This DIY video provides a comprehensive guide on replacing the 12-volt battery in a BMW i3 (2017 model). It highlights crucial distinctions between changing a battery in an all-electric vehicle versus an internal combustion engine car, primarily the mandatory and specific procedure for safely disconnecting the high-voltage battery. The video details the entire process from pre-charging the new battery, disassembling the front access panel, safely removing the old battery, installing the new one with a critical check for secure terminal connections, and finally, demonstrating how to register the new battery with the car's system using an iCar Wi-Fi adapter and the BimmerLink app. The importance of this registration for optimal battery lifespan and vehicle performance is emphasized, along with common symptoms of a failing 12V battery.
Changing the 12V Battery in a BMW i3: A Step-by-Step DIY Guide
0:00:01 - Introduction to 12V Battery Replacement: This DIY guide focuses on changing the 12-volt battery in a 2017 BMW i3 with 52,000 miles, highlighting differences from gasoline cars and the need for battery registration.
0:00:24 - Pre-Charging the New Battery: Before installation, it's crucial to fully charge the new battery (e.g., Remy Aux 18L, $140), which took about 36 hours on a trickle charger. Do not install a partially charged battery.
0:01:02 - Removing the Front Access Panel: The process begins by removing the front panel using a 4mm hex head tool, being careful to avoid dropping bolts or scratching the bumper due to low torque settings into plastic.
0:02:03 - Disconnecting the High-Voltage Battery (Crucial Safety Step): A key difference from ICE cars, the high-voltage battery must be deactivated for safety. This involves pulling down a specific connector until "OFF" is visible and inserting a safety pin (like a hex key) to prevent accidental re-engagement. (A newer 2021 model's red clip mechanism is also shown for comparison).
0:03:00 - Removing the Battery Bracket: The 12V battery, located deep in the compartment, is secured by a metal bracket. Remove the two 10mm bolts holding this bracket, being careful not to drop them into the car's recesses.
0:04:26 - Disconnecting Battery Terminals: Disconnect the negative terminal first. Removing the wiper fluid filler tube provides better access. Use a ratcheting wrench for tight spots. Safety Tip: Cover disconnected terminals with a glove to prevent accidental contact.
0:06:53 - Removing the Old Battery: Wiggle the battery out to access the positive terminal, which has an "explosive terminal" designed for crash disengagement. Loosen two 10mm bolts to free the positive terminal before wiggling the battery out. An old battery from July 2019 was found, suggesting a previous replacement where the vent tube might have been lost.
0:08:40 - Preparing and Installing the New Battery: Attach brass terminal adapters to the new battery's posts. Carefully slide the new battery onto its supporting tray, centering it before reinstalling the mounting bracket.
0:10:00 - Critical Terminal Security Check: After installing the new battery and connecting terminals, ensure all three connection points are securely tightened: the brass bracket to the battery, the two 10mm bolts for the main car cables, and especially the hex bolt on the terminal itself. Loose connections can lead to electrical faults.
0:11:16 - Reinstalling Components: Reattach the vent tube (if present, noting its less critical role in the i3's open compartment), ensuring it's oriented correctly. Reconnect the negative terminal, followed by the positive terminal, tightening all fasteners.
0:13:01 - Re-engaging High-Voltage Battery: Remove the safety pin and re-engage the high-voltage battery connector by pushing a small tab and sliding it into the "ON" position.
0:14:14 - Post-Installation Test & Importance of Registration: The car should start without major issues, though the date/time and trip odometer may reset. Key Takeaway: While the car functions, registering the new battery is vital for its long-term health and optimal car performance, as BMW systems (since ~2008) adjust charging parameters based on battery age and type.
0:15:15 - Battery Registration Process: Plug an iCar Wi-Fi adapter into the OBD-II port in the driver's footwell. Use the BimmerLink app ($35) on a smartphone to register the "new battery - same capacity and type" in the car's system.
0:16:36 - Conclusion & Troubleshooting Tips: This is a relatively easy DIY that can extend battery life by 4-5 years. Common symptoms of a failing 12V battery include random alarms or error messages. The next video will cover brake fluid flushing for the i3.