GB1161752A - Battery Charging Systems for use in Road Vehicles - Google Patents

Abstract

1,161,752. Automatic voltage control. JOSEPH LUCAS (INDUSTRIES) Ltd. Nov. 25, 1966 [Dec. 15, 1965; March 4, 1966], Nos. 53190/65 and 9512/66. 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 an output circuit connected directly across the battery and including transistor 16 and the field winding 15 of the generator, an output drive stage including transistor 17 which controls transistor 16, and an output voltage sensing stage 23, 24, 25, 26 which controls transistor 17, the output drive stage being connected across the battery in a series circuit including a switching transistor 22 controlled by the ignition switch 29 of the vehicle. In operation, when the ignition switch 29 is closed transistor 22 is turned on and the resulting current flow through resistor 21 and the base/emitter circuit of transistor 16 renders the latter conductive so that current also flows in the field winding 15; at the same time a warning lamp 32 is energized over a generator-controlled switch 31. When the output voltage has built up to a certain value the switch 31 moves to its alternative position, whereby lamp 32 is extinguished and transistor 22 is shortcircuited so that the voltage sensing chain 23, 24, 25 is connected directly across the battery terminals. The transistors 16, 17 then operate in known manner to maintain the output voltage at a constant value. The arrangement may include a temperative compensating thermistor (33) and such a modified circuit is described with reference to Fig. 2 (not shown). The generator may be an alternator with a rectified output.