Auxiliary Battery Malfunction
Thread Starter
Member
Joined: Nov 2017
Posts: 127
Likes: 27
From: Lincoln, CA
2018 S450
Auxiliary Battery Malfunction
This message just popped up today! I had to make two stops and it occurred both times so I don't think it's intermittent. I have an appt with the dealer Thursday morning to get it replaced. Anyone with experience with this failure? Should I be ok to use the car until then?
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
Super Member
Joined: Jul 2006
Posts: 623
Likes: 131
From: pittsburgh
'25 740i; '15 targa4s; '24 cayenne
i had the same failure in my g550; the dealer replaced it under warranty. no probs since. you can drive the car. you might get a few other driver assistant systems failures; i did. they were all corrected with the new battery and everything returned to working normally.
Senior Member
Joined: Dec 2002
Posts: 348
Likes: 20
From: Florida
W124, W126, W140, W220, W222, R129
This message just popped up today! I had to make two stops and it occurred both times so I don't think it's intermittent. I have an appt with the dealer Thursday morning to get it replaced. Anyone with experience with this failure? Should I be ok to use the car until then?
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
Member
Joined: Sep 2012
Posts: 126
Likes: 22
2009 C350, 2015 S550
I had the same issue in the past month. As others have stated you will get distronic inoperable etc.
I think yours will be a capacitor and not a battery. Dealer said they switched in 2015 and if it had a battery iwould have had to pay, if capacitor it would of been covered under my CPO.
Turns out I had the battery still so had to shell out 282.
I think yours will be a capacitor and not a battery. Dealer said they switched in 2015 and if it had a battery iwould have had to pay, if capacitor it would of been covered under my CPO.
Turns out I had the battery still so had to shell out 282.
Super Member
Joined: Dec 2014
Posts: 819
Likes: 184
From: New England/Florida
2005 SL 500. 2015 S550. 2016 GLE400 2018 S560
Aux battery failure
When I had my 2015 S550 I experienced the auxiliary battery failure at the start of my drive from southern Florida to RI. Made the trip fine but distronic did not work for most of the trip. That was annoying but you can still drive the car. It was fixed under warranty. Read somewhere that if you do not operate car for over a week Mercedes recommends putting on trickle charge. I do that now with my 2018 560 and 2016 GLE 400 and haven’t had a battery problem since.
MBWorld Fanatic!
Joined: Apr 2016
Posts: 1,493
Likes: 254
2014 S550 AMG, 2017 XT5
When I had my 2015 S550 I experienced the auxiliary battery failure at the start of my drive from southern Florida to RI. Made the trip fine but distronic did not work for most of the trip. That was annoying but you can still drive the car. It was fixed under warranty. Read somewhere that if you do not operate car for over a week Mercedes recommends putting on trickle charge. I do that now with my 2018 560 and 2016 GLE 400 and haven’t had a battery problem since.
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Thread Starter
Member
Joined: Nov 2017
Posts: 127
Likes: 27
From: Lincoln, CA
2018 S450
Super Member
Joined: Dec 2014
Posts: 819
Likes: 184
From: New England/Florida
2005 SL 500. 2015 S550. 2016 GLE400 2018 S560
Battery malfunction
I jinxed myself. Turned on ignition this morning and what pops up? Auxiliary battery malfunction! Took delivery of my car in September 2017. Made appointment for replacement under warranty Monday.
Thread Starter
Member
Joined: Nov 2017
Posts: 127
Likes: 27
From: Lincoln, CA
2018 S450
Newbie
Joined: Apr 2019
Posts: 7
Likes: 1
Maybach S550
This message just popped up today! I had to make two stops and it occurred both times so I don't think it's intermittent. I have an appt with the dealer Thursday morning to get it replaced. Anyone with experience with this failure? Should I be ok to use the car until then?
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
If the battery goes belly up what happens? Would I still be able to get it to the dealer? The car is my 22018 S450. Thanks in advance for any input.
The dealer should replace it free of charge if the car is still under warranty.
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 377
From: San Jose area
'19 E63S sedan
So a failed aux battery can give you a lot of odd alerts for all kinds of systems, although none will usually prevent the car from operating.
Recent cars have a capacitor bank instead of an actual battery. This "voltage converter" is what the system calls the aux battery. They seemed to have had a batch of bad capacitors that leak and cause this problem.
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Joined: Apr 2016
Posts: 1,493
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2014 S550 AMG, 2017 XT5
Other way around. The main battery is the starter battery. The aux battery powers other systems. (If the starter battery goes, it's not just auto start that doesn't work -- it's any start.)
So a failed aux battery can give you a lot of odd alerts for all kinds of systems, although none will usually prevent the car from operating.
Recent cars have a capacitor bank instead of an actual battery. This "voltage converter" is what the system calls the aux battery. They seemed to have had a batch of bad capacitors that leak and cause this problem.
So a failed aux battery can give you a lot of odd alerts for all kinds of systems, although none will usually prevent the car from operating.
Recent cars have a capacitor bank instead of an actual battery. This "voltage converter" is what the system calls the aux battery. They seemed to have had a batch of bad capacitors that leak and cause this problem.
Ok, Who sent the Virus..... My Aux Battery just went today. Eco Start Stop Inactive, Distronic Inactive, Active headlight inactive....
So battery lasted 5 Years....
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Joined: Mar 2006
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From: San Jose area
'19 E63S sedan
Junior Member
Joined: Jan 2015
Posts: 20
Likes: 18
From: Near Richmond, VA
2015 S550 4matic / 2003 E55 AMG
My 2015 S550 with 62k miles just gave me this warning. Where is the Aux battery located on a 2015 S550? It's under the hood in my E55. I've only owned this car for 30 days, so I haven't spent much time under the hood yet.
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From: Europe
223.168 & 213.012 & 906.633 & 214.005
On the right at the trunk. A DIY task but more complicated to detach than one would assume.
Senior Member
Joined: Dec 2008
Posts: 378
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2015 S550, 2017 GLS450
Yep, the battery is far more likely to fail early if you use the start/stop function which I immediately turn off. It's annoying as heck that this cannot be programmed to be off when I start the car in the morning.
Junior Member
Joined: Jan 2015
Posts: 20
Likes: 18
From: Near Richmond, VA
2015 S550 4matic / 2003 E55 AMG
Thank you.
My local MB dealer parts counter has the best people working there. They are always very helpful with advice if asked. I'm choosing to replace this myself rather than deal with the hassle of dropping the car off, then getting a ride back to the dealer.
They advised me this battery is buried in behind the fuse box on the right side of the trunk. How bad could it be? I may take a few pictures to help those who are also dealing with a timed out Aux battery in a 2015 S550.
My local MB dealer parts counter has the best people working there. They are always very helpful with advice if asked. I'm choosing to replace this myself rather than deal with the hassle of dropping the car off, then getting a ride back to the dealer.
They advised me this battery is buried in behind the fuse box on the right side of the trunk. How bad could it be? I may take a few pictures to help those who are also dealing with a timed out Aux battery in a 2015 S550.
Super Member
Joined: Sep 2015
Posts: 725
Likes: 189
From: Chicago area
2015 E400 and 2015 GLK350
This is a very common failure. My 2015 E400 aux battery failed the first time when the car was only 6 months old. Dealer replaced under warranty. A couple of days ago, go the warning again -- 3.5 years later. Back to dealer, just before the factory warranty expires, to get another battery. Hopefully, should be good for another 3-4 years, by which time, I may be looking for a different car. BTW, I NEVER use auto start-stop. Part of my startup routine is to shut that "feature" off. Didn't help battery life at all. I think all of the other features, like blind spot monitors, collision prevention systems, etc., take more power. I also think that these batteries are built to the lowest possible specification/price point, so they will always have a shorter life span than the main batteries.
Also, in our 2015 GLK, the aux battery required replacement at 3.5 years. Wife ALWAYS uses auto start-stop. We get same service life of battery with or without the start-stop usage.
Also, in our 2015 GLK, the aux battery required replacement at 3.5 years. Wife ALWAYS uses auto start-stop. We get same service life of battery with or without the start-stop usage.
Junior Member
Joined: Jan 2015
Posts: 20
Likes: 18
From: Near Richmond, VA
2015 S550 4matic / 2003 E55 AMG
Remove the flip up floor panel 2 T20 screws
remove the rear trim panel. Two push/pull clips, then pry up to lift the panel straight up
Play safe and disconnect the neg battery term from the main battery.
View of the goal. The Aux battery is in a black plastic case that has a snap on lid. You don't remove the case, just pop off the lid
10mm nut x 2 that hold down the fuse box. You need to just move this a little to the side to gain full access
Flip up the Aux Battery cover, then unbolt the neg then pos terminal. The battery will lift out
Junior Member
Joined: Jan 2015
Posts: 20
Likes: 18
From: Near Richmond, VA
2015 S550 4matic / 2003 E55 AMG
I took a voltage reading of the aux battery and it appeared to be the same as the new battery. So I guess it's more than a voltage issue. The install was pretty straight forward. The one thing I forgot to do was reconnect the plug for the 12v power outlet. I almost took everything apart to reconnect that plug, but I don't think I'll ever need it. Don't forget to plug that thing back in. One surprise was I didn't have to relearn the windows or sunroof. It seems all memory was saved, even with both batteries disconnected.
Senior Member
Joined: Dec 2013
Posts: 258
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From: Southern California (L.A.)
2019 S65 Coupe, 2017 S650 Maybach Convertible, 2020 S560 Sedan, 2022 Porsche 911 Turbo S
One thing I learned a long time ago (from a Lexus tech when I had weird alerts coming from my LS-430 at that time) was that the new cars are very sensitive to low voltage or poor performing batteries. When you start to get all kinds of weird "fail" messages, check the battery. Iven if its within spec, but on the low end of it, you could have issues. When in doubt, replace the battery. Low and behold, once he replaced the battery all the issues went away. So now its the first thing I check if I ever get weird failures.
MBWorld Fanatic!
Joined: Apr 2016
Posts: 1,493
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2014 S550 AMG, 2017 XT5
I took a voltage reading of the aux battery and it appeared to be the same as the new battery. So I guess it's more than a voltage issue. The install was pretty straight forward. The one thing I forgot to do was reconnect the plug for the 12v power outlet. I almost took everything apart to reconnect that plug, but I don't think I'll ever need it. Don't forget to plug that thing back in. One surprise was I didn't have to relearn the windows or sunroof. It seems all memory was saved, even with both batteries disconnected.
