Thinking about purchasing a new car? Use our new Car Loan Calculator to estimate your monthly car payment!

How to Replace the Car Key Battery in a Mercedes Benz

by Vanessa Padgalskas

Most newer Mercedes Benz vehicles come with a SmartKey. If the batteries in your Mercedes Benz SmartKey are depleted, you cannot use the SmartKey to get in the car or start it. You can remove the mechanical key hidden in the widest end of the SmartKey and use that, but changing the batteries is a simple process that anyone can do.


Turn the SmartKey face down so the blank side of the key is facing up. Press down on the plastic backup key tab to unlock the mechanical key. The mechanical key will pop up when it is unlocked.


Move the key away from the edge where it is located and toward the opposite edge. Sliding the key will unlock the battery compartment.


Pull on the battery compartment to remove it. It should easily slide out from the SmartKey.


Remove the two batteries from the battery compartment. Always replace both batteries at the same time.


Place the new batteries in a lint-free cloth and use the cloth to insert the new batteries under the contact springs with the plus (+) side facing up.


Slide the battery compartment into the SmartKey until it locks, then slide the mechanical key into the SmartKey to close it. Test the SmartKey by trying to unlock your car door.


  • You can purchase new batteries and recycle your old batteries at a Mercedes dealership.

Items you will need

About the Author

Vanessa Padgalskas was born and raised in Spokane, Wash., and currently resides in Portland, Ore. Padgalskas graduated from American University in 2007 with degrees in international studies and economics. She holds a law degree from Lewis and Clark Law School.

More Articles

Photo Credits

  • Victor Holguin/Demand Media