We have a 2005 Cayman S and it has suddenly developed a Parasitic Battery Drain.
Pretty New Battery (less than 6 Months)
Doesn't get driven regularly and we went to it and was dead as a dodo.
Jumped it and drove it for 300 miles in a day and 36 hours later was dead again
Charged over night, disconnected and within 24 hours was dead again, no start, key stuck in ignition.

Have removed the fuse for the Radio in case that was the issue, no change, no we are not leaving the lights on or the interior lights.

Does anyone have any ideas on this as we are scratching our heads?

 

Be sure you are taking the key out of the ignition and locking the car. With the key in the ignition even if the ignition is switched off or even if the car is unlocked alot of the car's electrical system stays active in "anticipation" the car will be used. The engine controller sucks up a lot of juice when it is running.

Be sure both the front trunk lid light and the rear trunk lid are out. You can pop the light assembly out and disconnect it from the car's wiring harness to ensure the light is not staying on and draining the battery. Might mention though with another car an inside rear passenger seat reading lamp was left on -- was not very bright and it was only in a dark garage that I noticed it was on -- and while the engine cranked a bit longer than normal -- which in my experience can be a sign of a low battery -- the battery didn't run down.