GB1356609A - Circuit for rapid or boost charging accumulators - Google Patents

Abstract

1356609 Charging batteries VARTA AG 10 Dec 1971 [11 Dec 1970] 57556/71 Heading H2H A circuit for rapidly charging a battery from a source of pulsating voltage comprises a switch between the voltage source and the positive battery terminal, a two-state control circuit being provided to control the operation of the switch so as to terminate charging of the battery when the battery is fully charged. The source of pulsating voltage may be unsmoothed rectified A.C., either full or half wave rectified. A battery (not shown) is connected to terminals +, -, and is arranged to be charged from a pulsating D.C. source, derived from the unsmoothed output of a bridge rectifier, over a thyristor T1, Whilst the state of charge of the battery is below a predetermined value the potential tapped off a potentiometer P1 is such that a control circuit including transistors T2, T3, T4 assumes a first state in which all the transistors are non- conductive. With the control circuit in this state firing pulses for the thyristor T1 are derived by means of a resistor R2 and diode D2 with the result that the thyristor fires early in each half wave of the pulsating D.C. supply, the battery then receiving charging current whenever the instantaneous magnitude of the pulsating voltage exceeds that of the battery. As the charging of the battery proceeds and reaches a predetermined value, the potential derived from the potentiometer P1 becomes sufficient to fire the transistors T2, T3, T4 to place the control circuit in its second state. The firing of transistor T2 places the control electrode of the thyristor T1 at the negative potential of the battery thus inhibiting firing of the thyristor to terminate the charging of the battery. The control circuit may be overridden by manual operation of a switch Ta. Trickle charging may be obtained by means of a resistor R8 and diode D3 in parallel with the thyristor T1. A battery discharge circuit may be incorporated if required which circuit comprises a capacitor C2 and thyristor T6 which is triggered by a transistor T7 such that whenever the control circuit is in its first state with the transistors non- conducting the thyristor T6 is rendered conductive to discharge the battery except that when the battery has attained its predetermined charge the thyristor T6 remains cut off.