If you do it on the positive side, i know you need something more than 80 amps @ 12V. I fried that sucker. I knew it wouldnt work because your starter pulls alot of amperage, so the higher, the better. Usually, those switches are in 120V, so 100 amps @ 120V is 1000 amps @ 12V. So make sure you dont get confussed with the ratings.

In a DC circuit if you break the circuit anywhere, there will be no current flow. It doesnt matter which terminal you disconnect, its just a little bit safer and more of a standard to disconnect the negative. Id say try disconnecting both terminals and see if the batt dies. If so maybe you got a bad batt.