GB1354491A - Battery charger - Google Patents

Abstract

1354491 Charging batteries SOC DES ACCUMULATEURS FIXES ET DE TRACTION 19 July 1971 [21 July 1970] 35375/70 Heading H2H A battery 19 is charged by means of a ballast capacitor 5 connected thereto by a rectifying bridge 2 across whose inputs is connected a coil 4 forming part of a relay which operates in response to the application of a voltage above a predetermined level to open contacts 3 and isolate the charging circuit from the A.C. mains. To charge the battery it is connected to the circuit and the contacts 3 are closed manually. Any attempt to close the contacts before connecting the battery or to disconnect the battery while it is being charged causes mains voltage to aappear across the terminals of the rectifier on open circuit: this voltage also appears across coil 4 in series with a capacitor 7 and the circuit is arranged so that this is sufficient to trip the relay and open the contacts 3. If the battery is of the type whose temperature increases rapidly at the end of the charging period (e.g. the fully sealed Ni-Cd type) then one or both of two thermostats 17, 18 operates to close a connection across the terminals of capacitor 7, causing the battery voltage to be applied to the relay coil 4. As before, this is sufficient to open the contacts and terminate the charging process. The ballast capacitor 5 may be replaced by a ballast resistor or inductor and capacitor 7 may be replaced by a resistor, or it may be omitted altogether (Fig. 2, not shown) when the thermostats are replaced by one which is arranged to open-circuit the charger if the battery temperature rises as above.