Finally the XHP70.2 emerges!

i have ordered a few xhp70.2 from digikey, and disappointly have burnt up 2x, i am coming to the conclusion that these are much more current sensitive in my setup than the xhp70, and probably different from one to another. i noticed the meter to spike pass 18A both times (narsil ramping).

first, using a s70s as a host with TA FET Narsil driver, updated with SIR404, 16awg, spring bypass, littokalas

second, same setup but with reduced 22awg (this setup works with my L6, but it only draws 16A)

i am not sure how to get these to work at +18A, any suggestions?
has anyone found the max safe current?

https://www.digikey.com/short/31d2jm

LedNLight has some XHP70.2 TIRs listed. There are more manufacturers of XHP70 compatible TIRs, but I haven’t collected the data.

Poor re-flow / heat sinking maybe? Here is my SD75 2S2P bypassed battery carrier, Narsil Lexel built T/A SIR800 pulling just over 20 amps on VTC5’s, so that’s what I run in it. No problems so far…

My VTC5A’s turned the 70.2 instantly blue at 22-23 amps IIRC? :open_mouth:

I measured between the driver lead and the LED.

At extreme currents like 18A everything has to be perfect to keep the LED alive. That is a truly insane amount of power for such a small comportment. Over 120W worth of power to be exact!

To be honest I am impressed that they work at all at those currents. I would never expect it to.

Dropping the current down to 10-12A is what I would personally do. Above that you will reach a point of exponentially more heat and less extra lumens as power increases.

I measured 17.9A at the tail with a clamp meter on my L6 and it's surviving so far. The cells will drop pretty quick at this rate, and the heat is a problem of course. On LK cells w/solder top, it started at 9,100 lumens, dropped to 8,230 in 30 secs.

you guys are nuts lol.

I have over (12) XHP70/70.2 lights in my keeper (never to sell) collection, and this little UTorch UT02 is one of my favorites!

Machined out the head for a 32mm Maxtoch DTP board, 70.2 P2-1A Lexel built T/A Narsil driver, with reasonable out put 9amps at turn on and just over 8 amps around 30-40 seconds, or how ever long it took to try and grab the shot of the clamp meter in 3 attempts… :smiley:

i am not sure how to know if the reflow is any good, maybe when i “bop” the led it created voids in the solder. i will try again. without “bopping” the led. any reflow tips?

maybe after this i will learn to accept less than insane maximum :slight_smile:

(Had to fix that for you :wink: ^)

I BOP them too, maybe too little solder and BOPPING does no good? I usually have squirt outs at 4 points after BOPPING?

Did the LED go blue before Poofing? Or was it an instant Poof?

If it was a long slow burn out (meaning not an instant Poof) maybe thermal contact was insufficient?

Please don’t get discouraged, It’s a bummer, yes, but 8-9,000lm out of these 70.2’s after all, is quite something to behold!! :wink: :+1:

when i bop the led some solder did squirt out, i then push the led a tad to see if it will pull itself back onto the pad. i wonder instead of bopping to squirt, i would bop and hold till the led cools down for better contact.

the led did go blue before “poofing”, long enough for me to realize “oh sh!t” that is not the color i want.

i wish Narsil have a ramp speed setting, current setting is too fast for me to stop it from going full power, a much slower speed would allow me to stop once i see some blue tint.

Be careful you are not overheating the LED when reflowing as well. It is easy to do if you are not using a temperature controlled heating source.

good thoughts, going to make use of the FLIR one for the next reflow :slight_smile:

Could you fit more than 8?

Dunno, only a wild guess here because of course the GT is the widest head light around.

I noticed with the 3 XHP70.2 P2 3B's in the MT03, I don't notice the yellow ring around the halo. Not sure it made a difference, but I scraped off the yellow on the edges of the LED. Pretty sure my MT07 and L6 have the yellow ring.

I'll have to try it on the L6 or MT07 and see if it makes a difference.

You think that might reduce the yellow around the main beam? Let us know of your findings, I was wondering if a sliced dome close to the surface of the die might reduce that too…

Possible? I know KawiBoy mentioned this, or something like this on dedomed LED's - though maybe it could be the same for domed LED's.

All I do know is I did it on all 3 in the MT03 and I don't see a yellow halo. Dunno, might have time this evening to try it.

I reflowed this XHP70.2 N4-3A 5000K from fasttech on my Acebeam EC50 Gen II 5000k, but there isn’t any difference, my integrating sphere shows the same lumens for all modes with both leds

This is not that surprising. I am sure that light uses a regulated driver. At the same currents the total wattage is less due to the lower Vf of the LED. This means that while it is more efficient it doesn’t produce anymore lumens until you drive it harder.

The same thing can be seen in my XP-L vs XP-L2 test (the XHP70 uses XP-L and the xhp70.2 uses XP-L2 dies, so it is a great comparison).

Basically you would need to boost the current to see more lumens. Right now you should get an improvement in battery life.

It’s also because the LED needs to be in a higher Bin to actually be birghter. An XHP70.2 in P2-Bin should make the light brighter at the same current. The differences are small though…

Yes the improvement should be a better battery life / longer runtime and less heat / longer Turbo-Mode with terminal regulation and thats all.