Running stoker without electricity

I see that there is an adapter for the stoker that allows it to run off a car battery or cigarette lighter.

If you had a fully charged, normal sized car battery, how long do you think it could power a Stoker? Are marine batteries better?

I'm wondering because some of the competitions charge an extra $50 for electricity. May be worth investing in another option if it makes sense.

This is a good option - http://tvwbb.infopop.cc/eve/forums/a/tpc/f/9270072103/m/1450022435

Thanks Larry - I can't believe I missed that thread.