2010 Mercedes C207 aux battery location

Jason • 10 September 2019

Need to know where the aux battery is on a 2012 e350 coupe "C207"

It is not in the trunk and I have taken the drivers side dash apart with no luck. All the info I can find is for a w212 that shows removing the panel on the side of the dash with a bolt holding the battery box. I do not have this. Any help would be appreciated or pictures of it's location.