Method and an apparatus for charging a rechargeable battery
First Claim
1. A method of charging a rechargeable battery, comprising:
- connecting an electrical source of energy to the battery,determining the value of one or more characteristic parameters of the charging process at a plurality of points of time during charging,determining, for each of at least two points of time, the apparent remaining period necessary to fully charge the battery the point in time time and stored reference values corresponding to the determined values;
terminating the charging process at a stop point determined from the apparent remaining time periods.
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Accused Products
Abstract
A rechargeable battery is charged by connecting the terminals of the battery to an electrical power source. In order to avoid overcharging and undue temperature increase in the battery cell, the course of a least one charging parameter, such as the increase rate of voltage, is surveyed during at least part of the process of charging the battery. This charging parameter surveyed is compared with a number of reference parameter courses representing idealistic or desireable processes of charging the battery for different starting states of charge of the battery. Such comparisons may for example be made by means of a microprocessor, which may also select the reference course with a starting state of charge similar to the actual starting state of charge of the battery. Thereafter the process of charging the battery may be controlled so as to approximate the course of said charging parameter to the selected reference course. The charging voltage may be limited to a maximum value (Vmax). When such value has been reached the charging process may be terminated after a certain predetermined time period being one of the reference values.
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Citations
52 Claims
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1. A method of charging a rechargeable battery, comprising:
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connecting an electrical source of energy to the battery, determining the value of one or more characteristic parameters of the charging process at a plurality of points of time during charging, determining, for each of at least two points of time, the apparent remaining period necessary to fully charge the battery the point in time time and stored reference values corresponding to the determined values; terminating the charging process at a stop point determined from the apparent remaining time periods. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for charging a rechargeable battery, said apparatus comprising
an electrical source of energy, a measuring device for measuring one or more characteristic parameters of the charging process at a series of points of time during charging, a control unit, receptive of indicia of the measured parameters, for calculating other characteristic parameters in accordance with the measured parameter or parameters, controlling the energy source and for terminating the charging process, the control unit including a storage circuit for storing the measured parameter or parameters values, calculated parameter values and reference values, and being adapted to control the charging process based on the values stored, characterized in that the control unit is adapted to determine, for at least two points of time, an apparent remaining charging period of time necessary to fully charge the battery from the point of time based on the measured characteristic parameter or parameters at that time and stored reference values corresponding to the determined values with the reference values, and terminates the charging process at a stop point determined from the apparent remaining time periods.
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23. A method of charging a rechargeable battery having a pair of terminals, said method comprising
connecting an electrical power source to the terminals of the battery, monitoring at least one charging parameter during at least part of the process of charging of the battery, comparing a sequence of values of said at least one charging parameter with stored reference parameter sequences representing idealistic or desirable processes of charging the battery for different starting states of charge of the battery, selecting the reference sequence corresponding to the sequence of values of said at least one charging parameter, and controlling the process of charging the battery so as to cause the sequence of subsequent values of said at least one parameter to approximate the selected reference parameter sequence; wherein the process of charging is controlled by controlling the voltage supplied to the terminals of the battery and the voltage supplied to the battery is controlled so that the charging current is kept relatively low at the beginning of the charging process. - View Dependent Claims (24, 25)
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26. The method of charging a rechargeable battery having a pair of terminals, said method comprising
connecting an electrical power source to the terminals of the battery, monitoring at least one charging parameter during at least part of the process of charging of the battery, comparing a sequence of values of said at least one charging parameter with stored reference parameter sequences representing idealistic or desirable processes of charging the battery for different starting states of charge of the battery, selecting the reference sequence corresponding to the sequence of values of said at least one charging parameter, and controlling the process of charging the battery so as to cause the sequence of subsequent values of said at least one parameter to approximate the selected reference parameter sequence; -
wherein; the monitoring step comprises measuring the current values of said at least one charging parameter at short time intervals during charging, the comparing step comprises comparing the measured parameter values with corresponding reference values of the reference parameter sequences, the selecting the reference sequence step comprising selecting the relevant reference parameter sequence on the basis of comparison of such measured values and reference values, and the controlling step comprising determining a remaining period of charging time based on said comparison, and terminating the charging process when said remaining period of time has expired. - View Dependent Claims (28, 29, 30, 31, 33)
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27. A method according 26, wherein the rate of change of the parameter values as a function of the charging time lapsed is compared to similar reference values.
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32. A method of charging a rechargeable battery having a pair of terminals, said method comprising
connecting an electrical power source to the terminals of the battery, monitoring at least one charging parameter during at least part of the process of charging of the battery, comparing a sequence of values of said at least one charging parameter with stored reference parameter sequences representing idealistic or desirable processes of charging the battery for different starting states of charge of the battery, selecting the reference sequence corresponding to the sequence of values of said at least one charging parameter, and controlling the process of charging the battery so as to cause the sequence of subsequent values of said at least one parameter to approximate the selected reference parameter sequence; wherein each of said parameter values is an average of a plurality of measurements within a certain period of time.
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34. A method of charging a rechargeable battery having a pair of terminals, said method comprising
connecting an electrical power source to the terminals of the battery, monitoring at least one charging parameter during at least part of the process of charging of the battery, comparing a sequence of values of said at least one charging parameter with stored reference parameter sequences representing idealistic or desirable processes of charging the battery for different starting states of charge of the battery. selecting the reference sequence corresponding to the sequence of values of said at least one charging parameter, and controlling the process of charging the battery so as to cause the sequence of subsequent values of said at least one parameter to approximate the selected reference parameter sequence; wherein the charging process is terminated if one of the monitored parameter values exceeds a predetermined value for the respective parameter. - View Dependent Claims (35)
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36. An apparatus for charging a rechargeable battery, said apparatus comprising:
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connecting means for connecting the battery to an electrical power source, means for monitoring at least one charging parameter during at least part of the process charging the battery, storing means for storing a plurality of reference parameter sequences representing idealistic or desirable processes of charging the battery for various starting states of charge of the battery, means for comparing the sequence of values of said at least one charging parameter with the stored reference parameter sequences and for selecting the reference course corresponding to the sequence of values of said at least one charging parameter, and means for controlling the process of charging the battery so as to cause the sequence of subsequent values of said at least one parameter to approximate the selected reference parameter sequence; wherein the control means are adapted to control the process of charging the battery by controlling the voltage supplied to the connecting means so that the charging current is kept relatively low at the beginning of the charging process, to limit the voltage supplied to the connecting means to a predetermined maximum, and to terminate the charging process when a predetermined period of time related to the reference sequence finally selected by the comparing and selecting means and starting when said voltage maximum has been reached. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A method of charging a rechargeable battery having terminals, comprising:
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selectively applying a voltage to the battery terminals to provide a charging current, measuring the voltage across the terminals of the battery during charging, cutting-off the charging current to the battery for a brief period before the voltage of the battery is measured, controlling the voltage supplied to the battery so that the charging current is kept relatively low at the beginning of the charging process. determining the value of one or more characteristic parameters of the charging process at a plurality of points of time during charging, selecting a point of time. determining a remaining charging period necessary to charge the battery from the selected point of time based upon the determined parameter values at that time and stored reference values corresponding to the determined values; terminating the charging process when the remaining charging period of time has lapsed.
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49. A method of charging a rechargeable battery having terminals, comprising:
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selectively applying a voltage to the battery terminals to provide a charging current, applying a constant charging current to the battery during a first portion of the charging period, and then gradually reducing the charging current until charging is terminated, determining the value of one or more characteristic parameters of the charging process at a plurality of points of time during charging, selecting a point of time, determining the remaining charging period necessary to charge the battery from the selected point of time based upon the determined parameter values at that time and stored reference values corresponding to the determined values; terminating the charging process when the remaining charging period of time has lapsed.
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50. A method of charging a rechargeable battery having terminals, comprising:
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selectively applying a voltage to the battery terminals to provide a charging current, controlling the charging current fed to the battery by pulse width modulating a constant voltage source, determining the value of one or more characteristic parameters of the charging process at a plurality of points of time during charging, selecting a point of time, determining the remaining charging period necessary to charge the battery from the selected point of time based upon the determined parameter values at that time and stored reference values corresponding to the determined values; terminating the charging process when the remaining charging period of time has lapsed.
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51. An apparatus for charging a rechargeable battery, said apparatus comprising
an electrical source of energy for selectively providing a voltage to the battery, a measuring device for measuring one or more characteristic parameters of the charging process at at least one point of time during charging, a control unit, receptive of indicia of the measured parameters, for calculating other characteristic parameters, controlling the energy source and for terminating the charging process, the control unit including a storage circuit for storing measured parameter values, calculated parameter values and reference values, and being adapted to control the charging process based on the values stored, characterized in that the control unit is adapted to: - control the voltage supplied to the battery so that the charging current is kept relatively low at the beginning of the charging process;
determine an apparent remaining charging period of time necessary to fully charge the battery from the point of time based on the measured characteristic parameter or parameters at that time and stored reference values corresponding to the determined values; and
to terminate the charging process at a stop point determined, in accordance with predetermined criteria, from the apparent remaining time periods.
- control the voltage supplied to the battery so that the charging current is kept relatively low at the beginning of the charging process;
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52. An apparatus for charging a rechargeable battery said apparatus comprising
a constant voltage source; -
a measuring device for measuring one or more characteristic parameters of the charging process at at least one point of time during charging, a control unit, receptive of indicia of the measured parameters, for calculating other characteristic parameters, controlling the energy source and for terminating the charging process, the control unit including a storage circuit for storing measured parameter values, calculated parameter values and reference values and being adapted to control the charging process based on the values stored, the control unit being adapted to;
control the charging current to the battery by pulse width modulating a constant voltage;
determine an apparent remaining charging period of time necessary to fully charge the battery from the point of time based on the measured characteristic parameter or parameters at that time and stored reference values corresponding to the determined values; and
to terminate the charging process at a stop point determined, in accordance with predetermined criteria, from the apparent remaining time periods.
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Specification