SLK280 (3 litre) auto. Battery drain?

[brucemillar]

2008 registered (2007 model) SLK280 (3 litre) auto. 52K miles.

Guys. This is for a friend of mine. His car has now had four batteries replaced due to a battery drain issue. The battery drains in a 1 - 2 weeks.

Both the AA and Mercedes have failed to find the fault/cause. Any clues where he should look first. Are there any known issues with these cars - seat modules etc?

 

[BlackC55]

How much is it draining?

 

[brucemillar]

How much is it draining?

Olly. It drains a fully charged battery in less than a week.

Sent from my iPhone using MBClub UK

 

[vijilants]

Why not put an ammeter inline with the battery positive and check the drain....its bound to show up on the ammeter and then knock the circuits off at the fusebox till you find out which one is causing the drain ?

 

[Terry_]

Why not put an ammeter inline with the battery positive and check the drain....its bound to show up on the ammeter and then knock the circuits off at the fusebox till you find out which one is causing the drain ?

If only it was always that simple

 

[brucemillar]

Why not put an ammeter inline with the battery positive and check the drain....its bound to show up on the ammeter and then knock the circuits off at the fusebox till you find out which one is causing the drain ?

That may well be the plan. However Mercedes (two dealers) have had the car in and can't find the fault. Also the AA have been unable to find any issue.

The thinking is that this is a dreaded intermittent connection issue. So when checked no issue is evident.

The poor guy has paid a small fortune to Mercedes and now the AA say he has exhausted his call outs and will charge if he calls again with a flat battery.

 

[Dec]

As a 2007 model, it is old enough to have a faulty alarm siren, which could cause a drain.
If it has a faulty siren, it might not be possible to interrogate it properly with a diagnostic system.
The car might need to be locked so the alarm is armed in order to track down a drain.

Dec

 

[vijilants]

That may well be the plan. However Mercedes (two dealers) have had the car in and can't find the fault.

To be honest from my experience, unless the STAR system tells the dealership Mercedes Benz technician what's wrong, more often than not, they havn't got a clue and then simply start replacing parts inthe hope that the problem will go away. Gone are the days in dealerships where real mechanics or auto electricians exist.

Personally I would engage a very good Independant or Auto electrician to deal with this, and not Mercedes.