The question is in the title. Isn't an alternator just another word for an electric motor? The thing is, I don't know if there is anything particularly special about an alternator or not. I mean if it is just an electric motor, meant to be spin by mechanical force in order to generate power, then the opposite should work, putting power into it would generate mechanical force..

 

its designed to be more efficient at generating than at spinning itself so it would probably spin but it probably wouldnt be good for it.

 

Not necessarily true. The field coils in the alternator need to be energized to create current flow, as they act like the permanent magnets in the "can" of an electric motor. But if you take a permanent magnet motor and spin it, you will get voltage production.

 

The alternator is an AC device. DC current will not make it spin.

http://en.wikipedia.org/wiki/Alternator