Originally Posted by a11y
Load of bullsh*t IME (not makkan's post - just about the need to recode!).
I replaced the battery on my 57-plate e90 330i 2 weeks ago. Did it myself using a guide I found on here - just unplugged the old one and attached the new one. I ensured the replacement was the same spec (amp rating and capacity) to avoid any problems as I've heard thatís where they can develop.
You can get away with it, without coding it.
Correct way is to register the battery.
It reset the values of power feed from alternator to battery and vice versa.
So the computer knows that it is a new battery and alternator is not over feeding your battery (which may lead to pre-mature failing of new battery).
I am sharing the ideas which have been discussed on states side.