Toyota Prius battery life is affected by the number charge and discharge cycles the battery experiences. The typical life span of a Prius battery is from five (5) to seven (7) years, or about 180,000 miles. After this time, the Prius’ performance will start to decline, because the battery is not able to handle the load placed on it. The vehicle has a computerized battery power management system that prevents the battery from deep discharges, and continuous “top-off” charging that shorten battery life. Since most gasoline burning vehicles rarely make it to 180,000 miles, replacing a Prius battery when it dies still makes the Prius a cost-effective vehicle.