There are a couple of options for battery replacement, however no matter what you chose you will need to register your battery. This page will show you how to replace and register your battery. You will need a class 49 AGM battery. The factory battery specs are 12v 90ah with 900CCA, you want to use a battery that matches these specs. Factory BMW part number is 61 21 6 919 342. It is important that the battery matches these specs as like everything else on the car its complicated, the Power module controls the alternator charging and if the specs do not match it can not only create issues in these cars but can also potentially be a fire hazard.
I also read that you can register your battery with Foxwell NT510, I am not familiar with this unit and use IPNA myself.
