My ex took her BMW to a local mechanic for a alternator replacement. She also had the BMW battery replacement done. They took care of the alternator and battery replacement, but now the window doesn’t go up or down, the dash board lights are not lit, the auto rear view mirrors don’t work, and the turn signals don’t operate. I don’t know much about BMW, but I know from what I’ve read on forums, it’s might have to do with reprogramming. She brought back to the mechanic and he seem defensive when I asked him about registering the battery. He was screaming and said that the vehicle has a lot of miles and that he would have to look at it further. Which to me doesn’t sound like he knows what his talking about. Perhaps someone can help me cause I am at my limit with this.

RESPONSE

BMW battery replacement does ask for registering to prolong the life of the battery. However, if the new battery is not “registered” the car will run and the battery will charge. This would have no impact on the windows or lights.  I would look for a blown fuse or two.

The car was brought to the mechanic shop not running at all (I assume). Installed a new battery and alternator. Car runs and they return it to the customer. The mechanic was not asked or paid(I assume) to look at the window or turn signal operation.

If these items were functioning fine before the BMW battery replacement was needed, there is the possibility of a fuse being blown or something around the same time. Especially if anyone tried to jump start the car.

Since the BMW battery replacement was performed it is the right thing to return to the mechanic shop with your concerns. I can say polite manners go a long way on both sides of the counter.

BMW Battery Replacement registration

Most all of today’s BMW models have adaptive charging and power management systems. Part of this management is monitoring the battery’s capacity and its charge and discharge profiles. When a battery is changed, the power management system needs to be run through a diagnostic cycle in order to properly recognize (register) the different battery and the different capacity, charge and discharge profiles.

If the new battery is not “registered” the vehicle will run and the battery will charge. However, in the long run, the life of the battery will likely be compromised due to improper charging parameters.  There are no DIY tools available for your to perform the registering yourself.  You will need to see a BMW dealer or an independent shop that has the proper tools to diagnose and program the late model BMWs.

How to Register a BMW Battery

The electrical system in a BMW car is complex. BMW set things so that you will have to take your car to the BMW dealership if you need to replace the battery; the new battery must be “registered” with the car’s computer or it will have a shortened life span, not power your car properly and not receive proper charging from your car’s electrical system. Registering the battery is the phrase used to describe resetting the car’s computer so it will accept the new battery and work properly with it. Like I said above, you can skip registration but may expect a shorter battery life.

References: Bavauto, ehow