How do you remove the battery from a BMW 550i?

Answer 1

The battery is in the trunk, same side as the gas cover door.

First, you need to remove the covers (twist the plastic retainers (2x) 1/4 turn)

remove the bar that keeps the battery down (2 screws)

disconnect the negative terminal (easy)

on the positive terminal, lift the red cover out of the way, and disconnect one set of cables. then lift up the other part of the red cover and loosen the screw to remove from the positive terminal.

loosen the (long) screw that holds the battery down, it is closest to you.

disconnect the venting tubing, on the far side of the battery

Lift up the battery, making sure that you're not pulling/tugging on any wires (i had to disconnect one cable connection, but i might not have been necessary. just be careful)

put in your new battery, and repeat everything in reverse.