Where is the auxiliary battery located in the Mercedes-Benz S350?
2 Answers
On the right side of the trunk. Below is relevant information about the auxiliary battery: 1. Auxiliary Battery: It is a small battery, generally referring to the battery that powers the entertainment system, windows, and lighting system during startup. 2. The auxiliary battery can also be considered a large capacitor: On one hand, it powers the entertainment, lighting, and other systems when the engine starts, when the engine is not running, or when it is operating at low speeds. On the other hand, it assists the main battery in supplying power when there are too many electrical devices or high power consumption. It also helps stabilize voltage by absorbing instantaneous overvoltage in the circuit to protect electrical devices. 3. If the vehicle experiences an auxiliary battery failure: It will not affect normal driving. If the vehicle is under warranty, the fault can be repaired.
I've been driving a Mercedes-Benz S350 for quite some time, and the auxiliary battery is located under the floor of the trunk. To be more specific, it's in the luggage compartment area at the left rear corner. You can see it by lifting the carpet or the toolbox cover. It mainly supports the auxiliary starting system and electronic power steering, acting as a backup when the main battery is low to ensure the car is always ready to go. I had to replace it once because the car wouldn't start despite multiple attempts, and after much troubleshooting, I realized this little component had reached the end of its lifespan. I recommend checking its voltage every year or two using a multimeter to see if it's around 12 volts; if it drops below 11 volts, replace it immediately to avoid trouble in emergencies. Mercedes-Benz designed it quite meticulously—though the location is hidden, it's well-protected. When handling it, avoid pulling forcefully; just gently release the fixing clips.
