What is the normal range for car battery drain?
2 Answers
Car battery drain is normally around 45 milliamperes. Causes of car battery drain: Ground leakage from automotive electrical components and circuits such as electrical devices, wiring harnesses, sensors, controllers, and actuators; self-discharge and power loss due to short circuits or oxidation shedding of battery plates; electrical switches not being turned off when parking. Solutions for car battery drain: Check whether the battery voltage and charging are normal and whether the battery terminals are rusty; remove the negative terminal of the battery, set the multimeter to the maximum current range, connect the red probe to the negative cable, and connect the black probe to the battery terminal and secure it; turn off all interior and exterior electrical devices, lock the doors, observe the current level, and adjust to the appropriate range.
I've experienced battery drain several times and later did some research on this issue. After normal engine shutdown and locking, the vehicle's static current should be within 50 milliamps, and must not exceed 80 milliamps at most. This is similar to the concept of a phone in standby mode, where essential devices like the anti-theft system and clock need to remain operational. If it exceeds 100 milliamps, the battery won't last three or four days. Last week, I helped my buddy test his old Tiguan, and we found a 130 milliamp drain because the dashboard wasn't properly closed. Further investigation revealed it was caused by a leakage from the aftermarket dash cam. I recommend using a multimeter to measure the current: connect the red probe to the positive terminal of the battery and the black probe to the negative terminal, then set the multimeter to the mA range. If the reading exceeds the normal value, check the circuit, especially any aftermarket electrical installations, as they are the most common culprits.
