Battery replacement !!!
From E60 / E87 (introduced in 2004), all BMW vehicles have an IBS (Intelligent Battery Sensor).
If you replace the battery (same capacity), it must be registered by a tester.
If this does not happen, the IBS and the power management work with the values of the old battery and there may be a reduction or shutdown of individual consumers.
This affects: All vehicles after the E60 such as: E87 1 series, E90 3 series, etc.
Except: E46 3 series, E83 X3, E85 Z4 (on-board electronics both based on the E46, therefore no IBS)
Imagine it like this:
You have a new battery and it was not registered. The state of charge of the old battery is still saved. This was completely over.
Now you get into your car in the morning at -10 degrees. Seat heating on level 3, rear window heating, etc. You have been driving for 20 minutes and you wonder why the rear window does not become free and the seat is not warm even though the LEDs light up ... well. This comes from not registering the battery.
I also carry out this registration as well as teaching and adapting larger capacities, which is very important since otherwise the alternator will not supply enough voltage.