W211 Battery Drain "Consumer Units" etc.

[holbay]

My E320 has been doing the same problem but today at a funeral it would not start so called the RAC and the guy jump started it and put meter on the battery and reading was 12.02 volts and with engine revs lifted it went to 12.1 this is not good enough to maintain a battery but on the way home the info display lit up in red saying ( alternator/battery go to workshop and reduced braking efficiency go to workshop ) the braking message is due to the brakes need power to operate properly but my brakes were working ok. So has anyone cured this by fitting one of those solar panel chargers to the car, i am thinking if we are having to charge a battery every so often that a solar panel on the back window should stop the drain..

 

[Dec]

It sounds like a serious drain if you needed a jump star after having started the car earlier that day.
Is it a drain or is it a faulty battery or a faulty alternator, revving the car should have produced about 14v - 14.2v.

You can’t fix a drain or a faulty battery or a faulty alternator by recharging the battery, eventually, whatever is at fault will get worse and then let you down.
You will need to find whatever is at fault and fix it.

Dec

 

[holbay]

I suspect the alternator so will get car on the ramp friday to check it..

 

[holbay]

Ok got car to work today and put meter on battery and found the voltage to be 14.4v all good and it starts ok but all of a sudden when idling the revs fluctuate up and down by about 50 to 100 rpm and the car lights go up and down too. If i rev it hard it will sometimes even out and lights are normal then it happens again, so i am assuming the alternator brushes are worn down to the limit. But before i haul the alternator off due to my car must have a split charging system for the small battery in the engine bay is there any other control gear for charging that can cause these problems.. George..

 

[Dec]

There is this here… http://mbfan.ru/Instruktsii/W211_ Dual Battery_ABC.pdf

Dec

 

[holbay]

Thanks Dec do you know how to perform normalisation on the items at the end of the document in particular the automatic air conditioning. Thanks

 

[Dec]

Unfortunately not, sorry.

Dec

 

[Ardveen1]

Hi, an update on battery drain on W211 E220. I ran star diagnostics on the car and it showed an error on the passenger side heated door mirror. I adjusted the mirror to view the wiring to the heater element and with a long nose pliars i removed both wires from the element. The car has been lying up for the last 2 weeks and started today with no problem. This was never the case before, max 3 days before flat battery. Happy days - look like the mirror element was the problem