How to Install a Battery in a BMW 330i

1. Park your 330i and turn off the engine. Open the trunk and raise the floor panel. Locate the battery in the right rear corner of the trunk.
2. Loosen the two fasteners a 1/4 turn, using a screwdriver. Loosen the third fastener in the upper-center side trim panel. Remove the fasteners. Slide the side trim panel slightly upward.
3. Disconnect the battery cable on the negative terminal, followed by the battery cable on the positive terminal. Loosen the center screw on the battery retaining strap to disconnect the strap. Lift the battery out of the trunk. Be very careful not to spill any fluid from it.
4. Place the new battery carefully in the battery compartment. Make sure that it is seated properly. Connect the battery cable on the positive terminal, followed by the battery cable on the negative terminal. Attach the cover on the new battery and secure it with the three fasteners. Replace the floor panel and close the trunk.