I've got an old but low mileage Mercedes and This problem puzzles me. The car stalls after a short time(30 seconds to 1 minute) after start up and the battery warning light on the dash lights up. I have changed to a new 800cca battery, and did not solve the problem. I then went to change the alternator and serpentine belt and belt tensioner, and problem still exists! It seems the exterior bulb warning light is also on. Since I have changed everything, what else could be the problem?