Where is the auxiliary battery of Mercedes-Benz W212 located?
3 Answers
The auxiliary battery of Mercedes-Benz W212 is located on the right side of the trunk. Function of the battery: The battery is an important component of a car, responsible for powering all electronic devices in the vehicle and also for starting the engine. Lifespan of the car battery: It is typically 3 to 4 years, but many car batteries fail before reaching this lifespan due to incorrect usage habits of the owners. Avoid sitting in the car for extended periods using electronic devices without starting the engine. In winter, try to avoid parking the car outside overnight. The low outdoor temperatures in winter can reduce the battery's lifespan.
In the Mercedes-Benz W212, the auxiliary battery is typically hidden in the bottom area on the right side of the trunk, specifically beneath the spare tire well or in the right corner. After opening the trunk, lift the thick carpet or remove the spare tire to locate it. I once helped a friend replace it and found that its purpose is to support the start-stop system and other auxiliary functions. It is much smaller in size compared to the main battery. Extra caution is required during replacement—disconnect the main battery first to avoid short circuits and electric shock risks, as the circuitry can malfunction if disturbed. Having a pair of gloves and a wrench on hand makes the job easier. If neglected for too long, it can degrade and cause the start-stop system to fail. I once experienced a situation where the car's warning lights kept flashing. The placement is well-designed and doesn’t interfere with daily space usage, but regular checks are necessary to ensure stable connections.
The auxiliary battery in the W212 is located under the trunk. You can find it by lifting the floor mat or removing the spare tire, usually fixed on the right side. I believe this arrangement is because Mercedes wants to isolate the main circuit to reduce interference while making maintenance easier. During daily driving, if the start-stop system isn't working, you should suspect it's faulty. If you're doing it yourself, always remember to turn off the engine and all power sources to avoid injury or causing malfunctions. I once tried to replace it but forgot about the main battery, nearly causing a spark. Now I'm extra cautious every time I handle it. The location isn't too hidden, but beginners should avoid taking risks—it's safer to go to a professional repair shop.
