W212 Auxiliary Battery What and Where?

[Solarwinds]

Having got my dashtop phone charger hardwired in by a local mechanic it has stopped working and in addition I am getting the old Auxiliary Battery Malfunction message.

Suspect this may be from the mechanics comments "i found a black box, looked like a tracker and took a live feed off that"...

Am hoping I can get the live feed taken from somewhere else but if I need to obtain a new aux battery when Google searching I am finding two very different looking things...which one is it for a 2011 W212 and is the location at the side dash entrance?

 

[mersum1es]

If you have gear selector in steering rack, right one is the one. You don't have start/stop?

 

[Solarwinds]

I don't have start stop function correct. I think I read the auxiliary battery assists with convenience functions?....I did search the boot but found nothing there

 

[Solarwinds]

OK OK so thanks to mersum1es in Finland, still reading about this, so not every model gets the bigish aux battery in the boot like this, not sure what it does really, looks fab with the red leads etc..



My issue is with the tiny (well much smaller) battery that sits inside the side panel of the dash looks like



Apparently when this is feeling ill it also throws up "Auxiliary Battery Malfunction" message.

MBWorld.org quote

"The battery is for the electronic shifter in the event your main battery dies and the car needs to be towed. It also serves for some other functions like the brake hold feature. Parts guy at MB dealer stated it did not need to be hooked up to drive."

Suspect my chap hooking it up as a feed to power my phone charger has ensured it threw a hissy fit.

 

[malcolm E53 AMG]

My E350cdi estate has the bigger 12Ah battery in the boot I wasn’t sure until I did a bit of searching a few months ago.

 

[Solarwinds]

My E350cdi estate has the bigger 12Ah battery in the boot I wasn’t sure until I did a bit of searching a few months ago.

Yes its funny isn't it?...why some have it and others don't, I replaced my main battery recently and there was a lot of questioning from the supplier as to if my car had stop/start and this would affect my choice of battery type. So that aux battery isn't just for the start/stop function, it must be for some other feature.

 

[sonic]

My 212 E350CDI 2011 does not have stop/start or an aux battery.
Cars with stop/start have larger & higher cranking amp batteries.

 

[Solarwinds]

Hmmm

Mercedes-Benz Auxiliary Battery Malfunction Explained

Are you facing auxiliary battery malfunctions in your Mercedes Benz? Click here to have the detailed knowledge!

xenons4u.co.uk

 

[Solarwinds]

All's well that ends well. The mechanic found an alternative power source, message "Auxiliary Battery Malfunction" disappeared and phone is charging nicely from its magnetic Mount thing, so the power cable plugs into that, the phone Case is magnetic and just clips on via the magic of magnetism. Its made by Mous if anyone is interested and the magnetism does not interfere with NFC payments or wireless charging.

Should have asked him to swap out the battery for a new one as they are Cheap.

Still looking for a conclusive answer that only cars with stop/start have the additional battery.

 

[mersum1es]

Hell no. steering rack gear selector is the feature which wants that 'tiny' battery, problem is that 'aux battery'definition is used for both. Thats why I asked ID for battery, because start/stopr and gear selector battery would have different ID in SDS

 

[Solarwinds]

Yeah see what you are saying but forgetting the tiny (gear selector) battery for now.

Do cars that have stop/start have the additional larger boot battery and cars that don't er don't if that makes sense?...in a nutshell that's what I was wondering.

 

[EmilysDad]

Yeah see what you are saying but forgetting the tiny (gear selector) battery for now.

Do cars that have stop/start have the additional larger boot battery and cars that don't er don't if that makes sense?...in a nutshell that's what I was wondering.

my ML350 has stop/start. The larger battery is under my seat & the smaller motorbike sized battery is in the 'boot'