Battery chargers with polarity control means

Claim 1

IN A BATTERY CHARGER, THE COMBINATION OF A SOURCE OF CHARGING POTENTIAL; A PAIR OF CHARGING LEADS CONNECTED TO SAID SOURCE AND EACH PROVIDED WITH A CONNECTOR FOR CONNECTION TO A TERMINAL OF THE BATTERY TO BE CHARGED; AND AUTOMATIC MEANS FOR ACTIVATING THE CHARGER ONLY WHEN SAID CONNECTORS ARE CONNECTED TO A BATTERY WITH THAT POLARITY PROPER FOR CHARGING OF THE BATTERY, SAID AUTOMATIC MEANS COMPRISING A CONTACTOR HAVING CONTACTS AND A WINDING FOR ACTUATING SAID CONTACTS, SAID CONTACTS BEING CONNECTED IN ONE OF SAID LEADS; FIRST CIRCUIT MEANS CONNECTING SAID WINDING TO SAID SOURCE; A TRANSISTOR OPERATIVELY CONNECTED TO ESTABLISH ENERGIZATION OF SAID WINDING VIA SAID FIRST CIRCUIT MEANS WHEN SAID TRANSISTOR IS IN A GIVEN OPERATIVE STATE; AND SECOND CIRCUIT MEANS CONNECTED TO AT LEAST ONE OF SAID CONNECTORS AND SAID TRANSISTOR AND BEING OPERATIVE TO CONTROL THE OPERATIVE STATE OF SAID TRANSISTOR IN ACCORDANCE WITH THE POLARITY PRESENT AT THE CONNECTORS WHEN CONNECTED TO A BATTERY, SAID SECOND CIRCUIT MEANS INCLUDING A SERIALLY CONNECTED NON-LINEAR IMPEDANCE PROVIDING INCREASED RESISTANCE AS CURRENT FLOW IN SAID CIRCUIT MEANS TENDS TO INCREASE.