How To Replace The Battery in a BMW Key Fob

Replacement battery (3V with solder tabs)

Soldering iron and solder

Desoldering pump or solder wick (to remove old solder)

Reverse tweezers (to hold the circuit board in place)

Carefully open the key fob to access the internal circuit board.

Identify the battery location, power and ground connections, and soldered prongs.

Use reverse tweezers to hold the circuit board securely in place.

Apply the desoldering pump or solder wick to remove the existing solder from the battery’s connection points.

Gently wiggle and remove the old battery from the board once the solder is loosened.

Align the new battery in the same orientation as the old one.

Insert the battery so that the tabs fully extend through the circuit board.

Use reverse tweezers to keep the battery flat against the board—this ensures a proper fit inside the key fob housing.

Carefully solder the battery tabs to the circuit board, ensuring a strong and clean connection.

Remove any excess solder residue or debris to prevent electrical issues.

Double-check that the battery is securely soldered and flush against the circuit board.

Inspect the key fob’s buttons to ensure they are still functioning and that no components are missing or displaced.

Close the key fob casing securely.

Test the key fob to confirm it is working properly with the new battery installed.