I recently setup a second battery in my 96 gt, mainly for the new alarm and a few other accesories, and the same day had my radar detector die and my exhaust solenoids die as well. When I say die, I mean fried without blowing a fuse...dont ask how..they just dont work anymore. I set the second battery up so it was grounded to the frame, then connecter the positive cable to a 200amp battery separator, then that to the positive of the main battery. Both are in my trunk, and the main battery is grounded to the frame of course. The solenoid is rigged to only connect the 2 batteries when the key is turned on, but I installed an overide switch so that I could disconnect them when I wanted. Everything works fine, no fires heh and the second battery charges at around 15 v with the car running, just like the main battery. I wired the battery separator to a key on fuse box I had made for other accesories, which is up front under the glove compartment. So the wire that turns on the solenoid does run past the wire that opperates both the radar detector (it is a whistler 2/ 16" gauge with remote sensors) and the electronic exhaust valve solenoids if that makes a difference, but its on its own fuse. Nothing else got "fried" not a single fuse popped, I hooked the radar detector up to just one of the batteries when separated, and it still didnt work. All grounds are perfect, no loose wires or anything, its just dead. Could this be some sort of reaction to either the dual batteries and the way they are setup or the huge magnet to operate the battery separator? Is this some sort of magnetic interference? Im at a total loss as to why these two accesories would fry. The exhaust valves had 12v by the way, everything should work but they are fried like I said. Any advise would be great, thanks guys.