Instead of a 2xAA flashlight, I would suggest you look into a 1xAA light that can run on Alkaline, Lithium, or a rechargeable in NiMH or LiION (a.k.a. "14500"). That gives you a lot of options on how you want to power it. And you can get some darn bright flashlights in this size if that's what you want. The brightest will be when you power it with a 14500 LiION.