[ramtin325i]

First of all, did you have the battery load tested or did you just check the voltage? When a battery starts failing it may show a good voltage at low loads, you need to take it to the shop so they can perform a proper load test.

Regardless I'd highly recommend taking it to the shop and having the entire charging system checked. It's a system. Replacing one failing electrical component is rarely good enough, as one failed component will usually toast other components. If the regulator is bad it can toast the alternator and battery, so if you just replace the battery it will fail again. :facepalm: If you then replace the battery (again) and the alternator, they will both fail AGAIN. :facepalm: :facepalm: It's very costly to fix the charging system piecemeal. You need to have the entire system tested and then replace ALL the failing components.

Now I'm speaking about cars in general based on 10 years working for an parts/service center. Maybe someone else here can speak more specifically about BMWs and the E46. I still haven't got a code reader so I'm not familiar with the extent of the BMW diagnostics, which look really extensive. Anyone? :help:

good luck, I hate electrical problems.

Very good write up. bump