Replacing your E90 battery is a relatively easy task. In this model, it is located in the trunk on the right side, hidden by a trim panel. Of course, you should only use a high quality battery for your BMW.
When changing the battery, certain components and equipment may need attention. For instance, you might need to reset the clock, reenter radio presets, initialize power windows, adjust the steering angle sensors, and initialize the sunroof. This is all pretty simple but good to be aware of before starting.
Once you have the battery replaced, you need to register it with the vehicle’s computer system. This gives the DME the battery age and health data that it uses to ensure proper charging.
To replace your BMW E90 battery, begin in the trunk. Twist the trim panel lock counterclockwise to remove it. Disconnect the negative battery cable using a ratchet and 10mm socket. Move it aside and cover it so no accidental contact with the battery terminal occurs before you finish removing the old one or install the new one.
Next, release the locking clips on either side and open the battery safety terminal. You will see another locking clip. Release it to open the battery power module cover. Using your ratchet with a 13mm socket, remove the battery power module nut. Now, using your original 10mm socket, loosen the positive battery cable.
Detach the clips on either side of the battery and lift the battery module up and out to remove it. Next, remove the battery hold down using your 10mm socket. Now, disconnect the battery vent hose. Now you can remove the old battery from the trunk. There are cables in there that can get in the way so be sure to move them around to clear a path first, as it makes it much easier.
Before installing the new battery, clean the compartment. Clean any corrosion from the battery cable ends and check the battery vent line. Make sure it is not pinched and is properly routed. If it looks damaged or worn it’s best to replace it while you have the battery removed.
Now you can install the new battery in the compartment and attach the vent line. Connect the positive cable. Then connect the negative cable. Now install the battery hold down bracket, then reattach the trim cover.
Once you have it all installed, use a BMW scan tool to register the new battery. A BMW shop can do this for you if you don’t have this tool.