OK Don wrote: > A heavy duty relay would work nicely also - not a mechanical device, > little loss due to cable runs, low current to a switch in the car.
I thought about that, but it'd only work if he intended to turn it off every time he parked the car. Otherwise the current to energize the relay coil would run the battery down. I'd be tempted to use a Ford starter contactor, but they're probably not designed for continuous duty.
