I have a mercedes E220 CDI (211) year 2004.
As i know this car has two batteries. One (the main) is in the rear...
It has another one in the front right (near the engine)... What´s the porpuse of this battery?
It gives power to the ECU?

Thanks

 

In simple terms you should never have a flat battery again.

The second battery ensures that there is always enough power to start the car and run essential services. The other looks after non essentials etc. ICE, nav, interior lighting etc. although things are not quite as simple as I suggest.

Stuart.