The 12-volt battery in the 2012 ML350 is located in the cargo area, tucked away on the left-hand side of the trunk behind a trim panel. It is not in the engine bay, a design choice that frees space under the hood and aids weight distribution.
Mercedes shifted the 12V battery to the luggage compartment for easier access during routine maintenance and to keep heat away from the engine bay. In the 2012 ML350 (built on the Mercedes-Benz M-Class platform), the battery sits behind interior trim in the left rear of the cargo area, requiring removal of some floor panels to reach it.
How to locate and access the trunk-mounted battery
Here are the typical steps to access and service the trunk-mounted battery in the ML350.
- Open the trunk and lift the carpeted floor panel to reveal the left-side storage area.
- Remove the side trim panels or cover to expose the battery housing behind it.
- Take off the battery cover and identify the negative (-) and positive (+) terminals.
- Disconnect the negative terminal first, then the positive terminal when removing or servicing the battery.
- Unfasten the hold-down bracket and lift the battery out, supporting it securely.
- Install a replacement battery of the correct specification, reseat the bracket, and reconnect the terminals (positive first, then negative).
- Reinstall the battery cover, trim panels, and floor panel, then close the trunk.
Concluding note: Always exercise caution when handling car batteries, wear eye protection, and ensure the vehicle is off and in park with the parking brake applied. If you’re not confident performing battery work, seek a certified Mercedes technician.
Summary
The 2012 ML350 stores its 12-volt battery in the trunk on the left side of the cargo area, behind trim panels and under the floor panel. Access it by removing the floor covering and side trim, then lift out the battery if replacement is needed. For routine checks, verify connections and the bracket before resealing the panels.