How long does it take to fully charge a car battery?
2 Answers
It takes approximately 20 hours to fully charge a car battery. Taking a 12V60Ah battery as an example, the charging method is as follows: use constant voltage and current limiting for charging, charge at a constant voltage of 14.8V with a current limit of 15A for 16 hours, then charge at a constant current of 3A for 4 hours, totaling 20 hours. A fully charged battery can be identified by the following phenomena, or by observing the battery eye turning green: 1. A large number of bubbles are generated inside the battery, known as the "boiling" phenomenon; 2. The terminal voltage rises to its maximum and does not increase further within two hours; 3. The electrolyte level rises to its highest point and does not increase further within two hours.
As someone who frequently takes long-distance drives, I've found that fully charging a battery generally takes 6 to 10 hours, depending on the battery capacity and charging method. For example, a standard 45Ah car battery for household vehicles takes about 9 hours to charge fully with a 5A portable charger, but switching to a 10A fast charger reduces the time to 4-5 hours. However, the actual condition of the battery plays a significant role—if it's completely drained, it takes even longer. Temperature is also a factor; in winter, I usually wait an extra 1-2 hours. For safety, avoid overcharging to prevent battery swelling or damage—I often rely on the charger's indicator light; when it turns green, the battery is fully charged. For daily maintenance, I recommend checking the charging condition every six months to extend battery life.
