Just bought two cuz Ima greedy *******. I used a battery powered charger on tour in July to keep the cell phone and GPS going (unfortunately refused to charge the MP3 player...). Even with just the two gadgets, for two weeks, I still went through most of a 24 pack of alkalines. Lithiums are damn expensive, but would have been smarter, because the alkalines didn't deliver enough current even when fresh to charge my devices more than half-way. Of course, at a price like this, solar starts to make a little sense. Hmm.