Temperature/voltage controlled battery charging circuit

摘要

A battery charging circuit particularly adapted to recharging NiMh batteries utilizes a thermistor to develop a control voltage corresponding to the temperature of the battery being charged and compares such voltage to an accurately measured battery terminal voltage. At a preset condition of a combination of the two voltage readings, the charging circuit converts from charging at a relatively high and fast charging rate to a relatively slow rate corresponding to a trickle current passing around a SCR through which the fast charging current normally flows. The circuit components are selected such that the battery achieves a charge of substantially 95% capacity before switching to the relatively slow rate and enables display of a state of charge indicating that the 95% capacity charge has been achieved and without any "popping" or cyclic ON-OFF effect.