our batteries, but have used smaller ones for various tasks as well. My husband knows more and will probably weigh in here.

We have a good friend who is making hats with small solar cells in them. You can either charge devices directly or store the energy to a battery for later use. Pretty cool!

For flashlights, I keep one or two hybrids around. They have their built-in own solar charger and also have regular AA batteries. Fot cell phones, MP3 players and ipads, there are all kinds of hybrid chargers out there. Best get one with a built-in battery for emergencies.

This one looks like a great buy and is on sale for about $27
Opteka BP-SC4000 Ultra Thin Solar Powered High Capacity (4000mAh) Backup Battery and Charger for Cell Phones, iPhone, iPod, and Most USB Powered Devices
http://www.amazon.com/Opteka-BP-SC4000-Powered-Capacity-4000mAh/dp/B005ZSVZRY/ref=pd_sim_sbs_sg_6

but I bought an inexpensive one years ago and it was trash. It was poorly made, and worked for about a year before croaking. So what I would do if I decided to try this again is buy the best model that I could afford----and like I do with everything, although I seem to be the only one these days, I would find one in a store where I could see it before I did the purchase. I would make sure it is well made of quality products. That would not insure that it would be good quality that lasted, but it would be more likely than what I got (online).

campers have been using this kind of stuff for a long time now.