What is the normal discharge current of a car battery?
2 Answers
Sleep current: domestic cars below 40mA, high-end cars below 80mA. Extended information: 1. Test range: Use a multimeter to adjust to the current test range, the maximum current test range. After starting the engine, connect the multimeter test leads in series between the generator line and the battery. Observe the pointer position on the multimeter, which indicates the current during vehicle operation, i.e., the car's discharge current. 2. Check for discharge: Turn off all electrical equipment, including doors and anti-theft devices. Disconnect the positive cable of the battery and gently touch the terminal. If there is no spark or it is very faint to barely visible, it means the car itself is not discharging. If the spark is obvious, locate the electrical equipment that is self-discharging.
I usually pay attention to battery maintenance when driving. The normal discharge current after turning off the engine should not exceed 50 milliamps. This value refers to the current when the car enters sleep mode after being locked, as systems like the computer control system maintaining memory will consume a little power. I've measured it several times with a multimeter, and most cars are around 30 milliamps. If it exceeds 50 milliamps, it may indicate a potential leakage issue, such as a dashcam with high standby power consumption or a faulty door lock module. Previously, I installed a GPS tracker in my car, but due to improper installation, it caused a discharge current of 90 milliamps, and the car wouldn't start after three days. So, I recommend avoiding random electrical installations, especially devices connected to constant power. Always confirm whether they are turned off after shutting down the engine. Regularly checking the discharge current is essential; detecting high levels early can prevent being stranded on the road.
