Changing the battery on my C207

[upnorth62]

Stop/Start hasn't worked properly for some time now and I've had problems starting it recently.
Had to get the neighbor to jump start it once, it fired up instantly so I don't think it's an alternator problem.
Also getting a warning about auxiliary battery failure which which is disabling the brake hold.
Looks like main battery is the original MB battery so it's over nine years old.

So, I've seen the KillerHertz vid for changing the battery, which seems straightforward, but I'm a bit concerned about maintaining voltage.
I'm assuming that the auxiliary battery will keep enough power on while I swap the main battery out but if I'm getting warnings about auxiliary battery failure then am I putting myself at risk of losing settings, or worse?

 

[OneForTheRoad]

Just make sure all the windows and roof are closed . I just changed my c207 main battery , I didn't have any after issues at all.

 

[geoffus]

I had the same problem a while back, made a short guide here :

New Battery cured Stop Start. | Electronics and Audio

The original battery on my E250 was dated 2014 and began struggling recently to start he car. The stop start function had also stopped working so main battery looked suspect. Just had a new battery arrive and promptly fitted it. Stop Start is now back to fully working and the Eco button goes...

forums.mbclub.co.uk

 

[upnorth62]

Hi
Thanks for your replies on this.

Any thoughts on that Auxiliary battery?
Strangely it measures 12.7 volts so I can't see why I'm getting a warning about it.
The main battery is measuring 11.95v (both readings taken this morning when the car was cold)

 

[OneForTheRoad]

Hi
Thanks for your replies on this.

Any thoughts on that Auxiliary battery?
Strangely it measures 12.7 volts so I can't see why I'm getting a warning about it.
The main battery is measuring 11.95v (both readings taken this morning when the car was cold)

Maybe it's 9 years old also ?

 

[upnorth62]

It's an FIAMM with a mercedes mark on it but I can't be sure if it's the original auxiliary or not, I only bought the car last year.
TBH it looks pretty new but I'd guess that cover has never been off so it's a bit difficult to tell.

I guess my question is really this.
Does the auxiliary battery provide the power to retain all of the settings if I swap the main battery out?

 

[OneForTheRoad]

It's an FIAMM with a mercedes mark on it but I can't be sure if it's the original auxiliary or not, I only bought the car last year.
TBH it looks pretty new but I'd guess that cover has never been off so it's a bit difficult to tell.

I guess my question is really this.
Does the auxiliary battery provide the power to retain all of the settings if I swap the main battery out?

You may have to reset the windows, not sure of which settings your refering to. I just took it out and put a new one in.

 

[upnorth62]

I just took it out and put a new one in.

That sounds like good news to me.
Gonna take it for a bit of a drive to make sure the auxiliary gets a good charge before I swap the main battery out.
Thanks for your help.

 

[ToeKnee]

I believe Mercedes batteries, and possibly others, have a 4 digit code stamped on one of the battery posts signifying month and year of manufacture of the battery.