I have an old external battery for Apple devices (has 30 pin Apple Dock Connector), and I want to repurpose it to be an external battery for all my USB devices.

Anyway, I don't have much experience with this kind of thing, so if someone could give me some good advice on how to accomplish this, it'd be great! I only really need to convert it to any kind of USB cable, since I can just get converters from there.