My understanding of the 'battery' idiot light on the Benz (and my experience based on a recent similar problem on my 300SD) is that the light is grounded through the brushes; when they wear out the light goes out altogether (one of the very few examples of dumb design in a Benz). I guess this means you should look to your battery first. Too bad - brushes are dirt cheap!

__________________
1980 300SD (The Green Machine!)
180D Ponton (paid $100 Cdn - sold $200!)