Fast Charging Rechargeable Battery Charger: The battery charger is compatible with 2 or 4 AA, AAA Ni-MH/Ni-CD rechargeable batteries. Smart indicators: RED for charging, GREEN for fully charged. Unique USB design, convenient for traveling, widely compatible with 5V USB-enabled devices like power bank , adapter and so on. Smart USB battery charger features quick charges for rechargeable batteries. (AA*2 1000mA±50mA, AAA*2 500mA±50mA ; AA*4 500mA±50mA, AAA*4 500mA±50mA). Advanced MCU control system, intelligent △V and -△V cut-off charging method and automatical trickle charging mode prevent over-voltage, over-current and over-heating.