List,
I have a battery cut off switch (red key) and it's extreemly useful, just as Chris says. Mine is mounted just to the right of the black battery cover (where the two pieces of carpet join and can "poke" out between the two if left in. I have used it extensively during my restoration. No point having the door lights on for 9 hours!
Just my two small pennies worth!
Dan, Vin#5641, "Maddie"