Originally Posted by dougmc

For buying new sets out on the road, yes, AAA wins (really, AA wins even more, but you've chosen lights that only take AAAs). But beyond that ...

1 18650 battery is approximately the same size as 3xAAA batteries, but lasts longer. NiMH AAA's have about 700-1000 mAh, and alkaline AAAs are about 1200 mAh. 18650 cells have the same voltage as three AAAs (so it replaces three of them), but have capacities around 2400 mAh.

They cost $4 each, which is about the same price as 6xAAA (buying three batteries twice because they have half the capacity) alkalines -- and being rechargeable, you can use them over and over.

Being Li-Ion, they'll keep a charge for many months if not used (same as alkalines, but not non-LSD NiMH cells.)

Unless you're touring (and your trips last for many weeks and you don't want to bring a charger and won't even have electricity), I'd suggest that just buying enough 18650 batteries to last through your longest trip would be a cheaper (and more environmentally conscious) plan. It would also be lighter than bringing the needed AAA batteries with you, though of course it's not lighter than simply buying alkalines as you need them and throwing away the dead ones. (You probably won't be able to find a proper place to recycle them on the road most of the time.)

Though if you insist on buying alkalines as you need them rather than going rechargeable, I'd suggest getting a light that takes AAs instead. AAs cost about the same as AAAs but have about 2-3 times the energy -- so it'll cost that much less for the same amount of light. Something like the Planet Bike Blaze 2W would be a fine light.