How Long to Charge a Dead Car Battery?
2 Answers
When a car battery is dead, theoretically it takes about 20 hours to charge using a portable charger, and over 5 hours when charging by running the engine (with the engine speed exceeding 2000 RPM and not idling). The method for replacing a car battery is as follows: 1. Loosen the negative terminal nut, disconnect the negative terminal. Use a wrench or hex socket to loosen the negative terminal's fastening nut, then gently pry open the fastening block with a flat-head screwdriver to remove the negative terminal. 2. Disconnect the positive terminal using the same method. 3. Remove the locking strap by loosening the nut securing the battery's locking strap, then release the strap to remove the battery. 4. Install the new battery using the same method, but follow the "positive terminal first, negative terminal last" sequence during installation.
I once encountered a situation where my car battery was dead. The charging time indeed varies from person to person, but the basic principle is that taking it slow is more reliable. Ordinary home chargers typically have a power output between 5-10 amps, and most batteries have a capacity in the range of 50-70Ah, so it generally takes about 8 to 15 hours to charge. If you're in a hurry and use a fast charger, you might reach the starting voltage in 1-2 hours, but this can accelerate battery aging. I prefer slow charging because it allows for a more stable internal reaction in the battery, avoiding overheating and damage. During the charging process, make sure the environment is well-ventilated, and ensure the positive and negative terminals are securely connected without looseness. After charging, it's best to check with a voltmeter; a fully charged state is around 12.6 volts. To prevent future issues, I often plug in the charger for maintenance once every week or two when parking in the garage. This significantly extends the battery's lifespan and avoids the trouble of breaking down halfway.
