Average battery life on a Prius?

My 2001 Prius has over 190,000 miles. I have had it serviced every 5,000 miles. Service has consisted of changing oil, rotate the tires and occasionally replace the cabin filter. At 125,000 miles service called for replacing the engine and inverter coolant. At 185,000 miles it finally needed new brake pads. The car has averaged about 45 mpg (calculated, not from the display) during its life. It is fun to drive with plenty of go and little noise. Undoubtedly it is by far the best car that I have ever owned.