Originally Posted by pedalMonger

Getting a Fenix light to use as helmet mounted is on my wish list (not a priority since I already have some DiNotte lights, but could see adding a Fenix when the days start getting shorter in the Fall), so I did some research. The P3D is one of the models I am interested in, and being able to use rechargeable batteries is of course important.

So anyway, I found this thread at candle power forums. http://www.candlepowerforums.com/vb/...d.php?t=160826

A lot of confusing discussion amongst the torch junkies, tech lingo about experimenting with odd sized batteries that the light wasn't designed for. But what I got out of the thread, is that using some variation of "volt protected" CR123 li-ions (RCR123?) is the best route. "Unprotected" rechargeable batteries can get damaged I guess, if they are drained to low.