Tracking fading battery capacity in a plugged-in portable electronic device
First Claim
1. A method for estimating a capacity change of a battery in a portable electronic device powered by an external power source, the method comprising:
- performing a first open circuit voltage measurement on the battery while the battery rests at a first state of charge;
while the portable electronic device remains electrically coupled to the power source;
charging or discharging the battery to a second state of charge;
monitoring a current through the battery while charging or discharging the battery to the second state of charge; and
deriving a net change in charge of the battery from the monitored current;
performing a second open circuit voltage measurement on the battery while the battery rests at the second state of charge; and
estimating a capacity change of the battery based on the first open circuit voltage measurement, the second open circuit voltage measurement, and the net change in charge of the battery.
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Abstract
A system for tracking the capacity of a battery in a portable electronic device is described. While the portable electronic device remains plugged in to a power adapter, the system estimates the capacity of the battery by performing the following operations. The system measures a first open-circuit voltage for the battery while the battery rests at a first state of charge. Next, the system causes the battery to transition to a second state of charge. While the battery transitions to the second state of charge, the system integrates a current through the battery to determine a net change in charge for the battery. Next, the system measures a second open-circuit voltage for the battery while the battery rests at the second state of charge. Finally, the system estimates a capacity for the battery based on the first open-circuit voltage, the second open-circuit voltage and the net change in charge. This capacity measurement is repeated and the multiple results are fit to a line. The slope of fitted line is then used to estimate how the true battery capacity has faded since last measured using traditional methods that require the battery to be rested at a low state of charge.
7 Citations
20 Claims
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1. A method for estimating a capacity change of a battery in a portable electronic device powered by an external power source, the method comprising:
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performing a first open circuit voltage measurement on the battery while the battery rests at a first state of charge; while the portable electronic device remains electrically coupled to the power source; charging or discharging the battery to a second state of charge; monitoring a current through the battery while charging or discharging the battery to the second state of charge; and deriving a net change in charge of the battery from the monitored current; performing a second open circuit voltage measurement on the battery while the battery rests at the second state of charge; and estimating a capacity change of the battery based on the first open circuit voltage measurement, the second open circuit voltage measurement, and the net change in charge of the battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A portable electronic device having a battery and adapted to be selectively coupled to an external power source, the portable electronic device comprising a controller configured to:
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perform a first open circuit voltage measurement on the battery while the battery rests at a first state of charge; while the portable electronic device remains electrically coupled to the external power source; charge or discharge the battery to a second state of charge; monitor a current through the battery during the charge or discharge; and derive from the monitored current a net change in charge of the battery; perform a second open circuit voltage measurement on the battery while the battery rests at the second state of charge, estimate a capacity change of the battery based on the first open circuit voltage measurement, the second open circuit voltage measurement, and the net change in charge of the battery. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A non-transitory computer readable storage medium having embodied thereon instructions to cause a processor in a portable electronic device to perform a method, the method comprising:
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perform a first open circuit voltage measurement on a battery of the portable electronic device while the battery rests at a first state of charge; while the portable electronic device remains electrically coupled to an external power source; charge or discharge the battery to a second state of charge that is within 5% of the first state of charge; monitor a current through the battery during the charge or discharge of the battery to the second state of charge; and derive from the monitored current a net change in charge for the battery; perform a second open circuit voltage measurement on the battery while the battery rests at the second state of charge; and estimate the capacity change of the battery based on the first open circuit voltage measurement, the second open circuit voltage measurement and the net change in charge for the battery. - View Dependent Claims (19, 20)
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Specification