^^^^^ Yeah, 6V in series vs. 3.7. From what I know of LEDs, they tolerate a wide voltage range, but indeed, won't last as long at higher voltage. Most any other device would probably not be as forgiving; an old-school tungsten bulb, for example, would probably burn out in seconds or minutes at nearly twice the rated voltage.

I'd be more tempted to run two very weak CR123As, or one good one and one dead one (as a conductor), in such a situation.

Turns out I have a slew of 18650s, from an abandoned project to rebuild a Ryobi 18V battery pack. I just ordered a light like the one depicted by [MENTION=252435]RubeRad[/MENTION] , with a charger and bracket.