In times of emergency, you may be required to jump-start your car. Jump-starting the battery of a car does not fix your car problem for long, but it is a sure way to quickly get your car battery active again when it runs down unexpectedly. It usually takes about 30 mins after a jump-start for the battery of a car to charge. This would require you to drive around for about 30 mins to charge the car battery to full capacity.