GB1097451A - Improvements relating to apparatus responsive to battery voltage - Google Patents

Abstract

1,097,451. Battery charging systems. D.P. BATTERY CO. Ltd. June 10, 1965 [March 11, 1964], No. 10331/64. Heading H2H. The charging current to a battery is controlled in dependence of rate of change of battery voltage. The charging current is arranged in three stages. In the first, the output of a bridge 23-26 is applied to capacitor 30 which is periodically connected through contacts 9/1a, 9/1b operated by a timer 9 in a cycle of about five minutes, to the input of a D.C. amplifier 32. When a Zener diode 28 breaks down on the battery voltage rising to say 2.3 volts per cell the bridge output is reversed and the amplifier 32 operates a relay 1 which is held by standing current until de-energized by timer contacts 9/2. Operation of relay 1 energizes a relay 3 and hence a relay 6 which initiates stage 2. Capacitor 30 is again periodically connected to the amplifier in series with another capacitor 31 which is charged after a number of cycles to approximately the voltage of the capacitor 30 on the previous cycle. On the next occasion the relay 1 is operated through timer contacts closing, the relay 4 is operated and held through coil Y, relay 8 also being maintained energized through contacts 4/2. So long as the battery voltage continues to rise the relay 1 will be energized each timer cycle, but when the change of voltage is insufficient to cause the relay 1 to be energized the relay 4 is released by the opening of timer contacts 9/4 hence the next time contacts 9/3 open, the relay 8 is released, contacts 8/2 breaking the charging supply circuit, and contacts 8/1 energizing relay 5 which is held through coil Y and contacts 5/1. Contacts 5/3 change the bridge series resistance from 21 to 22 and contacts 5/4, 5/5 reverse the input to the capacitor 30. Contacts 5/2 opening releases relay 6 hence contacts 6/1 shunts capacitor 31 and reconnects the capacitor 30 directly to the amplifier input. The resistor 22 passes an increased current through the bridge so that the Zener diode 28 breaks down at a lower battery voltage. When the battery voltage drops te say 2.2 volts per cell the Zener ceases to conduct hence the next time contacts 9/1A, 9/1B change over, relays 1, 4 and 8 are energized until broken by contacts 9/4, after say four minutes, after which the cycle is repeated when the battery voltage again falls. If the battery is disconnected a potential divider 36 and Zener diode 38 causes a transistor 37 to conduct energizing a relay 2 and disconnecting the supply through contacts 2/1 and relay 8. In an alternative arrangement the capacitors are eliminated and the resistance 22 is replaced by a motor driven rheostat which is advanced each time the relay 1 is operated. The circuit may be modified by replacing the relay 1 by a volt meter which gives an indication of rate of change of voltage. Alternatively the amplifier output may be connected to a null reading potentiometer or to a computer giving a continuous indication of battery performance.