[olddog]

I had to think a bit, but the switch opening on the positive side only disconnects the battery from the car's circuits. The alternator will continue to power the car, if the engine is running when you open the switch.

I am thinking that the alternator does not tie to ground, but I'm not certain this is true. Logically it should, but I don't recall connecting a ground wire to one and the brackets are painted. If it does not, then this is why the switch should be on the negative side, as it would kill the entire electrial system.

As for the current draw, as some have argued this both ways, the amperage draw is the same on both the negative and positive side of the battery, when the battery is providing the power. When the alternator is providing the power, I'm not certain, without seeing a drawing of the alternator regulator circuit.

I hope an expert can sort this out for us.