When my 4Runner sits for a week without driving it, the starter will spin noticeably slower than usual. After 9 days it needs to be jumped. I am currently using a 3-year old Napa Orbital battery (similar to Optima) and it has eaten an Optima about every three years. (Optima is getting a bad wrap these days, so who knows...) Everyone keeps telling me that modern cars will draw a battery down that quickly when not driven, but I have my doubts. How many vacationers do you know that fly out for 9 days to come back to a dead battery in the airport parking lot? It doesn't seem like a common occurrence to me.

I do not have any full-time power electrical system mods--everything I have added electrical-wise turns on with the ignition.