White LED lumen testing
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jtr1962
Flashaholic
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!Haha this is total madness, but I like itA single die emitter putting out 500 lumens, amazing!
By the way, did you receive my R2's already?
Cheers!
3 or 4 of the R2s you sent me will find a new home in a bike light I'm making.
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
Flashaholic
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.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.
jtr1962
Flashaholic
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.
Calina
Enlightened
Thank you for this fascinating test. I am truly amazed by the thoughness of these small dies.
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.
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.
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
Enlightened
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.
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
Flashaholic
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!
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
Flashaholic
Me too. I thought for sure I would hear a pop by 2.5 amps but the emitter just kept on cooking!
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.
Yes, I've measured many low-output, wide-angle LEDs as you can see here:
jtr1962
Flashaholic
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.
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).
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.
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
Flashaholic
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.
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
Flashlight Enthusiast
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.
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
Flashaholic
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.
I kind of thought that to be the the case. Thanks.
