Battery charge monitor and fuel gauge
First Claim
1. An apparatus for determining an incremental battery charge value comprising:
- a battery;
means for providing charging current to said battery;
means for measuring the charging current being provided to said battery at a predetermined interval;
means for measuring the temperature of said battery; and
means coupled to said means for measuring charging current and said means for measuring battery temperature for developing an incremental charge value of said battery during said predetermined interval, said incremental charge value being based on the measured current value times said predetermined interval less a fraction of said measured temperature.
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Accused Products
Abstract
A battery charge controller and fuel gauge which accurately monitors the voltage, temperature, and charge and discharge current of a rechargeable battery, and calculates the battery'"'"'s charge capacity and charge level. Each time the battery is fully discharged, any calculated charge level remaining is divided by two and subtracted from the previously calculated charge capacity. When the battery is fully charged, the charge level is set equal to the charge capacity. During subsequent charge and discharge, the current is converted to a coulomb count and added or subtracted from the charge level to maintain an accurate charge level. Fast charge inefficiency due to temperature is considered by subtracting a temperature proportional factor before the charge level of the battery is updated. The charge level, voltage and temperature are used to determine the optimal fast charge termination point to achieve full charge and prevent temperature abuse and overcharge. A fast charge is applied only if the battery is within proper voltage and temperature ranges. The charge controller includes a microcontroller circuit within the same battery pack as the battery, which is powered by the battery when AC power is unavailable. The microcontroller circuit consumes very little power, measures circuit errors to assure data accuracy, times periods of self-discharge and updates the charge level accordingly. The microcontroller circuit also includes memory to store the battery charge information and a communication port to provide the charge information to a computer system connected to the battery pack.
158 Citations
23 Claims
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1. An apparatus for determining an incremental battery charge value comprising:
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a battery; means for providing charging current to said battery; means for measuring the charging current being provided to said battery at a predetermined interval; means for measuring the temperature of said battery; and means coupled to said means for measuring charging current and said means for measuring battery temperature for developing an incremental charge value of said battery during said predetermined interval, said incremental charge value being based on the measured current value times said predetermined interval less a fraction of said measured temperature.
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2. An apparatus for monitoring battery discharge during periods of self-discharge, the apparatus comprising:
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a battery; means for determining the charge level of said battery and setting a battery charge level value prior to entering a self-discharge state; means for determining the amount of time spent in said self-discharge state; and means coupled to said means for determining battery charge level and said means for determining the time spent in said self-discharge state for reducing said battery charge level value by an amount based on said time spent in said self-discharge state. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for monitoring battery charge level of a battery in a computer system, the apparatus comprising:
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a battery; a computer system powered by said battery; means for charging said battery; means for maintaining a charge level value of said battery; means for monitoring charging current of said battery and increasing said charge level value based on said charging current of said battery; means for monitoring discharging current of said battery based on normal operations of said computer system and decreasing said charge level value based on said discharging current of said battery; means for determining when said battery discharges to a predetermined level; means for maintaining a value representative of a full charge value of said battery; and means coupled to said means for determining when said battery discharges to a predetermined level, said means for maintaining said full charge value and said means for maintaining said charge level value, for changing said full charge value by amount equal to a portion of said charge level value remaining when said battery discharges to said predetermined level. - View Dependent Claims (19, 20)
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21. An apparatus for monitoring battery charge level comprising:
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a battery; means for charging said battery; means for discharging said battery; means for maintaining a charge level value of said battery; means for monitoring charging current of said battery and increasing said battery charge level value based on said charging current of said battery; means for monitoring discharging current of said battery and reducing said battery charge level based on said discharging current of said battery; and means for indicating that said battery charge value is invalid under predetermined conditions. - View Dependent Claims (22, 23)
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Specification