What is minimum electrical required to start my car?

When I was 14 years old my Dad made me help him repair lawn mowers (for his friends). He would make me hold the plug wire to judge if the mower had enough spark. I would hold the wire and he would turn the flywheel (by hand). @#&^%$^)(&)&)(*_)....I never did get used to the shock!:mad::mob::poke::soapbox: