XML2 U3 blowing at lowish current

Flashlight Modding and DIY Parts
1

Hi Guys.

I vaguely remember reading about a new batch of xml2’s having exceptionally odd vf’s and thought the problem had sorted itself out.

However I’ve just received a new batch of 8 xml2 u3s from mtn electronics and they seem to be drawing very, very low current direct drive from an NCR18650PF at max 4.1 amps, and running around 5 amps through my maxtoch driver I’ve blown three!

So, in order to try save some leds, I thought I better check and see if this is a common problem with u3’s

Cheers!

Chris

2

Yes. Not only U3`s either.

There seems to be a "lottery" though. Some emitters (similar bin and tint) are better/less bad compared to others.

3

Just worked out the actual current based on the sense resistors, and should be 5.7 amps, what do you think is the max for these heaps of junk?

4

Safely? About 5A max if the driver does not have any rippe/current/voltage spikes. I know several can U3 emitters can handle 6A (based on own data and reports from others), but that is really pushing your luck.

Check the data in the thread I linked too in my previous post for some details.

I would recommend you to go for XP-L if you have plans for 5,7A or higher through a buck driver. So far they seem more capable at high amps.

5

I just replaced an XM-L with a new XM-L2 U3 on a Sinkpad in a light that was pushing 5.6 amps with a LGHE2 high drain battery and an east092 DD driver, new emitter would only draw 2.6 amps, I was really surprised to see such a large drop.

I proceeded to do some hot rodding but the max I could get out it was 3.4 amps. It was noticably brighter though and should have a longer runtime.

6

Ill give one a burn on stock driver tonite (3.75ish amps) and report back

Chris

7

xml2-u3 de-domed in maxtoch sn6x-2x with completely stock driver, but with 20 awg added to springs and LED, 277 kcd at 3.75 LED amps, 2.25 at the tail cap.

I ran the last one at 5.5 LED amps with an xml2-u2 1A de-domed for 330 kcd, so it’s not entirely disappointing as it seems to be plenty efficient, just not very capable of high current.

Chris

8

Any info on the "burn in"?

Output is also a lottery it seems. Several different people with several different emitters have also measured similar or even lower performance compared to XM-L2 U2 at similar amps. Ive had some reports PMèd to me from various members who have been disappointed with emitters they have bought. So its not always great news in the performance department either, despite that amps is kept reasonable (ehm, typically well above 3A). Seems like you need a little bit of luck in order to get great performance.

Glad to hear your sn6x-2 is doing well after mod. :)

Getting U3 that is capable of very high amps (6,5A+) and high light output (higher compared to U2) seems to require a whole lot of luck.