GB1232401A - - Google Patents

Abstract

1,232,401. Battery charging circuits. ALKALINE BATTERIES Ltd. 6 March, 1969 [9 Jan., 1968], No. 1261/68. Heading H2H. Battery, particularly in an emergency standby system, is first given a main charge which is terminated when its voltage reaches a predetermined level. This is followed by a further charge, the duration of which depends on that of the main charge. In the circuit of Fig. 1, a main battery 14 is charged from a supply 12 by way of a rectifier 11 and the normally closed contacts 16 of a voltage-sensitive switch 17, 18. At the same time, an auxiliary battery or cell 21 is also charged through a resistor 22. When the voltage of the main battery reaches a certain value, the switch 17 will operate to open contacts 16 and also to close a contact 20 which connects the auxiliary battery 21 in series with a relay 25 which now operates to close contacts 26 and so reconnect the main battery to the supply. Thus, further charging of the main battery will continue until the auxiliary battery is sufficiently discharged, when the contacts 26 will open and the main battery will be disconnected. The time taken for the auxiliary battery to discharge depends on the period for which it was charged, which is the same as the duration of the main charge for the main battery. A high resistance 29 may be connected directly across the contacts 16 and 26 to maintain a continuous trickle charge to the main battery. In an alternative embodiment, Fig. 2 (not shown), charging is controlled by a transistor trigger circuit.