AspectSolar’s EnergyBar 250 portable battery pack fits in a backpack and features a slim 20AH cell that can power anything from a USB device to a television. The device can fully recharge a laptop up to five times, or a mobile device up to 30 times on a single charge. Connect it to a portable solar panel, and you can keep your electronics going indefinitely. The EnergyBar 250’s Lithium Iron Phosphate battery has a life span of around 10 years and a self-discharge rate close to zero, ensuring it will be ready to go to work even after sitting around for a while. The case is weather resistant and slim enough to be easily tucked away in a nav table when not in use. $499.