In this video, we will show you how to replace the 12V battery in your BMW i3. One of the first signs that your BMW i3 has to be replaced comes through through the instrument cluster which will display a “Battery discharging while stopped” message. Of course, you can always head over to your local BMW dealership to have the battery replaced, but some of us enjoy the DYI process. As always, this is just a guide and in no form or shape a recommendation to replace your own 12V battery. There are several safety checks you need to perform, like disconnecting the High Voltage Safety Connector. If you’re not comfortable with this, please seek the help of a professional.

If you’re still interested in doing the work yourself, our own Chuck put together a comprehensive video taking us through the entire process. We used the Remy 12V Battery AUX18L which costs around $140 and the iCar Pro OBD2 Diagnostic Interface. You’d also need the Bimmerlink App from the App store for iPhone/Android.

Step-by-Step Guide for BMW i3 12V Battery Replacement:

  • Buy new 12V Battery and trickle charge until fully charged
  • Open Front Trunk
  • Remove Covers over Driver’s Side and Passenger Side in front trunk
  • Disconnect Main Battery with High Voltage Safety Connector (Service Disconnect)
  • Block disconnect – use safety pin to prevent accidental re-activation.
  • Remove “Frunk” Bucket
  • Remove Battery Hold Down Brackets
  • Remove Battery Vent Tube
  • Remove Windshield Wiper Fluid Fill Tube
  • Disconnect Battery Terminals
  • Remove 12V Battery
  • Remove Brass Terminals and transfer to new battery
  • Move new 12V Battery up into frunk on battery tray
  • Reattach Battery Positive and Negative Cables
  • Move into final position, install Vent tube
  • Reinstall Hold Down Brackets
  • Re-engage High Voltage Battery
  • Replace Frunk and side covers.
  • Move to cabin and use iCar to register new battery

Tools needed

  • 4mm Hex socket or hex key to remove frunk
  • 10mm Socket
  • 10mm open ended wrench
  • 10mm ratcheting wrench – not necessary but huge time saver
  • Leather Gloves
  • iCar OBD2 Diagnostic Interface
  • Battery Tender to trickle charge the new 12v battery