This is all 100% correct. In addition, the size of the battery is critical as well. If the car came with, say, an 80Ah battery and you install a 90Ah battery (AGM or wet cell) you'll need to have the car recoded to update the charging map to match the battery size.
Registration is a simple service function within the DME (if you have the proper tools), but changing the battery type or size requires coding which typically requires a visit to a qualified shop.
Quote:
Originally Posted by VP Electricity
I recently had a conversation with a very helpful BMW tech about this, and here's what I learned:
There are two kinds of batteries BMW uses - standard and AGM (Advanced Glass Mat, like Optima, Odyssey, and Kinetic).
The white ones are standard, the black ones are AGM.
Each type of battery has a "charging map" that BMW has created from research. This changes the characteristics of the alternator's output depending on how long the battery has been in the vehicle. This "timer" is what starts when you register the new battery.
HOWEVER:
The car can only hold one "map" at a time. If you have a standard battery (which my car came with) and you upgrade to an AGM battery (which is what I did), then the registration process is NOT sufficient. Your car doesn't have the right map to use for an AGM battery!
You need to recode the car to tell it that you have a AGM battery, so that you can download the new charging map into it, and THEN it knows what to do.
This is also true if your car came with a black AGM battery, and you have downgraded to a standard type battery. You now need to get the car coded for the new battery.
An Autologic shop can do this far easier than the dealer.
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