Just to say right off the bat, I goofed. When changing the battery on my 2003 530 I accidentally grounded the positive battery terminal. There was a nice spark when I did this, and now it seems there is an electrical issue. When the car is running at idle, I get 14VDC at the battery, but when the blinkers, window switches and such are used, the voltage drops to 13.4VDC. This can be seen in the various lights through out the car fluctuating (dimming, then brightening). The car never really completely dies due to electrical system failure. Is there a a common thing, or point to strart, in trying to locate the source of the electrical fault? Or is this going to be a trip to the dealer? I have a fair amount of DIY experience, so pulling something apart to diagnose will not be a big deal.