I see 2012 gen 3s for sale with 10k miles on them. How much damage is done to the hybrid battery if it dies completely from sitting for months at a time?
You are making an incorrect assumption. The hybrid battery typically will NOT "self discharge" like the 12 V ones do. The recommended storage point is something like half charged.
My Prius basically sat for a year while I worked abroad. A friend was supposed to drive it periodically but hardly ever did. The 12v battery died but the hybrid battery was fine and still is 7 years later.
Toyota's guidelines, recently mentioned in another thread, are to put the car in READY for half an hour every two months for charge maintenance of both batteries, as both lose charge during storage. I think of two months as longer than I expect the 12 volt battery to hold up, but then the dealer storage conditions may be with the short pin removed, which could explain the difference.
