auxiliary battery malfunction S 350 bluetec

[Malcolm Johnson]

Really just to pass on this battery location on this version of S. It is in the boot. Looking into the boot, the hinge cover over the spare wheel is held by two T20 screws one in each plastic plug. When these are removed take the cover away. To get access to to the battery remove /lifting from the left side the vertical panel (rear of rear seats) in the boot.
The panel comes away to reveal the battery.

 

[John77]

I find the auxiliary battery a pain. If I do not drive the car for a few day the dash says consumer function switched off. I did put on a new battery, but still the same until it charges itself. Taken it off and fully charged for 2 days. No difference. Apparently, it is mainly the command unit that drains it.

 

[Malcolm Johnson]

When i checked the battery at the weekend it could not be charged fully, when left to rest for 24 hours, only shows 9,6 v across terminals, dead battery.
New battery arrived today, get around to fitting it Thursday morning. See how we go?

 

[Malcolm Johnson]

Hello all,
A week has passed, since i fitted the new Varta Auxiliary Battery. All good and working normal again. FYI

 

[Botus]

what age and what size battery are we talking about?

the early twin battery cars up to mid 2007 get a massive 25kg consumer battery in that location - plus the much smaller starter one under the bonnet
then they went single battery under the bonnet
later cars seem to get the baby aux battery under the dash as well - which on another forum they say is get get the car out of park shuld odd things happen

 

[Malcolm Johnson]

Had a look under the dash first, but no battery, just a small one in the boot behind the rear wall. The stop start is up and running again.
That was first of the four batteries to change the starter next. Then starter & auxiliary on the SL before 1st April, plus new ball joints.
wear and tear.