How to Replace 12 Volt Battery | BMW i3

Introduction

This tutorial provides a step-by-step guide on how to replace the 12-volt battery in a BMW i3. Replacing the battery is essential to prevent electrical glitches and potential car issues. Additionally, we'll cover how to register the new battery with the car's computer using the BimmerLink app, helping you save money and time.

Step 1: Prepare the New Battery

• Use a Remy Ox 18 battery or a compatible 12-volt battery.
• Charge the new battery to 100% before installation to avoid damaging the car.
• Place the battery on a charger overnight to ensure it's fully charged.

Step 2: Ensure Safety

• Make sure the car is completely turned off before starting any work.
• Disconnect the high voltage system to prevent electric shock. This is a crucial safety step when working on electric vehicles.

Step 3: Remove Front Covering

• Pop the front and remove any protective coverings.
• Remove the front box using six bolts:
  • Four T25 star key hex bolts on the top.
  • Two T30 star key hex bolts at the bottom.

Step 4: Remove the Battery Bracket

• Use a 10mm socket wrench and an extender to remove the battery bracket.
• There are two bolts; be careful not to drop them. A magnet can help retrieve any dropped bolts.

Step 5: Disconnect Battery Cables

• Remove the windshield washer filling tube by turning it counterclockwise and lifting it.
• Use a 10mm socket to disconnect the negative battery cable. Cover the terminal with an insulating material to prevent shorting.
• Pull out the battery vent hose (gray tube) from the battery.

Step 6: Remove the Old Battery

• Pull the battery out slightly to access the positive terminal.
• Use a 10mm wrench to remove the positive battery terminal.
• Remove terminal adapters using a T30 star hex.

Step 7: Install the New Battery

• Place the new battery in position.
• Attach the terminal adapters to the new battery and hand tighten them.

Step 8: Reconnect Components

• Connect the battery vent hose back into place.
• Reinstall the negative battery terminal and tighten securely.
• Reattach the battery bracket.
• Reinstall the windshield washer fluid tube.

Step 9: Reactivate the High Voltage System

• Reactivate the high voltage system by ensuring all connections are secure.
• Some safety mechanisms may need to be pried slightly to allow reconnection.

Step 10: Register the New Battery

• Plug a dongle into the OBD2 port of the car.
• Set your phone to airplane mode and enable Bluetooth for the dongle.
• Open the BimmerLink app and connect to the dongle.
• Navigate to the 12-volt battery section in the app.
• Check the state of charge (should be around 99% for a new battery).
• Select the option to register the new battery.
• Confirm that the new battery is the same size as the old one.
• Ensure the car is off, the ignition is in position two (press the start button without the brake), and there are no errors.
• Click register in the app. You should receive a confirmation that the battery has been registered successfully.

Conclusion

Replacing the 12-volt battery in a BMW i3 is a straightforward process when following these steps. Always prioritize safety by disconnecting the high voltage system and ensuring the new battery is fully charged. After installation, remember to register the battery with the car's computer to ensure optimal performance. By following this guide, you can save money and avoid potential issues with your electric vehicle.