Is it coincidental, that a number of users on this forum are experiencing various electrical problems with their 8-12 year old models? Then when asked, they reveal that they replaced their battery 'recently' and that it was 'registered' by a process that may have been completed properly (or not).
Here is what the experts say:
https://www.bimmer-tech.net/blog/ite...d-registration
Before we dig into the process of battery registration, let’s focus on what BMW battery registration actually is. To put it simply, battery registration is a process of updating your vehicle with information that a brand new battery has been installed in your car. What's important, it should be performed each time you change the battery in your 2002 or newer BMW.
As your battery gets on in years and gradually loses its charging capacity, the vehicle adjusts the amount of energy needed to recharge to operate at optimal levels. The older the battery the more charging it requires. Registering your battery lets your engine control module (known as DME — Digital Motor Electronics) know that a new one is installed and as a result, the vehicle will reset the old battery statistics and won’t try to overcharge the new battery thinking the previous one is still inserted.
Apart from the registration procedure, you also have to code your BMW computer. It’ll be necessary each time you replace your battery, no matter its specifications - whether your battery is similar or extremely different from your old one.
Why is battery registration important on BMW?
The electrical system of BMW models manufactured after 2002 got very sophisticated, as it started to adjust charging to the age as well as the type of the battery. If you’re changing your BMW battery for a new one having different capacity or type, your DME has to be updated with this info. It happens for example when you’re switching between batteries with lower and higher cranking ampere ratings or swapping a Liquid Lead Acid battery for an AGM battery. However, swapping your old battery for an identical one also doesn’t free you from the obligation to go through a BMW battery reset procedure, as your vehicle has to program the battery capacity again.
What happens if you don't register BMW battery?
Registration is required so that your car knows about the changed specifications and can adjust to the new battery settings. Otherwise, if you don’t properly code BMW battery, it could result in many electrical problems; the battery life may decrease, you could overcharge or undercharge your battery, or in the worst case scenario, cause considerable damage to your vehicle’s alternator and electrical system — at this point your battery may fail prematurely.
What are the electrical errors that might occur? Certain modules of your BMW may turn off as a consequence of your car presuming that the battery life is low and wanting to save it. So, at that point your windows and mirrors may not close/open, your radio and interior lights might not work properly, or other modules not needed for starting or driving a car can fail.
Which BMW models require battery registration?
All BMW models manufactured after 2002 require battery registration, as they are significantly more advanced in terms of electrical environment, which aims to improve the gas mileage. Models developed since 2002 are equipped with the system of Intelligent Battery Sensors (IBS) that contains micro processors monitoring and measuring charge, discharge, voltage, current and battery temperature.