Whenever you're traveling away from civilization, it's pretty important to have a backup power supply. While most portable batteries run flat fairly quickly, the Universal Waterproof Solar Charger keeps soaking up power from the sun. It works with most mobile devices, and you can grab one now for $13.99 via the Popular Science Shop.
In many places around the world, you may not see a wall socket for several days. If you're relying on your GPS device or mobile phone, this can be a serious problem. With the Solar Charger, you leave home with enough juice to refill your phone a full 1.5 times per charge.
To start recharging the large 5,000mAh battery once again, you simply hang the charger on the outside of your backpack via the supplied mountain clip. Plus, the charger is waterproof and shockproof, so you can take it anywhere. You'll charge your devices via the dual USB ports, which deliver 1A and 2.1A respectively. The charger also comes with a USB-to-micro USB adapter and a 4-pin adapter, meaning you can power pretty much any small device.
This charger is normally $49.99, but you can get it now for $13.99 with a choice of four colors.