GB1399151A - Battery charging circuits - Google Patents

Abstract

1399151 Battery charging systems WESTINGHOUSE BRAKE & SIGNAL CO Ltd 3 Jan 1973 [14 Jan 1972] 1979/72 Heading H2H A battery charger circuit which normally supplies a predetermined charge comprises timing means and means responsive to the charge condition of the battery during an initial time period which will stop the continuation of the predetermined charge if this would result in overcharging. The charging circuit comprises input terminals LN which are connected to a bridge rectifier via inductances L1, L2 and L3. The timing circuit comprises unijunction transistor T1 which via latch T2, T3, is arranged to enable gate T4 for the initial period. If gassing cell voltage, or other condition during the interval indicates overcharging might occur a more negative signal, appears on lead B which, via transistors T4, T5, T6 and T7 causes relay RL2 to release which releases relay 52 remains the shunt from across coil L1, so slowing down the charging rate. The charger also comprises a main timing circuit (not shown) which at the end of a first period (longer than the initial interval) applies a signal on lead C which also, via transistor T5, causes L1 to the placed in the charging circuit regardless of the charged condition. If during this first period, gassing conditions occur, a signal on line E, via transistors T9, T10, T11, releases relay RL1 which releases relay S1 and removes the shunt across coil L3 thus reducing the charging rate. At the end of a second period, a signal on lead D via transistors T14, T15, releases relay RL3 to release relay 53 which treats the charging circuit via contact 53/1. If the battery is removed, Zener diode Z1, via transistors T12, T13 senses the change in voltage to release relay RL3 via transistors T14, T15, to break the charging circuit at 53/1.