How many hours does it take to charge a dead car battery?

[VanRichard]

A dead car battery needs to be charged for 20 hours. Taking a 12V 60Ah battery as an example, the charging method involves constant voltage and current-limited charging. Charge at a constant voltage of 14.8V with a current limit of 15A for 16 hours, followed by a constant current of 3A for 4 hours, totaling 20 hours. Methods to determine if the car battery is fully charged include: 1. A large number of bubbles appear in the battery, indicating a boiling phenomenon; 2. The 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. While the car is running, the generator will recharge the battery, but it is necessary to recharge the battery promptly when it is severely depleted.