Battery charger capable of evaluating battery charge state
First Claim
1. A method for evaluating the quantity of energy stored in a charged battery, said method comprising the steps of:
- tieing opposed terminals of the battery across a load resistor and measuring the voltage across the load resistor to produce a measured voltage-at-load of the battery;
measuring the temperature of the battery;
determining a temperature coefficient based on the temperature of the battery and a first set of reference data;
determining an adjusted voltage-at-load based on the measured voltage-at-load and the temperature coefficient; and
determining the stored energy in the battery based on the adjusted voltage-at-load and a second set of reference data.
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Accused Products
Abstract
A battery charger (20) for charging batteries that evaluates the post-charge state of the batteries. A load resistor (70) and a temperature sensor (286) are associated with each battery. After the charging of the battery, a processor (124) receives signals indicating the voltage-at-load of the battery when it is connected to the load resistor and the battery temperature. A memory (282) internal to the battery stores historical voltage-at-load data for the battery. The processor based, the voltage-at-load, the battery temperature and the historical voltage-at-load data for the battery determines an average voltage-at-load for the battery. Based on the average voltage-at-load and data specific to that battery, the processor determines the charge state of the battery. Data representative of the charge state is presented on a display (30) integral with the charger. Data useful for determining both the average voltage-at-load and the charge state for the battery are found in a memory (70) in a module that is removably attached to the charger or in the battery memory (282).
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Citations
34 Claims
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1. A method for evaluating the quantity of energy stored in a charged battery, said method comprising the steps of:
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tieing opposed terminals of the battery across a load resistor and measuring the voltage across the load resistor to produce a measured voltage-at-load of the battery; measuring the temperature of the battery; determining a temperature coefficient based on the temperature of the battery and a first set of reference data; determining an adjusted voltage-at-load based on the measured voltage-at-load and the temperature coefficient; and determining the stored energy in the battery based on the adjusted voltage-at-load and a second set of reference data. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of charging a battery, said method comprising the steps of:
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applying a charging current to the battery; after said step of applying the charging current to the battery is completed, connecting opposed terminals of the battery across a load resistor; measuring the voltage across the load resistor to produce a measured voltage-at-load for the battery; determining the temperature of the battery; determining the stored energy in the battery based on the measured voltage-at-load and the temperature of the battery; and displaying an indication of the stored energy in the battery. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A charger for providing energization current to a battery, said charger having:
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a base unit having a display; a current source disposed in said base unit configured to be connected to the battery for supplying a charging current to the battery; a load resistor and a switch, said switch being connected to the battery and said load resistor for selectively connecting the battery across said load resistor; and a processor unit disposed in said base unit, said processor unit being connected to; said current source for regulating the application of current by said current source to the battery; said switch for selectively actuating said switch to selectively tie the battery across said load resistor; a temperature sensor associated with the battery; said load resistor for receiving a signal representative of the voltage across the load resistor; and to said display, and said processor unit;
actuates said switch to tie the battery across said load resistor;
receives from the load resistor a signal representative of the voltage across the load resistor;
receives from the temperature sensor a signal representative of the temperature of the battery;
determines the stored energy of the battery based on the voltage across said load resistor and the temperature of the battery; and
causes said display to present an indication of the stored energy of the battery. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A charger for charging a rechargeable battery, said charger including:
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a base unit, said base unit having a socket for receiving the battery; a current source disposed in said base unit for applying a charging current to the battery; and a processor disposed in said base unit, said processor being connected to; said current source; a load resistor and a switch that selectively connects the battery across the load resistor; a temperature sensor that monitors the temperature of the battery; and a memory that is removably attached to said base unit, said memory storing reference data, and said processor; reads the reference data in the memory; controls said current source to regulate the charging of the battery by said current source; selectively actuates the switch to selectively tie the battery across the load resistor; determines from the load resistor a measured voltage-at-load for the battery; determines an adjusted voltage-at-load for the battery based on the measured voltage-at-load, the temperature of the battery as indicated by the temperature sensor and the reference data read from the memory; and determines the stored energy of the battery based on the adjusted voltage-at-load for the battery and the reference data read from the memory. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A module for use with a battery charger, said module including:
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a shell defining a socket for receiving a battery; a securement mechanism attached to said shell, said securement mechanism configured to releasably fit said shell to the battery charger; a plurality of conductive members attached to said shell for establishing a conductive path between the battery charger and the battery over which a charging current is applied to the battery; and
over which the voltage across the battery can be measured; anda memory unit secured to said shell;
said memory unit storing reference data readable by the battery charger from which, for a given voltage-at-load of the battery, and a given temperature the stored energy of the battery can be determined. - View Dependent Claims (28, 29)
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30. A rechargeable battery pack comprising:
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a housing; at least one rechargeable cell disposed in said housing; a first set of terminals attached to said housing that are attached to said at least one rechargeable cell, wherein energy is applied to said at least one rechargeable cell through said first set of terminals and current is drawn from said at least one rechargeable cell through said first set of terminals; a temperature sensor disposed in said housing from providing a signal representative of the temperature of said battery; a memory disposed in said housing, said memory containing reference data readable by a processor from which, for a given voltage-at-load of said at least one rechargeable cell and for a given battery temperature, the energy stored in said at least one rechargeable cell can be determined; and a second set of terminals attached to said housing and connected to said memory wherein the reference data in the memory are read through said second set of terminals. - View Dependent Claims (31, 32, 33, 34)
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Specification