How Long To Charge Car Battery Idling. Your alternator only outputs about 13 of its rated amperage at idle speed. The most common rate for car battery chargers is around 4 amps.
Letting your car idle can do good to your cars engine. The general consensus is you have to drive the car at least 30 minutes to put any meaningful charge on it. So it takes almost 4 hours of idling to fully recharge a dead battery.
How long should I idle my car to charge the battery.
So it takes almost 4 hours of idling to fully recharge a dead battery. But you asked how long to leave a car running to charge battery. There are several factors to consider. You may be wondering how long it will take your car battery to charge while you drive around.
