Or one of these: http://www.fasttech.com/product/1283...pack-for-18650

I have a few of the one-battery version ML102, and they work fine for keeping my mp3 player, mini Action Cam (Midland XTC 200), and USB rechargable blinkies charged on a tour. The camera and player can even work while charging. They are also a great Li-Ion battery charger.

Of course...these are first world problems. Take a look at this guy and his story: http://edition.cnn.com/2009/WORLD/af...lawi.wind.boy/

There's cell towers and cell phones in Africa, but his area had no power to charge the phones.

Maybe someone can come up with a portable carbon-fiber/titanium windmill that spins your dyna-hub all night. Or windmill blades that snap to your spokes, so your dyna-hub wheel itself is the windmill...