H all, wife has a 2002 valventronic e46 96000km on it, got red battery symbol on/off in the space of 3 days, one afternoon car wouldn't start at all.
Got a jump start & drove fine, NO red symbol, next a.m started fine again NO batt.symbol, but being blinded by everyone its the battery its the battery and not reading posts here we got a new battery....
After new battery red symbol came on, revved up engine and it went away and we drove on monitoring it, few hours later it would come on every 200-300 meters.
So we decided to take to mechanic same day on the way there NO red batt light came on...!
Mechanic could see via his OBD diag too that at the time we had red batt symbol even with new battery about a 10v charge was coming off alternator.
He has replaced the regulator and the spinning part he called the clutch that had some play it it up and downwards and a wheel that was making squeaking noises (sorry poor nomenclature, not idea what technical names are)....and will see how it goes
But what are the other parts that can go wrong?, can the the actual core of the alternator cause this erratic issue, and I swear about a year ago when we Batt.symbol was again on and off and then had the EML light come on , and eventually car went into limo mode 2 times, we got crankshaft and camshaft sensors, ignition coils, sparks and engine flush and oil change, ccv tube replaced we had no issue at all for a year....