What is the appropriate current for charging a car battery?
2 Answers
Car batteries are charged with a 12V current. The functions of the battery are: 1. To provide a strong current to the starter when starting the engine; 2. To assist the generator in supplying power to electrical equipment when the generator is overloaded; 3. To supply power to electrical equipment when the engine is idling; 4. To protect the electrical appliances in the car. The working principle of a car battery is: It uses a lead-acid battery based on the primary cell principle, where the positive plate is lead oxide and the negative plate is pure lead. When the load is connected, the lead on the negative plate reacts with sulfuric acid to form lead sulfate and lose electrons, while the lead oxide on the positive plate reacts with sulfuric acid to form lead and water, gaining electrons, thereby generating an electric current.
The charging current for car batteries is generally recommended to be around 10% of the battery's capacity. For example, a 50 Ah battery is best charged at 5 amps, which is the standard practice. Too high a current can cause overheating, damage the battery, or even lead to explosions, while too low a current will result in slow charging and affect usability. I often help customers with this in the shop, and it's important to consider the battery type. For instance, lead-acid batteries should not exceed 15%, while AGM batteries can handle slightly higher currents but still require caution. Charging time is also relevant—a 5 amp current will take about ten hours to fully charge a depleted battery. However, if you're in a hurry, you can briefly use a higher current for a quick charge, but never exceed 20%, as it can be dangerous. In summary, investing in a good smart charger that automatically adjusts the current is both convenient and safe. Regularly checking and cleaning the electrodes can also improve charging efficiency and prevent malfunctions.
