2000 Passat battery starter and alternator good but some thing is draining the battery
Do you have a meter? With a fully charged battery, remove one of the cable from the battery post and place your meter between them and see how much amperage you are drawing. Anything over the 80-90milliamps is excessive. You can then start pulling fuses to see what the culprit is. If you are drawing a minimal number of amps, it might be a light somewhere. If it's a lot (8+) it might be a motor running when it shouldn't. (I find in a lot of these cases it's a stuck wiper arm motor, especially in rear hatches.) Of course, you could have a different sort of problem with bad grounds or shorts, in which case you'll just have to hunt it down. The meter trick can still help you isolate circuits.