I just found out that this is a more logical technique to use a battery to jump a car. A battery will tend to have more juice than a typical jump box. I like to know if it is possible to leave a car running for about 5 minutes to recharge the battery used as jumper so that it can be reused on the same trip with full confident. It would be much better than having to carry a battery charger and find a place to recharge it. Thank you for your help.