Heat is a killer of batteries. Living in the south and southwest is brutal on battery health. Hypermiling will add heat to the battery pack. Excess heat will degrade the battery pack. Air cooled battery packs are insufficient for such regions many months of the year.. Going to the extreme ends of state of charge also have an effect on battery health and longevity. Living in New Hampshire is not like living in the southwest. Keep this simple fact in mind.

 

Way ahead of you on that. I'm very data driven. Temps make about 50-60K miles difference in battery failures between Phoenix conditions and the extreme northern U.S. latitudes. One of the aforementioned service providers with whom I have a relationship operates exclusively in the upper 1/4 of the country. Another ships across the entire country.

Received calls from two people today with high mileage Prii. They've owned for 3 and 6 months, respectively.