Method and apparatus for monitoring batttery capacity with charge control
First Claim
1. A battery charge controller for controlling the operation of delivering charge to a battery from a charger, comprising:
- a charging device operating at a defined charge rate to selectively determine the rate of the charging operation of the battery from the charger;
a battery capacity indicator for providing a charge state of the battery corresponding to the amount of charge stored in the battery relative to a capacity value for the battery, the capacity value indicative of the total charge that can be stored in the battery;
a charge control circuit for determining said defined charge rate, said charge control circuit operable to vary said defined charge rate as a function of said charge state in accordance with predetermined criteria, said predetermined criteria requiring said defined charge rate to be at a first charge rate when said charge state is less than a value substantially equal to said capacity value, and requires said defined charge rate to be at a second and lower charge rate after said charge state has reached a value not substantially less than said capacity value, said charge control circuit operating at said second charge rate for a predetermined amount of time during which said charge state has reached a value not substantially less than said capacity value; and
a capacity determining circuit for determining said capacity value, said capacity determining circuit having;
a register for storing a charge state value indicative of said charge state,a charge monitor for measuring charge input to the battery, said charge monitor incrementing said charge state value when charge is delivered to the battery,said incrementing operation of said charge monitor inhibited when said charge state value is substantially equal to said capacity value such that said charge state does not increase substantially above said capacity value,a capacity determining device for determining said capacity value by measuring a discharge operation of the battery from a predetermined charge state to a fully discharged state, andsaid charge control circuit when operating at said second charge rate for said predetermined amount of time operable to increase said predetermined charge state such that a new capacity value can be generated by said capacity determining device upon a later discharge operation to a fully discharged state.
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Accused Products
Abstract
A battery detect circuit (32) is connected to the battery with the current input to the battery and extracted from the battery measured with a sense resistor (50) and then converted to charge and discharge pulses with a V/F converter (52). A microcontroller (64) is operable to increment a Nominal Available Charge (NAC) register (180) during a charge operation, and to increment a Discharge Count Register (DCR) (184) during a discharge operation. The NAC register (180) indicates the available charge, which value is output to a display (34). The maximum value to which the NAC value can rise is limited by a value stored in the last measured discharge register (182). This value represents the value stored in the DCR (184) whenever the battery is discharged from an apparent full state to a fully discharged state. This results in a qualified transfer to the LMD register (182) such that no knowledge of the actual battery charge is necessary. The charge rate is varied as both a function of temperature, voltage and also of the state of charge. A fast charge rate is initiated when the charge state is above a predetermined low voltage threshold and less than full. When the charge state reaches a level within approximately 80% of full charge, the charge rate is reduced. At full capacity, the charge rate is further reduced to a top off charge rate which continues for approximately two hours. If the temperature falls below a predetermined low temperature threshold, the charge rate is again reduced to a safe, slow, effective rate. Trickle charge is provided to replenish charge adaptively in accordance with a self-discharge counter. The trickle charge operates to momentarily pulse the battery (10) at a predetermined charge rate.
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Citations
15 Claims
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1. A battery charge controller for controlling the operation of delivering charge to a battery from a charger, comprising:
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a charging device operating at a defined charge rate to selectively determine the rate of the charging operation of the battery from the charger; a battery capacity indicator for providing a charge state of the battery corresponding to the amount of charge stored in the battery relative to a capacity value for the battery, the capacity value indicative of the total charge that can be stored in the battery; a charge control circuit for determining said defined charge rate, said charge control circuit operable to vary said defined charge rate as a function of said charge state in accordance with predetermined criteria, said predetermined criteria requiring said defined charge rate to be at a first charge rate when said charge state is less than a value substantially equal to said capacity value, and requires said defined charge rate to be at a second and lower charge rate after said charge state has reached a value not substantially less than said capacity value, said charge control circuit operating at said second charge rate for a predetermined amount of time during which said charge state has reached a value not substantially less than said capacity value; and a capacity determining circuit for determining said capacity value, said capacity determining circuit having; a register for storing a charge state value indicative of said charge state, a charge monitor for measuring charge input to the battery, said charge monitor incrementing said charge state value when charge is delivered to the battery, said incrementing operation of said charge monitor inhibited when said charge state value is substantially equal to said capacity value such that said charge state does not increase substantially above said capacity value, a capacity determining device for determining said capacity value by measuring a discharge operation of the battery from a predetermined charge state to a fully discharged state, and said charge control circuit when operating at said second charge rate for said predetermined amount of time operable to increase said predetermined charge state such that a new capacity value can be generated by said capacity determining device upon a later discharge operation to a fully discharged state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for controlling the operation of delivering charge to a battery from a charger, comprising the steps of:
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providing a charge control circuit to vary the rate at which charge is input to the battery; determining a charge state of the battery relative to a capacity value for the battery, the charge state corresponding to the amount of charge stored in the battery and the capacity value indicative of the total charge that can be stored in the battery; varying the charge rate of the charge control circuit to a defined charge rate, the defined charge rate being a function of the charge state of the battery that varies in accordance with predetermined criteria, the defined charge rate wherein the charge rate is disposed at a first charge rate when the charge state is less than the capacity value and then disposes the charge rate at a second and lower charge rate when the charge state is determined to be substantially not less than the capacity value, the second charge state operated at for a predetermined amount of time that the charge state is determined to be substantially not less than the capacity value; and determining the capacity value, comprising the steps of; providing a register for storing a charge state value that indicates the charge state, monitoring the charge provided to the battery from the charger and incrementing the charge state value in the register during a charging operation, the step of incrementing inhibited when the charge state value is substantially equal to the capacity value, measuring a discharge operation of the battery from a predetermined charge state to a fully discharged state to provide the capacity value, and the step of operating the charge control circuit at the second charge rate for the predetermined amount of time operable to increase the predetermined charge state such that a fully discharging operation at a later time will vary the capacity value to a new capacity value. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification