Battery charger for towed vehicles and the like

摘要

An electrical charging circuit for applying a controlled charge to a receiving device, such as a battery, and particularly such as a battery carried on a towed vehicle such as a trailer for actuating the trailer brakes during emergency situations such as unexpected disconnection from the towing vehicle, i.e., break-away. In a basic sense, the charging circuit includes a voltage potential-responsive element or component for sensing the charged level of the receiving device coupled to the circuit and enabling or disabling the circuit charging operation, together with a variable-conductance circuit component for producing a generally constant charging voltage output to the receiving device over a wide range of applied voltages but also operable to provide a first amount of current flow to the receiving device at a given applied voltage and temperature but a second a limited amount of current flow when the voltage across the charging circuit is sufficiently large. In its most preferred embodiment, the voltage responsive component may be a diode switch, and the variable-conductance circuit component may be a positive temperature coefficient (PTC) thermistor.