RIP Nuwai ALX-032

Well I just got this nice new set of UltraFire "880mAH" rechargeable Li-ion batteries and I was testing them in my Nuwai ALX-032... well something went wrong and RIP Nuwai! The light just shut down on its own and I took the batteries out only to smell the characteristic burnt electronics smell. Strange because I have used this light with rechargeable batteries since day one, why did it die now?

I seem to recall the Nuwai ALX-032 is a 5-watter taking 3 cells which are normally primary cells.

Although it may have some sort of regulator, I don't think it bucks current as far as I know.

So using rechargeables which have a peak voltage of more than 3v each can be potentially damaging if the V-in of the 5W does not exceed 9W.

The life of a LED is very short if its continually battered with much higher
Voltage and hence current than its supposed to withstand. (This will lead to
unacceptable heat - thermal runaway)

This is a possibility if I'm thinking about the correct Nuwai

Actually its a 3W light with 2 123A batteries... but I think you may still be right, it may not have any kind of buck feature built in to it.