Goal Zero Guide 10 Plus Battery Pack - $39.99

At about the size of a cell phone, this ultralightweight USB solar charging system can fit in your pocket. Itll recharge your cell phone one to three times per charge, and a built-in LED flashlight runs 20+ hours per charge. Use it as a single unit power pack to power your device or as a power source to recharge the batteries for use in any AA or AAA battery-powered device. Stores power for charging devices day or night. (Charge AA/AAA batteries from the sun in six hours with Nomad 3.5 solar panel or two hours from the Nomad 7.) Can also charge via USB. Includes a four-pack of AA rechargeable batteries. - $39.99