How long do you need to leave car running after you have it jumped to make sure it starts on its own if it has been about two months since it last ran?

Answer 1

Depending on the vehicle, it is not a good thing to expect the vehicles alternator to charge a dead battery. They are really not designed to do that and can lead to expensive problems in the near future. A healthy battery sitting for two months should not be dead. You may have other issues there. Start with having the battery tested at your local auto parts store. If the battery tests good but just run down, use a battery charger and give it a 24 hour trickle (2 or 3 amp) charge to bring it up to snuff. Then have a parasitic draw test done to see if there is something draining the battery when the vehicle is parked. A healthy parasitic draw would be .050 amps or less.