[Warning: train of thought ahead.]

New project: how to get my scooter to supply power to a USB port. My ipod in particular - its battery dies a lot (partly because its 3-4 years old, and partly because I don't remember to charge it) I realized that I spend a lot of time sitting right on top of a big-ass car battery, and an idea sparked (Yes, puns are the lowest form of humor. Except bilingual puns, those are worse.).

So I ride an Amigo RT. It has 2 12-volt batteries wired in series for a total of 24 volts - although I should borrow a voltmeter and check this. According to the information at atbatt.com, each battery (and thus, the whole pack) supplies around 18 amps - give or take a bit depending on the specific brand, age, etc. (Note: I will be revising this as I do more research. My knowledge of circuits is pathetic for an EECS major, even if I haven't taken any EE classes yet, and I need to fix that.) USB power is 5 volts, with a range of .1-.55 amps. So that's if I tap directly into the battery. I should check, though, if I can tap into the headlights, that opens up some interesting options (reducing the no-load drain, tucking the port inside a casing, etc).

Firewire would be easier, as it takes a broader range of voltages (14-30? Can that be right? Closer to 24, anyway, than USB), but then it will only work with my ipod - not with my cellphone, and not with any future devices I might have. And assuming most wheelchairs use similar power supplies, I should be able to move this from chair to chair when I upgrade, so future-proofing would be nice. Plus, USB is just cooler.

I think my next step is to call Amigo and get some more detailed specs.