Yup, three years. Get out your wallet. Them batteries are gonna need replacing soon if not already now.
***
That, of course, is untrue. The first generation Prius went on sale in 1997. Even then, the battery life was estimated at 7-10 years. And that turned out to be an underestimate. But since then, the battery technology has been improved, primarily in terms of charge management, giving the battery a projected life approximately the same as the rest of the car, i.e. about 25 years.