Where is the auxiliary battery located in the Mercedes ML350?
3 Answers
The auxiliary battery of the Mercedes ML350 is located under the front passenger seat, visible after removing the cover panel. The Mercedes ML350 is equipped with two batteries: a main battery and an electronic gearshift battery. It's important to note that during battery replacement, power should not be interrupted to avoid putting the vehicle's computer system into sleep mode. Additional details are as follows: 1. To ensure continuous power supply during replacement, use the "jumper" method by connecting the new and old batteries in parallel with cable clamps before removing the old battery. 2. During replacement, be careful not to connect the positive terminal to the vehicle body, as this may cause a short circuit, which is extremely dangerous.
Last time I helped my neighbor repair his old ML350, I specifically researched the location of the auxiliary battery. The auxiliary battery in this car is particularly hidden, tucked behind the inner fender liner on the right front wheel arch. You have to first remove the windshield plastic panel on the front right side of the engine bay, then unscrew several bolts near the engine bay side of the wheel arch, and peel back the sound insulation material to see it. This battery is even smaller than an electric scooter battery, just a black box with two electrode connectors. It mainly powers the start-stop system, so extra caution is needed when replacing it—you must ensure the vehicle remains powered during the operation, or it might trigger a system lockout. Personally, I think Mercedes' design is a bit user-unfriendly, but it's probably for weight distribution balance.
My 2014 ML350 had its auxiliary battery replaced last year. This little thing isn't in a conspicuous spot in the engine bay, but rather tucked behind the inner fender liner above the right front wheel. Remember to prepare a set of long-handle screwdrivers before starting - the working space is extremely cramped. I checked the service manual to confirm it requires a 12V14Ah AGM battery, with the Mercedes OEM part number A0009820008. A word of caution: don't try to save money by using a regular battery as replacement - the start-stop system is particularly picky about batteries. I once saw a guy at the repair shop getting all sorts of power steering fault codes after his DIY replacement, all because of incompatible auxiliary battery.
