I replaced my battery two or three months ago in my e90 and did not perform a battery adaptation reset (i.e. registration).
Frankly I think the reset is a scam and is not needed.
1. The very word adaptation leads me to believe that if the car can adjust current upwards for an aging battery that does not hold it's charge, it should be able to adapt downwards for a battery that doesn't need such a heavy charging load.
2. Other vehicles like Fords, Nissans, motorcycles, etc (non-BMW "sophisticated" cars) can charge their batteries when they age or under heavy load, and back off charge when the load goes away or the battery is new and can hold the charge.
I think BMW says you need to do this "reset" so dealers have another avenue to lure us consumers in so they can pay for their expensive programming equipment that they must buy from BMW with unneeded software resets. The car will learn what the appropriate charge level should be based on *load* just like the unsophisticated cars above do.
Sorry for the rant.
Last edited by john_e90bimmer; 05-26-2011 at 10:19 AM.