One of the easy ways to test for whether the car is charging or not is to get a simple 12 volt tester. Should be 12.7 or so without the car running and into the mid to upper 13's with it running.

If the car will run and only puts out 12. something, then you either have:

1. a bad alternator or
2. a bad voltage regulator (easier and cheaper)

The battery can also surprise you by acting strong when in fact its not. For example, you can jump the car, get it running and notice that 13. something volts are kicking out. But the battery may only hold a charge for a day or two. That can also be tricky.

Good luck

dp

__________________
DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed