White LED lumen testing

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:

ViReN said:

jtr1962, great work. many thanks.

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

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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.

Erasmus said:

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

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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.

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.

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.

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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!

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.

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

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?

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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.

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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.

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

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?

Click to expand...

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!

Click to expand...

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.

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.

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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.

Pardon my ignorance, but WTF is that?

YES I CAN SEE THE DOLPHIN!!!



:nana:

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.

So...

...what is the age of the tree?

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.

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.

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.

Awesome work as always!

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