IE35976B1 - Battery charging apparatus - Google Patents

Abstract

1370301 Battery charging systems ELECTRIC POWER STORAGE Ltd 13 Jan 1972 [14 Jan 1971] 1822/71 Heading H2H Battery charging apparatus wherein means are provided for temporarily interrupting the charging current for periods called open-circuit intervals the duration of each of which depends upon the fall in the battery voltage during the open-circuit interval is provided with means responsive to the duration of the open-circuit intervals and which latter means comprise a capacitor which is alternately charged and discharged respectively during successive opencircuit intervals, the charged state of the capacitor having an initial predetermined value, further means being provided for detecting if the charge of the capacitor has failed to return to the initial predetermined value whereby to terminate at least a phase of the battery charging process. The capacitor is charged and discharged by way of a constant current device including a transistor and the initial predetermined value of the capacitor is a fully charged state. During the first open-circuit interval the capacitor discharges and during the second open-circuit interval the capacitor recharges, the charging rate being arranged to be slightly lower than the discharging rate. If during this second interval the state of charge does not return to the fully charged condition the charging process is modified so that the battery continues to be charged at a lower rate indefinitely. The means for detecting the voltage level of the capacitor charge includes a long tailed pair of transistor stages and a transistor switching device is incorporated in the apparatus to modify the charging process should any open-circuit interval exceed a maximum predetermined time. The invention in the present Specification is stated to be an improvement in, or modification of, that disclosed in Specification 1,233,186. [GB1370301A]