Recharge Smart Charger features a countdown timer that shows how long until batteries are charged and a Battery Fuel Gauge that shows the charge status. Large visual display can be viewed from across the room. Bad Battery Alert detects alerts and shuts off charging when a non-NiMH or old NiMH battery is inserted. Charger charges two or four AA or AAA NiMH rechargeable batteries and charges batteries at a safe, steady rate, which improves the long-term health of the NiMH battery. Smart Charger includes four AA rechargeable batteries. Energy Star qualified.