Not your typical RED BATTERY WARNING light. Need insight.
Thread Starter
Newbie
Joined: Oct 2016
Posts: 6
Likes: 0
From: Carteret NJ
Mercedes E63 W212
Not your typical RED BATTERY WARNING light. Need insight.
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
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
Senior Member
Joined: Jan 2016
Posts: 375
Likes: 34
From: Louisiana
Most of them
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?
Thread Starter
Newbie
Joined: Oct 2016
Posts: 6
Likes: 0
From: Carteret NJ
Mercedes E63 W212
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.
Last edited by gumbi4u; Oct 24, 2016 at 11:48 PM.
Thread Starter
Newbie
Joined: Oct 2016
Posts: 6
Likes: 0
From: Carteret NJ
Mercedes E63 W212
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.
Junior Member
Joined: Feb 2013
Posts: 28
Likes: 4
'04 C230 Kompressor Sedan
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.
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.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
ALT BELOW 11VDC
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.
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.
Observe the voltage/current data directly from IC Display in the Sce Menu:
-- normal voltage swing between 12.6V and 14.9V
-- then voltage goes extremely low voltage (11v) followed by high current (90A): that's "drained by driving" yoyo.
This causes chassis chaos including roadside overheat and limp-mode.
New ALT does not fix the yo-yo below 11V.
Experimental ALT-LIN is reported helping.
Last edited by CaliBenzDriver; May 28, 2025 at 05:33 PM.
