My 2001 325i has a charging system problem. While driving the car several lights on the instrument cluster flashed on, then off. Upon reaching home, the car wouldn't restart. I recharged the battery and it restarted fine but voltage readings at the battery (and at the charging posts under the hood) with the car running measured only 12.6 volts and gradually dropped over several minutes of idling to 11.8 volts. I assumed the alternator or voltage regulator were at fault so I removed the alternator and took it to a local parts store (Autozone) to be checked. They tested it twice and said the alternator and regulator tested good. I've reinstalled the alternator and checked all fuses in the glove box and also the 250 amp fuse in the trunk and all tested good. FYI, the battery is only a couple months old. I'm finding the same thing as before... the system isn't charging the battery and the voltage at the battery while the car runs, gradually drops. I'm assuming the voltage should be 13.7 volts or so with the car running, if the alternator is working to recharge the battery. What else is there in the charging system besides the alternator and voltage regulator? Any suggestions on what else to check?
Still Puzzled Thanks for the suggestion. I took the battery in to be tested and they said it tests OK. Before removing it I did the voltage test again across the battery with the engine running. On this occasion, the first in the last 4 or 5 times I've measured it, it showed that the alternator was charging the battery. It indicated 13.6 volts or so. So apparently, the lack of charging is intermittent. After having the battery tested I also checked the electrolyte levels and it was quite low in each cells. I filled them back up with distilled water. Not sure why the levels were so low, especially since the battery is so new. Anyone have any ideas? Could this be a clue to the problem? Since the car hadn't run been run for a couple weeks, the battery was a little discharged, so I'm charging it over night. The Bentley service manual says to check the engine to ground connection but I can't tell where it is. Can anyone advise? Given that my most recent test seemed to show the charging system working OK, I'm probably going to start driving it again but I'm nervous that there's an intermittent problem somewhere. Anyone have any suggestions on where else to check?
Update: Took the car in to the dealership. They diagnosed a bad alternator, and replaced it. Solved the problem. Apparently it was an intermittent problem.
