Emitter Test Results pt4: XML2, XP-E2, XP-G2, and Nichia219! (along with sinkpad tests)

very nice work… thank you very much…!!!

I also need to know where to get xm-l2…

Yes he is. But the difference is not that big, see here:

Taken from here: http://www.taschenlampen-forum.de/modding/13515-bastis-bastelbude-13.htm...

Testing of a copper star on Alu, Cu and Ms (brass) heatsinks.

Thank you for the test Match. Nichia 219 in sight? :D

Great info. Thank you Match!

So it appears that even running multiple healthy parallel cells wouldn’t run very long at 5A. Guess one needs to consider getting the equipment needed to measure capacity and rate of discharge if they want to push an XML2 hard.

I would love to see the difference with sinkpad to aluminum. This difference was talked about elsewhere. It would really be good to KNOW what that difference would be. Remember the heat capacity of aluminum is about twice that of copper, even though the thermal conductivity is about half. Sinkpad to Aluminum is the practical construction technique, lets see how effective it would be.

Thanks for doing the measurements.

WOW!

Thanks for doing those tests.

Thanks Match!! This confirms what I've been seeing in the few XM-L2/SinkPAD builds I did and posted about. I ordered a Small Sun ZY-T08 exactly because of the 2 parallel battery configuration - perfect for a hot XM-L2/SinkPAD/Nanjg 3.85A or 4.2A setup.

Also, these results don't mean you won't see much of an advantage from single cell applications - even at lower measured amps, results are impressive over XML U3's on aluminum. I've also seen outstanding results with an XML U3 on a SinkPAD and having the same high Vf issue with that, so it's not so much an advantage of the XM-L2, it's the SinkPAD's advantage. For single cell applications, switching to lower resistance batteries directly results in higher amps, higher measured lumens/throw - I've done this on a few lights by testing with an AW IMR 2000 mah.

So, I'm seeing greater gains with a SinkPAD upgrade than upgrading to an XM-L2 emitter only, so, Match's results seem to confirm this. I'm not saying XM-L2's have no merit - they do with efficiency, and with equal bin, equal tint, they should do better than an XML, but unfortunately the best/brightest available XML emitter is a U3 1A/1B/1C, while the best/brightest XM-L2 is U2 1A/1C now, and I've only used XM-L2 U2 1C's and XM-L2 T6 3C's up til now.

That explains why I only get 3.3a where an xm-l takes 3.7a.

I have a light in mind for an xm-l2 swap now. Just need to get a sink pad to suit.

Thankyou match. :bigsmile:

If you compare the same mass (1kg for example) but now do the math for the volumetric heat capacity (hint: the one of copper is higher).

But just take a look at post #26. Even brass is good enough.

I hope someone puts out a constant voltage/current driver soon so we can push these babies to 5amps on 2x li ions

If I had a 2 li-ion light, I’d be doing an MT-G2, not an XM-L2.

How about a boost drive for a L2 at 5 amps? 8)

That’s right, I am not saying Aluminum is better, I am saying that it is more practical, therefore for most applications it is what will be used. So it would be good to know how it performs when mated with the copper sinkpad. I suspect it wouldn’t do that much worse than copper all the way. If it is only a few percent difference, then that would be great. The thermal path from the junction of the LED to the back side of the copper sinkpad is the most critical part. The further away you get from the LED, the less important thermal conductivity becomes because the cross sectional area is greatly increased. It would be really good to know how Aluminum performs past the copper sinkpad.

MT-G2's are great for flood, haven't seen/heard of a good throw setup with one yet. What relic38 and rdrfronty are thinking about with the BTU is potentially one of the best applications of the XM-L2/SinkPAD's

the first pics has also xpg2 ,are you going to test them as well?

thanks for the data Match, it’s fantastic to see such controlled experiments especially as the data can then be compared back to previous emitters.

So the XM-L did ~875lm @3A, the XM-L2 (U2 I presume) does ~1000lm at 3A and the XM-L2 on a sinkpad does ~1100lm. 225lm extra for an emitter swap is pretty amazing! At 1.5A the figures are ~550, 630 and 650lm, which probably explains why I didn’t see much difference by eye when I swapped my XM-L T6 for XM-L2 T6 on Sinkpads.

It’s interesting that, despite the higher Vf, the XM-L2 on Sinkpad is more efficient at ~101lm/W @3A vs. 96lm/W on a plain aluminium star. Pretty damn amazing how far things have come in the last couple of years.

I just modded a KE-5 that did 4.8A (stock T6 on 16 mm alum star) - 920 lumens stock, to Nanjg @3.85A U3 1B/20mm SinkPAD and got 1,100 lumens. So, lower amps, cooler running, better output. At stock, that light got noticeably warm at 30 secs - after the mod I ran it to 6.5 mins where hottest spot got to 118F, pretty hot, but that's tailstanding on it's own @room temperature.

The XML2 is a U2 bin, and IIRC the XPE2 I sent was Q5 or what ever the top available bin for them is.

Yes, you are correct texaspyro. There is some loss because of the smaller amount of metal in a flashlight.

I think however you will be pleased to know I have conducted some testing on this. In the body of a small to medium size light ( like a 30mm head diameter) I put one of these XML2 on a sinkpad and wired it directly to my bench power supply. Even in the small light body XML2 sees gains at the 1 minute mark as high as 5800-6000ma. The output does have a gradual but steady decline at this current. Its more stable at slightly lower current like 5000.

I will be posting a thread reflecting some of the data in this experiment over the weekend.

great measurements!

If you put this combo in a well heatsinked flashlight that can handle the 5A (say, a few 18650's parallel, or one fatty INR), I wouldn't bother using a driver at all, just direct drive it on the batteries: 1600 lumens at 4.2V, still 1250 at 3.8V

Why is the forward voltage higher with XM-L2 on copper vs aluminum at the same amperage?

Bort: I think it’s because the emitter runs cooler on copper.

Also keep in mind that given two emitters of the same basic type, bin, and tint can still perform differently. Good 'ol cree tolerances.