Volkswagen Repair: 1998 bettle wont start after a day of not driving, digital volt meter, negative terminal

Question
I have changed the battery twice on this car since i bought it used 2 years ago! the starter is fine, the alternator is fine and we have no idea whats wrong with it, we thought it was a sunroof problem, it's temperamental and it opens by itself, when it does that I can't start it in the morning, but lately nothing is on, the lights are all off (sunroof too ) and i still can't start the car if I havent been driving it for a few hours.

help please

Answer
Most common reason for the vehicle to be dead and has no crank is the alternator. If you say its good then its good. So the next step if it is not the alternator, Cables or the high amperage charging cable is called a parasitic drain. Its not a hard test but the process is to shut the car off the battery needs to be fully charged. The hood needs to be popped and the latch closed. Then lock all the doors. Then take of the negative terminal on the battery and to get a digital volt meter and hook one end up to the post and the other end up to the terminal end. The post and the terminal end can not be touching. Only the clamp can touch the two. You check the milli amps in the circuit. Average on your vehicle is 40 ma. 120ma is max. This is a easy test and if you have a volt meter and need more help just let me know. Ok if you think that sunroof is draining the battery then there is only one reason for this. The motor must be constantly running. The problem is in the wiring, sunroof switch, or the motor control module which is the motor. I have never heard or seen the sunroof killing the battery. So if it is that problem then these components should be checked. Lets say you drive your car. It starts up fine and lets just say the battery is fully charged not 3/4 but 100%. You drive 20 miles and stop to eat a restaurant and see a movie. Come back to start your car and it doesn't crank. Well the fully charged battery is down to dead. A couple of problems occur to cause this one the charging circuit is bad. Possible the alternator or the cables. This includes the ground and the fuse box on top of your battery. Or you have one really big parasitic drain. 20+ amps. A parasitic drain is very hard to pin down. Most of the time the problem is with non Original products hooked up to the factory wiring. Low jack, Amplifier, Navigation unit and so on. Or it might be a light on or basically anything. When you run the parasitic draw test and you see that you have 5amps or any thing out of spec then start pulling fuses one at a time to see which current track it is on. As soon as the amperage drops down to nothing or low that was the powered dram. Then you need a wiring diagram to test components and wiring. One more thing to look out for is that when you lock the car do you hear a beep. If not then the alarm is not setting. Then you have the vehicle not falling asleep. This will kill the battery but not in a couple of hours. The beetles like to leak water in your third brake light switch and mess up the trunk lock switch which can set off the alarm and leave the trunk light on. Well good luck. Keep me in touch.