What is the normal amount of car battery drain?

[VonPeter]

Car battery drain typically has a normal value of around 40mA, though this can vary depending on the vehicle model. Some high-end cars may experience up to 80mA. The reason for this dark current is that certain electrical components in the car need to maintain data memory functions continuously, and anti-theft sensors also require long-term power supply to ensure the car's alarm system remains operational. Car battery drain refers to the gradual discharge of the battery when the vehicle is parked, which can affect engine startup or cause electrical malfunctions. Causes of car battery drain include: 1. Short circuits or oxidation shedding of battery plates; 2. Ground faults caused by electronic components and circuits such as car electronics, wiring harnesses, sensors, controllers, and actuators.

[DeFelicity]

I used to worry about whether my car would leak too much electricity and drain the battery if left unused for a long time. Later, I found out through research that a normal leakage current should be below 50 milliamperes to be considered safe, meaning the battery would only lose a tiny amount of charge over a month. If the leakage exceeds 80 milliamperes, you should be cautious, as it might be due to aftermarket modifications or loose wiring. Testing for leakage is actually quite simple—just use a multimeter set to the current measurement mode, disconnect the negative terminal of the battery after locking the car, and measure the current in series. Pay attention to whether any abnormal dashboard lights stay on after parking for extended periods. Once, my car's battery died prematurely because of an aftermarket dash cam that consumed power too quickly, forcing me to replace it. So, I recommend avoiding unnecessary modifications to prevent increased leakage.

[SanVictoria]

As someone who often works on cars myself, I don't think car electrical leakage is anything to make a fuss about, as long as it's kept within 80 milliamps, which is considered normal range. This is mainly due to standby consumption by electronic modules like alarm systems or radio memory functions. If the leakage exceeds standards, you need to systematically check the causes: first inspect battery terminals for corrosion or looseness, then examine any aftermarket GPS or headlight modifications; or simply perform a test by measuring the current when parked with a multimeter. Remember not to forget to turn off headlights and such, which can save power and reduce leakage risks. During routine maintenance, take the opportunity to check the battery condition—this extends vehicle lifespan while saving money and hassle.

[GabrielaLynn]

The normal leakage current should be between 30 to 50 milliamperes. I think exceeding 80 milliamperes indicates a problem. Excessive leakage can drain the battery overnight, especially in winter when it may fail to start. Causes include aging wiring or electrical devices operating unnoticed, such as a Bluetooth audio system not properly turned off. Testing is simple—just clamp the multimeter to the battery and read the value directly. It's advisable not to delay; if an abnormality is detected, get it checked promptly.