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      12-23-2010, 02:45 PM   #11
fdriller9
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Drives: '06 AW 330xi
Join Date: Mar 2009
Location: North Jersey/Philly/NYC

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2006 330xi  [3.22]
Quote:
Originally Posted by mthomas View Post
I wonder if part of the problem with these cars is that there are so many electricaly powered systems necessary for operation that the battery must be returning maximum output at all times, thus a necessity to maintain a maximum charge, thus the necessity to register the battery. It seems as if most vehicles simply use the battery to start the engine, then allow the alternator to run everything. Based on the numbers of issues reported in the forums that have been caused by a low battery, it would seem that many systems are powered directly from the battery, and the alternator is only powering the battery.
Well I think I remember reading that our cars can have 3 different types of batteries from the factory. I think it was 70, 80, or 90 amp depending on which options you have.

Replacing a battery with the wrong spec will either over or under charge it.