floatingbmw
01-08-2015, 09:06 PM
Trying to get to the bottom of a charging/discharging problem on my 2007 E91.
The car is nearly always hard-starting (sluggish to turn over) if it has sat for more than 5 hours. It has never FAILED to start, but on some morning it is extremely reluctant.
My local dealer's service dept is pretty useless so I have been taking it to an independent shop.
They replaced the battery and the charging system (regulator). He checked the alternator and its output was fine, so that is off the table. Within a week or so the hard-starting was back. Lived with it for the better part of a year, then went back a few months ago. He thought I might need a new starter but after putting the battery on a charger, it started right up.
So based on the above, we have a healthy battery, healthy alternator, healthy starter, and most likely a healthy regulator.
It seems like something must be discharging the battery while it sits. No lights stay on, nothing on the panel stays on. I do however hear a very quiet high-pitched whining sound when the car is off and parked in the garage. So quiet that I can't locate it's source, even with the hood open.
If anyone has been down this road, please advise. I would think a good dealer be able to resolve this without hours of diagnostics and chasing down red herrings? I read about the battery cable replacement but I question if it could be that simple, although obviously I will take care of that.
The car is nearly always hard-starting (sluggish to turn over) if it has sat for more than 5 hours. It has never FAILED to start, but on some morning it is extremely reluctant.
My local dealer's service dept is pretty useless so I have been taking it to an independent shop.
They replaced the battery and the charging system (regulator). He checked the alternator and its output was fine, so that is off the table. Within a week or so the hard-starting was back. Lived with it for the better part of a year, then went back a few months ago. He thought I might need a new starter but after putting the battery on a charger, it started right up.
So based on the above, we have a healthy battery, healthy alternator, healthy starter, and most likely a healthy regulator.
It seems like something must be discharging the battery while it sits. No lights stay on, nothing on the panel stays on. I do however hear a very quiet high-pitched whining sound when the car is off and parked in the garage. So quiet that I can't locate it's source, even with the hood open.
If anyone has been down this road, please advise. I would think a good dealer be able to resolve this without hours of diagnostics and chasing down red herrings? I read about the battery cable replacement but I question if it could be that simple, although obviously I will take care of that.