Method of predicting the state of charge as well as the use time left of a rechargeable battery
First Claim
1. A method of estimating the state-of-charge for a rechargeable lithium battery, comprising the steps of:
- determining whether the battery is in an equilibrium state or in a non-equilibrium state; and
if the battery is in an equilibrium state, measuring the voltage across the battery and converting this measured voltage into an equilibrium state-of-charge value;
if the battery is in a non-equilibrium state, calculating the charge withdrawn from or supplied to the battery by means of current integration, and subtracting this charge from or adding it to a state-of-charge value calculated earlier.
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Abstract
Disclosed is a method of estimating the state of charge of a rechargeable lithium battery. The first step of said method is to determine whether the battery is in an equilibrium state or in a non-equilibrium state. If the battery is determined to be in an equilibrium state, the voltage across the battery is measured and converted into an equilibrium state-of-charge value. If the battery is in a non-equilibrium state, the charge withdrawn from or supplied to the battery is calculated by means of current integration, and this charge is subtracted from or added to a state-of-charge value calculated earlier.
Also disclosed is a method of estimating the time that an application can be used under predefined conditions.
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Citations
10 Claims
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1. A method of estimating the state-of-charge for a rechargeable lithium battery, comprising the steps of:
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determining whether the battery is in an equilibrium state or in a non-equilibrium state; and
if the battery is in an equilibrium state, measuring the voltage across the battery and converting this measured voltage into an equilibrium state-of-charge value;
if the battery is in a non-equilibrium state, calculating the charge withdrawn from or supplied to the battery by means of current integration, and subtracting this charge from or adding it to a state-of-charge value calculated earlier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
determining the state of charge of the battery as claimed in claim 1; - and
calculating the battery voltage as the sum of the equilibrium voltage and the overpotential.
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7. A method as claimed in claim 6, characterized in that the overpotential is calculated from a function having at least a time-dependent part.
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8. A method as claimed in claim 6, characterized in that the overpotential is calculated from a function having at least a temperature-dependent part.
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9. A method as claimed in claim 6, characterized in that the overpotential is calculated from a function at least comprising a capacity-dependent part.
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10. A method as claimed in claim 6, characterized in that the overpotential is calculated from a function having at least one term which is inversely related to the remaining capacity of the battery.
Specification