At 12:46 AM 8/25/2012, Don Hanson wrote:
>    They even have some that have a feature to save your
>alternator...whatever that means....

You have to disconnect the alternator field coil before the battery;
otherwise the sudden spike on disconnect (only if the engine is
running) may destroy alternator diodes or  electronics elsewhere in
the vehicle depending how the cutoff switch is wired.

Marine Off-1-Both-2 battery switches are constructed to make before
break so as to avoid this, and for a few bucks extra you get an extra
pair of small terminals that cuts off the supply to the alternator
field before the switch goes all the way to Off.

Yours,
David