I think you'll find that you'll need some sort of medical control in place. If that's the case, the rest is moot.

If you do it anyway, I can only imagine the liability you'd be facing if something were to go wrong.

The Chicago Fire Dept. was recently successfully sued when one of their AED's failed due to a dead battery, $3.2 million. If you were to have an AED out in the field and you attempted to use it on another person only to have it fail due to maintenance issues, well it doesn't take a lot of imagination to see what could happen.

I'd check with the state health dept. wherever you'd be using the device before making any purchases.

Having said all that, the one I have on hand for my job is nice, an Allheart model. It uses a non-rechargeable battery that's good for quite a few months of storage. The pads are datestamped and must be replaced regularly.