06 bug drains battery over night - 2006 Volkswagen New Beetle

On most 12v cars,the #1 cause is a light left on somewhere in the vehicle.#2 cause is a bad diode in the alternator and #3 is a bad battery which self discharges and is usually over 5 years old.
An easy first step is to disconnect the charged battery over night.If it still has a full charge the next morning,after you reconnect it and if the car starts,you can rule out the battery as the culprit.Now,if the battery passed the first test,now we go onto #2 test and disconnect the alternator output wire from the alternator overnight.If the battery still has a full charge the next day we will now know the alternator has a bad diode and will need to be repaired/replaced.If the battery was found to be low on charge the next morning with the alternator disconnected we will now have to go on to test #3 to find the drain in the vehicle. Disconnect the positive battery cable and place a 12v regular bulb type test light between the positive cable and the battery positive post.You should have a bright light on the test light if you have a drain in the vehicle from the battery.(don't worry about a dim light as electronics need a little memory voltage) We are looking only for a bright light.With the key off (as it would be overnight) you are now going to remove one fuse at a time while watching the brightness level of the test light.Take one fuse out, look at the light and if no change in brightness put the fuse back in and on to the next fuse,one by one until you see the light go out or dim.The fuse that dims or removes the bright test light will be the circuit that is draining your battery.Now you have your "battery drain" circuit identified and can inspect/repair the item/items on that circuit.
REMEMBER an open door,trunk or hood may cause a FALSE bright light on your test light because of courtesy light switches and alarm switches so manually close those switches if you need to keep one of the doors or hood/trunk open to gain access to the multiple fuse boxes in many vehicles.
DO NOT TURN ON THE KEY during this test, as all power to the vehicle is now going through the test light and things won't be happy if you do.