TRANSISTOR CONTROLLED BATTERY CHARGER

1,194,242. Battery charging systems. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 9 June, 1967 [9 June, 1966; 17 Aug., 1966 (2)], No. 26780/67. Heading H2H. A battery charging circuit comprises voltage dividing resistors R1, R2 connected at the midpoint 4 to the base of a transistor TR1 forming with a transistor TR2 a Schmitt trigger circuit controlling a current amplifying transistor TR3. The circuit is arranged so that when the battery reaches a determined voltage, just short of the gassing point, the potential at point 4 relative to the conductors 3 causes TR1 to conduct and TR2, TR3 to block, but as the battery voltage falls this state is reversed and charging proceeds in a series of small intervals of decreasing current magnitude (see Fig. 3, not shown). In a modified circuit, Fig. 6 (not shown), a load may be alternatively supplied through a switch SW1-5. In position a the load voltage, as measured across C2, VR is maintained constant by transistor TR3. On failure of the supply the battery supplies the load in an uncontrolled manner through a transistor TR6 switched to its conductive state. The battery is not charged through TR6 due to its unidirectional properties. When the battery voltage falls to a determined discharge value, transistors TR4-6 block and this circuit must be reset, but in a modification, Fig. 9 (not shown), when the battery voltage recovers the circuit is again supplied until the battery voltage falls again. In switch position b the load is disconnected and the circuit is reconnected to charge the battery in a manner as described in connection with Fig. 1A. A number of other arrangements are described in the Specification.