Abstract: A battery-charging circuit capable of promptly detecting, during quick charging, an abnormality of a secondary battery of a battery, if any, and making it impossible to continue the quick charge thereafter. As a battery-charging circuit for quickly charging a secondary battery with a predetermined charging current from a battery-charging power source having a constant-characteristic, the battery charging circuit includes a voltage-measuring device for measuring the secondary battery voltage at predetermined regular time intervals; a voltage-setting device for presetting a reference voltage value at a level higher, by a predetermined magnitude, than an expected charge complete voltage value; a comparator device for comparing with the preset reference voltage value a battery voltage actually measured during the quick charge operation; and a current limiter circuit for stopping the quick charge when the battery voltage has risen to the reference voltage value.

Abstract: A method for charging a storage battery includes providing an electric charger having a rapid charge voltage level and a trickle charge voltage level, a total-timer for measuring a total time which has elapsed since initiation of a charging operation, a peak-timer for measuring an amount of time which has elapsed since a peak voltage is reached during rapid charging of the storage battery, and an arithmetic circuit in the peak timer for determining a function of an elapsed time and a value of a charging rate. The arithmetic circuit of the peak-timer determines an elapsed time value of the peak-timer as a function of an elapsed time value of the total-timer and a value of a charging rate. The elapsed time value of the peak-timer is initially set at substantially the same time as an initial setting of a value of the total-timer. The peak-timer is started at a predetermined elapsed time after starting of a rapid charging operation.

Abstract: The present invention relates to a device for detecting whether a battery is connected to an electric charger or the battery is disconnected therefrom. This invention is simple in construction, and can effectively carry out the operation thereof. The device of this invention includes a heat sensitive element connected through a temperature detecting line to a data processor and a reference voltage source connected to the end of the heat sensitive element. After at least one battery is connected to the device and an electric charging into the battery is completed, the battery is removed, whereby a data processor detects the resulting voltage change through the temperature detecting line similarly operating as a voltage detecting line.