How long does it take to fully charge a dead car battery by driving?

[Elise]

It takes about 3 to 4 hours of driving to fully charge a dead car battery. The functions of a car battery are: 1. Providing power to the starting system, ignition system, and electronic fuel injection system when starting the engine; 2. Supplying power to the car's electrical equipment when the engine is off or idling at low speed; 3. Assisting in powering electrical devices when the generator's output is insufficient; 4. Mitigating voltage surges in the electrical system to protect the car's electronic equipment; 5. Storing excess electricity generated by the alternator. Methods for maintaining the battery include: 1. Starting the car regularly to charge the battery; 2. Adding distilled water or a special replenishing fluid when the electrolyte level is low; 3. Frequently checking the ventilation holes on the battery cover during daily driving; 4. Inspecting the battery's positive and negative terminals for signs of oxidation; 5. Checking all parts of the circuit for aging or short circuits; 6. Turning off all electrical devices when leaving the car.