gumbi4u

Hey guys, first time caller, long time listener.

Have an odd issue with my 2011 E63.

Last week the red battery light popped up while driving. JUST A RED BATTERY, no error saying visit workshop. Checked battery, previous owner had dropped a regular wet battery in it but was only a year old. Tested the alt and was showing 11.81v. Figured its the voltage regulator. Dropped a new one in and also dropped in a proper AGM battery. All was well for two days. Battery light popped back on again tonight. Now Im baffled. The old regulator has one of the brushes grinded down quite a bit. So it was certain its just the regulator. BTW car has about 15k miles on it.

Could it be the battery sensor acting up since its just a battery symbol and not the visit workshop error? The aux battery was replaced a few months back but there was a clear error for that and has been fine since. Hope you guys can shed some light on this.

Thanks

dinman

i had a very similar issue on my 2010 e63, replaced volt regulator first, then the battery went out. Haven't had any issues in the past 16k miles. What does your voltage/amps look like in the "vehicle data" menu? Are the amps jumping around more than they should?

otakki

What's the normal voltage for this car?

gumbi4u

Thanks for chiming in. The voltage consistently stays at 11.81v . The Amps went from -43.1 to 37.00 and stayed around 37.00. I stuck an Autologic to it and got P0365 "The output for the actuation of the alternator has a malfunction."

Its looking more and more like the alt itself is shot.

EDIT: Usually a P0365 would be a crank sensor code. I dont know if the autologic is acting up or the codes are wrong due to the oe tune I dropped on it about a week ago.

gumbi4u

Ok pulled the alternator and the slip ring is worn on one side completely. No gold contact at all. We had dropped a second regulator on it and worked for about 5 mins. Changing the alternator. Should do the trick.

dinman

Glad you got it figured out man. On a side note, crazy that your alternator was out at 15k

BenzKompressor

I am fighting this with an '09 C63. Replaced the alternator less than 6 months ago with a genuine Bosch remanned unit from FCPeuro.com. Car was great until yesterday. Got the red battery warning in the dash. In pulled off the freeway and shut the car down.
Put it in the vehicle info menu and started back up. Stayed at 11.8V and roughly around -27A.
When I floored it and kept it floored, the battery voltage momentarily came up to 12.7V and I got a +40A. Once rpm came down, no more charging and back to 11.8V -27A. Also getting the 0365 fault using my MB diagnostic system (xentry). Luckily I have a free replacement from FCPeuro... but not looking forward to performing the job AGAIN. Radiator fan has to come out, and there's NO way to do this job without safely lifting the car. Luckily, I have access to a 2-post lift.

Also today I took the battery out and had had it tested: 12.89V and 885CCA actual, it's rated at 850CCA. So the battery "should" be good. I've got it out of the car still and on my battery tender plus.

With all this info, I'm fairly confident it's the alternator AGAIN.

xheamgbenz

I did my regular on mine also and it fix it