This charger is 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.