sublettm,

Diesels do not need a functioning alternator to run, or, for a while, to start. After running the car's accessories and starting a few times without being charged the battery will show signs of distress, like not wanting to turn the engine over.

Sounds like you may have a bad alternator. Typical failures can come from worn brushes in the voltage regulator, a relatively easy item to replace. Two screws and a plug on the back of the alternator and you roll the voltage regulator down and out. If the brushes are a quarter inch long or shorter the brushes are shot. If they are worn unevenly or there are gouges in the contact surfaces, you likely need an alternator rebuild or a rebuilt alternator. Alternator replacement is also within the do-it-yourself range for most of us, although it helps to have some instructions. Try a search or post a request if you get to that point.

Good luck and I hope this helps. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)