Wall charger recharges AA or AAA rechargeable batteries, up to four at a time. A series of beeps indicate when charging starts and when batteries are fully charged, maximizing battery performance and ensuring a full charge every time. A second series of beeps indicate that the battery in the charger has reached its full charge. Battery Type: NiMH, Battery Size: AA, AAA. Charge Time: 3 Hours. Power Source(s): AC.