Auxiliary battery confusion
Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Auxiliary battery confusion
Hi All,
I have an auxiliary battery malfunction on my GLC and research has revealed a lot of confusion and some misinformation.
This is what I have figured out and I am happy to be challenged.
Some Mercedes have an actual battery as an auxiliary battery (a small sealed acid type)
The GLC has a module instead with capacitors and is sometimes referred to as a "voltage converter"
As far as I can determine they both serve the same function for stop start systems.
That is, when the starter motor engages after stop start, it can cause a voltage drop across the system. Remember your old cars when the lights dimmed when you started?
The auxiliary battery is meant to iron out this voltage drop so sensitive electronics aren't effected. This is why in the GLC it can be done with capacitors. In no way do they help the engine crank (they are way too small), they simply provide a short term boost to stabilise the voltage for the low power electronics.
Mine has failed and stop start doesn't seem to work at all, which makes sense. I am going to replace the module and see how it goes. The main battery seems to be fine so I doubt it is the issue. I will update the post once I have it sorted. FYI I always disable stop start, which is probably why the main battery is fine.
The interesting thing is that given on the GLC it is not a wear and tear item like a regular battery, it should be covered under normal warranty. Unfortunately mine is out of warranty by a year.
cheers,
Redrover
I have an auxiliary battery malfunction on my GLC and research has revealed a lot of confusion and some misinformation.
This is what I have figured out and I am happy to be challenged.
Some Mercedes have an actual battery as an auxiliary battery (a small sealed acid type)
The GLC has a module instead with capacitors and is sometimes referred to as a "voltage converter"
As far as I can determine they both serve the same function for stop start systems.
That is, when the starter motor engages after stop start, it can cause a voltage drop across the system. Remember your old cars when the lights dimmed when you started?
The auxiliary battery is meant to iron out this voltage drop so sensitive electronics aren't effected. This is why in the GLC it can be done with capacitors. In no way do they help the engine crank (they are way too small), they simply provide a short term boost to stabilise the voltage for the low power electronics.
Mine has failed and stop start doesn't seem to work at all, which makes sense. I am going to replace the module and see how it goes. The main battery seems to be fine so I doubt it is the issue. I will update the post once I have it sorted. FYI I always disable stop start, which is probably why the main battery is fine.
The interesting thing is that given on the GLC it is not a wear and tear item like a regular battery, it should be covered under normal warranty. Unfortunately mine is out of warranty by a year.
cheers,
Redrover
Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Senior Member
Joined: Nov 2007
Posts: 432
Likes: 64
From: Delray Beach, Fl
GLC SUV 350e Verde Silver Metallic
The Mercedes Me Connect App many times shows the “starter battery” needs to be recharged by driving.
After a short drive it says “charged”. My question is What gives? Is the battery or the module failing?
Maybe the App is supper sensitive. Should I head for the dealership for replacement?
MBWorld Fanatic!
Joined: Apr 2016
Posts: 1,131
Likes: 194
From: Ireland
GLC 300d 4matic
I have only had my 2nd GLC for a week but certainly haven't had a message like this so far.
If you are in a very cold climate there may be more of a draw on the battery and if you are only doing short trips or low mileage it may be affecting the battery charge.
If you are in a very cold climate there may be more of a draw on the battery and if you are only doing short trips or low mileage it may be affecting the battery charge.
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Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Perhaps someone could answer some questions below which might relate to this discussion. My GLC has 1,100 miles.
The Mercedes Me Connect App many times shows the “starter battery” needs to be recharged by driving.
After a short drive it says “charged”. My question is What gives? Is the battery or the module failing?
Maybe the App is supper sensitive. Should I head for the dealership for replacement?
The Mercedes Me Connect App many times shows the “starter battery” needs to be recharged by driving.
After a short drive it says “charged”. My question is What gives? Is the battery or the module failing?
Maybe the App is supper sensitive. Should I head for the dealership for replacement?
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Member
Joined: Mar 2007
Posts: 157
Likes: 36
From: Suffern, NY
2020 GLC300 & 2009 SL550 (previously had 1999 CLK / 2006 E500 / 2011 GL450)
Perhaps someone could answer some questions below which might relate to this discussion. My GLC has 1,100 miles.
The Mercedes Me Connect App many times shows the “starter battery” needs to be recharged by driving.
After a short drive it says “charged”. My question is What gives? Is the battery or the module failing?
Maybe the App is supper sensitive. Should I head for the dealership for replacement?
The Mercedes Me Connect App many times shows the “starter battery” needs to be recharged by driving.
After a short drive it says “charged”. My question is What gives? Is the battery or the module failing?
Maybe the App is supper sensitive. Should I head for the dealership for replacement?
So, while I can't explain why the app is telling you the battery needs charging, it may simply be the headroom. Given you only have 1,100 miles, how long have you had the car, and what types of trips do you take? Are they primarily short distance and/or is the car driven infrequently? If so, the battery might not be getting topped off when driving, and all of the electronics in the car could be slowly draining the battery if it's not driven often.
Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Hi All,
I have an auxiliary battery malfunction on my GLC and research has revealed a lot of confusion and some misinformation.
This is what I have figured out and I am happy to be challenged.
Some Mercedes have an actual battery as an auxiliary battery (a small sealed acid type)
The GLC has a module instead with capacitors and is sometimes referred to as a "voltage converter"
As far as I can determine they both serve the same function for stop start systems.
That is, when the starter motor engages after stop start, it can cause a voltage drop across the system. Remember your old cars when the lights dimmed when you started?
The auxiliary battery is meant to iron out this voltage drop so sensitive electronics aren't effected. This is why in the GLC it can be done with capacitors. In no way do they help the engine crank (they are way too small), they simply provide a short term boost to stabilise the voltage for the low power electronics.
Mine has failed and stop start doesn't seem to work at all, which makes sense. I am going to replace the module and see how it goes. The main battery seems to be fine so I doubt it is the issue. I will update the post once I have it sorted. FYI I always disable stop start, which is probably why the main battery is fine.
The interesting thing is that given on the GLC it is not a wear and tear item like a regular battery, it should be covered under normal warranty. Unfortunately mine is out of warranty by a year.
cheers,
Redrover
I have an auxiliary battery malfunction on my GLC and research has revealed a lot of confusion and some misinformation.
This is what I have figured out and I am happy to be challenged.
Some Mercedes have an actual battery as an auxiliary battery (a small sealed acid type)
The GLC has a module instead with capacitors and is sometimes referred to as a "voltage converter"
As far as I can determine they both serve the same function for stop start systems.
That is, when the starter motor engages after stop start, it can cause a voltage drop across the system. Remember your old cars when the lights dimmed when you started?
The auxiliary battery is meant to iron out this voltage drop so sensitive electronics aren't effected. This is why in the GLC it can be done with capacitors. In no way do they help the engine crank (they are way too small), they simply provide a short term boost to stabilise the voltage for the low power electronics.
Mine has failed and stop start doesn't seem to work at all, which makes sense. I am going to replace the module and see how it goes. The main battery seems to be fine so I doubt it is the issue. I will update the post once I have it sorted. FYI I always disable stop start, which is probably why the main battery is fine.
The interesting thing is that given on the GLC it is not a wear and tear item like a regular battery, it should be covered under normal warranty. Unfortunately mine is out of warranty by a year.
cheers,
Redrover
Thread Starter
Junior Member
Joined: Sep 2016
Posts: 68
Likes: 8
From: Sydney, Australia
GLC 250d
Newbie
Joined: Jul 2016
Posts: 5
Likes: 0
From: Portland
GLC 300 4MATIC
I have the same issue. I have purchased the part and am ready to install. Do I need to erase/reset the code after the new part is installed, or does it go away automatically? If I need to reset the code, which scanner is recommended to do this?
Any help is greatly appreciated.
Any help is greatly appreciated.
Senior Member
Joined: Jan 2019
Posts: 497
Likes: 196
From: Palm Beach, Fl
2016 S550 sport, 2018 GLC300, M3, Zo7, 2021 Sierra Denali
I recently had the same issue and brought to the dealer. They determined my main battery was low, which caused the problem with the capacitors. They replaced the main battery with a fresh one and the SS now works as designed. Much to my dismay, as I hate hitting the button to shut it off everyday now!!
