I recently purchased a 2005 330cd convertible, battery was fine when I received it, I had the BM54 upgraded, added a 12" sub and fitted an ipod cable to the sat nav. Now after 2 days of sitting there the battery on the car goes totally flat, and I mean totally. Any ideas on what could possibly be doing this? Have I cocked up on the wiring or something?
Any help would be great.