At some point, you'll be caught without power. If you're lucky, it won't last long, but it's worth learning about other ways to keep your gear powered. This deep-cycle battery, charged by a bicycle-powered generator, will do the trick.
The video above is a brilliant walkthrough of how the whole thing works and what it takes to build it. You'll definitely need some components and time to make this happen (not to mention some skill with electronics projects), like a magnetic DC motor (the kind you'd find in an electric wheelchair) and a charge controller based on this design that keeps the battery from overcharging.
Once it's all up and running, you can attach a bike and use it to charge the battery. The beauty of the setup is that it uses pedal power to charge the battery, not to power the devices, so the lights don't go out right after you get off the bike — you can charge the battery a bit every day, get some exercise and still use your emergency radio, keep the TV turned on or use your phone.
Thanks to Becky for sending in the video!