Enhanced voltage-based fuel gauges and methods
DCFirst Claim
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1. A method of improving performance of a battery fuel gauge comprising:
- providing a voltage based fuel gauge that monitors a terminal voltage of a battery and determining the battery'"'"'s state of charge based on a battery model;
providing a coulomb counter to provide a measure of current into and out of the battery;
determining a first remaining charge in the battery using a product of a full capacity of the battery times the state of charge as determined by the voltage based fuel gauge;
determining a second remaining charge in the battery using a combination of the first remaining charge in the battery and the current into and out of the battery as provided by the coulomb counter, the current into and out of the battery dominating the determination of the second remaining charge in the battery except during low or zero currents; and
continually updating the second remaining charge by repeatedly subtracting a value responsive to the second remaining charge from the first remaining charge to repeatedly obtain an updated second remaining charge, the first remaining charge dominating the second remaining charge during low or zero currents.
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Abstract
Enhanced voltage-based fuel gauges and methods that increase the accuracy of voltage-based fuel gauges and allow the use of voltage-based fuel gauges to detect current, and particularly excessive current from a battery without the use of a sense resistor. When used with a coulomb counter, the outputs of a voltage-based fuel gauge and a coulomb counter may be combined in a manner that allows the combination to provide better performance that either alone may provide. Various embodiments and methods of operation are disclosed.
25 Citations
13 Claims
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1. A method of improving performance of a battery fuel gauge comprising:
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providing a voltage based fuel gauge that monitors a terminal voltage of a battery and determining the battery'"'"'s state of charge based on a battery model; providing a coulomb counter to provide a measure of current into and out of the battery; determining a first remaining charge in the battery using a product of a full capacity of the battery times the state of charge as determined by the voltage based fuel gauge; determining a second remaining charge in the battery using a combination of the first remaining charge in the battery and the current into and out of the battery as provided by the coulomb counter, the current into and out of the battery dominating the determination of the second remaining charge in the battery except during low or zero currents; and continually updating the second remaining charge by repeatedly subtracting a value responsive to the second remaining charge from the first remaining charge to repeatedly obtain an updated second remaining charge, the first remaining charge dominating the second remaining charge during low or zero currents. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer readable storage medium having stored thereon a sequence of instructions which, when executed by a computer, cause the computer to perform the following:
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determine the battery'"'"'s state of charge from the terminal voltage of a battery using a voltage based fuel gauge without using a measure of the current into and out of the battery; determine a first remaining charge in the battery using a product of a full capacity of the battery times the state of charge as determined by the voltage based fuel gauge; determine a second remaining charge in the battery using a combination of the first remaining charge in the battery and the current into and out of the battery times time; and repeatedly update the second remaining charge by repeatedly subtracting a value responsive to the second remaining charge from the first remaining charge to repeatedly obtain an updated second remaining charge. - View Dependent Claims (10, 11, 12, 13)
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Specification