How Long Does it Take for a Car Battery Jump Starter to Charge?
A car battery jump starter is a device that is designed to give a battery that doesn’t have enough power to start enough of a boost to do it. Usually, if the car’s battery isn’t drained too badly, you will only need to keep the jump starter connected for a few seconds before the car will start. If the battery has been drained more, you may need to keep it hooked up for a few minutes before enough of a charge is able to transfer for the car to start.
For more info, see Car Battery Ratings Explained