Crash-testing a XM-L2 and a XP-G2 on copper Sinkpads

Pretty clear from the graphs the Vf tracks higher for the XP-G2 across the spectrum of amps -- wish I knew this sooner, but this sure does explain a lot.

Thanks djozz!! Great work/info!!

Dedomed XPG2 R5 3D/Sinkpad/big CPU heatsink, 1-2-3-4 cells in parallel, direct drive

Samsung INR-15Q, unprotected
1cell - 2.56a 3.61v
2cell - 2.93a 3.75v
3cell - 3.15a 3.81v
4cell - 3.24a 3.85v

Panasonic NCR 2900mAh, unprotected
1 - 2.53a 3.59v
2 - 3.07a 3.77v
3 - 3.28a 3.85v
4 - 3.42a 3.89v

Wow, that's interesting #'s. I got the 15M's and 20Q's, and the 20Q's are very good - seem identical to the 20R's, but to see them beat out by standard Pana's with qty 2 or higher in parallel, is kind of mind blowing -- not sure why? Do you know?

Also, the 2.56A for a single 15Q seems rather low - I'm definitely getting higher #'s with a Nanjg driver and 22 gauge wires with a 20Q. Mine are tailcap measurements though...

The 15Qs have been sitting a while, they were all 4.08-4.09v at the start, the grey Panasonics were just charged yesterday. Also, I only have one meter so I had to change the wiring around between the voltage & amperage measurements, could be something got jiggered. I have big fat wires on my battery box but the leads after that were single 22AWG, and the test leads for the meter are full length, something like 3 feet each, stock Fluke leads. Mostly it's only interesting in showing how splitting the load across multiple cells and the resulting higher voltage affects things.

I figured more than one INR would have killed it dead instantly, I was surprised by those numbers.

Hey, I changed my mind. I just ordered a new MT-G2 for a flashlight built I am going to do when I have the time.

This leaves me with one spare (5000K 6V) for yet another crash-test on a Noctigon board that I may do one of these days. But please give me a reason not to do this test (like: he or she has done that already and the results can be found here, or: relax !, I will do this test for you and I am doing a much better job at it than you do) because I am still reluctant to demolish a perfectly good MT-G2 .

Umm . . . I don't think anyone is going to say those things! We're waiting for you to do it! :) Thanks for these tests by the way! This is very helpful information to many of us!

-Garry

Very nice and useful graphs!
I have bookmarked this page! :wink:

Djozz, would be nice have a chart going to 10A or slightly beyond on the MT-G2. You dont have to kill it just for the sake of killing it. But if output seem to continue to rise, then I would not mind seeing what 12A would do, despite not knowing of any drivers that will do that kind of output.
There is not that much point in going far beyond 10A just for the sake of killing it. But it would be nice to know if there is some headroom left at 9A. 0:)

I agree with R86, no need to destroy it. I’m more interested in finding where adding more current results in no increase or a decrease in output. In the case of the XP-G2, this occurred before failure. The XM-L2 was still trending higher when it failed.
This information is very helpful, just don’t feel the need to destroy the emitter if the useful information has already been captured.
I probably would have tried this already if I had a supply with that current carrying capability (6A max for me).
Thanks for your efforts on this! :beer:

ok, I don't know what to expect actually, the MT-G2 is a multi-die emiiter, the combined surface area is much higher than a xm-l and the solder path is huge so if the thermal path is built like the xml2 the dies should be able to handle 20+ amps, but if the bond wires can handle that? When the weakest wire goes the rest follow directly because of increased current. Wait and see...

I don't think you'll need to kill it, I suspect the light output will fall off a cliff long before anything goes ZZZZAP.

In terms of ºC/W versus area the Luxeon T comes out on top.

LED: ºC-mm^2/W

MK-R: 13.6

XM-L2: 10

XP-G2: 8

Lux T = 5.44

XP-E2: 9

The XP-G2 is slightly larger yet has a higher thermal resistance value than the Luxeon T. The T's thermal resistance is less than double that of the MK-R despite the latter having over four times the area through which to transfer heat. Not sure why the XP-E2 appears to fare worse than the XP-G2 in this regard but I rashly conjecture and am likely wrong that it has something to do with the way ºC/W is measured and the following tidbit:

Max Rated Wattages/Square Millimeter (85ºC)

MK-R: 1.9

XM-L2: 2.48

XP-G2: 2.25

Lux T: 1.57

XP-E2: 3.15

I just saw this. That was awesome. Simple and to the point; turn it up 'till it blows.

Also interesting that the XM-L2 kept getting so much brighter at higher currents. I was under the impression that anything much over 3 amps went to heat with increased lumens dropping off. Is the upgraded XM-L2 different or am I missing something else?

Sorry if this has already been discussed . . .

learningFoy

:O

This is y I luv the amps and the coppa

And copper.

It just hit me. I already have a xml2 on a copper sinkpad that is reflowed to a copper slug that is reflowed to a brass pill in a Torchlite SV-D2. The light has really good heat sinking. Driven at 4.5 amps the light has no issues at all. Some people have been driving MG-T2’s hard in them.

So, I want to change out the driver and push that xml2, but not hurt it. Any opinions what current I should use? I want to try 7 amps. Is that pushing too close to the limit for this type of flashlight being used outside in hand?

Very roughly, 7A at 3v (XML) is the same power (watts) as 3.5A at 6v (MTG2). Actual numbers will be different and also you have to figure in driver efficiency and a whole bunch of other stuff but that should be enough to get you started.

That helps put it in perspective. Thanks. I need to try to do this tonight. Wife is out of town. So it’s time to play with my flashlight.

Do it.

Also, what driver? I need to find a two cell driver that does 6-7 amps for an XML2

I’m going to use my go to driver for the first attempt. The Manafont “3T6” driver. People have been resister mod’ing those for multi-emitter lights with good success.