I hike a lot, and I'm planning a backpacking trip, and my camera battery always seems to die waaaay too quickly. I can, and will (one of these days) buy an extra battery, but that doesn't help me much when I'll be in the wilderness several days at a stretch and each battery lasts only half a day. I've been looking into making a super lightweight, portable charger for my camera battery, along the lines of this but, obviously, for the camera battery and not an Ipod. My main goals are to keep costs and weight down and to not fry the battery. Does anyone have any thoughts on how to make a project like this work for a camera battery charger? Or, failing that, does anyone know of a *cheap* solution to my problem?