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:
Holy cow, these LED’s preform just as good in a light as they do on the bench! If I can now just find a neutral tint version preferably in 90+ CRI with cheap shipping.
I just built an S2+ with the second XP-L2 that was sent to me (I like to get 2 of any LED’s I test so that I have a spare in case something goes wrong or if the first test results are inconsistent for some reason, plus I like to install one in a light so I can see what it looks like in the real world).
Wow, this is easily the brightest single emitter tube like I have!
The really surprising thing is how much more efficient it is. With the TA17 drivers I have a regulated 350ma mode that generally nets me around 120-150 lumens depending on the LED, the highest I have seen was 180 with an XP-L V6 HD IIRC.
With the XP-L2 I am getting 200 lumens @ 350ma!
I then have a 2.45A regulated mode that normally nets me around 850-900 lumens, with the XP-L2 I am getting 1150 lumens!
Then we come to turbo, here are the results with different cells, these are all from a cold start, this is why I retest the peak output on the bench from a cold start to see what it would do in a flashlight.
Cheap laptop pull – ~6A – 1950 lumens
GA – ~7A – 2100 lumens
30Q – ~8.5A – 2300 lumens
Now of course things get hot fast and the output drops fast as well but I didn’t feel like testing each at 30 seconds. Still, 2300 lumens @ turn on from an EDC S2+ is seriously impressive!
It is also nice to see that the cold start test on the bench is indeed a good indication of what happens in a real light. It also explains why the numbers people report from flashlights are sometimes higher then what djozz’s tests says they would be.
After I got done being impressed with it on the sphere I then started looking at the beam.
Edit, just built a 5700k 90+ CRI XP-G3 for direct comparison. Updated the rest of the post accordingly.
First thing I noticed is that it is much like the XG-G3 with the tint shift as others have mentioned around the edge of the beam. The tint shift is basically the same as the G3, the tint plays a larger factor then the type of LED I think.
Compared to the 5700k G3 I would say the tint is close in the hot spot although the L2 has more red in the beam giving it a slight purple hue when white wall hunting. When used in the wild it is actually not that bad of a tint, but still too cool for my tastes.
I am thinking I would want 4000k to get a neutral tint, this one is far too cool for my liking, CRI is not about average for a 70CRI.
The beam size is naturally larger then the G3 but not a ton, maybe 25% larger.
Overall except for the cold tint I really like this LED, the tint shift is not ideal but it is livable for the performance you get. A good TIR lens that mixes the beam would really improve things, the TIR I am using helps but doesn’t fix the tint shift.
If these can be found in neutral tints and 90+ CRI I can easily see these becoming the go to LED’s for myself.
In other news I was comparing the graphs from the XP-L2 and XHP35 (test not released yet) and I am pretty sure that we are reaching the limits of the 3535 footprint at around 40W. Both LED’s have the same general curve shape when looking at wattage, I am guessing that 40W is just the limit for how fast the heat can be moved out of the LED no matter what star you have it mounted on. Honestly that is seriously impressive for that tiny footprint.
This does make me look forward to an XM-L3 to be released with this latest die tech, it is possible it could reach even higher numbers due to the larger footprint.
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.
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Giving money and power to government is like giving whiskey and car keys to teenage boys. -- P.J. O'Rourke , Civil Libertarian
My LED Test series - XP-L2 V5 - Nichia 219C 90+ CRI - Latticebright "XM-L" - XHP35 & PWM efficiency - XHP50 - XP-L V5 - XM-L2 U2 - XP-G3 S5 - XP-L HI V2 - Oslon Square & direct comparison to Djozz tests