a battery charging system includes a charging path for charging batteries which have a variety of different charging parameters requiring different optimum charging algorithms . the battery charging system comprises a charging algorithm sensing circuit . at least one battery cell having a positive and a negative terminal and an optimum charging algorithm is to be charged . an impedance having two terminals and a value related to a predetermined charging algorithm of the cell approximating the optimum charging algorithm is coupled to one of the positive or negative terminals of the battery cell . a capacitor combines with the impedance to form a characteristic related to the predetermined charging algorithm . battery terminals connected to the cell and to one of the terminals of the impedance form a battery for connecting the cell into the battery charging system with the cell in the charging path , and the impedance and the capacitor in the charging algorithm sensing circuit .