My '05 Mini S with sunroof is currently at the dealer with water in the battery box issues. It was discovered when I went to replace my original battery with 28,300 miles on it. Water and corrosion were noted in the box. Yes, I have to replace my BST cables ( trunk to front bay) and the fuse box located in the box is also fried. It is an expensive repair and we should all be concerned. My car is in the process of having the electrical system fixed and the dealer will they look for the cause of the leak. I will include the battery box as a regular part of my monthly inspection from now on.