How to Install a Battery in a BMW

1. Open the trunk. Pull back the carpet on the floor, then lift up the base of the trunk by hand to reveal the battery.
2. Unbolt the battery tie-down from the floor of the trunk using the 3/8-inch ratchet and socket. Lift the tie-down off of the battery. Disconnect the negative terminal from the battery using an open-end wrench, then remove the positive terminal. Lift the battery out of the trunk.
3. Set the replacement battery into the trunk. Connect the positive terminal to the new battery using an open-end wrench, then connect the negative terminal.
4. Set the tie-down onto the replacement battery and bolt it down using the 3/8-inch ratchet and socket. Drop the trunk floor back down over the battery, then lay the carpet back onto the floor.