Apparently you can use ato charge your mobile devices, but if you need more power for emergency purposes, the following SOSCharger self-powered may be more suitable for you.
The SOSCharger is a practical portable charger designed to offer you two different methods to charge your iPhone, Android phone or other mobile devices. As we can see from the images, the USB charger features an integrated hand crank and a built-in generator. When the backup battery is out of juice, you can wind the hand crank in order to generate power to charge your smartphone via an integrated USB port, 3-5 minutes of winding gives you 5-12 minutes of talk time. Moreover, you can also quickly charge the 1500mAh backup battery via any A/C adapter with USB output. Apart from that, the LED indicator shows you the status of the backup battery.
At present the team of SOSCharger is raising fund at Kickstarter. Pledging $35 will let you own the self-powered backup battery. If you’re interested, jump to Kickstarter official site for more details. Additionally, if you need other options you might like to check BoostTurbine backup battery and more via “backup battery” tag.