Non-isolated thermally responsive battery charger

摘要

A non-isolated battery charger for direct connection to an AC source provides rectified DC current to the battery being charged. A thermostat in a heat conducting relationship with the battery senses battery temperature and discontinues the charging current when the temperature of the battery rises after attaining full charge. In one form of the invention, a trickle charge path is provided to the battery to maintain its charge state after the full charge has been attained. The trickle charge path is provided by an impedance shunting the thermostat and is operative as a current path when the thermostat is in its open condition. The trickle charge path can be a resistor where the thermostat is in the DC part of the charger circuit or a capacitor where the thermostat is in the AC part of the charge circuit. In another form of the invention, a latching function is performed by a pair of thermostats so that the charger circuit is 'latched' into is trickle charge operating state after the attainment of a full charge condition to prevent undesired cycling of the charge current between the full charge and trickle charge conditions. A switching circuit is provided by which the charging current and energy stored in the battery can be provided to a load so that the charger circuit can function as a supplemental power supply as well as a battery charger.