GB1175209A - Battery Charging Systems for use in Road Vehicles. - Google Patents

Abstract

1,175,209. Automatic voltage control. JOSEPH LUCAS (INDUSTRIES) Ltd. April 7, 1967 [April 25, 1966], No.52896/66. Divided out of 1,161,751. Heading G3R. A battery charging system for a road vehicle comprises a generator 14 for charging the battery 11 and a voltage regulator for the generator, the regulator having a sensing stage 15, 16, 17 which senses the battery voltage, and a control stage operable by the sensing stage for varying the current flow to the field winding 23 of the generator to regulate the output voltage thereof, the control stage being connected to the battery through the series circuit of a resistor 25, e.g. a warning lamp, and the ignition switch 26 of the vehicle, the said sensing stage being connected directly across the battery, i.e. not through the ignition switch, at least when the ignition switch is closed, and means being provided for effectively shortcircuiting the said series circuit when the generator produces an output. As shown in Fig. 1, the control stage may include a transistor 22 having its collector/emitter path in series with the field winding 23 and its base connected over a resistor 19 and a line 21 to the series circuit 25, 26, alternatively, the control stage may include a contact in the field circuit, the opening and closing of the contact being controlled by a voltage sensing coil Fig. 2, (not shown). The means for shortcircuiting the series circuit 25, 26 may comprise a switch operable by the generator output or, when the generator is constituted by an alternator with a rectified output, the means may comprise additional diodes 27 connecting the phase points of the alternator to the line 21 so that the potential on line 21 can reach that on line 12 when the generator produces an output. In operation, initial closure of the ignition switch 26 allows current to flow through the lamp 25 and the field winding 23; when the generator output has built up sufficiently the series circuit 25, 26 is effectively shortcircuited by the diodes 27 so that the lamp 25 is extinguished, the field current, under the control of the voltage regulator, then being supplied by way of the diodes 27.