Question: how often do you have to replace prius battery?
Answer: He pointed out to Torque News that Prius batteries are warranted for 10 years or 150,000 miles in California-compliance states and eight years or 100,000 miles in non-California compliant state. In his experience, the batteries last about 12 to 15 years (the oldest Prius cars on the road are now 20 years old).