XM-L and an IMR 18650


Flashlight Enthusiast
Aug 10, 2008
I just got my IMR 18650. Charged it up and put it in my XM-L direct drive light. Suffice to say it is the lowest internal resistance cell available and it shows. Current at the tailcap was a scary 7 amps on a fresh charge to only 4.10 volts. I'm sure it can climb even higher if I fully charge it to 4.20 volts.

Anyone care to guess the led output at 7 amps? It certainly is bright, my guess would be about 1300 lumens, that's with a conservative lumen derating of about 60 lumens/watt which is what the xr-e achieves when driven to about 1.75 amps which is what 7 amps to 4mm^2 translates to. Oh and I put it in my 1.5 amp regulated xp-g light and tailcap current now registers 1.9 amps. I suppose it's now fully driving the xp-g to it's max potential so I guess I'll just leave it in my xp-g light and not use it in my xm-l light. I don't want to put a driver in my xm-l because I like 4.5 amps with a standard li-ion and no off the shelf driver can go that high efficiently on 1x18650.