skywagon, I'd go thru the manual if I were you. I recall reading that the car should not sit for more than two weeks without being driven or you could risk completely discharging the big battery. I don't have my manual in front of me or I'd look up the page # for you.
i cannot find anything in the manuel that states that, may need to buy a service manuel. The dealer must have a way to charge the big battery, there is an orange plugin in front of the battery, I have had this out and it looks like a place to plug in a charger. certainly folks will be leaving these cars sit for a period of time, what if you are confined to a hospital bed? calling a tow truck under such conditions is going to get costly unless a person hooks an auto start on it activated by telephone but you would need a way to shut it off also, this would start the engine and charge big battery. there has to be a failsafe way to do this and I will find out how lol

TCH-43mpg
VW TDI--48
08 LS 600 HL-20
08 LX 470-16