Battery charger with automatic cut=out at full charge - monitors charging voltage to control supplied charging current using reference obtained from battery terminals

摘要

The charger (1) is used to charge a battery (11) which exhibits a max. charging voltage slightly before it is fully charged, this voltage subsequently decreasing until full battery charge is obtained. The charger (1) has a store (5) reacting to the max. charging voltage being obtained to memorise a voltage which has a given relationship to the charging voltage characteristic. The stored value is fed to one input of a comparator (62) also receiving the output of a voltage monitor (4) across the battery terminals and providing an output controlling a cut-out circuit (2) for disconnecting the charger (1) at full charge. The charger allows the battery to be fully charged instead of being disconnected at the max. charging voltage. By obtaining the reference voltage from the voltage across the battery terminals temp. variations do not effect the correct cut-off point.