My name is Allen and I'm new here! I was wondering if anybody knows of a USB powered charger for the BP-511A batteries for a Canon 50D. I'm doing a few treks and I have USB solar charger, but I need a USB charger for my batteries, which would be better than lugging five or six sets of batteries in the pack! Will be in hot and humid conditions to boot. Does anyone know of any chargers like this?