I solved my problem. Maybe yours is the same. The auxiliary fan in front of the condenser would come on and run all the time while the car is running. I had replaced everything, but noticed that when that fan was on, even when nothing else was running, it ate into the battery. I disconnected that fan and wound up replacing the mechanical fan I couldn't afford a new thermostatic clutch for anyway with an electric fan that cools the radiator and the condenser just fine. Without the auxiliary fan, my engine runs cooler, my AC is colder and best of all, my car starts. I just left the wires sitting under the bumper with nuts on the ends.

Hope this helps.

 

Kaeley, if the alternator and battery bench test good and the voltage regulator is new, it is almost certainly a problem in the wiring harness. Visually inspect the battery and engine grounding wires and replace them if they even look remotely suspect.

 

i got a used alternator off a 240d at picknpull i got it bench tested and it passed do i put it in and it didnt work. Then somebody suggested i replace my glow plug relay. so before i did that i just went over to the glow plug relay and whacked it a couple of times every time i hit it, it would start charging. so i replaced it with one i had laying around...and it worked. The car charges fine every time i start it up. thanks to eveyone who helped. so happy to get to the bottom of this