Red Battery Light
Thread Starter
Senior Member
Joined: Jul 2016
Posts: 387
Likes: 44
From: Near Philadelphia
2005 Porsche 911, 1991 Jeep Grand Wagoneer, 2012 Mercedes C300 4Matic
Red Battery Light
2011 C300 4Matic. Wife was driving to the gym and radio shut off. She drove for about 5-7 minutes and parked the car. Met her there. Brought my code reader and nothing showing. Checked battery terminal at actual battery 12.6 then turned on car and it went up to 14.8v.
Turned the car on and drove home no problem. Drove somewhere else about 20 minutes each way and no problems either. Don't want to leave her stranded. Searched all possible issues. Possibly either the alternator or the voltage regulator. Would rather not spend $500 on a complete alternator. Bosch battery replaced in late 16 with a Sept 16 ship date.
Turned the car on and drove home no problem. Drove somewhere else about 20 minutes each way and no problems either. Don't want to leave her stranded. Searched all possible issues. Possibly either the alternator or the voltage regulator. Would rather not spend $500 on a complete alternator. Bosch battery replaced in late 16 with a Sept 16 ship date.
Last edited by Atlas Grey; Mar 25, 2019 at 11:41 PM.
Thread Starter
Senior Member
Joined: Jul 2016
Posts: 387
Likes: 44
From: Near Philadelphia
2005 Porsche 911, 1991 Jeep Grand Wagoneer, 2012 Mercedes C300 4Matic
Well to close the loop. I replaced the alternator and regulator. Do yourself a favor and order from autozone not oreillys. After putting in the reman oreillys unit it had to come back out and the zone one has no issues. This is bot a job for the faint of heart. There is a lot more to it than the 3 minute video on you tube. Be warned
