GB1499175A - Motor vehicle battery charging system - Google Patents

Abstract

1499175 Battery charging systems DUCELLIER ET CIE 11 April 1975 [24 April 1974] 14917/75 Heading H2H A motor vehicle battery charging system includes an indicating lamp, which may be a light emitting diode, which is illuminated under two conditions which are when the battery charging voltage is below a first predetermined value and when the charging voltage is above a second, higher, predetermined voltage. Closure of an ignition switch 14 causes breakdown of a zener diode 30 and with an alternating voltage generated at the alternator terminal 13, the base potential of a transistor 28 is such that the transistor is conductive which causes a second transistor 19 to become conductive to illuminate an incandescent lamp 17 to indicate that the output voltage of the alternator is insufficient to charge a battery 12. As the speed of the alternator increases, the output voltage thereof increases until it reaches a value at the terminal 13 which causes transistor 28 to become non- conductive and hence transistor 19 also becomes non-conductive so extinguishing the lamp 17. If, due to a fault condition, the voltage applied to the battery becomes excessive, a zener diode 22 breaks down whereupon the transistor 19 again becomes conductive to re-illuminate the lamp 17 to indicate the existence of the fault condition. In other embodiments the lamp 17 may be replaced by a light emitting diode connected in parallel with the transistor 19 or a third transistor may be used, one of which is controlled by the output from the exciter 15.