Universal NiCad charger - one charger for all NiCad cells

2-30 — elektor february 1982 universal NiCad charger universal It is not possible to connect NiCad cells in parallel in order to charge them from one power source simultaneously be- cause of the tolerance in the charge characteristics and the various initial charge conditions of the cells. The charge current can only be determined exactly if the cells are connected in series. The current depends on the capacity (number of mA) of the cells. Most of them can be charged in 14 hours with a current that is 0.1 x number of mAh. This current will ensure that the cells won"t be damaged if they are left on charge for too long, and for a charge XiCad chargerof at least 14 hours, it doesn"t matter whether the cell is completely ex- hausted or not. It will be obvious that a universal charger must have an adjust- able output current, because each different type of cell requires a specific one charger for all NiCad cells charging rate. The circuit diagram Figure 1 shows the complete circuit d...