anyway, we all need to take a break from our hobbies once in a while. That sounds like what happened with you. I know my interest here goes in cycles. Sometimes I'll fanatically play around with LEDs. Other times a month or two will go by that I don't touch a light.



> Thank you for testing those LEDs. It is nice seeing multiple tests of of the same emitter, and it really allows it to sink in how awesome the P7 really is.


Yep, the P7 amazed me first time I played with one. After that even Cree R2s look pathetic by comparison.



> You mentioned that the U2 binned P4s became angry blue at 2000mA, but how did they fare between 1000mA and 1500mA? It is too bad (even though somewhat expected) that the total flux started dropping befor current reached 2A. I wonder why it performs more poorly (as in hitting peak flux before decreasing with higher currents) than a Lumileds K2, considering the P4 has the die bonded directly to a copper slug. 1.5A is a comfortable current for a K2, and they are not bothered by 2A one bit. I noticed that my TFFC K2s never had problems with 2.5A in some tests (tested for only several minutes).


The P4s did OK until maybe 1200 or 1300 mA. They didn't start to turn angry blue until past 1500 mA but as you can see their output started leveling off well before then. No idea why except perhaps the die isn't as well coupled thermally to the copper slug as with the K2.



> I still think that your work is amazing. It seems as though few at the CPF appreciate actual lumen measurements for these common emitters. Your figures are wonderful when I begin designing a new lighting device or preparing for a mod. Could a moderator please move this to the LED section where it belongs? How about making it a sticky in addition? I do not understand why such a thread as this was never made a sticky, at minimum, in the LED flashlights section. :thinking:


Thanks, and let's hope a mod agrees with you as this thread usually ends up being bumped down fairly quickly in the LED flashlights section.



> Just a thought: PhotonFanatic is selling TVOD TFFC K2 emitters (200 min lumens @ 1A), and TNC_Products is selling UWOE TFFC K2 emitters (220 min lumens @ 1A) over in the Marketplace. Could I send a couple your way for testing down the road? I use the TUME K2 emitters, and I love the creamy tint and the low Vf qualities, so I think that these would be just as nice. I believe that decent TFFC K2s can finally be had by all now (after many had a bad taste in their mouth from the TFFC K2's high Vfs in the past).


Sure, no problem sending me a few to test. I haven't yet tested recent K2s. I'm particularly curious as to how high a current they can handle.



> Oh, did anyone have the chance to send jtr a MC-E emitter? I have a JE6 bin 320lm @350mA Warm White MC-E emitter on a star (I wired it in series) available for testing if you are interested. I bet there would be more interest in the 430lm cool white MC-Es, but you never know. Just PM if you are interested in some new TFFC K2s or a WW MC-E.


I haven't received an MC-E for testing yet, so a warm white one is welcome. PM on the way regarding this and the K2s.



> Again, thank you for your hard work and your time put into those Seoul P7
> and P4 emitters! :thumbsup: :twothumbs


As always, glad to be of some help here! And also glad the spreadsheets came in handy!


----------



## EntropyQ3

Hi.
A bump and a request.
The request being that you do more fine-grained testing of the powerLEDs at the lowest currents. All non-PWM lights have an interest in not falling off the efficiency peak to the left, so knowing exactly where it is would be quite useful - 5mA, 10mA, 15mA, 20mA? This could help determine where the lowest output level would fall for a current controlled light.

Also wanted to say that this is the thread on CPF that I keep coming back to over and over again to check different aspects of different emitters. A wonderful resource! :wave:


----------



## jtr1962

EntropyQ3 said:


> Hi.
> A bump and a request.
> The request being that you do more fine-grained testing of the powerLEDs at the lowest currents. All non-PWM lights have an interest in not falling off the efficiency peak to the left, so knowing exactly where it is would be quite useful - 5mA, 10mA, 15mA, 20mA? This could help determine where the lowest output level would fall for a current controlled light.


I'll see if I can do this in the future. Note however that it presents a measurement problem. Generally since power LEDs are wide angle emitters by the time I get down to 20 mA the output is only a few lux at 1 meter. Since my meter on its lowest setting has a resolution of 0.1 lux this introduces some granularity into the measurements. Next few tests I'll try measurements at very low currents and see if I get anything interesting. I vaguely remember when testing a Rebel 100 that the efficiency peaked at ~150 lm/W at 20 mA, and then remained more or less flat until about 3 or 4 mA, at which point it started dropping. Of course, the limited resolution of my meter made these measurements less than than precise.



> Also wanted to say that this is the thread on CPF that I keep coming back to over and over again to check different aspects of different emitters. A wonderful resource! :wave:


Thanks for the compliments!


----------



## jtr1962

I just looked at an old PM where someone requested that Rebel 100 test at very low currents which I mentioned in the post above. Here were the results:

1 mA: 117.0 lm/W
5 mA: 147.4 lm/W
10 mA: 152.1 lm/W
15 mA: 152.4 lm/W
20 mA: 150.7 lm/W
25 mA: 149.5 lm/W
30 mA: 148.0 lm/W
40 mA: 145.4 lm/W

Efficiency does remain more or less flat from 30 mA down to 5 mA, at which point in takes a dive. Remember also that regardless of efficiency levels, at some point the current and therefore power input to the LED is so low that light output isn't enough to be useful. For example, at 5 mA you're only getting about 1.9 lumens. Even if efficiency didn't drop you would be getting about 1/3rd of a lumen at 1 mA-not enough to be useful for much of anything. Also, at very low currents the efficiency of most drivers drops dramatically because the supply current to the driver chip becomes an appreciable fraction of the total power. Of course, some drivers are better than others in this regard. Therefore, even if LED efficiency remains flat or increases at low currents, overall _system efficiency_ may still drop, making stepping down current further pointless (except perhaps to extend battery life).


----------



## padmab

Hi,

I came accross this forum when I was searching for LED manufacturers. The information you have been posting on this forum is greatly useful. I am looking for an equivalent led for the one attached below. I am currently buying this from besthongkong. This LED is currently used by us for home lighting applications where LUMENS and Life of the lamp are critical requirements. Can you recommend good alternatives for this ? Thank you in advance for your help 

THe LUMEN requirement is 180 + Lumens
2 Watt Power draw or less
12 V input supply voltage (10.5 to 13 V range )
No reverse polarity protection required 

Click on the link below for image
http://img38.imageshack.us/i/ledimage.jpg/


----------



## DM51

Somehow, this thread has found its way into the wrong forum - perhaps during the CPF restructuring a while back. It is still a very good reference thread. I'm moving it to the LED forum.


----------



## jtr1962

DM51 said:


> Somehow, this thread has found its way into the wrong forum - perhaps during the CPF restructuring a while back. It is still a very good reference thread. I'm moving it to the LED forum.


Thanks. :twothumbs The LED forum is really where this thread belongs.


----------



## saabluster

WOW! Its about time. Thanks DM!


----------



## DM51

saabluster said:


> WOW! Its about time.


Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced. I remember the thread from quite some while ago, but I can't remember seeing the more recent revivals. As I said above, this one probably wound up in the wrong place by accident, during forum reorganisation or in some such way.

It is not possible for CPF staff to read every single post, or continually monitor every single thread. We rely a lot on members reporting things to us, whether it is a case of misbehavior or a post in the wrong forum. I see there was some comment a few posts above to the effect that this thread kept being bumped down the list too quickly, and there was even the wish correctly expressed that it should be moved from LED Flashlights to LED; but no report or request about this was sent to moderators as far as I can remember, or one of us would have moved it.

Sometimes misplaced posts and even threads just do slip through the net unnoticed. If members see something that needs doing, the solution is to report it directly, giving details of your request or suggestion, either by using the "report post" button, or by PM to a staff member.


----------



## saabluster

DM51 said:


> Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced. I remember the thread from quite some while ago, but I can't remember seeing the more recent revivals. As I said above, this one probably wound up in the wrong place by accident, during forum reorganisation or in some such way.
> 
> It is not possible for CPF staff to read every single post, or continually monitor every single thread. We rely a lot on members reporting things to us, whether it is a case of misbehavior or a post in the wrong forum. I see there was some comment a few posts above to the effect that this thread kept being bumped down the list too quickly, and there was even the wish correctly expressed that it should be moved from LED Flashlights to LED; but no report or request about this was sent to moderators as far as I can remember, or one of us would have moved it.
> 
> Sometimes misplaced posts and even threads just do slip through the net unnoticed. If members see something that needs doing, the solution is to report it directly, giving details of your request or suggestion, either by using the "report post" button, or by PM to a staff member.



I didn't report it because this is what it says when you click on the tab to report.
*
"Note*: This is ONLY to be used to report spam, advertising messages, and problematic (harassment, fighting, or rude) posts."

It does not seem to follow these guidelines. I will make a note to myself to include this exception. I also thought it would be presumptuous on my part to make a formal request that the thread be moved since it was not my thread.

Due to extremely valuable information within this thread it is my recommendation that it be a sticky. It deserves to be there and would certainly be a help to the many CPF users old and new alike. Thanks again.:thumbsup:


----------



## saabluster

padmab said:


> Hi,
> 
> I came accross this forum when I was searching for LED manufacturers. The information you have been posting on this forum is greatly useful. I am looking for an equivalent led for the one attached below. I am currently buying this from besthongkong. This LED is currently used by us for home lighting applications where LUMENS and Life of the lamp are critical requirements. Can you recommend good alternatives for this ? Thank you in advance for your help
> 
> THe LUMEN requirement is 180 + Lumens
> 2 Watt Power draw or less
> 12 V input supply voltage (10.5 to 13 V range )
> No reverse polarity protection required
> 
> Click on the link below for image
> http://img38.imageshack.us/i/ledimage.jpg/


First off we need to know what your CRI or color temp requirements are.


----------



## HarryN

Hi JTR- Thank you very much for all of the work and somehow managing to keep it all organized. I have done some very simple testing in the past, and just keeping the data straight is a major task. This thread and the spreadsheets are incredibly useful and interesting.

DM51 - Thank you for all of your efforts with housekeeping on the forum.

Gryloc - One of the lesser promoted features of the K2 is its "anti drooping" epi technology. PL has presented on this at several conferences in the past, but perhaps not very well in their literature.

In a nutshell:
- The die are "less sensitive" to color shifting vs current than in the past, which was already pretty decent
- The die are "less sensitive" to output vs temp than in the past, which used to be kind of average, and now seems to be quite good.
- The die are tested at the stated current (typicall 1000 ma or 1500ma) for color binning. More or less, this makes the color binning more accurate than if they were testing at 350ma.

Perhaps this is part of the reason for the mentioned performance.

JTR - I am probably just somehow missing it, but I could not find the K2 or K2 TFFC results in the thread or on the spreadsheets. (might just be from too much time with flashlights  ) Could someone point me to the likely obvious location for the plots - or perhaps JTR - do you need some K2s or LEDEngin LEDs ?


----------



## DM51

saabluster said:


> Due to extremely valuable information within this thread it is my recommendation that it be a sticky.


Done.


----------



## Calina

HarryN said:


> JTR - I am probably just somehow missing it, but I could not find the K2 or K2 TFFC results in the thread or on the spreadsheets. (might just be from too much time with flashlights  ) Could someone point me to the likely obvious location for the plots - or perhaps JTR - do you need some K2s or LEDEngin LEDs ?


 
You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.


----------



## spencer

There are multiple tests for power LEDs throughout this thread. You just have to look for them. 

Very nice on the sticky idea.


----------



## HarryN

spencer said:


> There are multiple tests for power LEDs throughout this thread. You just have to look for them.
> 
> Very nice on the sticky idea.



Hi, I have followed JTR's work for some time. Last night and today I went back and read the last 200 posts, as well as downloaded and read both of the zip files. Last but not least, I did a search for K2 and K2 TFFC. At that point, I offered to help JTR with some samples (that I would buy)

I am not saying it is not there, but while I could find rebel and Lux III info, I did not find K2 TFFC info, nor any LEDEngin info. If someone happens to remember what post number it is, please let me know.

Thanks

HarryN


----------



## TorchBoy

*Re: White 3mm, 5mm, 10mm LED lumen testing*



Calina said:


> You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.


Could that be reflected (no pun intended) in the thread title?


----------



## Calina

If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.

Great thread by the way and thanks to DM51 for making it a sticky.


----------



## TexLite

DM51 said:


> Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced.



I always did a search for the thread title, I never looked through the appropriate sub-forum.

Maybe others were doing the same.

Thanks for the forum switch and the sticky DM51. 



Calina said:


> You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.





TorchBoy said:


> Could that be reflected (no pun intended) in the thread title?





spencer said:


> There are multiple tests for power LEDs throughout this thread. You just have to look for them.
> 
> Very nice on the sticky idea.





Calina said:


> If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.
> 
> Great thread by the way and thanks to DM51 for making it a sticky.



As Spencer noted, there are multiple power LED's in this thread, even multi-die emitters.

Maybe links in the first post to the different individual posts of the different emitters would be helpful.

Another alternative would be to click on the individual post number and bookmark the "view single post".

And many thanks to jtr1962 for all the hard work and for the highly informative thread. Congratulations on the sticky.

-Michael


----------



## jtr1962

HarryN said:


> Hi, I have followed JTR's work for some time. Last night and today I went back and read the last 200 posts, as well as downloaded and read both of the zip files. Last but not least, I did a search for K2 and K2 TFFC. At that point, I offered to help JTR with some samples (that I would buy)
> 
> I am not saying it is not there, but while I could find rebel and Lux III info, I did not find K2 TFFC info, nor any LEDEngin info. If someone happens to remember what post number it is, please let me know.


No, I didn't do any tests on the K2, K2 TFFC, or LEDEngin but if you want to send me samples I'll be happy to do so. Thanks also for the compliments and your ongoing interest in this thread. :thumbsup:



Calina said:


> If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.


I'll reedit the first post so that the power LED information is more readily accessible. When I first started this thread, I had no intention to test power LEDs but one thing led to another (no pun intended). Now with smaller LEDs seemingly in a state of stagnation with few new products worth testing, I suspect that the bulk of my future testing will be power LEDs. As such, I agree the information should be more readily accessible without needing to look through some 300 posts. I just need to find the time to do so as my free time has been in pretty short supply the last 2 months.

BTW, thanks to the mods for making this thread a sticky, and to those fellow CPFers who asked for it to be made one. The work is still ongoing even if a little sparse lately. :twothumbs

Almost forgot to ask the mods-is the 10,000 word post limit still in force? Unfortunately, I can't edit the first post or reorganize any info there so long as this is the case since it will cause a lot of the info to be lost.


----------



## saabluster

jtr1962 said:


> Almost forgot to ask the mods-is the 10,000 word post limit still in force? Unfortunately, I can't edit the first post or reorganize any info there so long as this is the case since it will cause a lot of the info to be lost.


No. You can edit away.:twothumbs


----------



## padmab

saabluster said:


> First off we need to know what your CRI or color temp requirements are.



Hi Thank you very much for your reply.. My color requirements are as mentioned below 

Color: Pure White color Light
Temp requirement : 14000 to 15000 mcd

I was worried on seeing that my post has been moved to LED forum. I tried my level best to search my post through hundreds of posts in LED forum, but I couldn't find it. 

I am new to Candle power forums and it would be great if someone could help me find answer to my queries regarding good LED suppliers


----------



## saabluster

padmab said:


> Hi Thank you very much for your reply.. My color requirements are as mentioned below
> 
> Color: Pure White color Light
> Temp requirement : 14000 to 15000 mcd
> 
> I was worried on seeing that my post has been moved to LED forum. I tried my level best to search my post through hundreds of posts in LED forum, but I couldn't find it.
> 
> I am new to Candle power forums and it would be great if someone could help me find answer to my queries regarding good LED suppliers


It seems there is a misunderstanding of just what color temp is. May I suggest starting your own thread asking the above question so that the discussion may take place outside of this thread? It would be better as this is somewhat off topic here.


----------



## jtr1962

As requested, I collected all of my power LED tests in this post in chronological order and linked to it in the first post (link to original post by clicking the date).

Also, I'm repeating a message from the first post regarding LED recommendations as the volume of PMs I've received asking about which LED to use has gotten to be annoying:

*Although I have tested many LEDs in this thread, I am not in a position to recommend specific LEDs for use in flashlights or other devices to people. I feel the need to mention this because I have received quite a few PMs asking me which LED would be good for such and such project. I feel it would be best to start a new thread asking for LED recommendations rather than asking me. I just don't have the time or desire or ability to help people determine which LED to use in any given project.*

*08-09-2005*

I made a jig for testing power LEDs. Here are my results for a Q3J Luxeon, a Lamina BL-2000, a Seoul Semiconductor W32182 bin RSX0I star, and a Cree 7090 XR-E bin P4:



















Here are the relevant spreadsheets.

I have 5 Q bin Luxeons. Four of them seem about equal in brightness and the fifth is about 10% dimmer. Assuming then that the dim one is at the low end of the Q-bin (say 31 lumens), then the other ones should test in the mid 30s. My results give me 37.1 lumens, a little past the middle of the Q-bin. I think this more or less verifies the accuracy of my methods. At worst my results are less than 10% too high.

*12-03-2006*

Cree 7090 XR-E bin P4 (purchased November 2006)

I purchased these from CPF member Erasmus. These are tint bin WH and flux bin P4 (80.6 to 87.4 lumens at 350 mA). The color temp of these seems a close match for my 5000K fluorescents which makes the WH bin perfect for interior lighting although perhaps a bit warm for flashlights. I measured the 50% beam angle at 95.3° which is somewhat wider than the 75° given on the spec sheet. Despite the out of spec beam angle, the overall flux at 350 mA is 85.67 lumens which is within the range of the P4 bin (and also a verification of the accuracy of my methodology). Vf at 350 mA is 3.25V and overall efficiency is a very impressive 75.37 lm/W. Even at 700 mA efficiency remains above 60 lm/W. Luminous flux at 500 mA is about equal to the Lamina Ceramics BL-2000 arrays but the power input is only around 1.7 watts instead of the 4.7 or so watts used by the Lamina array. Although these obviously aren’t a 20 mA part if they were they would break previous records by a huge margin, coming in at nearly 112 lm/W. There’s really nothing more to say about these than hasn’t already been said by me and many others. They represent a huge step forwards in LED technology.

Here is the efficiency versus current chart:






*02-04-2007*

I finally got around to testing the two Cree XR-E emitters 3rd_shift sent me. The purpose of this test was to determine the difference between an emitter with and without the dome. The unmodified Cree XR-E bin P2 emitter tested as follows:






Output was 70.67 lumens at 350 mA. This is right in the middle of the P2 bin (67.2 to 73.9 lumens). The same bin emitter with the dome removed only had an output of 54.35 lumens at 350 mA. The beam angle was wider as well (122° versus 83.3° for the unmodified emitter). The relative intensity versus angle for the two emitters is shown below (domeless emitter in magenta):






Apparently the silicon encapsulant combined with the dome helps to extract a considerable amount of light from the die. The output of the domeless emitter is 24% less than the stock emitter.

*02-04-2007*

Seoul Semiconductor W42180 bin U (tested February 2007)

I purchased a U bin Seoul Semiconductor emitter from milkyspit recently. The results of the test are shown below:






I believe the results speak for themselves. The efficiency at 350 mA is a very impressive 82.1 lm/W and the output is 96 lumens. This is a new record for power LEDs and also matches my best results for single die 5mm LEDs. Beam angle is close to 130° which means these have a light distribution similar to a Luxeon emitter. Since the emitter is rated for 1000 mA I felt comfortable going to 1500 mA, at which point output more or less leveled off. The output scales with current almost identically to the Cree XR-E bin P4 which I tested in December but this is no surprise since both emitters use the same die. Note that the U bin has a range of 91 to 118.5 lumens so these are at the low end (which I expected). I anticipate that the Cree XR-E Q3 bins will offer similar results. Shown below is a chart of Vf, power, and lumens at various currents.






*09-04-2007*

*Lumileds Rebel White LXML-PWC1-0100 (acquired July 2007)*

*Note: Earlier results multiplied by correction factor of 1.116 and post edited accordingly (See post #138 for explanation).*

I purchased a pair of these from Future Electronics for evaluation. I only tested one of the two samples. Color bin was not specified, but these are similar in color to the WH Crees, so I'd guess that they are V0s. I soldered the Rebel to a small length of brass bar with two holes drilled in the ends. I screwed the bar to my heat sinked power LED test jig with some thermal grease at the interface for better heat transfer. Beam angle measured 100.1°, a bit narrower than Luxeon IIIs, and the beam pattern is close to, but not exactly, lambertian. In the course of testing I learned how important it is to keep the lens of these LEDs clean. My initial test results gave roughly 91 lumens at 350 mA. I tried cleaning the lens with alcohol and then rerunning the tests. The final results were 96.7 lumens at 350 mA, but I later determined that I needed to apply the correction factor for my light meter. This revised the results to 107.9 lumens which is within spec. At 700 mA the Rebel put out 183.1 lumens, just about dead on the specified 180 lumens. Output continued to increase with current, reaching over 290 lumens at 1500 mA, which is as high as my current source goes. Moreover, the output curve wasn't entirely flattened out, even at 1500 mA. I would guess that output would continue to increase to 2 amps, albeit not very much over the output at 1.5 amps. Vf was extremely low and didn't rise very fast with current. It was 3.14V at 350 mA but only 3.43V at 1500 mA. Efficiency at 350 mA was 98.2 lm/W, a new record for power LEDs, and tantalizingly close to the magic 100 lm/W. Interestingly, with the apparent stagnation in small LED efficiency since early 2006, power LEDs are now actually more efficient than indicator-type LEDs. Moreover, efficiency at 1000 mA, the maximum specified operating current, was still a very decent 69.4 lm/W, about on par with CFLs, and stayed above 56 lm/W even at 1500 mA. Maximum efficiency was reached at 20 mA, and it was an incredible 150.7 lm/W. This translates into a conversion efficiency of over 45%. Efficiency remained above 100 lm/W until around 325 mA. Overall the Rebels have broken all previous records, but I suspect their time on top will be short-lived as I have yet to acquire the Cree XR-E Q5s for testing.


Original post:

_I purchased a pair of these from Future Electronics for evaluation. I only tested one of the two samples. Color bin was not specified, but these are similar in color to the WH Crees, so I'd guess that they are V0s. I soldered the Rebel to a small length of brass bar with two holes drilled in the ends. I screwed the bar to my heat sinked power LED test jig with some thermal grease at the interface for better heat transfer. Beam angle measured 100.1°, a bit narrower than Luxeon IIIs, and the beam pattern is close to, but not exactly, lambertian. In the course of testing I learned how important it is to keep the lens of these LEDs clean. My initial test results gave roughly 91 lumens at 350 mA. I tried cleaning the lens with alcohol and then rerunning the tests. The final results were 96.7 lumens at 350 mA. Since this is less than Lumiled's tolerance for lumen measurement this is still within spec. More importantly, at 700 mA the Rebel put out 179.63 lumens, just about dead on the specified 180 lumens. Output continued to increase with current, reaching over 260 lumens at 1500 mA, which is as high as my current source goes. Moreover, the output curve wasn't entirely flattened out, even at 1500 mA. I would guess that output would continue to increase to 2 amps, albeit not very much over the output at 1.5 amps. Vf was extremely low and didn't rise very fast with current. It was 3.14V at 350 mA but only 3.43V at 1500 mA. Efficiency at 350 mA was 88.0 lm/W, a new record for power LEDs. Interestingly, with the apparent stagnation in small LED efficiency since early 2006, power LEDs are now actually more efficient than indicator-type LEDs. Moreover, efficiency at 1000 mA, the maximum specified operating current, was still a very decent 62.2 lm/W, about on par with CFLs, and stayed above 50 lm/W even at 1500 mA. Maximum efficiency was reached at 20 mA, and it was an incredible 135 lm/W. This translates into a conversion efficiency of over 40%. Efficiency remained above 100 lm/W until 200 mA. Overall the Rebels have broken all previous records, but I suspect their time on top will be short-lived as I have yet to acquire the Cree XR-E Q5s for testing.
_




















*10-01-2007*

Relevant description of change in methodology:

I changed my setup somewhat immediately before the tests of the Rebel 100 and the Hebei LEDs. I set up a series of baffles and totally enclosed them to block out any ambient light:






I even put a removeable cover to block ambient light near the light meter:











The purpose of these modifications was to eliminate guestimating the background light which needed to be subtracted from the light meter reading. For 5mm LEDs this was at most about 0.5 lux, but for power LEDs it was considerably more. Prior to this, I would block out the direct portion of the beam with a piece of cardboard, note the reading, then subtract it from the unblocked reading. This method always bothered me because it introduced another variable. While the background reading was fairly steady, it did vary enough depending upon the placement of the cardboard to cause concern. Hence my use of the term guestimating at the start of this paragraph. The modified setup introduces consistency. When I block off the small hole where light enters from the LED, the reading is at most 0.1 lux, even in a undarkened room. I still do my testing in a darkened room, but with the new setup I don't have to!

Now this is all good and well except that when I tested the Rebel 100 I was getting somewhat less than the minimum of 100 lumens (96.7 lumens @ 350 mA to be exact). However, according to the results of the CPF light meter testing which I had participated in my light meter was reading low for white LED light. The correction factor was 1.116. I applied the correction factor to my Rebel 100 results in post #127 and the numbers are more in line with what I should have gotten.

The only question remaining was whether or not I could reliably compare my earlier results with my new ones. To answer this question I decided to retest the P4 bin Cree XR-E which I had tested last November. The original results were 85.67 lumens at 350 mA. The _uncorrected_ results using the modified tester were 80.24 lumens at the same 350 mA. This was about 6.4% low. The corrected result was 89.55 lumens, within 4.5% of my original results. I also ended up with a somewhat narrower beam angle (new results in red, old in blue):






It seems then that although I did not apply any correction factors to my earlier results the inherent methodology resulted in slightly wider beam angles which more or less compensated for the lower absolute lux readings. Remember that all of my earlier power LED test results pretty much fell within the ballpark of where they were supposed to for a given bin. The only problem is that LEDs obviously come in different tints, and I suspect I would need different correction factors depending upon the tint. Based on the fact that my light meter was nearly dead-on with incandescent light, the correction factor would increase with increasing color temperature. However, since guestimating correction factors would make this testing more art than science, I'll stick to using the official correction factor of 1.116. The fact that my corrected result for the P4 Cree is a little high probably has to do with that LED being a warmer (WH) tint bin.

*10-01-2007*

*Cree 7090 XR-E Warm White bin P4 (acquired September 2007)*

I ordered some Q5 Cree XR-Es from CPF member *Erasmus*. Along with the Q5s Erasmus sent me a Cree XR-E warm white bin P4 for testing. The P4 bin is specified at 80.6 to 87.4 lumens at 350 mA. The color temperature looked like roughly 3300K, so I would say the tint bin was 7A. Since the color temperature was in the incandescent range, I didn't need to apply a correction factor. The output of 83.0 lumens at 350 mA is solidly within the P4 flux bin.

Results are shown below:
















*10-01-2007*

*Cree 7090 XR-E bin Q5 (acquired September 2007)*

I ordered 10 Q5 Cree XR-Es, bin WG, from CPF member *Erasmus*. The Q5 bin is specified at 107 to 114 lumens at 350 mA. The color temperature of the WG bin is roughly 6000K. The results are a little low (105 lumens at 350 mA), but remember that this is a cooler bin. My correction factor is probably a little too low for such a cool tint, and this is what accounts for the discrepancy. In any case, the difference between the actual measurement and the manufacturer's specification is less than 2%, and my setup is far from 100% accurate anyway. Even if this difference is real, it is well outside what would be noticeable with the eye.

Vf is 3.20V @ 350 mA, efficiency is a very impressive 93.7 lm/W. Note that this is a little less than the corrected results for the Rebel 100 (98.2 lm/W @ 350 mA). However, the Rebel's higher efficiency is nearly all due to its lower Vf (3.14V @ 350 mA), and the fact that it is a warmer tint (and hence reads a little higher on my light meter). Also note that despite the slightly lower output at 350 mA the Cree bests the Rebel in terms of raw output at higher currents (298.5 versus 290.5 lumens at 1500 mA). The Rebel 100 still has a slight edge in efficiency at 1500 mA (56.5 versus 54.7 lm/W) due to its Vf increasing less with current than the Cree Q5. I took the Cree all the way to 2000 mA and it managed 334 lumens.

Results below:
















*03-27-2008*

*Cree 7090 XR-E bin R2 (acquired March 2008)*

I borrowed an R2 Cree XR-E, bin WG, from CPF member *nein166* for testing. The R2 bin is specified at 114 to 122 lumens at 350 mA. The color temperature of the WG bin is roughly 6000K. The results are as show below:



















These results are nothing short of amazing! The output at 350 mA is nearly 122 lumens, well above any previous results for power LEDs at that current. Despite the middle of the road Vf of 3.31V, efficiency at 350 mA is still 105.3 lm/W. It remains above 100 lm/W past 400 mA. Even at 1000 mA, efficiency is nearly 75 lm/W. Things get even more interesting at low currents. Under 50 mA, efficiency hovers around 145 lm/W. This represents a wall-plug, or power-to-light conversion efficiency, of around 45%.

Output scales with current in pretty much the same manner as other XR-Es I've tested. At 1000 mA output is over 270 lumens. It approaches 400 lumens at 2000 mA. Cree has continued to raise the bar for LED performance. While we won't see as dramatic improvements as in the past, Cree has continued to squeeze every last ounce of perfomance from its XR-E line of LEDs. I expect we'll have R4 bins and beyond by this time next year.

*07-06-2008*

This was a test of a Cree XR-E R2 *saabluster* sent me mounted on a heat pipe attached to a copper plate:

I finally finished the testing. First order of business after drilling the holes and attaching the LED to my heat sink was to determine the nominal output the usual way. My results were 122.97 lumens at 350 mA, slightly above spec actually, but then again the margin of error for my testing is probably a few percent either way. Vf was a somewhat high 3.37V. Efficiency was 104.3 lm/W.

Next order of business was to begin increasing current until either the LED blew, or it didn't get any brighter. For this round of tests I used passive cooling. The heat pipe and copper plate spread the heat to the heat sink, which in turn dissipated it. The results were a little better than my usual setup. Apparently the heat pipe, or perhaps the combination of heat pipe and copper plate, did _something_. At 2 amps the output was 3.35 times the output at 350 mA, compared to 3.21 for the stock setup. The heatpipe provided a small (about 4%) advantage here. As I increased the current past 2 amps I was crossing my fingers for the LED to hold together. Finally at 2.5 amps the output stopped increasing. At 2.6 amps it was a little lower. Peak output was passive cooling was *436.7 lumens*. Vf at 2.5 amps was 4.22V, and total power input was 10.55 watts.

Obviously in the case of passive cooling you'll eventually reach a point of diminishing returns. However, it's a good indication of what a reasonably-sized flashlight body can do if you pump enough current into the LED. The next order of business was the ultimate output which the LED was capable of. To that end I set a large fan to actively cool the heat sink. Throughout the tests the temperature of the copper plate the LED was mounted on remained very close to room temperature. Once the temperature rise of the heat sink was factored out of the equation, I was able to get increasing output past 2.5 amps. The peak output was reached at 2.7 amps. At 2.8 amps it was a little less. The results at 2.7 amps were *453.9 lumens*, Vf was 4.32V, and a power input was 11.664 watts. This is the absolute maximum which this Cree R2 emitter can give under ideal cooling conditions.

Wanting to continue this "insanity", I bolted the copper plate and LED to the cold plate of one of my thermoelectric assemblies. By the time ice was starting to form on the plate, the LED was giving me *502 lumens* at 2.5 amps. Even though below ambient cooling was required, the 500 lumen barrier for a single emitter was finally broken. Even better, the emitter is none the worse for all the abuse it's been through. It didn't have to die in the name of science. :devil:

Here are some charts of the final results:

Lumen output using fan-cooled heatsink






Comparison of passive versus fan-cooled output






*10-20-2008*

*Seoul Semiconductor P7 Bin C (tested October 2008)*

I obtained a Seoul P7 of the highest brightness bin this week. The C bin is rated at between 740 and 900 lumens. For this test I epoxied the P7 to a 60mm heat sink. I tested the output with and without a fan cooling the heat sink. Here are the results:


























At the nominal current of 2800 mA the fan makes only a small difference. Output is 731 lumens without the fan, and 742 lumens with fan cooling. This is barely but still within ratings. Efficiency at nominal current is 70.7 lm/W, good but certainly not in the same league as the latest single-die Cree or Seoul LEDs running at a comparable current of 700 mA. However, that's to be expected since the thermal path per die for the P7 isn't as good as for the Seoul P4 or Cree XR-E. If you underdrive the P7 then you can get significantly greater efficiency. For example, at 1000 mA the efficiency is 97.9 lm/W, way better than even an R2 bin XR-E at that current, and output is 329 lumens, about 20% greater than the Cree at that current. At 350 mA the P7 can manage 115 lm/W and 125 lumens, both figures somewhat greater than the best single die LEDs. Efficiency peaks in the 125 lm/W area at currents under 100 mA. Output versus current actually remains linear to well under 10 mA, but with the slight drop in Vf you're only gaining a few percent efficiency compared to 100 mA.

The results when cranking up the current are interesting. Without the fan cooling the heat sink, the output levels off at 6 amps and 998 lumens. With the fan I was able to go to 7 amps and 1114 lumens, although the increase in output was flat from 6.8 to 7.0 amps. The increase from 6.5 to 6.8 amps barely registered on my light meter. Therefore, even with very good forced-air cooling there is no point taking the P7 past about 6.5 amps, and only then if you want to squeeze out every last lumen. In fact, if you consider that the eye can't detect brightness differences of 10%, then the absolute maximum current of the P7 should be no more than around 4.5 amps, even less with the heat sinking typically available in flashlight bodies. At 4.5 amps you will get about 1000 lumens with very good cooling. Note however that 1000 lumens is only 35% more than what the P7 will give you at its nominal current of 2.8 amps. The lumen increases from overdriving the P7 just aren't as dramatic as with single die LEDs. In a typical situation with less than stellar heat-sinking I doubt it even pays to go above the nominal 2.8 amp current.

*01-13-2009*

Gryloc sent me a pair of DSW0J Seoul Semiconductor P7s and one each of U2SW0H and U2SV0H P4s. One of the P7s appeared defective (it didn't light up until driven at around 1 amp, and output was reduced compared to the good one). Here are the results of the good P7:
















Output at 2800 mA is only a little lower than the speced value of 800 to 900 lumens. Note that I was able to reach nearly 1200 lumens at 7 amps. Unlike the last P7 test, this time around I always had a fan cooling the heat sink in order to maximize output.

Here are the results of the U2SW0H:
















Here are the results of the U2SV0H:
















The U2 bin is speced for 100 to 118.5 lumens. Both samples met this spec, although on the low side. Although not quite in the same league as Cree's best XR-E bins, these are close enough that most couldn't tell the difference by eye. Note that the efficiency of these really falls off above 1500 mA, and not much past 1500 mA the output levels off. At 2000 mA the output is quite a bit less, and the LEDs also turn an angry blue color. Hence, I only drove them a few seconds at that level.

*07-21-2009*

*Cree 7090 XP-E bin R2 (acquired May 2009)*

I borrowed an R2 Cree XP-E, from CPF member *nein166* for testing. The R2 bin is specified at 114 to 122 lumens at 350 mA. The color temperature of this sample was roughly 6500K. The results are as show below:
















These results are excellent! The output at 350 mA is nearly 114.6 lumens, meeting spec. Vf is a very low 3.13V and efficiency at 350 mA is 104.6 lm/W. It remains above 100 lm/W past 400 mA. At 1000 mA, efficiency is nearly 75 lm/W. Efficiency at very low currents peaks at around 133 lm/W around 40 mA. This isn't quite as good as the R2 XR-E samples I've testing. Also note that I've added a new test point at 10 mA for power LEDs so that the inflection point where efficiency drops shows up more clearly in my graphs. More interesting than the results at low current is the high current performance. Despite the tiny package, the XP-E does quite well at higher currents. At 1000 mA output is 252 lumens. At 2000 mA it reaches 330 lumens. While these figures aren't quite as good as the XR-E's ~270 and ~400 lumens, respectively, they are more than I expected given the XP-E's package size and thermal path. I'll also note that my mounting method was less than optimal. I attached the LED with Arctic Alumina thermal epoxy. Had it been soldered to the heat sink, I think my results would have been somewhat higher.

*07-21-2009*

CPF member *HarryN* arranged for several LEDs to be sent to me for testing. One was the LEDEngin LZ4-40NW10 10 watt neutral white star. The others were the K2 TFFC cool white -220 and the K2 neutral white -180. Here are the results:

*LEDEngin LZ4-40NW10 10 watt neutral white (acquired July 2009)*

The 10 watt LEDEngin is a 4-die series connnected LED designed for the general lighting market. The dome is about the same size as that of the SSC P7 and is translucent rather than clear. The output is speced at 400 lumens at 700 mA. Here are the test results:
















Color temperature looks to be around 4000K and beam angle is 90°, somewhat narrower than on most power LEDs but still fairly wide. Output at 700 mA meets spec almost exactly at 399.9 lumens. Vf is 13.96 V, or 3.49 volts per die, power input is 9.77 watts, and efficiency is only 40.9 lm/W. Keep in mind however that warm and neutral white LEDs generally don't perform as well as their cool white counterparts. Output doesn't scale much with current, leveling off at a bit over 500 lumens at 1300 mA. Overall the LEDEngin appears to be well made. It would be nice to see this product made with higher performing dice.

*Lumileds K2 TFFC neutral white -180 (acquired July 2009)*

This is the highest available bin of Lumiled's neutral white K2 presently available. The spec sheet does list a 200 lumen bin, but Future so far doesn't carry it. The 180 lumen spec is at a drive current of 1000 mA. Here are the results:
















Color temperature looks to be in the high 3000s. As can be seen, the K2 TFFC neutral white 180 exceeds the spec at 1000 mA with nearly 193 lumens. Lumileds also specifies typical figures of 85, 150, and 250 lumens at 350 mA, 700 mA, and 1500 mA, respectively. The test results at these respective currents were 86.8, 151.4, and 243.6 lumens, all either exceeding or very close to specification. Vf at 350 mA is 3.29 volts, and only rises to 4.03 volts at 2500 mA. This brings me to the area where I was most impressed with the K2. Its output scaled very well with current. While the scaling with current up to about 1500 mA was about the same as similar products from Cree, above 1500 mA was where the K2 shined (pun intended). Cree XR-Es typically level off in output once current gets slightly above 2000 mA. The K2 neutral white increased in output up to 2600 mA. It may have done even better if I had soldered it to the heat sink instead of using Arctic Alumina thermal epoxy. Peak output at 2600 mA was close to 285 lumens. Granted, this is only 14% more than the 1500 mA output, but it nevertheless indicates superior ability to deal with the thermal effects of higher current.

*Lumileds K2 TFFC cool white -220 (acquired July 2009)*

This is the highest available bin of Lumiled's cool white K2 presently available. The 220 lumen spec is at a drive current of 1000 mA. Here are the results:
















Color temperature is around 6000K and appears snow white, with no discernable tint. The K2 TFFC cool white 220 exceeds the spec at 1000 mA with over 227 lumens. Lumileds specifies typical figures of 105, 185, and 300 lumens at 350 mA, 700 mA, and 1500 mA, respectively. The test results at these respective currents were 101.8, 175.8, and 292.8 lumens, all less than but still within a few percent of specification. Vf at 350 mA is 3.28 volts, and only rises to 4.18 volts at 3100 mA. This again brings me to how well the output scales with current. The K2 cool white kept right on rising in output all the way to 3100 mA! It may have done even better if I had soldered it to the heat sink instead of using Arctic Alumina thermal epoxy. Peak output at 3100 mA was 390 lumens. This was over 33% more than the 1500 mA output. Good things are definitely occurring with the K2 TFFC's thermal management. Also interesting to note was that 350 mA efficiency was 88.6 lm/W. If Lumileds comes out with a -250 bin, then it should equal the Cree R2 at lower currents, and have dramatically better output at higher ones. Also noteworthy is that I accidentally spiked the current to about 3.6 amps with no ill effects on the emitter. The K2s are evidently quite robust.

Here is a chart of lumens versus current for the two K2s:






I also ran some tests under typical flashlight conditions. I decided to go with a 60°C constant baseplate temperature for these tests to simulate conditions in a typical flashlight. I used one of my thermoelectric cold plates in heat mode for my testing. Here are the results:

K2 Cool White -220






K2 Neutral White -180






LEDEngin LZ4-40NW10






The results are pretty much what I thought they would be except for the K2 neutral white. The K2 cool white lumens output more or less tracked the output at room temperature across the entire range, except scaled by a factor of roughly 92% to 94%. Same thing for the LEDEngin except the scale factor was closer to 90% over most of the range (although it did rise to 96% by 1300 mA which I thought was strange).

The K2 neutral white started out like the other two, holding at roughly 94% to 95% of room temperature output until maybe 1.7 amps. Above that the output dropped like a rock as seen in the chart. Yet at room temperature output continued to rise until about 2.6 amps (although this was still less than the 3.1 amps managed by the K2 cool white). Only thing I can think of here, since the dice are likely the same, is the phosphor. Perhaps the neutral white phosphor is a lot more temperature sensitive. That would explain my results here, and also to a lesser degree the results at room temperature where the neutral white maxed out at a lower current than the cool white.

Just for kicks after I finished these tests I put the thermoelectric back into cooling mode. I managed to get *463.7 lumens* out of the K2 cool white at a plate temperature of 0° C and a drive current of 3100 mA. I was even able to get *328.6 lumens* at the maximum rated current of 1500 mA by cooling the base plate down to -12.5°C ( 9.5°F).

*09-26-2009*

Here are the results of my most recent round of testing:

*Seoul Semiconductor N42182L bin S2SL0H warm white high CRI star (acquired September 2009)*

This is the first high-CRI LED I've tested. The S2 flux bin is speced at 60 to 70 lumens at 350 mA, and the SL0 tint bin is between 3250K and 3500K. Here are the results:














The N42182L slightly missed the S2 bin at 58.5 lumens at 350 mA. However, this is only marginally low, and likely within the margin of error of my tests. Vf is a low 3.08 volts at 350 mA, rising to 3.35 volts at 1000 mA. Efficiency at 350 mA is a pretty decent 54.2 lm/W given the nature of this LED (lower CCTs and high CRI both significantly reduce luminous flux). CCT did indeed appear to be in the low-middle 3000s as per the spec. Color rendering, especially with warmer colors, was much better than that of cooler LEDs. The N42182L didn't do particularly well at higher currents. Output peaked at 111.3 lumens at 1000 mA, only 1.9 times the value at 350 mA. This seems to be part of a general trend I'm noticing where warmer-tinted LEDs don't scale as well with current as their cooler cousins. It may have to do with the phosphor used perhaps being more sensitive to heat. There are certainly greater Stokes losses, which in turn translates into heat, in a phosphor outputting more longer wavelengths. 


*Lumileds Rebel neutral white -100 (acquired September 2009)
*
This is the highest available bin of Lumiled's neutral white Rebel presently available. Here are the results:














Color temperature looks to be around 4500K. This is no surprise. Due to nature of LED manufacture at present cooler bins tend to emit more output, and therefore the cooler binned neutral whites will be most likely to hit the -100 spec. The -100 neutral white actually falls a little short of the spec, coming in at 98.6 lumens at 350 mA. However, the margin of error in my testing likely exceeds the amount that the spec was missed. Vf at 350 mA is a very low 2.97 volts, and rises to a mere 3.30 volts at 2000 mA. Output with current scales even better than the cool white Rebel -100 I tested last year, and maxed out at 288.3 lumens at 2000 mA. Despite marginally missing the spec, efficiency at 350 mA is 94.9 lm/W (compared to 98.2 for the Rebel -100 cool white) due to the very low Vf. Overall the Rebel is slowly but steadily improving.


*Cree MC-E bin K tint 4A (acquired September 2009)*

I finally received an MC-E to test courtesy of *saabluster*! The K flux bin is 370 to 430 lumens at 350 mA per die, and the 4A tint bin is 4500K to 4750K. Here are the results:














I connected the dies in series as it was the easiest way for me given my power supply. As can be seen, the MC-E falls right in the middle of the K bin with 403.7 lumens at 350 mA. Efficiency at that current is an excellent 93.6 lm/W. Vf at 350 mA is a low 12.32 volts, or 3.08 volts per die. Output peaks at 915.2 lumens at 1200 mA. Vf at 1200 mA is 13.37 volts ( 3.3425 volts per die), and efficiency is a pretty decent 57 lm/W. CCT does indeed appear to fall into the 4500K to 4750K range. Overall, this is a very nice LED which handily meets specs, and provides an output sufficient for general lighting.


*Luminus Phlatlight SST-90 (acquired September 2009)*

Along with the MC-E, *saabluster* sent me a Phlatlight SST-90 mounted on a copper slug for testing. The SST-90 is a single die LED using a huge die of roughly 3mm x 3mm. Multiple bond wires and photonic lattice technology enable even surface current distribution. The die is bonded to the thermal pad with a resistance of only 0.64°C/W. The SST-90 is speced at 3.2 amps. After using my usual test apparatus to plot the radiation pattern I mounted the SST-90 on a fan-cooled Pentium 4 heatsink. It was obvious given the specs of this LED that the smaller extruded heat sink on my test apparatus would not be up to the task. I had installed a temperature sensor in the P4 heatsink for testing thermoelectric modules. This would come in handy and allow me to determine the LED's slug temperature. The thermal resistance of this heat sink is about 0.24°C/W. Therefore, the total thermal resistance between the die and ambient should be around 0.24 + 0.64, or 0.88°C/W. Without any further ado, here are the results:


















As can readily be seen, the SST-90 is impressive. Output at the rated current of 3200 mA is 925.4 lumens, Vf is 3.48 volts, and efficiency is 83.1 lm/W. To put things into perspective, the closest competitor to the SST-90 which I tested was the Seoul Semiconductor P7. At the same current the P7 only managed 842.6 lumens and 72.3 lm/W. As current rose, the SST-90 only increased its lead. The P7 ran out of steam at 7 amps and 1195.8 lumens. The SST-90 managed 1782.9 lumens, or 49% more, at the same current. By that time, I was muttering Will Smith's line from "Men in Black" when he fired off the big laser gun: "Now that's what I'm talking about". On the other end of the current scale, behavoir at low currents was very interesting. The die doesn't even emit light until drive current reaches 13 mA. Efficiency starts out low, and doesn't peak until 500 mA. It remains above 100 lm/W in the 350 to 700 mA range. And it falls very slowly, remaining above 60 lm/W even at the maximum rated current of 9 amps.

The SST-90 bought me into uncharted territory in terms of output and drive current. I continued to ramp up the current, expecting that eventually it would run out of steam and output would level off, but output kept increasing. I started telling my power supply in Star Trek fashion "Can you give us any more?" (anyone remember that line from the first Star Trek pilot?). By the time drive current hit 11.75 amps the answer was no, but the SST-90 would gladly have taken more if the power supply could have given it. Vf at 11.75 amps was still only 3.95 volts while output was 2530 lumens! And as can be seen in the lumens versus current chart, output wasn't even close to leveling off. I think the SST-90 could have exceeded 3000 lumens at perhaps 15-16 amps, assuming the bond wires were up to the task. However, since this SST-90 was a loaner, I wasn't about to try to parallel supplies to get more current into it. 2500+ lumens was impressive enough, as was 2136.3 lumens at the maximum rated current of 9 amps! And for good measure, intensity at 1 meter exceed 1000 lux. I dread to think about the intensity the SST-90 can put out with a suitable aspheric.

*10-10-2009*

*Cree XP-G bin R5 (acquired October 2009)*

A package containing my XP-Gs arrived from Cutter today. I had ordered R4 bins but Cutter substituted R5s. Naturally, the first thing I did after opening the package was to set up my test jig. The R5 bin is specified as 139 to 148 lumens. Color temperature of my sample appeared to be roughly 6500K. The XP-G was rather difficult to set up for testing due to its form factor. I mounted it on a PCB I had made for Rebels. It was necessary to modify the board a bit due to the different pad layout. I then thermal epoxied this on to a brass tab which was bolted onto my test jig. I'll admit the thermal path could have been a little better, but it didn't appear to affect test results very much. Here are those results:
















Beam angle is 125.4°, Vf at 350 mA was only 3.01 volts, output was 145.4 lumens (well within the R5 bin), and efficiency was an amazing 137.8 lm/W! Owing to the larger die size, output and Vf scaled very well. Vf at 700 mA was 3.17 volts, output was 265.3 lumens. The corresponding numbers at 1000 mA were 3.26 volts and 351.1 lumens. Output at 1000 mA relative to 350 mA was 2.415, a bit short of the roughly 2.48 in the spec sheet. However, I'll attribute this small difference to my fairly lousy thermal path. Despite this, output continued to rise with current well past 2 amps, peaking at 546.6 lumens at 2500 mA! My previous highest result for a single die normal-sized emitter was 436.7 lumens, also at 2500 mA, for a Cree XR-E R2 mounted on a heat pipe and copper block. I've little doubt the XP-G could break 600 lumens on a similar setup. Another amazing thing was that efficiency remained above 100 lm/W until 1200 mA. Even at 2000 mA it was 77 lm/W.

It has been mentioned that the XP-G's superior performance can be attributed solely to a larger die size, as opposed to a better die. My test results also indicate a superior die. This is evidenced by the higher peak efficiency of the XP-G, as opposed to the best-binned XR-Es. My best result for an XR-E was 148.3 lm/W at 20 mA. The XP-G peaked at 157.6 lm/W between 60 and 80 mA. The chart below is further evidence of this. The red line is a plot of lumens versus current for the XP-G. The white line is a plot of lumens versus current for two XR-E R2s in parallel. Two XR-Es in parallel roughly simulates the die size of the XP-G. Note that the XR-E R2s I tested mostly likely have the larger die size Cree was using, prior to switching over to a slightly smaller size, due to the fact that I tested them in June 2008. This makes the comparison valid. Note how the XP-G outperforms two XR-E R2s in parallel up to roughly 1700 mA. Above that the XR-Es have an edge owing to their superior thermal path (heat pipe and copper block as opposed to brass tab and thermal epoxy).






Also interesting to note is that the XP-G outperforms 4-die emitters such as the MC-E up to roughly 1500 mA. Even at 2000 mA the XP-G managed 528.7 lumens, while a K bin MC-E I tested only managed slightly more, 538.5 lumens, at 500 mA per die. Granted, an M-bin MC-E would do somewhat better, but even there the difference wouldn't be huge.

Overall, the XP-G is another quantum leap in performance from Cree.


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## jirik_cz

Nice summary, thanks for your hard work :thumbsup: Any chance of testing the MC-E ?


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## Calina

What can I say? I'm speachless. :rock::bow::thumbsup:


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## jashhash

Absolutely amazing results. Wish I had spent more time on this thread sooner. This really helps cut through all the bs currently out there regarding manufacturers bin coding.


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## bshanahan14rulz

Thanks, JTR


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## Marinebeam

I've looked at the spreadsheets, and as a non-math wiz, can someone explain what the 57.11 number is in the solid angle calculation? Where does it come from?


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## Marinebeam

To say it another way: I think the COS function in Excel needs radians, not degrees, so I think STR1962 is converting by changing to radians using 180/pi, but that equals around 57.3, not 57.11? I am stumped... Any help out there?

Thanks.


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## jtr1962

Marinebeam said:


> I've looked at the spreadsheets, and as a non-math wiz, can someone explain what the 57.11 number is in the solid angle calculation? Where does it come from?


I'm measuring in increments of 5 degrees. For each slice of 5 degrees, I need to compute the area in steridians. This is done by subtracting the spherical cap of the smaller angle from the spherical cap of the larger angle. The equation for calculating the spherical cap of a solid angle subtended by a cone with a total angle of 2Ø is:

2∏(1 - cos Ø)

The difference between the spherical caps would be:

2∏ ( cos A - cos B) where A is the smaller angle

I used the conversion factor 57.11 degrees = 1 radian because the COS function in Excel only takes radians. You're right that 57.29578 degrees equals 1 radian. Somehow I've been using 57.11 for reasons that escape me at this time. I may have seen that conversion factor somewhere without bothering to verify it. Regardless of the reason, it really doesn't make much difference (it lowers the final result by about half a percent). I guess I could change it on future spreadsheets.

Good catch. :thumbsup:


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## jtr1962

jirik_cz said:


> Nice summary, thanks for your hard work :thumbsup: Any chance of testing the MC-E ?


Thanks for the compliments. No MC-E testing as of yet. I'm game to test MC-Es or any other high-powered array such as the Bridgelux but can't afford to purchase them myself. At $30 or $40 a pop, such testing could get very expensive very fast. If anyone wants to send me any of these types of LEDs I'll be happy to test them. I'll even return them after testing if the sender wants them back. It's just beyond my means at this time to purchase them myself.


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## jtr1962

I completed testing of several LEDs I purchased recently:

*Osram LW E6SG PLCC4 white (acquired May 2009)*

I purchased 200 of these for use in model railroading lighting and LED night light applications. These are surface mount PLCC-4 style LEDs. Color temperature is around 5500K, somewhat warmer than usual for small LEDs and the beam is very smooth. Intensity was 1010 mcd at 20 mA. Output was 3.15 lumens and efficiency was an OK for nowadays 48.8 lm/W. Beam angle was a very wide 119°. Output scales well with current, and was 8.07 lumens at 100 mA. The claim to fame of these LEDs is a special silicon encapsulant which gives a lifetime of 50,000 hours at 25 mA and 25°C. I put them in 9 LED night lights so far in order to attempt to validate this claim. The LEDs which were previously in these night lights faded to practically nothing after 3 years of continuous use.






*Cree 7090 XP-E bin R2 (acquired May 2009)*

I borrowed an R2 Cree XP-E, from CPF member *nein166* for testing. The R2 bin is specified at 114 to 122 lumens at 350 mA. The color temperature of this sample was roughly 6500K. The results are as show below:
















These results are excellent! The output at 350 mA is nearly 114.6 lumens, meeting spec. Vf is a very low 3.13V and efficiency at 350 mA is 104.6 lm/W. It remains above 100 lm/W past 400 mA. At 1000 mA, efficiency is nearly 75 lm/W. Efficiency at very low currents peaks at around 133 lm/W around 40 mA. This isn't quite as good as the R2 XR-E samples I've testing. Also note that I've added a new test point at 10 mA for power LEDs so that the inflection point where efficiency drops shows up more clearly in my graphs. More interesting than the results at low current is the high current performance. Despite the tiny package, the XP-E does quite well at higher currents. At 1000 mA output is 252 lumens. At 2000 mA it reaches 330 lumens. While these figures aren't quite as good as the XR-E's ~270 and ~400 lumens, respectively, they are more than I expected given the XP-E's package size and thermal path. I'll also note that my mounting method was less than optimal. I attached the LED with Arctic Alumina thermal epoxy. Had it been soldered to the heat sink, I think my results would have been somewhat higher.


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## jtr1962

CPF member *HarryN* arranged for several LEDs to be sent to me for testing. One was the LEDEngin LZ4-40NW10 10 watt neutral white star. The others were the K2 TFFC cool white -220 and the K2 neutral white -180. Here are the results:

*LEDEngin LZ4-40NW10 10 watt neutral white (acquired July 2009)*

The 10 watt LEDEngin is a 4-die series connnected LED designed for the general lighting market. The dome is about the same size as that of the SSC P7 and is translucent rather than clear. The output is speced at 400 lumens at 700 mA. Here are the test results:
















Color temperature looks to be around 4000K and beam angle is 90°, somewhat narrower than on most power LEDs but still fairly wide. Output at 700 mA meets spec almost exactly at 399.9 lumens. Vf is 13.96 V, or 3.49 volts per die, power input is 9.77 watts, and efficiency is only 40.9 lm/W. Keep in mind however that warm and neutral white LEDs generally don't perform as well as their cool white counterparts. Output doesn't scale much with current, leveling off at a bit over 500 lumens at 1300 mA. Overall the LEDEngin appears to be well made. It would be nice to see this product made with higher performing dice.

*Lumileds K2 TFFC neutral white -180 (acquired July 2009)*

This is the highest available bin of Lumiled's neutral white K2 presently available. The spec sheet does list a 200 lumen bin, but Future so far doesn't carry it. The 180 lumen spec is at a drive current of 1000 mA. Here are the results:
















Color temperature looks to be in the high 3000s. As can be seen, the K2 TFFC neutral white 180 exceeds the spec at 1000 mA with nearly 193 lumens. Lumileds also specifies typical figures of 85, 150, and 250 lumens at 350 mA, 700 mA, and 1500 mA, respectively. The test results at these respective currents were 86.8, 151.4, and 243.6 lumens, all either exceeding or very close to specification. Vf at 350 mA is 3.29 volts, and only rises to 4.03 volts at 2500 mA. This brings me to the area where I was most impressed with the K2. Its output scaled very well with current. While the scaling with current up to about 1500 mA was about the same as similar products from Cree, above 1500 mA was where the K2 shined (pun intended). Cree XR-Es typically level off in output once current gets slightly above 2000 mA. The K2 neutral white increased in output up to 2600 mA. It may have done even better if I had soldered it to the heat sink instead of using Arctic Alumina thermal epoxy. Peak output at 2600 mA was close to 285 lumens. Granted, this is only 14% more than the 1500 mA output, but it nevertheless indicates superior ability to deal with the thermal effects of higher current.

*Lumileds K2 TFFC cool white -220 (acquired July 2009)*

This is the highest available bin of Lumiled's cool white K2 presently available. The 220 lumen spec is at a drive current of 1000 mA. Here are the results:
















Color temperature is around 6000K and appears snow white, with no discernable tint. The K2 TFFC cool white 220 exceeds the spec at 1000 mA with over 227 lumens. Lumileds specifies typical figures of 105, 185, and 300 lumens at 350 mA, 700 mA, and 1500 mA, respectively. The test results at these respective currents were 101.8, 175.8, and 292.8 lumens, all less than but still within a few percent of specification. Vf at 350 mA is 3.28 volts, and only rises to 4.18 volts at 3100 mA. This again brings me to how well the output scales with current. The K2 cool white kept right on rising in output all the way to 3100 mA! It may have done even better if I had soldered it to the heat sink instead of using Arctic Alumina thermal epoxy. Peak output at 3100 mA was 390 lumens. This was over 33% more than the 1500 mA output. Good things are definitely occurring with the K2 TFFC's thermal management. Also interesting to note was that 350 mA efficiency was 88.6 lm/W. If Lumileds comes out with a -250 bin, then it should equal the Cree R2 at lower currents, and have dramatically better output at higher ones. Also noteworthy is that I accidentally spiked the current to about 3.6 amps with no ill effects on the emitter. The K2s are evidently quite robust.

Here is a chart of lumens versus current for the two K2s:






Here's the other charts HarryN requested:

K2 cool white versus Cree R2 (two plots for the Cree-the higher one shows the results when mounted on a heat pipe):






K2 neutral white versus LEDEngin:






I plan to run some more tests on the K2s, including one of output versus current at typical flashlight conditions, and also a lifetime test of the other two neutral white emitters I have. Stay tuned for further results....

I completed the tests under typical flashlight conditions. I decided to go with a 60°C constant baseplate temperature for these tests to simulate conditions in a typical flashlight. I used one of my thermoelectric cold plates in heat mode for my testing. Here are the results (60°C base plate testing in red):

K2 Cool White -220






K2 Neutral White -180






LEDEngin LZ4-40NW10






The results are pretty much what I thought they would be except for the K2 neutral white. The K2 cool white lumens output more or less tracked the output at room temperature across the entire range, except scaled by a factor of roughly 92% to 94%. Same thing for the LEDEngin except the scale factor was closer to 90% over most of the range (although it did rise to 96% by 1300 mA which I thought was strange).

The K2 neutral white started out like the other two, holding at roughly 94% to 95% of room temperature output until maybe 1.7 amps. Above that the output dropped like a rock as seen in the chart. Yet at room temperature output continued to rise until about 2.6 amps (although this was still less than the 3.1 amps managed by the K2 cool white). Only thing I can think of here, since the dice are likely the same, is the phosphor. Perhaps the neutral white phosphor is a lot more temperature sensitive. That would explain my results here, and also to a lesser degree the results at room temperature where the neutral white maxed out at a lower current than the cool white.

Just for kicks after I finished these tests I put the thermoelectric back into cooling mode. I managed to get *463.7 lumens* out of the K2 cool white at a plate temperature of 0° C and a drive current of 3100 mA. I was even able to get *328.6 lumens* at the maximum rated current of 1500 mA by cooling the base plate down to -12.5°C ( 9.5°F).


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## Bimmerboy

Nice K2 results, JTR! Thank you for the testing. I think you've pushed me over the edge to finally try a couple of 'em.

Surprising nobody's sent you a M-CE yet. Bunch O' cheapies around here. :nana: Not exactly affluent myself (to say the least), but I've been tempted more than once to send one your way.

... may have to buy one for exactly that purpose in the near future, and have it sent to you. It'd be the _very_ least I could do in return for all your helpfulness, and for all the value I've received from hanging around this place.

lovecpf

PM incoming soon.


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## HarryN

Hi JTR - Thank you very much for all of the testing.

I did some hand plots from your data and reached an interesting (at least for me) conclusion. 

I plotted the K2 TFFC cool white and Cree R2 Lumens vs current, and the inflection point where each package was optimal was pretty obvious. (similar plot to your K2 TFFC neutral and cool vs current)

I then did similarly the K2 TFFC neutral white and the LEDEngin neutral white vs current ( I used x 4 for the LEDEngin since they are in series). Once again, each package had regions where it was optimal.

I wondered if you would mind posting two plots like this for general use, and to see if my hand plots were indeed correct.

Once again, thanks for all of the work. I think we are all spoiled by how much you have invested in time and equipment - I was happy to support providing a few LEDs. Where else could you get third party independent testing of LEDs for such a reasonable price?

Take care,

HarryN


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## kreston

So what was the most efficient (lm/W) led so far?
Guess it is XR-E Q5?


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## jtr1962

HarryN,

I added the plots you requested to the post with the K2 testing.

Bimmerboy,

If you do indeed want to send me an MC-E for testing it'll be greatly appreciated. I'll even return it after testing if you need it for a project.


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## tebore

kreston said:


> So what was the most efficient (lm/W) led so far?
> Guess it is XR-E Q5?



Looking at the data it's the XR-E R2 or depending on drive current used the 0100 bin Rebel.


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## jtr1962

I was crunching my data a bit in an attempt to find some metric for the amount of droop versus current. I think I found a good way to measure it. What I do first is take the output in lumens per mA (not lumens per watt). This shows how much light the LED die is producing per unit of current independent of resistance factors. At some current the lumens per mA peaks. I normalize the lumens per mA by dividing by this peak value. This means for all LEDs there is a current at which the normalized output per mA is 1, and it is less at both smaller and larger currents. The more slowly the normalized output per mA decreases with current, the lower the droop. Here is a plot of the normalized current per mA versus current for the two K2s, a Cree XP-E and XR-E R2 bins, and a U2 bin Seoul Semiconductor P4:






It appears that when the normalized lumens per mA drops to around roughly 0.4 there is no further increase in output with current. 0.5 seems to be a good rule of thumb to use for the maximum drive current in a practical application as there are only small increases in output past that point, and then only under ideal heat sinking conditions.


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## jtr1962

tebore said:


> Looking at the data it's the XR-E R2 or depending on drive current used the 0100 bin Rebel.


At the nominal 350 mA the Cree XR-E R2 has a very slight edge over the Rebel 100. At lower currents around 20 mA the Rebel edges out the Cree by a small margin (~150 lm/W versus high 140s).


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## HarryN

Hi JTR - I have become a bit confused with the test results of the XP-E R2, as there are several in there. Are the graphs of the K2 cool vs the R2 both tested under the same conditions? Would the graphs be closer if we plotted lumens vs power instead of lumens vs current? Just curious to see that much difference.

Cree has come a long way since their original power LED product.

It is interesting also to see the power regions where the K2 TFFC neutral white is the optimum choice, and then how the LEDEngin part really comes into its own at higher powers.

Thanks

HarryN


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## jtr1962

HarryN said:


> Hi JTR - I have become a bit confused with the test results of the XP-E R2, as there are several in there. Are the graphs of the K2 cool vs the R2 both tested under the same conditions? Would the graphs be closer if we plotted lumens vs power instead of lumens vs current? Just curious to see that much difference.


The Cree XR-E R2 was tested under two conditions. The lower plot was the same test setup used for the K2, so that's the fairest basis for comparison. The slightly higher one was a sample saabluster sent me attached to a heat pipe and a copper plate.

It won't make any significant difference plotting lumens versus power. The Vfs of the Cree and K2 are identical to within a couple of hundreths of a volt over the entire range, so the input power at any given current is practically the same. Extrapolating my data a bit, I think the -240 bin of the K2 would be a pretty close match to the Cree R2 at higher currents although it might give a little less light at lower ones.



> Cree has come a long way since their original power LED product.


Power LEDs in general have come a long way. I remember when a Q bin Luxeon was considered a great LED. Now we have LEDs which give the same amount of light at less than 100 mA as the Luxeon gave at 350 mA.


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## Garibaldi

Great work JTR! Have you done any long term studies on any of these? I'd be interested in seeing how quickly the Rebels, for instance, drop to their 70% lumen maintenance.


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## znomit

*R2 lumen per watt values*

Just an observation on your three sets of R2 measurements, XP-E and the two XR-E. 
The raw outputs are reasonably different, the XP has the lowest lumens/mA, and the fan cooled the highest(generally 7-8% higher), but from 200mA to 1A the lumen per watt values are nearly identical for all three.
The cooled XR-E is actually the worst performer over this range.

ps, thanks for all your work in this thread and other places JTR


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## nein166

Hey JTR I've been away from CPF for a while while moving, cool to see you got around to testing the XP-E, I'll have to give you a call in the future to discuss mounting options other than purposed mcpcb's.

I've got to come down your way and get those Nuetral P4s from our friend in Brooklyn, unless you both want to come up this way.


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## saabluster

jtr I have a Phlatlight SST 90 with your name on it if you'd like to try it out.


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## jtr1962

Garibaldi said:


> Great work JTR! Have you done any long term studies on any of these? I'd be interested in seeing how quickly the Rebels, for instance, drop to their 70% lumen maintenance.


Only long term test I have going so far is a Luxeon Q bin which at this point has around 48,000 hours on it. Unfortunately, I didn't have a light meter when I first started testing it. But the output has been holding steady from around the time I bought a light meter (roughly the end of year 1), and last time I checked (about a year ago). I have a feeling this LED will last longer than me.  But anyway, yes, I think long term tests of several of the more commonly used emitters (Cree XR-E, SSC P4, Rebel, K2 ) will likely commence in the not too distant future. I just need to think of a test setup regarding drive currents and so forth. Any input would be welcome. And I would most likely start another thread to post the ongoing results of such testing (which could potentially run for years).



znomit said:


> Just an observation on your three sets of R2 measurements, XP-E and the two XR-E.
> The raw outputs are reasonably different, the XP has the lowest lumens/mA, and the fan cooled the highest(generally 7-8% higher), but from 200mA to 1A the lumen per watt values are nearly identical for all three.
> The cooled XR-E is actually the worst performer over this range.
> 
> ps, thanks for all your work in this thread and other places JTR


Vf rises as temperature drops but output doesn't rise nearly as fast, so that most likely accounts for the lower lumens per watt of the cooled XR-E. Thanks also for the compliments.



nein166 said:


> Hey JTR I've been away from CPF for a while while moving, cool to see you got around to testing the XP-E, I'll have to give you a call in the future to discuss mounting options other than purposed mcpcb's.
> 
> I've got to come down your way and get those Nuetral P4s from our friend in Brooklyn, unless you both want to come up this way.


And once I receive the neutral P4s I'll be running a test on them. Also, I purchased a neutral white Rebel which is yet to be tested. And I still need to run the other tests I mentioned on the K2s from HarryN.



saabluster said:


> jtr I have a Phlatlight SST 90 with your name on it if you'd like to try it out.


Thanks, I would be happy to test it. Do you still have my address?


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## saabluster

jtr1962 said:


> Thanks, I would be happy to test it. Do you still have my address?


If I do I don't know where it is. PM it to me along with some instructions on how you would like it mounted or not.


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## HarryN

Just bumping this thread to see if anything new is happening.


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## jtr1962

HarryN said:


> Just bumping this thread to see if anything new is happening.


We've been having a hot, humid spell here last week or so. That type of weather just totally drains me of energy. After I do the stuff I have to do, there's nothing left for fun things. Weather is cooling down a bit soon, so hopefully in the near future things will pick up again in the jtr lab!


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## jtr1962

Post 313 updated with results of high temperature testing (i.e. constant 60°C base plate) for the K2 cool white, K2 neutral white, and LEDEngin LZ4-40NW10 10 watt neutral white star. I used a thermoelectric cold plate in heating mode for these tests. Summary of the results (60°C base plate testing in red):

K2 Cool White -220







K2 Neutral White -180






LEDEngin LZ4-40NW10






The results are pretty much what I thought they would be except for the K2 neutral white. The K2 cool white lumens output more or less tracked the output at room temperature across the entire range, except scaled by a factor of roughly 92% to 94%. Same thing for the LEDEngin except the scale factor was closer to 90% over most of the range (although it did rise to 96% by 1300 mA which I thought was strange).

The K2 neutral white started out like the other two, holding at roughly 94% to 95% of room temperature output until maybe 1.7 amps. Above that the output dropped like a rock as seen in the chart. Yet at room temperature output continued to rise until about 2.6 amps (although this was still less than the 3.1 amps managed by the K2 cool white). Only thing I can think of here, since the dice are likely the same, is the phosphor. Perhaps the neutral white phosphor is a lot more temperature sensitive. That would explain my results here, and also to a lesser degree the results at room temperature where the neutral white maxed out at a lower current than the cool white.

Just for kicks after I finished these tests I put the thermoelectric back into cooling mode. I managed to get *463.7 lumens* out of the K2 cool white at a plate temperature of 0° C and a drive current of 3100 mA. I was even able to get *328.6 lumens* at the maximum rated current of 1500 mA by cooling the base plate down to -12.5°C ( 9.5°F).


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## HarryN

Hi JTR1962,

Thank you very much for running those tests on the K2 at 60 C. That is particularly interesting information, as Lumileds is going to add another spec to their LEDs - the ratio of output at 60 C / performance under standard test conditions.

It seems that the K2 will do very well with this spec.

Any idea how the Cree or SSL parts will come out?

I can't believe that no one has sent an MC-E to you for testing yet, or at least paid for the parts like I did for some of the tests. Just amazing that this kind of resouce is out there for free and people cannot even buy some LEDs for you.

Thanks

HarryN


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## saabluster

HarryN said:


> Hi JTR1962,
> 
> 
> 
> I can't believe that no one has sent an MC-E to you for testing yet,


I had intended on sending him an M bin MC-E a while back but my resources have been low recently. I am going to send him a K bin 4A and an SST90 today.


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## jtr1962

saabluster said:


> I had intended on sending him an M bin MC-E a while back but my resources have been low recently. I am going to send him a K bin 4A and an SST90 today.


Received them today! Thanks! :twothumbs I should have time within a few days to run the tests.



HarryN said:


> Thank you very much for running those tests on the K2 at 60 C. That is particularly interesting information, as Lumileds is going to add another spec to their LEDs - the ratio of output at 60 C / performance under standard test conditions.
> 
> It seems that the K2 will do very well with this spec.
> 
> Any idea how the Cree or SSL parts will come out?


I'll see if I can do these tests on a Cree or SSC in the near future. The experiment itself doesn't take long to do, but setting it up does.


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## HarryN

Hi - that sounds great. I am just curious as heck to see how the SSC and Cree chips handle the heat under the more "real life - like" conditions at 60C.

Lumileds claims to have some strong technology in that area, and it will be very interesting to compare single and multi die LEDs of different brands together at 60C to see which ones really put out the most lumens at 5, 10, and 15 watts. I suspect that people are going to be surprised when you really run the test - which setup has more light output when you have 10 - 20 watts to play with:
- A pair of K2s
- A pair of single die Cree parts
- MC-E (4 die)
- P7 (4 die)

IMHO, this will really start to define future light builds.


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## jtr1962

Here are the results of my most recent round of testing:

*Seoul Semiconductor N42182L bin S2SL0H warm white high CRI star (acquired September 2009)*

This is the first high-CRI LED I've tested. The S2 flux bin is speced at 60 to 70 lumens at 350 mA, and the SL0 tint bin is between 3250K and 3500K. Here are the results:














The N42182L slightly missed the S2 bin at 58.5 lumens at 350 mA. However, this is only marginally low, and likely within the margin of error of my tests. Vf is a low 3.08 volts at 350 mA, rising to 3.35 volts at 1000 mA. Efficiency at 350 mA is a pretty decent 54.2 lm/W given the nature of this LED (lower CCTs and high CRI both significantly reduce luminous flux). CCT did indeed appear to be in the low-middle 3000s as per the spec. Color rendering, especially with warmer colors, was much better than that of cooler LEDs. The N42182L didn't do particularly well at higher currents. Output peaked at 111.3 lumens at 1000 mA, only 1.9 times the value at 350 mA. This seems to be part of a general trend I'm noticing where warmer-tinted LEDs don't scale as well with current as their cooler cousins. It may have to do with the phosphor used perhaps being more sensitive to heat. There are certainly greater Stokes losses, which in turn translates into heat, in a phosphor outputting more longer wavelengths. 


*Lumileds Rebel neutral white -100 (acquired September 2009)
*
This is the highest available bin of Lumiled's neutral white Rebel presently available. Here are the results:














Color temperature looks to be around 4500K. This is no surprise. Due to nature of LED manufacture at present cooler bins tend to emit more output, and therefore the cooler binned neutral whites will be most likely to hit the -100 spec. The -100 neutral white actually falls a little short of the spec, coming in at 98.6 lumens at 350 mA. However, the margin of error in my testing likely exceeds the amount that the spec was missed. Vf at 350 mA is a very low 2.97 volts, and rises to a mere 3.30 volts at 2000 mA. Output with current scales even better than the cool white Rebel -100 I tested last year, and maxed out at 288.3 lumens at 2000 mA. Despite marginally missing the spec, efficiency at 350 mA is 94.9 lm/W (compared to 98.2 for the Rebel -100 cool white) due to the very low Vf. Overall the Rebel is slowly but steadily improving.


*Cree MC-E bin K tint 4A (acquired September 2009)*

I finally received an MC-E to test courtesy of *saabluster*! The K flux bin is 370 to 430 lumens at 350 mA per die, and the 4A tint bin is 4500K to 4750K. Here are the results:














I connected the dies in series as it was the easiest way for me given my power supply. As can be seen, the MC-E falls right in the middle of the K bin with 403.7 lumens at 350 mA. Efficiency at that current is an excellent 93.6 lm/W. Vf at 350 mA is a low 12.32 volts, or 3.08 volts per die. Output peaks at 915.2 lumens at 1200 mA. Vf at 1200 mA is 13.37 volts ( 3.3425 volts per die), and efficiency is a pretty decent 57 lm/W. CCT does indeed appear to fall into the 4500K to 4750K range. Overall, this is a very nice LED which handily meets specs, and provides an output sufficient for general lighting.


*Luminus Phlatlight SST-90 (acquired September 2009)*

Along with the MC-E, *saabluster* sent me a Phlatlight SST-90 mounted on a copper slug for testing. The SST-90 is a single die LED using a huge die of roughly 3mm x 3mm. Multiple bond wires and photonic lattice technology enable even surface current distribution. The die is bonded to the thermal pad with a resistance of only 0.64°C/W. The SST-90 is speced at 3.2 amps. After using my usual test apparatus to plot the radiation pattern I mounted the SST-90 on a fan-cooled Pentium 4 heatsink. It was obvious given the specs of this LED that the smaller extruded heat sink on my test apparatus would not be up to the task. I had installed a temperature sensor in the P4 heatsink for testing thermoelectric modules. This would come in handy and allow me to determine the LED's slug temperature. The thermal resistance of this heat sink is about 0.24°C/W. Therefore, the total thermal resistance between the die and ambient should be around 0.24 + 0.64, or 0.88°C/W. Without any further ado, here are the results:


















As can readily be seen, the SST-90 is impressive. Output at the rated current of 3200 mA is 925.4 lumens, Vf is 3.48 volts, and efficiency is 83.1 lm/W. To put things into perspective, the closest competitor to the SST-90 which I tested was the Seoul Semiconductor P7. At the same current the P7 only managed 842.6 lumens and 72.3 lm/W. As current rose, the SST-90 only increased its lead. The P7 ran out of steam at 7 amps and 1195.8 lumens. The SST-90 managed 1782.9 lumens, or 49% more, at the same current. By that time, I was muttering Will Smith's line from "Men in Black" when he fired off the big laser gun: "Now that's what I'm talking about". On the other end of the current scale, behavoir at low currents was very interesting. The die doesn't even emit light until drive current reaches 13 mA. Efficiency starts out low, and doesn't peak until 500 mA. It remains above 100 lm/W in the 350 to 700 mA range. And it falls very slowly, remaining above 60 lm/W even at the maximum rated current of 9 amps.

The SST-90 bought me into uncharted territory in terms of output and drive current. I continued to ramp up the current, expecting that eventually it would run out of steam and output would level off, but output kept increasing. I started telling my power supply in Star Trek fashion "Can you give us any more?" (anyone remember that line from the first Star Trek pilot?). By the time drive current hit 11.75 amps the answer was no, but the SST-90 would gladly have taken more if the power supply could have given it. Vf at 11.75 amps was still only 3.95 volts while output was 2530 lumens! And as can be seen in the lumens versus current chart, output wasn't even close to leveling off. I think the SST-90 could have exceeded 3000 lumens at perhaps 15-16 amps, assuming the bond wires were up to the task. However, since this SST-90 was a loaner, I wasn't about to try to parallel supplies to get more current into it. 2500+ lumens was impressive enough, as was 2136.3 lumens at the maximum rated current of 9 amps! And for good measure, intensity at 1 meter exceed 1000 lux. I dread to think about the intensity the SST-90 can put out with a suitable aspheric.


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## ICUDoc

Yet another terrific post contributing to our knowledge- thanks mate. I note that at 16W the MC-E puts out 915 lumens but the Phlatlight is at 1246! That looks very impressive. What colour temp was it? And I wonder how much difference the excellent heatsinking made to the relative efficiencies?
Thanks again.


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## jtr1962

ICUDoc said:


> Yet another terrific post contributing to our knowledge- thanks mate. I note that at 16W the MC-E puts out 915 lumens but the Phlatlight is at 1246! That looks very impressive. What colour temp was it? And I wonder how much difference the excellent heatsinking made to the relative efficiencies?


Thanks!

Color temp of the SST-90 looked to be in the 6000s, probably around 6500K. And the relative heat sinking didn't make all that much difference at the currents the MC-E was running at. I had a fan blowing on the heat sink when I was testing the MC-E. The heat sink only reached perhaps 10°C over room temperature. I tested the SST-90 on the same heat sink as the MC-E up to 2 amps, then moved it to the other one, and retested. At 2 amps there was only a 2% difference in the flux, although this was at a 6.6W power level. So the MC-E might have done perhaps 5% better on the other heat sink, but the SST-90 still would have handily beaten it.


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## saabluster

OMG! Those are better results than I expected. I was a little sceptical when Luminus released their specs on these LEDs but I have to hand it to them. Luminus is much to be feared. I wonder how much of this performance if any comes from their strategic relationship with Nichia.:thinking: 

Excellent job as usual. BTW it's saab_luster _not blaster. Although thats not all that far off either. Thank you Thank you Thank you!


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## jtr1962

saabluster said:


> OMG! Those are better results than I expected. I was a little sceptical when Luminus released their specs on these LEDs but I have to hand it to them. Luminus is much to be feared. I wonder how much of this performance if any comes from their strategic relationship with Nichia.:thinking:


What really impresses me is how the SST-90 performs at high currents. It just takes want you give it and asks for more!



> Excellent job as usual. BTW it's saab_luster _not blaster. Although thats not all that far off either. Thank you Thank you Thank you!


You're quite welcome! And sorry about the mispelling.  I just fixed it. That's what happens when I post on a few hours sleep. 

Almost forget to ask but do you know what flux bin this SST-90 was? It falls into the WM flux bin ( 850 to 1000 lumens @ 3.2A ) by my tests.


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## saabluster

jtr1962 said:


> Almost forget to ask but do you know what flux bin this SST-90 was? It falls into the WM flux bin ( 850 to 1000 lumens @ 3.2A ) by my tests.


There was no flux bin provided as it was a pre-production sample.


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## milkyspit

ICUDoc said:


> Yet another terrific post contributing to our knowledge- thanks mate. I note that at 16W the MC-E puts out 915 lumens but the Phlatlight is at 1246! That looks very impressive. What colour temp was it? And I wonder how much difference the excellent heatsinking made to the relative efficiencies?
> Thanks again.



In fairness to the MC-E, the sample you're using for comparison is a markedly warmer tint using less efficient phosphors... a better comparison would involve a cool white MC-E of M-flux and similar color temp... my guess is that plus identical heatsinks would give the Cree at least a 20% better result, and more importantly, it's a far more valid comparison since test conditions would be more consistent in both cases.

Still, the Phlatlight did deliver a great showing, there's no disputing that! :naughty:


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## jtr1962

milkyspit said:


> In fairness to the MC-E, the sample you're using for comparison is a markedly warmer tint using less efficient phosphors... a better comparison would involve a cool white MC-E of M-flux and similar color temp... my guess is that plus identical heatsinks would give the Cree at least a 20% better result, and more importantly, it's a far more valid comparison since test conditions would be more consistent in both cases.


I agree 100% here. Looking at my earlier tests with the cooler binned P7s I was obtaining roughly 62-63 lm/W when driven at the 16 watt level, or roughly 1000 lumens. Add another 5% or so for the better heat sink, and that would be about 1050 lumens. An M-binned MC-E would probably slightly outperform the P7 based on the relative performance of the XR-Es and P4s, so I'd guess 1100 lumens at 16 watts on the same heat sink as the SST-90. OK, the SST-90 still beats it, but at least it's not the LED equivalent of a shut out!



> Still, the Phlatlight did deliver a great showing, there's no disputing that! :naughty:


You have a definite talent for understatement.  My jaw was dropping to the ground by the time the SST-90 hit 10 amps, and begged for more.  If this is the way LEDs are heading, then it's going be  .


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## saabluster

jtr1962 said:


> My jaw was dropping to the ground by the time the SST-90 hit 10 amps, and begged for more.  If this is the way LEDs are heading, then it's going be  .



BTW I managed to buy the last two CST-90s that are confirmed to be the top bin. These use the same die as the one I sent you but the die is directly mounted to a large piece of solid copper! They are rated up to 13A but we both know it can handle a bit more than that.:naughty: Question is can you power it up that high?


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## jtr1962

saabluster said:


> BTW I managed to buy the last two CST-90s that are confirmed to be the top bin. These use the same die as the one I sent you but the die is directly mounted to a large piece of solid copper! They are rated up to 13A but we both know it can handle a bit more than that.:naughty: Question is can you power it up that high?


Cool! Is your question "Do I have a power supply capable of going past 13 amps?" The answer is I do, although nothing electronically regulated like the one I usually use when testing LEDs. However, all this is giving me incentive to make some sort of current regulated switching supply which I can attach to my main supply. The power supply I was using is a linear supply I built. It can put nearly 12 amps and about 15 volts into a load. It was made mainly for testing thermoelectrics. As you can imagine, the heat sink for the MOSFETs got pretty warm powering a low voltage, high-current load like the SST-90. I think my idea of making a switching current regulator powered by the main supply makes more sense. I'm figuring I could probably design it to go past 25 amps. If huge, single-die LEDs are part of the future, then I need a better way of powering them than I do now.

Hopefully after I finish a few days of work, I'll get started. I'll obviously be using a chip which uses external MOSFETs and probably synchronous rectification. It might be a bit of a pain to design, although I suppose I'll find a ready market here if I'm able and willing to mass produce them. Anyway, were you thinking of sending me one of the CST-90s to test? I looked at the data sheet for those. They look like 16 or 17 amps should be no problem.


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## HarryN

Wow - very nice work. I would love to see how the rebel, MC-E and Luminus parts work at 60C as well so we can estimate real world output. Is there any way to fit that info into your test plans?


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## jtr1962

HarryN said:


> Wow - very nice work. I would love to see how the rebel, MC-E and Luminus parts work at 60C as well so we can estimate real world output. Is there any way to fit that info into your test plans?


I'll try to do that as soon as I finish up this latest round of work I need to do (building 100 regulator boards for a customer). Hopefully in a few days.

The SST-90 especially should be easy to do. I just need cut the fan speed enough to keep the heat sink at 60°C. The other two parts will need active heating over most of their operating range (although the MC-E at higher currents should produce enough heat to keep the heat sink at 60°C).


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## saabluster

jtr1962 said:


> Cool! Is your question "Do I have a power supply capable of going past 13 amps?" The answer is I do, although nothing electronically regulated like the one I usually use when testing LEDs. However, all this is giving me incentive to make some sort of current regulated switching supply which I can attach to my main supply. The power supply I was using is a linear supply I built. It can put nearly 12 amps and about 15 volts into a load. It was made mainly for testing thermoelectrics. As you can imagine, the heat sink for the MOSFETs got pretty warm powering a low voltage, high-current load like the SST-90. I think my idea of making a switching current regulator powered by the main supply makes more sense. I'm figuring I could probably design it to go past 25 amps. If huge, single-die LEDs are part of the future, then I need a better way of powering them than I do now.
> 
> Hopefully after I finish a few days of work, I'll get started. I'll obviously be using a chip which uses external MOSFETs and probably synchronous rectification. It might be a bit of a pain to design, although I suppose I'll find a ready market here if I'm able and willing to mass produce them. Anyway, were you thinking of sending me one of the CST-90s to test? I looked at the data sheet for those. They look like 16 or 17 amps should be no problem.



Judging by your earlier post I was not sure if you were able to test at the higher range safely. I am not the electronic wizard you are so most of what you said went over my head. I am perfectly willing to send you the CST-90 although unfortunately like the other one I will need it back as I have plans for it. I also have an MC-E M bin for you to test. I have a special little test for it as well which I will PM you about. Thanks!


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## txg

this is such a GREAT thread, keep it going jtr1962. thank you very much, very informative.

are you planning to test one of the new cree xp-g r4 leds?


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## jtr1962

txg said:


> this is such a GREAT thread, keep it going jtr1962. thank you very much, very informative.
> 
> are you planning to test one of the new cree xp-g r4 leds?


Thanks for the compliments! The thread will keep going so long as I'm alive and there are LEDs to test. As for the XP-G, I have some R4s on the way from Cutter for a bike light project, and I'll certainly be testing one of them!


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## NIMA1966

Hi JTR1962This link might help http://www.national.com/an/AN/AN-1937.pdf


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## JoeF

Thanks very much for your testing of white LEDs. I have some Light of Victory 1 Watt 10mm, and 0.5 Watt 8mm (140 degree viewing angle) white LEDs. Can I send a few to you? I tried to send a private message, but was denied access for some reason.


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## jtr1962

NIMA1966 said:


> Hi JTR1962This link might help http://www.national.com/an/AN/AN-1937.pdf



Thanks for the link. Interesting IC. Not sure if I'd want to use it however due to the weird input voltage requirements.



JoeF said:


> Thanks very much for your testing of white LEDs. I have some Light of Victory 1 Watt 10mm, and 0.5 Watt 8mm (140 degree viewing angle) white LEDs. Can I send a few to you? I tried to send a private message, but was denied access for some reason.


Thanks for the compliments. I'm glad you've enjoyed the thread!

PM privileges are only given after the first few posts, which is why you were unable to PM me. I might be interested in testing the 0.5 watt 8mm. I've already tested a few narrow beam 10 mm's however, so there is probably not much to be gained by testing another. Besides that, the very narrow beam angle emitters are a major pain to test.


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## jtr1962

*Cree XP-G bin R5 (acquired October 2009)*

A package containing my XP-Gs arrived from Cutter today. I had ordered R4 bins but Cutter substituted R5s. Naturally, the first thing I did after opening the package was to set up my test jig. The R5 bin is specified as 139 to 148 lumens. Color temperature of my sample appeared to be roughly 6500K. The XP-G was rather difficult to set up for testing due to its form factor. I mounted it on a PCB I had made for Rebels. It was necessary to modify the board a bit due to the different pad layout. I then thermal epoxied this on to a brass tab which was bolted onto my test jig. I'll admit the thermal path could have been a little better, but it didn't appear to affect test results very much. Here are those results:

















Beam angle is 125.4°, Vf at 350 mA was only 3.01 volts, output was 145.4 lumens (well within the R5 bin), and efficiency was an amazing 137.8 lm/W! Owing to the larger die size, output and Vf scaled very well. Vf at 700 mA was 3.17 volts, output was 265.3 lumens. The corresponding numbers at 1000 mA were 3.26 volts and 351.1 lumens. Output at 1000 mA relative to 350 mA was 2.415, a bit short of the roughly 2.48 in the spec sheet. However, I'll attribute this small difference to my fairly lousy thermal path. Despite this, output continued to rise with current well past 2 amps, peaking at 546.6 lumens at 2500 mA! My previous highest result for a single die normal-sized emitter was 436.7 lumens, also at 2500 mA, for a Cree XR-E R2 mounted on a heat pipe and copper block. I've little doubt the XP-G could break 600 lumens on a similar setup. Another amazing thing was that efficiency remained above 100 lm/W until 1200 mA. Even at 2000 mA it was 77 lm/W.

It has been mentioned that the XP-G's superior performance can be attributed solely to a larger die size, as opposed to a better die. My test results also indicate a superior die. This is evidenced by the higher peak efficiency of the XP-G, as opposed to the best-binned XR-Es. My best result for an XR-E was 148.3 lm/W at 20 mA. The XP-G peaked at 157.6 lm/W between 60 and 80 mA. The chart below is further evidence of this. The red line is a plot of lumens versus current for the XP-G. The white line is a plot of lumens versus current for two XR-E R2s in parallel. Two XR-Es in parallel roughly simulates the die size of the XP-G. Note that the XR-E R2s I tested mostly likely have the larger die size Cree was using, prior to switching over to a slightly smaller size, due to the fact that I tested them in June 2008. This makes the comparison valid. Note how the XP-G outperforms two XR-E R2s in parallel up to roughly 1700 mA. Above that the XR-Es have an edge owing to their superior thermal path (heat pipe and copper block as opposed to brass tab and thermal epoxy).






Also interesting to note is that the XP-G outperforms 4-die emitters such as the MC-E up to roughly 1500 mA. Even at 2000 mA the XP-G managed 528.7 lumens, while a K bin MC-E I tested only managed slightly more, 538.5 lumens, at 500 mA per die. Granted, an M-bin MC-E would do somewhat better, but even there the difference wouldn't be huge.

Overall, the XP-G is another quantum leap in performance from Cree.


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## rav

*jtr1962*, big thanks for the measurements. XP-G looks sensational.


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## Solo Rider

Jtr1962.

Yeah, good post, nice work, thanks.

:twothumbs

Solo.


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## NIMA1966

Try to drive LEDs with pwm the output will be lower but you can eliminate the thermal loss. 
At 1% duty cycle the output will be 100 times lower @ low currents but WILL peak FAR farther.
And finally you will calculate the lumens without the thermal effect


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## HarryN

Nice work as usual Joe. I would really like to see the comparable and more realistic 60 C results for an MC-E and the XP-G when you have a chance. Droop can be a big factor in LED applications, and it would be interesting to see if Cree has really worked its way past this.

Thanks

Harry


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## ICUDoc

Wow that efficiency at 1000mA is amazing! Now to find the right reflector...

And thanks very much again!


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## blasterman

> Another amazing thing was that efficiency remained above 100 lm/W until 1200 mA. Even at 2000 mA it was 77 lm/W.


 
Yeah...that's pretty startling. I'm hoping we see pure blue versions of these devils because they are likely to be a quantum leap over blue P4s, and we've already discussed a significant application for those. I'll let you know in a week or two how my initial experiment is going.

Otherwise, as somebody mentioned above, we need to hold some applause for the performance of these killer emitters and awknowledge that 6500k -vs- 4500k is like benchmarking dual core processors vs single core. Hyper efficient cool-white emitters is a given, but when you move to the neutral/warm-white phosphor category the efficiency hit is quite severe. This is really what I'm waiting to see with the XP-G.

Good testing regardless.


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## SFG2Lman

wow i can't believe this is the first time i have seen this thread...AWESOME work i love the sst-90 testing, and i can't wait to see how the cree S2 holds up :naughty:


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## TorchBoy

jtr1962 said:


> Also interesting to note is that the XP-G outperforms 4-die emitters such as the MC-E up to roughly 1500 mA.


Wouldn't it be fairer to compare an MC-E with two XP-Gs in parallel?


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## jtr1962

blasterman said:


> Yeah...that's pretty startling. I'm hoping we see pure blue versions of these devils because they are likely to be a quantum leap over blue P4s, and we've already discussed a significant application for those. I'll let you know in a week or two how my initial experiment is going.


Based on my rough estimates, a blue version of these should produce about 500 mW to 525 mW @ 350 mA. In other words, 50% conversion efficiency give or take. Such outputs would definitely help your experiment.



> Otherwise, as somebody mentioned above, we need to hold some applause for the performance of these killer emitters and awknowledge that 6500k -vs- 4500k is like benchmarking dual core processors vs single core. Hyper efficient cool-white emitters is a given, but when you move to the neutral/warm-white phosphor category the efficiency hit is quite severe. This is really what I'm waiting to see with the XP-G.


Maybe one reason Cree is withholding release of neutral and warm versions until late this year is to try and reduce the efficiency penalty. For any given CRI, there is no inherent reason a 4000K emitter should be less efficient than a 6500K one. In fact, one document I read shows efficiency peaking in theory at lower CCTs ( link-see page 12). It's just a matter of using the proper phosphor. Right now I'm reasonably sure most LED manufacturers just glob more of the same YAG phosphor on to get neutral or warm tints. This is pretty apparent looking at the spectra. The yellow hump for warm/neutral tints covers the same wavelengths as cool, only it's larger relative to the blue spike. They're effectively using globs of phosphor to block out some of the blue! Small wonder there's an efficiency hit (and only a marginal improvement in CRI from perhaps low 70s to high 70s). Now Philips/Lumileds may be doing something different with their Rebels, as evidenced by the neutral tints having the same rating as the cool ones.

High CRI is another animal entirely. Regardless of tint, you can expect a 20% or larger penalty when you use a special phosphor to get CRI into the 90s. So far Cree hasn't jumped on the high-CRI bandwagon at all, but it would be interesting to see a high-CRI LED based on the XP-G. Even an ~20% efficiency hit still implies 100-110 lm/W @ 350 mA. And I may be in the minority but I would love to see cool high-CRI tints as well.

In the meantime it is possible to both warm the cool tints somewhat, and improve CRI substantially, by adding small amounts of red and cyan. This won't work well for focused lighting, but for more diffuse general lighting using emitters with no optics mixing colors evenly shouldn't present a problem.


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## jtr1962

HarryN said:


> Nice work as usual Joe. I would really like to see the comparable and more realistic 60 C results for an MC-E and the XP-G when you have a chance. Droop can be a big factor in LED applications, and it would be interesting to see if Cree has really worked its way past this.


I'll set up the test jig one last time and test a few of the LEDs you mentioned (Cree XP-G, Rebel, MC-E, perhaps the SST-90 and a few others) at 60°C baseplate. I don't plan to make this testing a part of my regular procedure however unless I can automate it somehow. Right now it's just too time consuming to set up and manually regulate the temperature at each test point.



TorchBoy said:


> Wouldn't it be fairer to compare an MC-E with two XP-Gs in parallel?


In terms of die area you're 100% correct here. I was merely comparing a single XP-G to the multidie emitter to illustrate that we don't have long to go before the single die emitters reach the output levels of the MC-E. Right now the best binned MC-Es should manage perhaps up to 825 lumens at the maximum rating of 700 mA per die. The XP-G manages around 350-360 lumens at its maximum rating of one amp. The S2 bin should close the gap even further at roughly 400 lumens. Down the road in the not too distant future I can see higher S bins hitting 500 lumens @ 1 amp. I can also see Cree bumping the XP-G rating to 1500 mA as efficiency continues to increase. This could get us to 650-700 lumens, depending upon droop. This is close enough that it could make multidie emitters pointless. Not saying that will happen, but I tend to think with cost reduction per lumen being a priority, the industry would probably like to get away from multi-die emitters. They've always been more expensive and harder to make than their single-die counterparts. Granted, they may have some advantages in terms of matching Vf to power supply, but they also have lot of drawbacks as well. Note that there is an exception to this. Multi-die emitters using different types of dies (RGBA, for example), do and will continue to make a lot of sense.



NIMA1966 said:


> Try to drive LEDs with pwm the output will be lower but you can eliminate the thermal loss.
> At 1% duty cycle the output will be 100 times lower @ low currents but WILL peak FAR farther.
> And finally you will calculate the lumens without the thermal effect


This would be a good way of seeing the droop at higher current without temperature effects. For example, I could PWM the LED at a 1% duty cycle with peak currents of both 350 mA and 1000 mA, and compare the relative outputs. I have no plans to do this however at this time. As with the 60°C baseplate testing, it just adds to an already time-consuming test procedure (as it is each LED takes me over two hours to do between setting it up, getting the raw test data, entering it in spreadsheets, and doing the write-up here). With my business picking up lately, my time to do these tests is very limited compared to even a few years ago.


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## HarryN

Hi JTR - would you consider switching your standard test for these power LEDs to 60 C instead of 25 C ? It seems that most of the power LED mfgs now are not far from their specs for 25 C, but this data still remains - well - interesting but not that valuable.

Your test has the potential to be more realistic compared to the mfg specs as a 60 C test would be what real flashlight and lighting uses are like. Frankly, the only downside of your exhaustive testing is the new false claims that people make about their OTF lumens claims - and then they reference your data as the basis for the claim.

Just MHO, take it FWIW.

Thanks for all of the work.

Harry


----------



## jtr1962

HarryN said:


> Hi JTR - would you consider switching your standard test for these power LEDs to 60 C instead of 25 C ? It seems that most of the power LED mfgs now are not far from their specs for 25 C, but this data still remains - well - interesting but not that valuable.
> 
> Your test has the potential to be more realistic compared to the mfg specs as a 60 C test would be what real flashlight and lighting uses are like. Frankly, the only downside of your exhaustive testing is the new false claims that people make about their OTF lumens claims - and then they reference your data as the basis for the claim.
> 
> Just MHO, take it FWIW.
> 
> Thanks for all of the work.


Right now I'm not really measuring at 25°C baseplate. The LED is mounted on a 60 mm square heat sink which has some air flow. The heat sink does indeed get somewhat above ambient temperature as I ramp up the current (this is especially true with 4-die LEDs such as the P7 or MC-E), and the ambient temperature itself in the room is subject to variability throughout the year (although not much because the room is heated in winter and cooled in summer). What I'm doing is kind of halfway in between constant 25°C baseplate and constant 60°C baseplate. I'd roughly estimate my standard setup has a thermal impedance on the order of around 1.5°C/W (plus additional losses at the thermal interface between the emitter and heat sink). Overall this setup is a lot more realistic than data sheets which usually assume a constant 25°C junction temperature. In fact, my relative measurements between 350 mA and 1000 mA in my recent XP-G test were less than the data sheet precisely because I didn't keep junction temperature at a constant 25°C (indeed I couldn't do so unless I cooled the heat sink below ambient).

Besides that, I'm confused as to whether you would want me to standardize on 60°C baseplate temperature or 60°C junction temperature (manufacturers tend to use junction temperature). I probably couldn't even do the latter except by using the manufacturer's _estimate_ of junction to thermal pad impedance, measuring power consumption, calculating the rise of junction temperature above heat sink based on the measured power consumption, and then adjusting heat sink temperature accordingly. As heat sink temperature changes, Vf and therefore power consumption changes, so that means some recalculation of junction temperature rise. I dread to think of the logistics of trying to do this at one data point, much less at 30+ data points. Controlling base plate to a constant temperature is a little easier, but still not without problems. It takes a while until you adjust the thermoelectric module current just right to keep your heat sink at constant temperature. Maybe I can do this automatically via a PID controller, but even those still take some time to stabilize at setpoint.

I'll grant that not controlling either baseplate or junction temperatures precisely introduces some variability, but it also represents what can be achieved in the real world with halfway decent cooling. At low currents the emitter will be fairly close to ambient temperatures just as it is in my tests. At higher currents it may indeed be warmer than in my tests but this is relatively easy to correct. Looking at most of the spec sheets the difference in output between 25°C and 60°C baseplate temperatures is about 5-6%.

Believe me, it might be nice to standardize on some sort of constant temperature for testing purposes, but after testing a few emitters this way the HUGE amount of extra work relative to the knowledge gained seems minimal. For example, let's look at these two curves for the neutral and cool K2s:












The differences here between 60°C baseplate and my standard testing amounts to 6-7%. However, _I could have obtained virtually the same plot by just looking at the data sheets, and applying a correction for temperature._ The only noteworthy item I discovered here not obtainable from applying the data sheets was that the K2 neutral white falls on its face at a lower drive current than in my standard testing. But note that this occurred above the rated current of 1.5 amps anyhow. It would be of little interest to any reputable manufacturer who would keep current ratings within specs.

Anyway, it's not that I'm against doing things the way you suggest in principal but I see a couple of problems. First off, I lose any direct comparison between previous tests and current ones (unless I perform tests both the new way and old way). Second, after doing a few LEDs this way it's just too time consuming due to the logistics mentioned earlier. It takes about an hour to set up everything, and then probably another few hours to gather the data. Fortunately for us white LEDs don't vary their output by a huge amount with temperature. You need to increase temperature by 45°-50°C to decrease output by 10%.

It's fairly easy to guestimate output at 60°C baseplate or any other temperature by applying the relevant correction from the manufacturer's data sheet. I _strongly encourage_ anyone citing my data to correct for temperature rise in this manner (and also to correct for any optical losses). The thing is with so many different applications out there I can't possibly have data for all scenarios. Some lights may get much hotter than 60°C. On the other hand, I'm aware of larger flashlights, or general lighting applications, which actually mimic the conditions in my tests (i.e. heat sink doesn't get much higher than 10°C over ambient).

I hope none of this post came off as overly dismissive as it wasn't meant to. You offer valid suggestions to make my tests more meaningful. And in fact if the logistics weren't against it I would probably follow your suggestions. It's just that during the last two years I've find myself with a lot less time to devote to the experimentation I enjoy due to the need to earn money and/or take care of personal matters at home. I WILL try to do a few constant 60°C tests on some common emitters in the near future as I said I would just to see if they reveal anything new. But after that I doubt I'll have time to do much beyond my usual testing. Truth is after doing a lot of the things I have to do I'm just too fatigued to do the things I want to do.

EDIT: To add a bit more here the way LEDs are trending I'm seeing less and less point doing testing at elevated temperatures. For example, look at this chart for the XP-G:






The red line represents total input power to the LED and the white line represents waste heat. In the coming years the white line will be trending towards zero even though it will obviously never get there. In light of this, I tend to think our flashlights and general lighting will operate ever closer to room temperature. This is especially true of portable lighting. There are limits to the amount of energy any cell can store, and this is improving very slowly compared to LEDs. For any given runtime, this represents a hard limit on the amount of power delivered to the LED. As more of this power comes out as light due to improved LEDs, thermal pad temperatures will continue to approach ambient temperature.


----------



## spencer

jtr1962 said:


> And I may be in the minority but I would love to see cool high-CRI tints as well.



I would like to see this as well. Maybe not really cool tints like WC but something in the 5000K range. Mmmmmm.


----------



## JoeF

Thanks again, jtr1962, for your testing, and for responding to my question above.

I have ordered some warm white LEDs from eBay seller shop4leds (the same as TopBright?):

8mm (straw hat) 140 degree warm white 210,000mcd (300mA)
8mm (straw hat) 140 degree warm white 80,000mcd (100mA)
4.8mm 120 degree warm white 12,000mcd (20mA)
5mm (piranha high-flux package) 120 degree warm white 23,000mcd (20mA)

I will be happy to send some for testing if you want. The figures above sound impressive, but of course they are just figures. Your testing of LEDs has been quite an education!


----------



## Ekke

JoeF said:


> 8mm (straw hat) 140 degree warm white 210,000mcd (300mA)
> 8mm (straw hat) 140 degree warm white 80,000mcd (100mA)
> 4.8mm 120 degree warm white 12,000mcd (20mA)
> 5mm (piranha high-flux package) 120 degree warm white 23,000mcd (20mA)
> 
> I will be happy to send some for testing if you want. The figures above sound impressive, but of course they are just figures. Your testing of LEDs has been quite an education!



According to this site those would be:
~870lm
~330lm
~38lm
~72lm

Would be nice to know The Real Specs. Sadly there are too many leds in the eBay that don't have correct specs. :thumbsdow


----------



## TorchBoy

It also says the calculation is inaccurate for wide angle LEDs (which you've realised).


----------



## jtr1962

JoeF said:


> I have ordered some warm white LEDs from eBay seller shop4leds (the same as TopBright?):
> 
> 8mm (straw hat) 140 degree warm white 210,000mcd (300mA)
> 8mm (straw hat) 140 degree warm white 80,000mcd (100mA)
> 4.8mm 120 degree warm white 12,000mcd (20mA)
> 5mm (piranha high-flux package) 120 degree warm white 23,000mcd (20mA)
> 
> I will be happy to send some for testing if you want. The figures above sound impressive, but of course they are just figures. Your testing of LEDs has been quite an education!


Those might be interesting to test although I can tell you right off those specs are exaggerated. The XP-G R5 had a narrower beam angle than those LEDs, and even so it only managed 160,700 mcd at 2500 mA. And the XP-G R5 is the most efficient production LED at this time. If the LEDs you listed really had those specs, they would be achieving in excess of 1000 lm/W which is physically impossible (maximum theoretical for phosphor whites is around 265 lm/W).

If you want to send them to me anyway PM me for my shipping address. Not sure when I'll get to them, however. Right now I'm in the process of re-landscaping the house. I might be at this until late November.


----------



## Nitroz

jtr1962 said:


> If you want to send them to me anyway PM me for my shipping address. Not sure when I'll get to them, however. *Right now I'm in the process of re-landscaping the house.* I might be at this until late November.



Yardwork over LED testing........pfffftttt!

Just kidding, thanks for the great work that you do.:twothumbs


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## jtr1962

Nitroz said:


> Yardwork over LED testing........pfffftttt!




Truth is the yard looked terrible and it really needed a makeover. I was mowing weeds all summer.  Besides that, we may start growing vegetables again next year. I might try starting seedlings under LEDs, kind of combine two of my hobbies into one.


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## jashhash

Thank you very much for your testing JTR. I really appreciate and respect your work a lot.


----------



## Justin Case

jtr1962 said:


> *Cree XP-G bin R5 (acquired October 2009)*
> 
> A package containing my XP-Gs arrived from Cutter today. I had ordered R4 bins but Cutter substituted R5s. Naturally, the first thing I did after opening the package was to set up my test jig. The R5 bin is specified as 139 to 148 lumens. Color temperature of my sample appeared to be roughly 6500K. The XP-G was rather difficult to set up for testing due to its form factor. I mounted it on a PCB I had made for Rebels. It was necessary to modify the board a bit due to the different pad layout. I then thermal epoxied this on to a brass tab which was bolted onto my test jig. I'll admit the thermal path could have been a little better, but it didn't appear to affect test results very much.



I have some XP-G R4s mounted on two different MCPCBs: 1) a 10mm diam, 2mm thick board, and 2) an 8mm diam, 1mm thick board (actually closer to 0.85mm). I have a total of seven XP-Gs, two on the 10mm board and five on the 8mm board. For whatever reason, the XP-Gs mounted on the 8mm boards consistently show a higher Vf than the two on the 10mm boards (sorry about the non-uniform drive currents, but the measurements were not originally done for Vf evaluation purposes).

8mm XP-G #1, [email protected]
8mm XP-G #2, [email protected]
8mm XP-G #3, [email protected]
8mm XP-G #4, [email protected]
8mm XP-G #5, [email protected]

10mm XP-G #6, [email protected]
10mm XP-G #7, [email protected]

XP-G #4 seems particularly poor wrt Vf.


----------



## jtr1962

Justin Case said:


> I have some XP-G R4s mounted on two different MCPCBs: 1) a 10mm diam, 2mm thick board, and 2) an 8mm diam, 1mm thick board (actually closer to 0.85mm). I have a total of seven XP-Gs, two on the 10mm board and five on the 8mm board. For whatever reason, the XP-Gs mounted on the 8mm boards consistently show a higher Vf than the two on the 10mm boards (sorry about the non-uniform drive currents, but the measurements were not originally done for Vf evaluation purposes).
> 
> 8mm XP-G #1, [email protected]
> 8mm XP-G #2, [email protected]
> 8mm XP-G #3, [email protected]
> 8mm XP-G #4, [email protected]
> 8mm XP-G #5, [email protected]
> 
> 10mm XP-G #6, [email protected]
> 10mm XP-G #7, [email protected]
> 
> XP-G #4 seems particularly poor wrt Vf.


If the 8mm board has better thermal transfer then the Vf will on average tend to be higher (Vf increases as temperature decreases at the rate of roughly 2.2 mV/°C). Since the 8mm board is thinner, it probably does indeed provide lower thermal resistance. So actually the higher Vf here is a good thing.


----------



## IMSabbel

jtr1962 said:


> If the 8mm board has better thermal transfer then the Vf will on average tend to be higher (Vf increases as temperature decreases at the rate of roughly 2.2 mV/°C). Since the 8mm board is thinner, it probably does indeed provide lower thermal resistance. So actually the higher Vf here is a good thing.



But of course the effiency drops with junction temperature.
Would be interesting to see if there is an optimal region.

When i cooled my P7s with liquid nitrogen it turned out to make them much more inefficient...


----------



## dainis15

Is there posibility to measure Flashlight lumens with setup like using for LED testing. I thinking that step must be at least 2.5°, because beam of Flashligt is more narrow than LED, and better will make measurements on both directions from maximum. I understand that results will be far from perfect, but for comparing lumens before Flashlight upgrading and after it will be OK. I also assuming, that beam must be simetrical in vertical and horizontal axis.
Is there possible get modified Excel spreadsheet for these measurements, for one fixed power level?

Thanks in advise, for any help! 
Dainis


----------



## jtr1962

dainis15 said:


> Is there posibility to measure Flashlight lumens with setup like using for LED testing. I thinking that step must be at least 2.5°, because beam of Flashligt is more narrow than LED, and better will make measurements on both directions from maximum. I understand that results will be far from perfect, but for comparing lumens before Flashlight upgrading and after it will be OK. I also assuming, that beam must be simetrical in vertical and horizontal axis.
> Is there possible get modified Excel spreadsheet for these measurements, for one fixed power level?
> 
> Thanks in advise, for any help!


It probably is possible although for the very narrow beam of most flashlights you would probably need 1° increments. You would also need some means to hold a variety of different flashlight bodies on your test jig. Modifying the spreadsheets for this is trivial-you just change put increments to 1 instead of 5 in the first column-the spreadsheet does the rest. I personally have zero interest in doing any lumens testing of flashlights, however. Don't have the time for starters. And there are far too many other variables such as regulated/unregulated, temperature, state of batteries. etc.


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## DelDotB

jtr1962 said:


> If the 8mm board has better thermal transfer then the Vf will on average tend to be higher (Vf increases as temperature decreases at the rate of roughly 2.2 mV/°C). Since the 8mm board is thinner, it probably does indeed provide lower thermal resistance. So actually the higher Vf here is a good thing.



My first post! Hurray! I just bought some of these xpg\\\'s on a bunch of different boards including the 8 mm and 10 mm ones mentioned above and all of the boards are aluminum. The 8 mm boards are only about 1 mm thick and the 10 mm boards are about 2 mm thick. does this small difference in thickness really matter for thermal resistance when measuring vf? the way I have measured vf, I set everything up ahead of time before I power up the LED. I also start from a cold state and put my xpg/boards on a larger piece of metal to help keep the aluminum board cool. Then I turn on the power, light up the LED and make my vf measurement. That takes about two seconds, which doesn\\\'t seem like it would be long enough to get anything hot enough to make a difference of several tenths of a volt. and if vf decreases at a rate of 2.2 mv/C, to get a vf difference of two or three tenths of a volt would mean a temperature difference of about 100 C. That seems very unlikely to me for a test of about two seconds in duration.


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## jasonck08

Love this thread! I always find myself coming here looking for data again and again!

I'd like to see some SST-50 tests!


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## lolzertank

Do you know how many lux a typical Cree XR-E R2 (any cool white bin will do, but R2 is best) bare emitter has in the center of the beam at some distance? I just got some from a somewhat dubious source, and I want to verify the LED's bin.

EDIT: Never mind, it just occured to me that my lux meter's accuracy is probably so low that I wouldn't be able to tell with any certainty whether my LEDs are a P2 or R2 bin.


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## metlarules

lolzertank said:


> Do you know how many lux a typical Cree XR-E R2 (any cool white bin will do, but R2 is best) bare emitter has in the center of the beam at some distance? I just got some from a somewhat dubious source, and I want to verify the LED's bin.
> 
> EDIT: Never mind, it just occured to me that my lux meter's accuracy is probably so low that I wouldn't be able to tell with any certainty whether my LEDs are a P2 or R2 bin.



I like your sigline. Its so true.


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## Erasmus

Cheers to Jtr1962 for the extensive testing


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## Nil Einne

jtr1962 said:


> *Cree XP-G bin R5 (acquired October 2009)*
> <snipped>
> Overall, the XP-G is another quantum leap in performance from Cree.



Hi, first thanks for all your testing. 

But did you forget to include the XP-G R5 data in the zip file? It was last updated in November but I can't seem to see the XP-G data in it and the most recent file by data modified is "Seoul Semiconductor S42180 bin S2 tests.xls" (from October) and I checked, that doesn't seem to be the right thing. Everything else is from September or earlier and nothing there looks right either (although I didn't check each document)

Cheers


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## jtr1962

Nil Einne said:


> But did you forget to include the XP-G R5 data in the zip file? It was last updated in November but I can't seem to see the XP-G data in it and the most recent file by data modified is "Seoul Semiconductor S42180 bin S2 tests.xls" (from October) and I checked, that doesn't seem to be the right thing. Everything else is from September or earlier and nothing there looks right either (although I didn't check each document)


The strange thing is the S42180 was done the same day as the XP-G R5, and yet the XP-G R5 isn't in the .zip file on my PC, either. Anyway, I just fixed it. The new version of the .zip file now has the XP-G R5.


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## IMSabbel

Now that SST-90s arent that exotic anymore, do you have any plans of running one of them as high as it will go?


----------



## jtr1962

IMSabbel said:


> Now that SST-90s arent that exotic anymore, do you have any plans of running one of them as high as it will go?


A better choice for that might be the CST-90. Before anyone sends me one though, I need to make and test a higher current power supply. The one I have now ( which I made ) only goes to 11 amps and change. The transformer windings can't take much over that for the periods I would need to test the CST-90. What I want to do then is make a switching supply which can use my existing power supply as the raw voltage. The biggest problem isn't really making a switcher for that kind of current, but rather measuring and controlling the output current to the kind of precision I need for my testing. It'll be done _eventually_. Once it is, then I'll make a request in this thread for a CST-90. I still have saabluster's SST-90 but it's not a candidate for a high current test since he wants it back. I also have an SST-50 which Fulgeo sent me quite a while back. I have yet to test but will in the very near future. That one is also a loaner, so I need to limit my test currents. Additionally, I have a bunch of small Cree 20 mA LEDs sent to me by JohnR66 which need testing. Now if only I had about 2 days free....


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## jasonck08

Any update on the SST-50 tests? Can't wait for the data!


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## jtr1962

jasonck08 said:


> Any update on the SST-50 tests? Can't wait for the data!


Not yet. To make a long story short I've been going crazy last few months with various issues ( home, business, this latest month long heat wave draining my energy ). Also, I've been putting a lot of cycling miles in last three months and pretty much put my other hobbies to the side for the time being. I think I'm going to try to do the testing this week however. Not much going on business-wise this week, and it looks like we may have a rainy day or two where I can't do any cycling. Besides the SST-50 and Nichia NS6L183, I'll be testing some neutral XP-Gs I purchased this month. Enough testing I'd say to fill the better part of a day.


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## blasterman

Sidebar, but Chauvet's Q-spot 260 moving head is powered by a CST-90.

Haven't seen one in action, but reviews put it in the same ballpark as 150watt discharge.

In a compact plastic fixture we can se how jtr1962's tests are so critical.


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## wquiles

jtr1962 said:


> Besides the SST-50 and Nichia NS6L183, I'll be testing some neutral XP-Gs I purchased this month. Enough testing I'd say to fill the better part of a day.



Which bin of the NS6L183 will you be testing? I used one in this build and I like it a lot.

Will


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## StupidPig

Information here is very valuable, thanks.

jtr1962, could you mind to explain a bit on how you convert the lux reading to lumen? I looked into your spreadsheet and it seems very complicated and I'm not quite understand. Thanks.


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## zzonbi

Remember 1lux=1lm/m2
So you basically add the lumens back, integrate. Now the finer you go dividing an area, the better. I guess jtr also uses symmetry in led patterns to cut down on sampling.


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## Vbeez

Subscribing this. Very valuable info.
Thanks


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## MikeAusC

jtr1962 said:


> . . . . . . For example, look at this chart for the XP-G:
> 
> 
> 
> 
> 
> 
> 
> The red line represents total input power to the LED and the white line represents waste heat. . . . . .



I know this was posted TWO YEARS AGO, but I'm wondering how you determined WASTE HEAT to produce this graph. It's hard to find verifiable information on waste heat from LEDs.


----------



## LEDninja

James Peng,
While the information you provide is very informative, most of us poor CPF members can not afford millions of dollars worth of equipment. We do the best we can with what we have. We do not need 8 decimals of accuracy. Why? because due to manufacturing tolerances a flashlight's tolerances can vary greatly from sample to sample.
Some flashlight manufacturers just quote the biggest number they can find on the LED manufacturers website. As a result almost all cheap flashlights using the SSC-P7 is listed as 900 lumens. When the Cree XM-L came out, to show the superiority of the new LED, these manufacturers claim 1000 lumens (Cree only claim 800 lumens, add loses due to driver and optics and ,,,). When the newer U-bin version of the XM-L came out guess what. They are listed at 1100 lumens. Despite your claim that the integrating sphere in another thread is too small, the reading of ~450 lumens is much more accurate than the numbers I see on ebay.

Another member asked me about a method someone discovered on getting approximate lumens cheaply. Please read it:
http://www.candlepowerforums.com/vb...uring-lumens&p=4322304&highlight=#post4322304
Looking at the numbers of this very crude method I noticed they are within 10% of the lights which are tested by the manufacturers to the FL1 standard.

I used to guess the lumens of my new lights because I have a number of lights of known quantity. I have a 7 LED light of 18 lumens, a Fenix of 29 lumens etc. When I bounce a new light off the ceiling and my reference lights I can tell if my new flashlight is <18 lumens, between 18 lumens and 29 lumens, >29 lumens etc. I was using my room as my 'integrating sphere.

When going out for a walk at night, does it matter if my flashlight is 90 lumens or 91 lumens. I would not be able to tell the difference. Now 200 lumens is definitely brighter. While a national lab needs to be accurate to umpteenth decimal places I do not.

bigchelis, Selfbuilt and JTR1962 are a few who have provided us with reasonably accurate numbers because they have the knowledge and the means to do so.

James Peng, has been banned as a spammer and all his posts deleted. - Norm


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## Farhaj

Thatz been a well explained demonstration on the type of LEDs.. If, you can help me with this; it would be Greatful. How much Lumens and Voltage Drops are required for a Generic Chinese 5mm LED to light up completely..


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## JohnR66

Farhaj said:


> Thatz been a well explained demonstration on the type of LEDs.. If, you can help me with this; it would be Greatful. How much Lumens and Voltage Drops are required for a Generic Chinese 5mm LED to light up completely..



The typical 5mm LED (white, I'm assuming given the thread title) has a forward voltage (Vf) of around 3.2 volts at 20ma. Generic Chinese 5mm LEDs are rubbish and will fade after a few hundred hours at 20ma. Better to run them at 10ma. If you want something better than the dim bluish light, look for better quality LEDs, such as Cree C503C or C503D series. Much brighter, whiter and last long even at 30ma current.


----------



## Farhaj

JohnR66 said:


> The typical 5mm LED (white, I'm assuming given the thread title) has a forward voltage (Vf) of around 3.2 volts at 20ma. Generic Chinese 5mm LEDs are rubbish and will fade after a few hundred hours at 20ma. Better to run them at 10ma. If you want something better than the dim bluish light, look for better quality LEDs, such as Cree C503C or C503D series. Much brighter, whiter and last long even at 30ma current.




I saw your this thread Forum on caculating lumens for white leds... http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing ..... 

I have this flash light DP-722b... I want to know its LED Lumens and Watts... 

I am sending you its Datasheet... *It is 5mm Straw Hat LED... can you please find it out for me the exact Lumens and watts for it..

*http://underwaterseaplants.awardspace.com/led.pdf


----------



## jtr1962

Farhaj said:


> I saw your this thread Forum on caculating lumens for white leds... http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing .....
> 
> I have this flash light DP-722b... I want to know its LED Lumens and Watts...
> 
> I am sending you its Datasheet... *It is 5mm Straw Hat LED... can you please find it out for me the exact Lumens and watts for it..
> 
> *http://underwaterseaplants.awardspace.com/led.pdf


Unfortunately, data sheets are often wrong, especially with generic Chinese LEDs. The only way to determine to lumens and watts is to actually test the LED. In fact, that's the reason why I started testing LEDs in the first place-because the data sheets either didn't exist, or couldn't be trusted.

Unfortunately, I stopped testing LEDs a while back on account of lack of time, and I doubt I'll ever have time again in the near future. All I can tell you is in all likelihood your flashlight is putting out less than 5 lumens per LED. 5mm LEDs just can't put out a lot of light due to their poor heat dissipation limiting the currents they can be driven at.


----------



## Farhaj

jtr1962 said:


> Unfortunately, data sheets are often wrong, especially with generic Chinese LEDs. The only way to determine to lumens and watts is to actually test the LED. In fact, that's the reason why I started testing LEDs in the first place-because the data sheets either didn't exist, or couldn't be trusted.
> 
> Unfortunately, I stopped testing LEDs a while back on account of lack of time, and I doubt I'll ever have time again in the near future. All I can tell you is in all likelihood your flashlight is putting out less than 5 lumens per LED. 5mm LEDs just can't put out a lot of light due to their poor heat dissipation limiting the currents they can be driven at.



You know any mathematically ways to calculate lumens per LED for the White Genereic 5mm LED.. according to the data given in data sheet..

I have these some data and pictures of LED..




















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----------



## jtr1962

Farhaj said:


> You know any mathematically ways to calculate lumens per LED for the White Genereic 5mm LED.. according to the data given in data sheet..


Just see what I did in my spreadsheets. I have links to my spreadsheets in the first post in this thread. If the data sheet has a graph for the light intensity versus angle you can normalize the numbers (if they haven't been normalized already), plug them into the spreadsheet, and then use the center intensity to get a rough approximation of the total lumens. However, this approach is far from exact because data sheets are often incorrect. Seriously, you can get a decent approximation with far less trouble by just measuring the current and voltage going to the LED, and multiplying by 75 to 100. For example, if the LED is being driven at 20 mA, and the voltage across it is 3 volts, then the input power is 0.02 x 3 = 0.06 watts. Most generic white LEDs these days achieve 75 to 100 lumens per watt at their nominal current (i.e. 20 mA for 5mm LEDs), so just multiply 0.06 by 75 to 100. That gives you 4.5 lumens on the low end, and about 6 lumens on the high end.

The only other way to get more accurate values is to actual measure the intensity at different angles then plug the numbers into a spreadsheet as I did. I had to make a jig to do this, and it's very time consuming which is why I don't do it any more.


----------



## Farhaj

jtr1962 said:


> Just see what I did in my spreadsheets. I have links to my spreadsheets in the first post in this thread. If the data sheet has a graph for the light intensity versus angle you can normalize the numbers (if they haven't been normalized already), plug them into the spreadsheet, and then use the center intensity to get a rough approximation of the total lumens. However, this approach is far from exact because data sheets are often incorrect. Seriously, you can get a decent approximation with far less trouble by just measuring the current and voltage going to the LED, and multiplying by 75 to 100. For example, if the LED is being driven at 20 mA, and the voltage across it is 3 volts, then the input power is 0.02 x 3 = 0.06 watts. Most generic white LEDs these days achieve 75 to 100 lumens per watt at their nominal current (i.e. 20 mA for 5mm LEDs), so just multiply 0.06 by 75 to 100. That gives you 4.5 lumens on the low end, and about 6 lumens on the high end.
> 
> The only other way to get more accurate values is to actual measure the intensity at different angles then plug the numbers into a spreadsheet as I did. I had to make a jig to do this, and it's very time consuming which is why I don't do it any more.




there are forumlas given on this page to convert various data into Lumens.. I used this http://www.rapidtables.com/calc/ligh...a-to-lumen.htm
and forund the results per led to 0.54 lm.. which is not at all possible in the real LED. so low.. 
then, I found out that theformula is good for only upto certain limit of wavelengths in LED.. not for the white LEDS.. 
I do not know the realty..

can you now explain..

Also, tell me where is that spreadheet which you are telling that can be valid for the Geric 5mm Strawhat chinese LED as this one http://underwaterseaplants.awardspace.com/led.pdf


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## jtr1962

Farhaj said:


> there are forumlas given on this page to convert various data into Lumens.. I used this http://www.rapidtables.com/calc/ligh...a-to-lumen.htm
> and forund the results per led to 0.54 lm.. which is not at all possible in the real LED. so low..
> then, I found out that theformula is good for only upto certain limit of wavelengths in LED.. not for the white LEDS..
> I do not know the realty..
> 
> can you now explain..



All these conversion tables make assumptions about the light distribution of the LED. In other words, they are at best approximations, which is why they may not agree with reality. As others have been trying to tell you in the other thread, you can't directly convert candela to lumens unless you make measurements of the light intensity versus angle as I did.



> Also, tell me where is that spreadheet which you are telling that can be valid for the Geric 5mm Strawhat chinese LED as this one





> http://underwaterseaplants.awardspace.com/led.pdf


Here is a .zip file containing all my spreadsheets. Unfortunately, this won't help you here because the datasheet for the LED you're interested in doesn't have a chart for intensity versus angle. Why don't you just ask the manufacturer how many lumens this LED puts out? They would know better than anyone here.


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## Farhaj

jtr1962 said:


> All these conversion tables make assumptions about the light distribution of the LED. In other words, they are at best approximations, which is why they may not agree with reality. As others have been trying to tell you in the other thread, you can't directly convert candela to lumens unless you make measurements of the light intensity versus angle as I did.
> 
> 
> Here is a .zip file containing all my spreadsheets. Unfortunately, this won't help you here because the datasheet for the LED you're interested in doesn't have a chart for intensity versus angle. Why don't you just ask the manufacturer how many lumens this LED puts out? They would know better than anyone here.



I asked them and they straight away said per led is upto 7-10 lumens or something like that.. so not sure they are telling the truth.. the datasheet has the Angle , mcd and Wavelenghts mentioned in it... can it not help to find the lumens from it... http://underwaterseaplants.awardspace.com/led.pdf


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## Farhaj

Yesterday, I sat and did some measurements for the FLASHLIGHT.. I calculated out the *VOLTS and Resistance for Each Mode ( 1 & 2) *... 








Can you guys now have a look and tell me what would be Its *WATTS, LUMENS and AMPERES EXACTLY..*.








The areas of the Battery Side along with the Circuit photo is attached along as well; to get a more clearer image of the Volts in the Battery produced.








Have a look at the readings and the PICS Below:


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## Farhaj

I did some more Calculations from the Measurements I did Earlier to calculate the watts and Amperes more Precisely..*Can this now help more in calculation of total lumens for light..
*


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## WhiteRabbit

Great job! The OP is *exactly *what I've been looking for... except that of course it doesn't include led's from the last 5 years. Is there anything just like this, but which covers current white LED's?


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## jayrob

jtr1962,

Wow I was just reading some of the testing you have done on various LED's...

Very impressive work! Thanks very much for sharing all of your work with us.

There is so much information in the thread, that it is hard to sift through and find what I'm hoping to find, and that is information on the SST-90, and more resent MT-G2 6V 5000K emitter.

Have you got a chance to test those?


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## jtr1962

jayrob said:


> jtr1962,
> 
> Wow I was just reading some of the testing you have done on various LED's...
> 
> Very impressive work! Thanks very much for sharing all of your work with us.
> 
> There is so much information in the thread, that it is hard to sift through and find what I'm hoping to find, and that is information on the SST-90, and more resent MT-G2 6V 5000K emitter.
> 
> Have you got a chance to test those?


Thanks for the compliments. I'm glad this thread is still drawing interest even though it hasn't been updated in a while.

The SST-90 results are in this post. I never tested the MT-G2 6V.

I stopped testing a while back due to lack of time. This year I've been doing a new consulting gig which leaves me very little free time. Bottom line-I don't anticipate adding to this thread in the near future. For what it's worth, LED manufacturers are characterizing their LEDs much better on their data sheets than in the past, so often you can get the information you need right off the data sheet.


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## jayrob

jtr1962 said:


> Thanks for the compliments. I'm glad this thread is still drawing interest even though it hasn't been updated in a while.
> 
> The SST-90 results are in this post. I never tested the MT-G2 6V.
> 
> I stopped testing a while back due to lack of time. This year I've been doing a new consulting gig which leaves me very little free time. Bottom line-I don't anticipate adding to this thread in the near future. For what it's worth, LED manufacturers are characterizing their LEDs much better on their data sheets than in the past, so often you can get the information you need right off the data sheet.



Thank you for your reply and again, thanks so much for all your work...


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