Abstract: A battery charger includes charge control circuits each connected in parallel with an associated one of serially-connected battery cells. Each charge control circuit includes a switching device; a comparator, having a hysteresis characteristic determined by two threshold voltages, e.g., a safe charging voltage and an optimum charging voltage, for comparing the battery voltage with one of the threshold voltages selected according to a changing direction of the battery voltage; a reference voltage source for generating a reference voltage corresponding to either one of the threshold values; and a driving circuit for receiving a comparator output to render the switching device conductive or cutoff. When the battery voltage falls between the threshold voltages, the switching device becomes conductive to cause a constant current to flow from the battery cell to the switching device.

Abstract: A charging voltage distribution apparatus dedicated to a charging apparatus for charging batteries connected in series comprises bypass circuits 15A and 15B connected in parallel with each of batteries B1, B2, etc. and a control circuit (consisting of circuit elements 4, 5, 6, 7, 8, 9, 11, 12, 13, and switches) for controlling amount of current to be routed into the bypass circuits 15A and 15B according to the voltage of a battery connected to the bypass circuits 15A and 15B. When the voltage of the battery exceeds a predetermined value, the control circuit makes the current to be routed into the bypass circuits 15A and 15B. When the batteries B1, B2, etc. connected in series have voltages exceeding the predetermined value, current is routed into the bypass circuits 15A and 15B. When the batteries have voltages lower than the predetermined value, charging current is fed for charging.

Abstract: A plurality of battery charging modules C, equal in number to a plurality of batteries B connected in series, are connected in series form a column of battery charging modules 6. Output terminals 7, 8 of this column 6 serve as the connecting terminals for a beginning terminal 2 and an ending terminal 3 of the series-connected column of batteries 1. A connecting point between consecutive batteries B connects to a junction point between consecutive battery charging modules C. This configuration enables the column of battery charging modules 6 to be connected with the column of batteries 1 and results in a set of parallel connections between the battery charging modules C and the corresponding batteries B.