I just purchase a 1984 190d and drove it to work for the first time today. Every thing was fine until I had to turn on the lights and the battery started to drain. By the time I made it to the filling station the battery was completely discharged. The alternator light does not come on. Could it still be the alternator. I dont have any electrical testing tools.

Or.......more obviously, a bad battery that won't hold a charge. Alt light would not come on because of that.

Also, worn brushes of regulator of alternator may be worn down and therefore not charging battery and also, no red light.