XP-L2 V5 Output & Death test by Texas_Ace Over 2200 lumens! Still worked after 15 Amps!

Sounds like it’d be a good emitter for diving lights or submarine fixtures, then! Can’t beat this power/luminosity proportion when the heating problem is solved by the sheer amount of coolant all around :smiley:

Oh, and that’d be a [+S2+] build, I think… haha

Just ordered parts for a S2+ triple XP-L2 V5 4000K setup (with a Mtn FET+1) from Mtn Elec. Can’t wait to get this little flame thrower assembled!

That will be one pocket rocket. Remember that you will most likely need to slice the domes on the XP-L2’s to fit under the optics.

I would also recomend the 15011 optic over the 15007, I get higher lumen output from it for some reason and with my XP-G2 triples it vastly improves the tint shift.

Richard states the triple XP-L2's fit the 15007 optic as-is, but for the 15008, 15009, 15010, and 15011 it requires the "XPL mod" to fit. He has a way of widening the optic - not sure if the widening method has been published. If you get the "XPL mod" for extra $1.50, no need to slice the domes.

Yeah, I saw that note and hope it’s the case when the parts arrive. I’ll make sure to check fitment before tightening things down. If necessary, I’ll probably slice (vs the mod). I think I’ve heard the mod described before as drilling out the recess a little with a modified torx bit or end mill bit.

My tests seem to correlate with what is stated in the first post. Ran upto 10amps on a beast of a heatsink and it was getting brighter up until i passed 10a. Great LEDs should have no problem whatsoever direct driving on 4.2v

Hi Tex, after 10A did the base of the dome lifted/separated from the phosphors?

Not at 10A but it did somewhere between ~12A and 15A. Not sure exactly when but my guess is around 13-14A is when it started.

By the time I reached 15A the dome was starting to burn which is part of why the output was reduced.

My XPL’s dome separated at ~10A. Improper heatsinking I think

Geez you guys and your crappy heatsinks, gotta step up your game!

I tried one of those at first but could not drill/tap the copper for anything. I snapped off 4 or 5 drill bits before giving up.

Although the one I use now is just as big but it is an aluminum core rated at 135W and I was able to drill and tap it in order to get a good connection for the mcpcb.

I don’t use thermal paste to help replicate a flashlights thermal path a bit better. Plus I hate cleaning and messing with thermal paste.

I used big aluminum block (the one in many of my pics) submerged in iced water. The problem seems to be the dirty contact under the already oxidized copper MCPCB. Forgot to clean it
I have a big Pentium 4 heatsink + fan but currently soldered to a 144AR VirEnce board as my work light. At 2A (~25watt) , it’s Ts only ~40-42C @28-30C ambient.

Edit: not Ts, its the heatsink fin temp. The fan rated at 12V but ran at 5V only powered by USB

??? You kidding me?
All high quality flashlights use thermal paste.
Using no thermal paste is HORRIBLE for temps, literally the worst thing you can do before sticking an insulator between the two surfaces.
Even toothpaste works better than no thermal paste.

No wonder your LEDs are dying at 10-15 amps, they are probably running like 100 degrees C higher than the heatsink.
Your 135W heatsink is nearly useless if you don’t use thermal paste.

The LED still worked at 15A, the dome just started to burn. Also 15A is an insane amount of power for a 3535 LED to handle, this is the first LED I have ever heard of to do such a feat.

Not running thermal paste is not a big deal. It increases the thermal resistance some but not that much. The point is that flashlights will run way hotter then a big fan cooled heat sink, not running thermal paste helps simulate this.

I ran an extensive battery of tests before settling on a testing protocol.

For example in this test I actually removed the LED and added thermal paste after 10A to give it every advantage as I pushed it towards death. If you look at the lumen graph though you will notice that lumen output is actually WORSE with the arctic silver 5 then with nothing at all. output dips slightly

After that I no longer cared about running thermal paste in these tests. In other tests I saw much the same thing, only very minor changes in lumen output with thermal paste vs none. A less then 3% difference in output is not worth talking about.

Paper numbers are great but real world results > paper.

This is 100% not true. It makes a huge difference.
There is a reason why it is absolutely unthinkable to run computers without thermal paste.

I have no idea what you did wrong in your test, because when running an LED cooler it should give more output.
You probably damaged the LED by running it without thermal paste, that’s why the output was worse when you continued after 10A.

If you apply the paste correctly and your heatsink actually works, then the curve should begin dropping at much more than 10 amps.
Temperature is what makes the output decrease the more amps you feed it.

And PS the point is not to have tons more output, the point is to prevent the LED from dying, and to extend its lifespan rather than having it degrade 2x faster than necessary.

Those are results from real tests.
You can look up any thermal paste benchmarks and you will see how horrible no paste is.
I can’t believe that this isn’t common knowledge in the flashlight world, it’s just ridiculous. In any other electronic or mechanical field everyone knows how important thermal paste is.

You should redo your test properly, using an LED which hasn’t been driven to 10 amps without thermal paste, and use an IR thermometer to monitor the die temperature.
Without thermal paste you will probably see 100 or 150C+ which is why your domes are burning. With proper cooling this will not happen.
Even a small flashlight-sized heatsink with thermal paste will perform better than a 135W heatsink with no paste.

Don’t be too dramatic Enderman. Unless you’re using extremely rough MCPCB and or heatsink at the mating surface….at our LED level applications thermal paste isn’t that magic.
I always try to lap the mating surface as fine and close as possible to get the largest contact area, so I will need the least amount of any magic paste in between. Thermal paste is just a substitute of air pockets. When your mating surfaces impeded by thermal paste, the result will usually worse than no thermal paste at all. That’s why even though thermal grease/paste have somewhat lower thermal conductivity than premium thermal pad, the grease/paste will always win. Less is better.
I seldom use ultra premium AS or whatever brands those online magazines tested, just simple ultra fine graphite mixed with silicone oil or….oftentimes just my moly-graphite bearing grease. The graphite powder is from Techline when I used to tune race engines back in 2000’s.

You can say what you want, I tested this a few times in back to back tests when setting up my setup.

The difference between thermal paste and no thermal paste was only a few percent difference in output. The LED was not damaged at the 10A point. I retested it after adding the thermal paste at low current and it still gave the same results as the first test. I know what I am doing.

You have obviously not personally built high powered LED flashlights, so it is pointless for me to continue this discussion.

People know what my experience on the subject is, they can make up their own minds as to what they think of the results.

It is very interesting that if I am “so wrong”, that my test results are within ~5% of Djozz’s tests, who does use thermal paste…… Which is very close to the difference I noted between my paste vs no paste tests……

This is BLF, we don’t argue as much as we test.

Back to topic:
Tex, so it should be that my result was abnormal? I don’t have any XPL left at the moment. Will try the CRI 90 XPL2 next time. Mark should have it sooner

Not sure I would say abnormal as we do not have much in the way of tests at that level. Generally the max you get on an FET driver is around 9A, so that is about the most people have used it at regularly.

In my case it lived longer but 10A is pushing the limits for sure. I mean all of the last gen LED’s died at between 6-8A, so it even living to 10A+ is amazing much less it making peak lumens at that point.

Basically it boils down to driving a 3535 LED at 10A is extreme and when running on the edge like that things will happen.

I was just curious. Yes, it’s extremely extreme. You perhaps do 6+ A more often than me. My most used setup is < 1A. Some goes up to 3A but it’s rare.
It’s good to know this LED is so resilient.