I've got a car jumpstart pack with a lighter socket on it, so I generally use that, although I have run it off the bike as well. It comes with both a lighter socket plug and a set of clips to go onto the battery terminals.
It's genuinely brilliant. It doesn't act like a rattle gun - you'd need big power for that - it just spins up for a few seconds then goes 'donk'.
Spin, donk, spin, donk, spin, donk, undone
I've got a pneumatic rattle gun on a shelf somewhere. It's useless because I don't have a big enough compressor to run it. Can't afford one, and don't really have the space for it.