Charges batteries in 4-8 hours with 1000 mW charge power. (To approx. 90% of full charge when using 1300mAh up to 2500mAh 2xAA NiMH Batteries (included). Based on charging AA batteries.). Comes with 4 premium AA Duracell Rechargeable Pre-Charged NiMH batteries that are 50% longer-lasting per charge* and guaranteed to last 10 years, or 400 recharges, whichever comes first. (*vs. 1350mAh within the first 200 cycles.). This battery charger works with all rechargeable AA and AAA NiMH batteries. Charges 2 or 4 batteries at a time. LED Charge Status Indicator shows when charging is complete and Auto Shutoff shows when batteries are charged.