Surefire KX2 Head on E1e body?

[j3bnl]

Looking at buying a Surefire KX2 Head and want to use it on an E1e body and run it on one of AW's RCR123 3.7V rechargeables.
Will this setup work?

 

[Bullzeyebill]

Do some searching. Much info on just that question. Short answer is you will have very little regulation. The KX2 has a constant current buck regulator and needs vin to be higher than vf to run in regulation. You have been around for awhile, go ahead and research.

Bill

 

[Ty_Bower]

What he said. I've tried running a KX2 on an 18650 cell. I'm not entirely satisfied with the performance. Even the large li-ion cells don't hold the voltage high enough to run in regulation for as long as I would like. It seems like a waste of the capacity of the cell.

It does run for a long time (on an 18650) but the output is dropping for a lot of the run. I'd just as soon run it direct drive, or maybe with some kind of LDO circuit.