Ok, this is the first official release of an LED test from my setup. I have a few others already complete that I will be releasing as I get the time to make the charts all pretty and ready for upload.
Cliff notes version
- My sphere and setup is finally calibrated to a level that I feel good about releasing numbers from
- I figured out how to turn a PVC sphere into a true integrating sphere that reads the lumen value directly on the lux meter so no math is involved
- The lumen readings line up perfectly with the Cree data sheet confirming that the readings are indeed accurate
- The XP-L2 is a tank of an LED, handling up to 10A without any damage and over 15A with damage but still working!
- Over 2200 lumens (2450 peak from cold start) from a 3V single die LED in a 3535 footprint, that is over 40w of power through a single LED! It handled 70W at peak while still working!
First off thanks to djburkes for donating the LED’s! If anyone else has a new LED that you think would be worth putting through the ringer, let me know.
So I will start off by giving a quick rundown of my setup. I have 2 spheres actually, the Josh BLF “standard” sphere and a PVC sphere I made using the stuff I learned from Joshes sphere. Long story short, I have been dialing it in for the last few months to get it as accurate as possible, I am quite happy with the current setup. It is FAR FAR better then the plain jane PVC setup I started out with.
If people would like to see what I did to my sphere, let me know and I might be talked into making a thread on it, the biggest difference is that it is a true integrating sphere and doesn’t allow any light to escape. It also reads the lumen readings out directly on my lux meter, no calculator needed!
Now that it is setup to my satisfaction I can start releasing numbers from it as I will not be changing it any more. Thus my numbers will remain comparable. They are also pretty accurate if I do say so myself, this test for example lines up perfectly with the Cree data sheet.
For the test itself I have the LED’s all reflowed to DTP copper stars unless otherwise noted, they are then mounted on a PC heat sink with fan that I setup to hold said stars. The fan is running the whole time.
I then start the test and work my way up in current using my DPS5015 to power it. I stop every .25A to take a voltage, current and lumen reading.
The voltage drop over the wires is calculated out in the corrected voltage column, thus giving the actual forward voltage (although remember in a flashlight that resistance will not be subtracted).
Now to the test itself!
Ok, so djburkes sent me 2 XP-L2’s to test. I have to say I was not expecting much from them to start but I am VERY impressed with the results! These things are TANKS! I took this guy all the way up to 15 amps and it still worked! Although it was hurt pretty bad at that point.
The test really went great up to around 10A (A whopping 40W), the LED was not even hurt up to this point as I retested it at 1A and it had only lost 1 lumen!
After that it started getting stressed, by 12A it had been hurt a bit and after 13A the tint started turning a bit blue. Somewhere around 14A it started burning the dome, it literally cooked the dome off but even at 15A it was still kicking! I left it there for a little while as well. An astounding 70W of power was passing through it!
The spikes in the graph are when I retested from a cold start to show what would happen in a well cooled flashlight over the first 30 seconds or so. I generally try to time this around peak output.
I plan to install the second LED in a Convoy S2+ tomorrow and see what kind of results it gets there but I was too excited and had to post this test now.
So enough with the talk, time for data!
Click images for larger versions that are easier to read! Or download and zoom in all you want.
I am quoting a post from later in the thread where I put the second LED in a S2+ to see what it did in the real world:
I tested an XP-L V5 as a comparison and the results were interesting. Keep in mind the lower Vf of the XP-L2. When compared by wattage the XP-L2 is slightly ahead of the XP-L the entire time. AKA, the XP-L2 is more efficient overall.
Also in the real world the lower Vf means we get much better numbers from the XP-L2 then the XP-L since we can pull much higher currents.