W211 Undervoltage charge battery fault
Member
Joined: Apr 2015
Posts: 164
Likes: 8
2005 E55 AMG
Is it possible that the auxiliary battery is what is throwing the code? Your main battery is in the trunk (Assuming this is the one you replaced) but there is also a tiny battery up front. Directly under neath the cabin air filter and washer fluid reservoir. Can find equivalent replacement online for dirt cheap.
My auxiliary battery went bad on my E55 about a year ago. Got a bright red battery error in the middle of my dash. Everything still worked fine but the message only went away once I swapped out that battery. Main battery was fine.
My auxiliary battery went bad on my E55 about a year ago. Got a bright red battery error in the middle of my dash. Everything still worked fine but the message only went away once I swapped out that battery. Main battery was fine.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
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From: MA
2008 E350 4Matic, 2011 E350 4matic
Oh yeah, it depends if he has an auxiliary battery. He didn't actually mention the year. There's only an aux battery for 2003-2006. The 2007-2009 didn't have one.
Member
Joined: Apr 2015
Posts: 164
Likes: 8
2005 E55 AMG
I wasn't aware that they got phased out after the facelift. Good to know. That's where I'd put my money if his primary battery is new. Especially considering he is having no negative impact on his car other than the dash alert.
Newbie
Joined: Jan 2020
Posts: 8
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2009 E350 AMG
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,225
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From: V E G A S
1922 Ford Model T / no OBD
Testing the battery is pretty tricky and if you check car voltage on its display, it shows 0.5V lower than on battery clamp.
But regardless 11.4 or 11.9V is discharged battery. Charge it with good charger and recheck with load tester.
But regardless 11.4 or 11.9V is discharged battery. Charge it with good charger and recheck with load tester.
Newbie
Joined: Jan 2020
Posts: 8
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2009 E350 AMG
made a world of a difference! when i drove it gave me 12.1 now it’s giving me around 14
thank you so much for ur help!
Member
Joined: Jun 2016
Posts: 161
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From: Orlando, Florida
2005 E320 CDI (SOLD); 2008 ML320 CDI 4MATIC
My brand new OEM AGM battery draws down after approximately 3-4 days.This YT video demonstrates a few good methods to narrow down where load is occuring including use of an infrared imager technique that I intend to try first.
