How long does it take to fully charge a car battery after it's depleted?
2 Answers
If the car battery is depleted, it generally takes 2 to 3 hours of idling to fully charge it. However, it is not recommended to charge the battery by idling the engine in such cases. If the battery is depleted, it's advisable to take it to a professional repair shop and use a specialized charger for charging. More information about car batteries is as follows: 1. The battery is a crucial component of a car. When the engine is not running, the battery supplies power to all electrical devices in the vehicle. After starting the engine, the alternator takes over the power supply for all electrical devices, and the battery is also responsible for starting the engine. 2. The battery is a wear-and-tear part that requires regular replacement. As the number of charge and discharge cycles increases, the battery's storage capacity decreases, which may lead to difficulties in starting the car.
How long it takes to fully recharge a car battery after it's drained doesn't have a fixed answer, as it closely relates to battery size, alternator performance, and the degree of discharge. Based on my experience, for batteries with capacities between 50-70Ah and alternators outputting around 100A, running the engine for 30 minutes might restore enough power to start the car, but a full recharge requires at least an hour or more. Don't just idle the engine; driving at higher RPMs charges the battery faster. I've seen a friend start the car for only 10 minutes before turning it off, only to find it wouldn't start again. If the battery is old or the weather is cold, charging time can extend up to two hours. The cause of the discharge also matters: if it's just from leaving lights on, partial charging while driving may suffice; frequent discharges might require checking the alternator or replacing the battery. For safety, I recommend driving for at least 40 minutes or idling for an hour after starting to avoid secondary issues from shutting off prematurely. Improper handling of a drained battery can shorten its lifespan, so using a charger for a thorough recharge is best.
