The charger was developed using a proprietary IC as the main up-converter / charger. This charger was designed to maximize charging current and efficiency in order to deliver optimal charge to the battery. It starts up automatically when a device is connected at the output, enabling the immediate operation of the device even if the battery is fully depleted. is intended for use with one standard 1. 5 V AA primary or secondary cell. It can, however, be used with any standard 1. 2 ?1. 5 V AA batteries. Higher quality or premium batteries are recommended, as their lower internal resistance increases performance of the charger. In order to optimize charging, the circuit decreases the charging current when the AA cell voltage falls below 1. 1 V, and stops charging altogether when it falls below 0. 6 V.