Battery state of charge metering method and apparatus
First Claim
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1. A metering system for measuring and indicating the state of charge of an electrical storage battery comprising an oscillator and a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge, means for detecting decreases in state of charge in terms of decreases in battery terminal voltage under load and connected for providing resultant gating signals for gating pulses from said oscillator to said digital integrator, said digital integrator being operator in response to said pulses to change the numerical value stored therein in one direction as the battery is being discharged, means connected to said integrator and for deriving an analog output voltage signal representive of the numerical value stored in said integrator comprising switching means for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in a predetermined number of the binary stages of said digital integrator to provide an output voltage signal having an average voltage amplitude corresponding to the length of said pulses, said means for detecting decreases in state of charge in terms of decreases in battery terminal voltage including means for detecting the terminal voltage of the battery and for generating a function of said battery terminal voltage,means connected to receive said analog output voltage signal for generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the numerical value stored in said integrator,and means for comparing said last-named voltage functions as a basis for determining a battery discharge condition requiring a decrease in the state of charge indication stored by said integrator and operable to change the numerical value in said integrator,said means for detecting the terminal voltage of the battery being operable to generate a function of the battery terminal voltage which is a substantially proportional fraction of the terminal voltage,said means for generating a variable reference voltage signal comprising a resistor network which is operable to receive said integrator function generator signal and to also receive a substantially constant reference voltage signal and to generate said variable reference voltage signal as a combined function of said integrator analog output voltage signal and said constant reference voltage signal,said variable reference voltage signal being lowered as a function of said integrator analog output voltage signal as the numerical value stored in said integrator indicates progressively lower states of charge,said variable reference voltage generating means being operable to generate an offset substantially linear function of said integrator analog output voltage signal.
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Abstract
The system includes a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge. A switching circuit is provided for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in the integrator to provide a time based resultant indication of the stored binary digital value. A filtering means is included to provide a substantially smooth analog output voltage having an amplitude corresponding to the summation of the pulses.
The system preferably includes a delayed high voltage reset feature to set the integrator to a full charge state in response to voltage levels accompanying charging of the battery.
94 Citations
24 Claims
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1. A metering system for measuring and indicating the state of charge of an electrical storage battery comprising an oscillator and a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge, means for detecting decreases in state of charge in terms of decreases in battery terminal voltage under load and connected for providing resultant gating signals for gating pulses from said oscillator to said digital integrator, said digital integrator being operator in response to said pulses to change the numerical value stored therein in one direction as the battery is being discharged, means connected to said integrator and for deriving an analog output voltage signal representive of the numerical value stored in said integrator comprising switching means for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in a predetermined number of the binary stages of said digital integrator to provide an output voltage signal having an average voltage amplitude corresponding to the length of said pulses, said means for detecting decreases in state of charge in terms of decreases in battery terminal voltage including means for detecting the terminal voltage of the battery and for generating a function of said battery terminal voltage,
means connected to receive said analog output voltage signal for generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the numerical value stored in said integrator, and means for comparing said last-named voltage functions as a basis for determining a battery discharge condition requiring a decrease in the state of charge indication stored by said integrator and operable to change the numerical value in said integrator, said means for detecting the terminal voltage of the battery being operable to generate a function of the battery terminal voltage which is a substantially proportional fraction of the terminal voltage, said means for generating a variable reference voltage signal comprising a resistor network which is operable to receive said integrator function generator signal and to also receive a substantially constant reference voltage signal and to generate said variable reference voltage signal as a combined function of said integrator analog output voltage signal and said constant reference voltage signal, said variable reference voltage signal being lowered as a function of said integrator analog output voltage signal as the numerical value stored in said integrator indicates progressively lower states of charge, said variable reference voltage generating means being operable to generate an offset substantially linear function of said integrator analog output voltage signal.
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6. A metering system for measuring and indicating the state of charge of an electrical storage battery comprising an oscillator and a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge, means for detecting decreases in state of charge in terms of decreases in battery terminal voltage under load and connected for providing resultant gating signals for gating pulses from said oscillator to said digital integrator, said digital integrator being operable in response to said pulses to change the numerical value stored therein in one direction as the battery is being discharged, means connected to said integrator and for deriving an analog output voltage signal representative of the numerical value stored in said integrator comprising switching means for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in a predetermined number of the binary stages of said digital integrator to provide an output voltage signal having an average voltage amplitude corresponding to the length of said pulses, said means for detecting decreases in state of charge in terms of decreases in battery terminal voltage including means for detecting the terminal voltage of the battery and for generating a function of said battery terminal voltage,
means connected to receive said analog output voltage signal for generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the numerical value stored in said integrator, and means for comparing said last-named voltage functions as a basis for determining a battery discharge condition requiring a decrease in the state of charge indication stored by said integrator and operable to change the numerical value in said integrator, a voltage sequence responsive means operable in response to a voltage sequence including a loss of voltage to indicate disconnection of the battery followed by reestablishment of voltage to indicate reconnection of the battery, said voltage sequence responsive means including a timing means and a gating means, said voltage sequence responsive means being operable in response to said voltage sequence to enable said gating means for a limited time interval after a predetermined time delay through the operation of said timing means, means for detecting a terminal voltage of the battery which is above a threshold indicative of a charged state of the battery, said voltage threshold detecting means being connected to provide a second input to said gating means, said gating means being operable to provide an output in response to the concurrence of said two inputs, said output of said gating means being connected to reset said integrator to a value corresponding to a full state of charge.
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7. A metering system for measuring and indicating the state of charge of an electric storage battery comprising
a digital integrator to store a numerical value indicative of state of charge and operable to change the numerical value in one direction in response to detected decreases in state of charge as the battery is being discharged, an indicating means connected to receive signals indicative of the numerical value stored in said integrator and to provide a visual indication of that value, means for measuring the terminal voltage of the battery to detect a voltage which is elevated into the battery charging range, a timing means connected for operation in response to said elevated terminal voltage detecting means and operable to reset said integrator to a value corresponding to a full state of charge after the terminal voltage remains elevated into said battery charging range continuously for a predetermined interval of time.
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8. A metering system for measuring and indicating the state of charge of an electric storage battery comprising
a digital logic circuit unit which includes a digital integrator operable to store a numerical value in binary digital form which is indicative of state of charge of the battery, said digital integrator being operable to change the numerical value stored therein in one direction in response to detected decreases in state of charge as the battery is being discharged, said digital circuit unit including a digital clock controllably connectable to provide pulses to said digital integrator to change the numerical value stored therein when required, an indicating means connected to receive signals indicative of the numerical value stored in said integrator and to provide a visual indication of that value, a switching means and means for connecting power from the electric storage battery for which state of charge is being measured and indicated to said switching means, said switching means being operable to connect the power from the storage battery to said digital circuit, an auxiliary power source comprising a separate battery connected to said switching means, said switching means being operable upon disconnection of the electric storage battery being measured to switch said auxiliary power battery to supply standby power to said digital circuit to maintain the numerical value stored in said integrator, said digital circuit including a power down control circuit, said power down control circuit being connected and arranged to detect the presence or absence of voltage from the electric storage battery independent of said switching means, said power down control circuit being operable when a power down condition of the electric storage battery is detected to disable said digital clock to minimize the power drain from said auxiliary power battery.
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10. A metering system for measuring and indicating the state of charge of an electric storage battery, comprising a digital integrator including a digital counter to store a numerical value indicative of state of charge and operable to change count value in one direction at a predetermined maximum counting rate in response to detected decreases in state of charge as the battery is being discharged, means selectively operable to cause said counter to change count in said direction at a faster rate in response to detected decreases in state of charge, said metering system including a digital clock, said means selectively operable to cause said counter to change count at a faster rate including a frequency divider counter arranged in circuit between said clock and said integrator counter which provides frequency divided clocking pulses to said integrator counter to normally maintain the counting rate of said integrator counter at said predetermined maximum counting rate, and said selectively operable means also including means for receiving a separate rate control logic input signal and including gating means connected between said frequency divider counter and said integrator counter, said rate control logic means and said gating means being operable to bypass said frequency divider to supply undivided clock pulses to said integrator counter for operation at a faster rate.
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11. A metering system for measuring and indicating the state of charge of an electrical storage battery comprising an integrated digital circuit unit including an oscillator and a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge, means for detecting decreases in state of charge in terms of decreases in battery terminal voltage under load and connected for providing resultant gating signals for gating pulses from said oscillator to said digital integrator, said digital integrator being operable in response to said pulses to change the numerical value stored therein in one direction as the battery is being discharged, means connected to said integrator and incorporated in said integrated circuit for deriving an analog output voltage signal representative of the numerical value stored in said integrator comprising switching means for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in a predetermined number of the binary stages of said digital integrator to provide an output voltage signal having an average voltage amplitude corresponding to the length of said pulses, said means for detecting decreases in state of charge in terms of decreases in battery terminal voltage including means for detecting the terminal voltage of the battery and for generating a function of said battery terminal voltage,
means connected to receive said analog output voltage signal for generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the numerical value stored in said integrator, and means for comparing said last-named voltage functions as a basis for determining a battery discharge condition requiring a decrease in the state of charge indication stored by said integrator and operable to change the numerical value in said integrator, said integrated digital circuit unit including a digital one out of N decoder connected to said integrator and having N outputs to indicate different numerical values stored in said integrator in terms of output signals appearing one at a time on different ones of said N outputs, a linearly arranged array of N discrete fixed-position indicating devices connected to said integrated digital circuit unit to receive the respective N outputs of said decoder, each of said indicating devices being operable to provide a visual indication in response to an output signal from the associated output of said decoder, the connections of said decoder outputs to said array and the operation of said one out N decoder being such as to provide for energization of one of said indicating devices at a time to indicate different values of state of charge in terms of different numbers stored in said digital integrator, said different values being indicated in a progression along said linear array to thereby simulate the movement of a galvanic meter pointer in moving from one end of said array for indicating a full state of charge to the other end of said array for indicating a depleted state of charge.
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21. A metering system for measuring and indicating the state of charge of an electrical storage battery comprising an oscillator and a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge, means for detecting decreases in state of charge in terms of decreases in battery terminal voltage under load and connected for providing resultant gating signals for gating pulses from said oscillator to said digital integrator, said digital integrator being operable in response to said pulses to change the numerical value stored therein in one direction as the battery is being discharged, means connected to said integrator and for deriving an analog output voltage signal representative of the numerical value stored in said integrator comprising switching means for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in a predetermined number of the binary stages of said digital integrator to provide an output voltage signal having an average voltage amplitude corresponding to the length of said pulses, said means for detecting decreases in state of charge in terms of decreases in battery terminal voltage including means for detecting the terminal voltage of the battery and for generating a function of said battery terminal voltage,
means connected to receive said analog output voltage signal for generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the numerical value stored in said integrator, and means for comparing said last-named voltage functions as a basis for determining a battery discharge condition requiring a decrease in the state of charge indication stored by said integrator and operable to change the numerical value in said integrator, said metering system being automatically adjustable for operation with batteries having either one of a first or a second predetermined number of cells and having two respectively corresponding different rated voltages, said means for detecting the battery terminal voltage and for generating a function of said terminal voltage comprising a voltage divider for generating a voltage which is a predetermined fraction of said battery terminal voltage, said voltage divider being operable to normally provide the desired fraction of said terminal voltage at a predetermined range of values for a battery having said first predetermined number of cells, said system including means for detecting a battery '"'"' terminal voltage which is beyond a predetermined voltage threshold indicative of the presence of a range of battery terminal voltages typifying said second predetermined number of battery cells, and a range switching circuit connected to said battery terminal voltage threshold device for operation when said second known number of battery cells is detected to switch another impedence into said voltage divider to recalibrate said voltage divider to provide the desired range of voltage functions to said voltage comparison means with said second known number of battery cells, said second known number of battery cells being greater than said first known number of battery cells so that the battery terminal voltage is higher with said second known number of battery cells and said battery terminal voltage threshold device is therefore operable for voltage above a threshold indicating the presence of said second known number of battery cells, a voltage sequence responsive means operable in response to a voltage sequence including a loss of voltage to indicate disconnection of the battery followed by reestablishment of voltage to indicate reconnection of the battery, said voltage sequence responsive means including a timing means and a gating means, said voltage sequence responsive means being operable in response to said voltage sequence to enable said gating means for a limited time interval after a first predetermined time delay through the operation of said timing means, means connected to said voltage divider for detecting a terminal voltage of the battery in terms of the output from said voltage divider which is above a threshold indicative of a charged state of the battery, said voltage threshold detecting means being connected to provide a second input to said gating means, said gating means being operable to provide an output in response to the concurrence of said two inputs, said output of said gating means being connected to reset said integrator to a value corresponding to a full state of charge, said range switching circuit including a second timing means for delaying the operation of said range switching circuit for a second predetermined time delay interval to avoid false operation in response to initial switching transients, said second predetermined time delay being substantially less than said first predetermined time delay to insure that said range switching circuit is operable to recalibrate said voltage divider for said second known number of battery cells prior to the resetting of said integrator by said gating means to avoid a false operation of said gating means in mistakenly detecting the higher voltage available from said second known number of battery cells as indicative of a battery having said first predetermined number of cells in a charged state.
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23. A method for measuring and indicating the state of charge of an electric storage battery comprising storing a numerical value in a binary digital form which is indicative of state of charge,
changing the stored numerical value in one direction in response to detected decreases in state of charge as the battery is being discharged, deriving an analog output voltage signal proportional to the numerical stored value in said integrator by generating a series of voltage pulses on a single output line with each pulse corresponding in length to the stored binary digital value to provide a time-based resultant indication of the stored binary digital value, filtering the pulses to provide a substantially smooth analog output voltage signal having a voltage amplitude corresponding to the duration of said pulses, detecting the terminal voltage of the battery and generating a function of said battery terminal voltage, generating a variable reference voltage signal which is a function of said analog output voltage signal representative of the stored numerical value, comparing said last-named voltage functions as a basis for determining a battery condition requiring a change in the stored numerical value state of charge indication, and wherein the generated function of the battery terminal voltage is a substantially proportional fraction of the terminal voltage, and wherein the variable reference voltage signal is generated as a combined function of said analog output voltage signal and a constant reference voltage signal, the variable reference voltage signal being lowered as a function of said analog output voltage signal as the numerical value stored indicates progressively lower stages of charge, and wherein said variable reference voltage signal is generated as an offset substantially linear function of said analog output voltage signal.
Specification
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Current AssigneeCurtis Instruments Incorporated
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Original AssigneeCurtis Instruments Incorporated
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InventorsFinger, Eugene P.
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Primary Examiner(s)Levy, Stewart J.
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Assistant Examiner(s)BAKER, STEPHEN M
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Application NumberUS06/321,671Time in Patent Office1,499 DaysField of Search324/426, 324/427, 324/428, 324/430, 324/429, 324/433, 324/435, 324/436, 340/636, 340/347 DA, 320/39, 320/48US Class Current324/433CPC Class CodesG01R 19/16542 for batteries charge condit...G01R 31/3646 for indicating electrical c...G01R 31/3648 comprising digital calculat...
