Battery Questions
Thread Starter
Member
Joined: Apr 2009
Posts: 175
Likes: 5
From: Virginia
2012 E350 - Cabrio; 2017 GLS 450
Battery Questions
Good morning everyone,
Odd thing that I've been seeing with all the posts about my/our cars. Apparently I am the only one without a second battery in my car? I've got a 2012 E350 and I don't have the secondary battery that everyone talks about. I'm in need of a battery replacement and I'm just educating myself on how to best go about doing it, when I discovered this phenomenon. And for those of you my age if you just sung the Muppets phenomenon song in your head, then I apologize now for that. LOL
But in all seriousness, am I the only single battery dude out there?
Thanks,
Matt
Odd thing that I've been seeing with all the posts about my/our cars. Apparently I am the only one without a second battery in my car? I've got a 2012 E350 and I don't have the secondary battery that everyone talks about. I'm in need of a battery replacement and I'm just educating myself on how to best go about doing it, when I discovered this phenomenon. And for those of you my age if you just sung the Muppets phenomenon song in your head, then I apologize now for that. LOL
But in all seriousness, am I the only single battery dude out there?
Thanks,
Matt
Super Member
Joined: Aug 2004
Posts: 954
Likes: 245
E550 Coupe 2wd (2016)
I can't say for sure if you do or do not have an aux batt, but is it possible you simply didn't notice it? Pretty sure it's next to the spare tire, on the right under a black plastic cover.
Some cars take a much smaller batt hidden in the dash, but I don't think it applies to yours.
My understanding is the cars with electronic shifters have the aux batt so the tranny could shift in/out of park when the main batt was dead. Maybe your tranny shifts mechanically and thus no need?
Some cars take a much smaller batt hidden in the dash, but I don't think it applies to yours.
My understanding is the cars with electronic shifters have the aux batt so the tranny could shift in/out of park when the main batt was dead. Maybe your tranny shifts mechanically and thus no need?
Super Member
Joined: Jan 2018
Posts: 532
Likes: 182
From: Atlanta GA
2012 E350 Cabriolet now SOLD to my son
2012 E350 has auxiliary battery in the left side of the dash...at least mine did..yes it is kinda buried...if its going bad, you will get a bunch of errors like ESP disabled, Distronic not available etc.
Member
Joined: Nov 2024
Posts: 152
Likes: 43
From: New Jersey/Philly
2010 E350 Coupe
Pre facelift here (2010 E350). I have no aux battery. Nothing in spare tire area, nothing deep inside the dash on left side. I understand the aux battery and start/stop have a deep relationship. Maybe if you don't have the start/stop option you also don't have an aux battery fitted on a 2012?
I did swap a main battery about 3 years ago, and it was just like any other "normal" car. I have also had the battery disconnected a few times (cleaning chassis grounds, moving alternator during engine mount install, etc) and have had no issues. The only time I had to do a window relearn or manually reset my clock was when I only disconnected the neg terminal, so now I always disconnect both sides.
I did swap a main battery about 3 years ago, and it was just like any other "normal" car. I have also had the battery disconnected a few times (cleaning chassis grounds, moving alternator during engine mount install, etc) and have had no issues. The only time I had to do a window relearn or manually reset my clock was when I only disconnected the neg terminal, so now I always disconnect both sides.
Out Of Control!!
Joined: Apr 2019
Posts: 11,929
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Pre facelift here (2010 E350). I have no aux battery. Nothing in spare tire area, nothing deep inside the dash on left side. I understand the aux battery and start/stop have a deep relationship. Maybe if you don't have the start/stop option you also don't have an aux battery fitted on a 2012?
I did swap a main battery about 3 years ago, and it was just like any other "normal" car. I have also had the battery disconnected a few times (cleaning chassis grounds, moving alternator during engine mount install, etc) and have had no issues. The only time I had to do a window relearn or manually reset my clock was when I only disconnected the neg terminal, so now I always disconnect both sides.
I did swap a main battery about 3 years ago, and it was just like any other "normal" car. I have also had the battery disconnected a few times (cleaning chassis grounds, moving alternator during engine mount install, etc) and have had no issues. The only time I had to do a window relearn or manually reset my clock was when I only disconnected the neg terminal, so now I always disconnect both sides.
Member
Joined: Nov 2024
Posts: 152
Likes: 43
From: New Jersey/Philly
2010 E350 Coupe
I caught a glimpse of your somewhat recent stable voltage thread in its first day and oh my how it blossomed! A wealth of knowledge there which I will be combing through when proper time allows.
Why do you think it was so that I had to relearn windows and manually adjust clock with neg side only disconnected, but with both sides disconnected all was well? I also had the yo-yo voltage prior to cleaning off a few rather suspicious looking grounds and now I get an almost constant 14.1 - 14.8 regardless of loads or driving conditions. Even a few 14.9 & two separate 15v appearances.
This, (along w/ my entire voltage journey) deserves its own thread, but I cannot pass up a potential quick learning session from you. One who is much further down this road than I and likely plenty of others who would read this.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,929
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
more power to you
Cali,
I caught a glimpse of your somewhat recent stable voltage thread in its first day and oh my how it blossomed!
A wealth of knowledge there which I will be combing through when proper time allows.
Why do you think it was so that I had to relearn windows and manually adjust clock with neg side only disconnected, but with both sides disconnected all was well?
I also had the yo-yo voltage prior to cleaning off a few rather suspicious looking grounds and now I get an almost constant 14.1 - 14.8 regardless of loads or driving conditions. Even a few 14.9 & two separate 15v appearances.
This, (along w/ my entire voltage journey) deserves its own thread, but I cannot pass up a potential quick learning session from you.
One who is much further down this road than I and likely plenty of others who would read this.
I caught a glimpse of your somewhat recent stable voltage thread in its first day and oh my how it blossomed!
A wealth of knowledge there which I will be combing through when proper time allows.
Why do you think it was so that I had to relearn windows and manually adjust clock with neg side only disconnected, but with both sides disconnected all was well?
I also had the yo-yo voltage prior to cleaning off a few rather suspicious looking grounds and now I get an almost constant 14.1 - 14.8 regardless of loads or driving conditions. Even a few 14.9 & two separate 15v appearances.
This, (along w/ my entire voltage journey) deserves its own thread, but I cannot pass up a potential quick learning session from you.
One who is much further down this road than I and likely plenty of others who would read this.
Actually you may have an in-dash battery supplying backup power when main is disconnected.
The solderless door moduls are built to becomes increasingly more unstable. Meaning they benefit from more frequent power Reboot to allow them to relearn CAN thresholds.
When I mean reboot it is all power out not only main unlesd you just want to AGM Float main without loosing "windows...".
I can see retraining all windows, roof, seats, clock, radio getting old quickly
-- Unfortunately there are no better ways I know to reboot F-SAM/CGW
One way to cut short the Mercedes-Bosch battery chaos is to disconnect the ALT-LIN to provide stable voltage. The ECU/TCU responds really well to that stable condition versus the stock [12.6v to 14.9V] swings.
Last edited by CaliBenzDriver; Feb 24, 2025 at 04:18 AM.
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Newbie
Joined: Jun 2022
Posts: 9
Likes: 1
2010 E350 Coupe
Cali,
I caught a glimpse of your somewhat recent stable voltage thread in its first day and oh my how it blossomed! A wealth of knowledge there which I will be combing through when proper time allows.
Why do you think it was so that I had to relearn windows and manually adjust clock with neg side only disconnected, but with both sides disconnected all was well? I also had the yo-yo voltage prior to cleaning off a few rather suspicious looking grounds and now I get an almost constant 14.1 - 14.8 regardless of loads or driving conditions. Even a few 14.9 & two separate 15v appearances.
This, (along w/ my entire voltage journey) deserves its own thread, but I cannot pass up a potential quick learning session from you. One who is much further down this road than I and likely plenty of others who would read this.
I caught a glimpse of your somewhat recent stable voltage thread in its first day and oh my how it blossomed! A wealth of knowledge there which I will be combing through when proper time allows.
Why do you think it was so that I had to relearn windows and manually adjust clock with neg side only disconnected, but with both sides disconnected all was well? I also had the yo-yo voltage prior to cleaning off a few rather suspicious looking grounds and now I get an almost constant 14.1 - 14.8 regardless of loads or driving conditions. Even a few 14.9 & two separate 15v appearances.
This, (along w/ my entire voltage journey) deserves its own thread, but I cannot pass up a potential quick learning session from you. One who is much further down this road than I and likely plenty of others who would read this.
Newbie
Joined: Jun 2022
Posts: 9
Likes: 1
2010 E350 Coupe
Still running fine-ish, definitely has a diminished capacity but no issues with starting anymore. I did end up getting a battery tender for when the car sits for a while, especially in the middle of winter.
Junior Member
Joined: Jul 2024
Posts: 73
Likes: 14
2015 mercedes benz e400 4matic
Good morning everyone,
Odd thing that I've been seeing with all the posts about my/our cars. Apparently I am the only one without a second battery in my car? I've got a 2012 E350 and I don't have the secondary battery that everyone talks about. I'm in need of a battery replacement and I'm just educating myself on how to best go about doing it, when I discovered this phenomenon. And for those of you my age if you just sung the Muppets phenomenon song in your head, then I apologize now for that. LOL
But in all seriousness, am I the only single battery dude out there?
Thanks,
Matt
Odd thing that I've been seeing with all the posts about my/our cars. Apparently I am the only one without a second battery in my car? I've got a 2012 E350 and I don't have the secondary battery that everyone talks about. I'm in need of a battery replacement and I'm just educating myself on how to best go about doing it, when I discovered this phenomenon. And for those of you my age if you just sung the Muppets phenomenon song in your head, then I apologize now for that. LOL
But in all seriousness, am I the only single battery dude out there?
Thanks,
Matt
Out Of Control!!
Joined: Apr 2019
Posts: 11,929
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
