Hysteresis type battery charger having output short circuit protection
First Claim
1. A storage battery charging apparatus comprising:
- an input terminal to be connected to a source of electrical energy;
an output terminal to be connected to a storage battery;
first means including a resistance divider circuit for monitoring a voltage applied to said output terminal by said battery;
a first reference voltage source;
comparator means responsive to said first reference voltage source and said battery voltage monitoring means for generating a comparison signal;
pass means connected between said input and output terminals and responsive to said comparison signal for applying a high charging rate current to the storage battery when the battery voltage measured by said monitoring means is below a first predetermined value and for supplying a trickle charging current to said storage battery when the battery voltage measured by said monitoring means is above a second predetermined value;
first and second light emitting diodes (LEDs);
first means responsive to said high charging rate current for energizing said first LED to display a high charging rate mode of operation;
second means responsive to said trickle charging rate current for energizing said second LED to display a trickle charging rate mode of operation;
current foldback control means for limiting the magnitude of charging current applied to said output terminal during excessive charging current demand, e.g., output short circuit, to less than that of said high charging rate current, said current foldback control means including said second LED connected in circuit with said pass means for reducing conductivity of said pass means during said excessive current demand.
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Accused Products
Abstract
A hysteresis type battery charger includes a circuit for monitoring battery voltage and in response controlling a pass transistor to supply charging current to a battery. When the battery voltage is below a first predetermined value, high charging rate current is supplied to the battery; when the battery voltage is above a second predetermined value, the battery is supplied with trickle charging current. First and second light emitting diodes (LEDs) are selectively energized to indicate whether the battery is receiving high charging rate current or trickle charging current. The second LED is connected in circuit with the pass transistor to provide charging current foldback during excessive current demand, e.g., short circuit. The battery charger includes a low battery monitor that is energized when the expected battery lifetime is at a predetermined value, e.g., one hour. Temperature compensating networks, are provided whereby battery charging and low battery monitor operating characteristics are substantially temperature independent.
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Citations
12 Claims
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1. A storage battery charging apparatus comprising:
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an input terminal to be connected to a source of electrical energy; an output terminal to be connected to a storage battery; first means including a resistance divider circuit for monitoring a voltage applied to said output terminal by said battery; a first reference voltage source; comparator means responsive to said first reference voltage source and said battery voltage monitoring means for generating a comparison signal; pass means connected between said input and output terminals and responsive to said comparison signal for applying a high charging rate current to the storage battery when the battery voltage measured by said monitoring means is below a first predetermined value and for supplying a trickle charging current to said storage battery when the battery voltage measured by said monitoring means is above a second predetermined value; first and second light emitting diodes (LEDs); first means responsive to said high charging rate current for energizing said first LED to display a high charging rate mode of operation; second means responsive to said trickle charging rate current for energizing said second LED to display a trickle charging rate mode of operation; current foldback control means for limiting the magnitude of charging current applied to said output terminal during excessive charging current demand, e.g., output short circuit, to less than that of said high charging rate current, said current foldback control means including said second LED connected in circuit with said pass means for reducing conductivity of said pass means during said excessive current demand. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12)
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2. A storage battery charging apparatus, comprising:
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an input terminal to be connected to a source of electrical energy; an output terminal to be connected to a storage battery; first means for monitoring battery voltage; pass means connected between said input and output terminals for supplying charging current to said battery selectively at a high charging rate in response to a relatively low monitored battery voltage and a substantially lower, trickle charging rate in response to a monitored battery voltage corresponding generally to a fully charged condition; a first display comprising a first light emitting diode (LED) energized during high current rate charging of said battery; a second display comprising a second LED energized during trickle current rate charging of said battery; and current foldback means for limiting the magnitude of charging current applied to said output terminal to less than that of said high charging rate current in response to excessive charging current demand, e.g., output short circuit, said current foldback means including said second LED connected to reduce conductivity of said pass means during said excessive current demand. - View Dependent Claims (3)
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Specification