bhorne is right,

I had the same exact problem with my 190 which ended up destroying two new batteries before I finally realized what was happending. The alternator regulator goes bad and starts overcharging your battery, if this happens it will boil the acids in your batter thus creating that nautious smell. Its an easy DIYS fix so definitely check it out.

__________________
Afshin

Current:
02 C32 AMG

Previous:
92 500E
84 190E 2.3 5 Spd