S320 CDI Battery Drains

[sajmeister]

Hi,

I have a S320 CDI Mercedes and the battery drains completly after 48 hours.
Any ideas what could be causing this ?

I have had 2 new batteries installed and they all have drained after 48 hours.

Thanks.

 

[television]

Hello and welcome to the forum, the only way that this can be solved is by having an ammeter in series and pulling the fuses one by one

 

[MIW615]

Hi,

I have a S320 CDI Mercedes and the battery drains completly after 48 hours.
Any ideas what could be causing this ?

I have had 2 new batteries installed and they all have drained after 48 hours.

Thanks.

When measuring the "drain" I would expect it to be around 50 - 60 ma, any more than that then do as Malcolm says untill you trace the offending circuit

 

[BlackC55]

You will find it very difficult to find.

Just pulling fuses does not always find the problem as some control units can cause a drain and they are not always fused. (40+ control units on some s classes)

There is a certain proceedure that it labour intensive for this kind of car.

Firstly remove the sat nav disc at they are prone to cause a current drain (stay on when car is switched off)

Look for any illumination still on inside the car when locked for 40 mins indicating a drain. (instrument cluster is a faverourite)

Make sure the battery is good.

 

[BlackC55]

0.06A-0.07A is absolute maximum drain.

It must be checked when the car is locked and asleep (30-40mins)

 

[hmang]

don't forget the alternator ...it could drain back through there

check with ammeter in line