Here is my usb charger i'll be trying out during the EC. Its a regular old 7Ah 12v sealed hobby battery and a car charger unit i found at walmart for about 10 dollars. Plus a couple of slide connectors and i put a switch in the side just for fun. Capable of charging 2 usb powered devices at a time. The 12v could easily be topped off with a small solar panel for extended trips.
