There are various brands of batteries that are useful for charging mobile devices off-the-grid, two of which are iCruiser and ALLPOWER. But both still have drawbacks. You must not far away from power for a certain period of time, if using iCruiser or devices by similar functions. If using ALLPOWER, you will worry about whether or not enough sunlight to ALLPOWER or devices by similar functions.
Another option might be a viable alternative in the future is created by Kraftwerk which brings the power of a fuel cell prototype packs for USB-powered devices.
Kraftwerk is taken from the German for “power plant”. The device works on the gas canisters and promised to charge your iPhone up to 11 times before needing a refill.
Here’s how these devices work, gas canisters, like we usually use to refill butane lighter or used in camping stoves, used to fill the internal tank. After the tank is full, thanks to the fuel cell system in it, it can be directly used to recharge mobile gadgets. Kraftwerk will notify its users if the gas in the tank is decreased by the LED system. Although promoted as a new technology in Kickstarter campaign to raise funds for production, Kraftwerk working principle is similar to the technology offered Lilliputian Systems Inc.