The battery on the 2006-2012 BMW 325xi is located in the trunk. To access the battery, open the trunk and remove the floor mat. The battery is located in a compartment on the right side of the trunk, behind the plastic cover.
To remove the battery, first disconnect the negative terminal by turning the 10 mm nut counterclockwise. Then disconnect the positive terminal by turning the 10 mm nut counterclockwise. Be careful not to let the positive terminal come into contact with the negative terminal, as this could cause a short circuit.
Once the terminals are disconnected, remove the battery hold-down clamp by unscrewing the 13 mm bolt. Then lift the battery out of the compartment.
To install the new battery, first position the battery in the compartment and secure it with the battery hold-down clamp. Then connect the positive terminal by tightening the 10 mm nut clockwise. Finally, connect the negative terminal by tightening the 10 mm nut clockwise.
Models older than 2006
For models older than 2006 the battery will located in the engine bay. To access it, open the hood and look for the black plastic cover on the right side of the engine bay. Remove the cover and you will see the battery and its terminals inside.
