I'm leaving my Prius in my garage until I need it in January, do I need to start it occasionally to keep the battery charged?
CWERDNA's post covers it very well. You have 2 batteries to worry about, the 12v and the Hybrid battery. The 12v battery on a 2006 will discharge slowly in part due to the smart keys SKS system. There is a switch beneath the steering wheel to turn SKS off, which should help retain 12-v battery charge for some period. However, as long as 3-months the above post was suggesting disconnect 12-v battery.
