What is the normal discharge level for a car?
2 Answers
Different car brands have varying discharge currents. Vehicles with fewer electrical appliances tend to have lower discharge currents, while those with more electrical appliances exhibit higher discharge currents. After the engine is turned off, the car's sleep current typically ranges between 40 milliamperes and 80 milliamperes. Below are the daily power leakage of car batteries and methods for inspecting car discharge: Daily power leakage of car batteries: A car battery loses approximately 1% of its charge daily. If the battery remains connected to the car, it uses a minimum current (commonly referred to as "sleep" current) of about 80mA to maintain basic functions. If the car is equipped with an anti-theft alarm, additional power is consumed, generally resulting in a daily power loss of around 2% to 3%. Methods for inspecting car discharge: First, use a battery tester to check if the battery has aged. If the test results are normal and the battery discharge is due to human factors, simply recharge the battery. If the battery gradually depletes while the vehicle is in operation, first inspect the generator or charging system for any faults.
I've always believed that a normal car's discharge rate should ideally be between 20 to 50 milliamps. I learned this the hard way with my previous 10-year-old car. At first, I thought it was just an aging battery, but when I measured it with a multimeter, the discharge current had surged to 80 milliamps. It turned out to be a wrongly wired dashcam installation—using constant power instead of ACC. Now, I'm extra careful with any electrical modifications, always checking the static current before calling it good. Actually, devices like door modules also consume power in standby mode, so it's crucial to measure and confirm after any modifications. Anything over 70 milliamps should raise a red flag, especially in older cars where wiring issues are more common—you might end up with a dead battery after just three days of parking.
