At what current do you kill LEDs - which driver was used?

Well vinh did a ton of TN31's and K40's by bridging the resistors, and I've done a few TN31's and one K40, and no reported problems, so far that is... I measured 5.5A at the LED, and forgot, but maybe 3A or higher at the cells (3 in series), so there's a lot being lost somewhere, and not greate runtime on high for sure - just the way we like it Smile.

I did same as you probably recall. Did most of the mods to reduce resistance too. I couldn't get reliable readings, but I would say they centered around mid 5's for me as well. I haven't had problems yet either.

So RaceR86. I know this thread is about LED deaths, but for sure there are folks running dedomed xml2's in TN31's at 5.5 amps to the emitter without failures. Supposedly there are others running in the mid 6's without failure, but I know of no confirmable cases yet.

Ledsmoke. You seem to live up to your name. Great info! :)


In terms of extreme output to an XM-L2/XP-G2 direct drive/linear driver is like hotlapping. You can get very good first lap/qualification. But you will never perform good in a race..Your second lap will be slower.. In the middle of the race you will be slow compared to the fast guys... And with these high currents, it does not take that long to get to the middle of the "race" if you get my drift. It does not seem like a direct/linear drive setup poses a threat to an XM-L2 and especially not to an XP-G2 even at peak.. 2-3 cells in parallel helps a lot on peak and maintaining output, but still the batteries will always be "fighting the Vf requirements"..

The TN31vn are the main reason why I have gotten the perception that 6,5A should be just fine. So I always assumed 7A should probably be okay... But I have never seen any emitter measurements showing 6,5A on those lights. So either those 6,5A are a bit inflated, or I would assume that the TR-3T6 driver have some current spikes that kills the LED since both me and ImA4Wheelr are playing mass murderers at what our DMMs says should be 6,4-7 amps. Makes we wonder if peak current should be lower than what I used to assume...

The main reason to know about LED deaths is to know where the limits are.. So confirming what works is also helpful... 5,5A to an XM-L2 should work if everything is done properly.. it seems... So how about 6 amps? and is 6,5A really too much?? Can 7 amps work nicely in a light? How does max output effect emitter life, and where is the sweetspot where you can be "safe" and avoid death?

We need more information before drawing any conclusions.. Best way to learn more about this is for various people to share their experience so keep em coming.. :)

Thinking vinh sold about 30-40 TN31vn's, saying they are 6.5A to the LED. Several posts here on BLF say they are 6.5A but I don't know of anyone that confirmed vinh's measurements. I have emailed with Wayne (vinh) and he did on one early unit, measure 6.5A, but not sure if he confirmed that measurement himself or not - I'm sure he didn't spend the time to check every single unit, because he must have gotten out 20 in just a couple of days. I think I got a good, solid 5.5A I checked and double checked - of course I was disappointed because I thought the mod was 100% exactly like what Wayne did, but dunno for sure I suppose - something could have been missed or forgotten something. I did a lot of tweak'n and checks to try to get it higher, but all attempts failed...

Hope I'm not derailing the thread, but it's all kind of related. If the TN31vn's do run at 6.5A and have been doing so for weeks and weeks now, and in volume, then maybe there's something to that super-sized copper star in those beasts that's saving the LED from getting a beating.

Edit: Ohh, and truthfully, I think the 6.5A is real because to get over 1,700 lumens from a de-domed XM-L2 (and a throw of 500 kcd) is unexplainable any other way.

Relic38s testing show basically zero difference between 16 and 20mm copper star. So I don't see how 20mm vs even larger should make a difference. Pill could make a slight difference at those extreme currents, but Ima4wheelr had a good pill it seems.

There is really no reason to doubt vinh.. But something does not add up. Again, makes me wonder if the 3T6 driver have some current peaks or something, which was one of my main reasons for starting this thread..

All information around the subject is useful information. :)

A start-up or even shutdown spike could be happening that could be damaging with those drivers. Those TN31 and K40 drivers are pretty amazin.

Ohh - vinh also did maybe 20-40 K40's the same way, so lots of units in the field, and I don't think they are all getting pampered. Wondering if he's getting reported failures - I'm sure he'd hear about it, but I bet most guys wouldn't go post about it - just common courtesy... My small handful of units out there are probably not getting stressed too much...

Boy, if vinh doesn't read this thread and had time to post, maybe I'll email him - would be good to know because he has the biggest volume of high amp lights out there by far, I'm sure...

My super shocker mods were measured at 5.5A to 6A, but at the carrier, not at the LED's, so can't really compare, plus they lose amps pretty quick, while the TN31 and K40's are truly regulated.

Yes true about the equivalent results between 16 and 20mm stars, but think he measured just output, and not "stress" or lifetime - pure speculation on my behalf...

I used this driver http://www.fasttech.com/products/1612/10005161/1404708-tr-0124b-84v-5-mode-led-flashlight-driver-for-lumi which I think is a TR-3T6 copy, thanks to the RaceR86 Ima4Wheelr 10ohm pot mod to a XM-l mounted on aluminum mcpcb thermal glued to a large computer aluminum heat sink and it died at a little over 6 amps. I then tried a XM-l mounted on a sink pad to the same heat sink and it died at 6.5 amps.
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I could try killing another XM-l and see if there is a current spike with the TR-3T6 driver. The 87V has a min max function that records the min and max. Only thing is I don’t have any spare XM-l’s to serve the death penalty on at the moment, already served the sentences. R.I.P.

Stock defiant super thrower led on the standard pill (l use this for testing drivers) blew in a milli second at 7.5 amps.

I did a decent job on my pill, but that TN31 base and head is impressive. The base is not only much larger than a 20mm Noctigon, it also thicker. I have to be honest and say that my setup isn't even in the same ball park as the TN31. That being said, I do agree that the driver is probably the problem.

Side note, but maybe related. I see a thermal pad gap in many Noctigon pictures. That can't help when we're pushing emitters this hard.

If I can figure out how to mod an SST-90 driver to <7 amps I'll be driving an XM-L2 in that range for my current project. I'll let you know how it turns out.

Which SST-90 driver and in which light?

Im considering to modify the driver from my lustefire 3xU2 a bit and use that instead of the MF TR-3T6 (I think its similar to a certain type of SST-90 driver) I should be able to make it work in a ZY-T08 and make it deliver the amps I want.. Its not on the top of my "mods to do list" though. So while I take my time.. Feel free to share.. :)

I can't remember where I bought it, but it may have been from DX.

Here are pics of it.

Thanks, looks like the 3-18V driver that IOS used to sell. A few others seems to sell it. LCK-LED being one of them..

Relic38 have resistor modded one (used for MT-G2). Feel free to share your experience about how it works in the high current driver thread (how far can you push it, and how fast does the overheat protection kick in and limit output once its modded).

If you kill the LED, or make it work nicely at 6A+, this is the thread. :)

As I think about it, I probably did buy it at IOS. Do you recall which amperage version they sold? I'm pretty sure 9 amps will not be survivable, but if it is a five or seven amp driver I will be in good shape.

I just checked my order history with IOS. I did buy it from them. It was listed as Boost/Buck 3-18V Triple XM-L Circuit Board". So it must be less than 9 amps. More likely much less.

Does Vinh mod his switches?

I have run this driver without problems with a XM-L2 U2 on a noctigon.

It’s a Ultrafire T-90 from wallbuys. I sold mine so I can’t check but it sure seems to be the same driver in the Lustefire U2.

I have used this driver to drive a single XM-L2 without problems and I can’t swear to it but I think it’s the same driver as in the Lustefire U2. I put a dry driver in my Lustefire and put this driver in a ZY-T08 to drive a MT-G2. I almost considered driving another XM-L2 de-domed with it, but I already have a ZY-T08 that is running a TR-3T6 driver with no problems, in fact I have two of them, one aspheric and one regular.

You guys must be using a resistor mod with your TR-3T6 and that is what is giving you the problems?

I’m waiting for the resin to dry on the MT-G2 so I don’t know yet how well it will run one MT-G2.

Im pretty sure it was rated 5A to single XM-l.

18650 wrote:

You guys must be using a resistor mod with your TR-3T6 and that is what is giving you the problems?

Yes, resister mods, but we're not sure its the driver giving problems as there are other differences that have not been isolated. Assuming reports of TN31's running at 6.5 amps without LED failures are accurate, then there is some cause other than over driving that has caused the LED failures we have so far documented in this thread. Since there are other variables, RaceR86 is trying to gather failure data to see if a pattern develops. So far there are 2 big differences between the successful TN31's and the dead LED's noted so far:

  • Heat sinking. The TN31 has a superior copper base and head.
  • Driver. The TN31's driver appears to regulate voltage and current.

I have fried my share of emitters and so far it has always been poor heatsinking that kills them or a short of some kind. Well that and bumping the wires on de-domed ones, that has taken out more than anything. But that is just being clumsy. I have also fried emitters by not allowing my epoxy to set up properly. I am using wakefield deltabond now and I let it set up overnight, amazing stuff.

I wonder how many problems people are having comes from not properly lapping and using cheaper stuff like arctic silver which from what I have read is not really all that great. I would think that if it’s running fine and then suddenly dies it’s either a short or the epoxy has loosened or dried and shrunk possibly from the heat.

That T90 I built was supposed to be running at close to 7amps and it had no problem on an aluminum base.