JP2008128964A - Calculating method of stabilizing open circuit voltage of battery, battery system, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and system which can correctly measure and calculate a stabilizing open circuit voltage with practical accuracy of circuit constant and practical measuring procedure. <P>SOLUTION: In this method, current of battery under charging, open circuit voltage of battery after charging, and current/voltage of battery after discharging are obtained. Then an intermediate value between the open circuit voltage and discharge voltage is calculated. By adding ratio between charging current and discharging current to this intermediate value, stabilizing open circuit voltage is calculated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for calculating a stable open circuit voltage of a battery, a battery device, and an electronic device including the battery, which are suitable for application to a battery used in an electronic device. More specifically, the present invention relates to a technique for calculating a stable open circuit voltage for knowing the true state of a battery.

In recent years, electronic devices using a battery such as a lithium ion secondary battery as a power source, such as a notebook personal computer and a mobile phone, have become widespread.
In an electronic device that uses a battery as a power source, the user needs to pay attention to the remaining capacity of the battery. Therefore, it is desirable to calculate the remaining battery capacity as accurately as possible.
As a method of calculating the remaining capacity of the battery, for example, a method using the relationship between the terminal voltage and the remaining capacity, or when the discharge capacity at the full charge capacity is defined as “0”, the discharge current is integrated from the full charge capacity. Various methods have been proposed and studied, such as a method of subtracting the calculated discharge capacity.

  Patent Document 1 discloses a “battery capacity detection method and apparatus and battery pack” as a method for calculating the remaining capacity using the internal impedance and the balanced voltage of the battery. The equilibrium voltage is a terminal voltage when the battery terminal is left open for a long period of time and the internal state of the electrode and the electrolyte is stabilized. This Patent Document 1 discloses a technique for measuring an equilibrium voltage curve indicating the relationship between a discharge capacity and an equilibrium voltage in a deteriorated battery and an internal impedance, and calculating a remaining capacity based on a voltage drop due to the internal impedance. In addition, it is described that not only the remaining capacity but also the remaining power has been accurately calculated.

  However, the measurement of the balanced voltage has to create an approximately unrealistic state in a normal use state in which “the battery terminal is left open for a long time”. That is not practical.

JP 2001-231179 A JP 2004-163360 A

  Patent Document 2 discloses a technique for indirectly calculating a balanced voltage within a practical range, obtaining an “apparent balanced voltage”, and calculating a remaining battery capacity based on this. Discharging is temporarily performed during charging, and an apparent equilibrium voltage is calculated using the value of the voltage drop.

FIG. 11 illustrates a mechanism for calculating the equilibrium voltage. Hereinafter, in this specification, the balanced voltage referred to in the prior art is referred to as “stable open circuit voltage”.
The graph of FIG. 11 schematically shows the change in the voltage between the terminals of the battery when shifting from the charging state to the state where the charging is stopped.
While charging, the voltage of the battery maintains a constant value, but when charging is stopped, the voltage drops rapidly. And asymptotically decreases. The tip of this graph is the stable open circuit voltage. Since the curve of this graph is similar to the curve of the square root, the calculation technique using the square root is used in the prior art as shown in FIG.

FIG. 12 is a graph comparing the stable open circuit voltage calculation method of FIG. 11 and the measured stable open circuit voltage.
This is a measurement of voltage and current when charging / discharging experiments were performed on a lithium ion battery cell.
This measurement was performed by the following experiment.
Charging object: 1 lithium ion battery cell Discharge circuit: 4Ω constant resistance discharge circuit A / D converter: 1mV accuracy Charging condition: Constant current constant voltage (CC / CV) Charging charge voltage: Maximum 4.2V
Charging current: Max 1.5A
Charging temperature: 25 ° C
As a test pattern, the pattern of charge (10 minutes) → pause (3 hours) is repeated until full charge, each time the voltage immediately after the end of charge (OCV1), and the voltage after a few seconds (OCV2), This is the result of measuring the voltage just before the end of the pause (measured stable open circuit voltage (hereinafter “measured stable open circuit voltage”)).
From the experimental results, it was found that an error of about 50 mV at maximum occurs between the actually measured value and the calculated value.
Note that the 1 mV accuracy of a converter that converts an analog signal into digital data (hereinafter referred to as an A / D converter) increases the cost of consumer equipment.

  As described above, the technique disclosed in Patent Document 2 is not practical because it requires a large calculation error of the stable open circuit voltage and requires high accuracy of the A / D converter.

  The present invention has been made in view of this point, and an object thereof is to measure a stable open circuit voltage with high accuracy and ease.

In the present invention for solving the above-described problems, first, the battery is continuously charged for a predetermined time, and then the charging current is acquired, and then the charging is stopped to bring the battery into a no-load state.
Next, after an elapse of a predetermined time, the open circuit voltage of the battery is acquired.
Thereafter, a load resistance is connected to the battery, and after a predetermined time has elapsed, the discharge voltage and discharge current of the battery are acquired.
When these are finished, the stable open circuit voltage is calculated based on the charging current, the open circuit voltage, the discharge voltage, and the discharge current.

  The stable open circuit voltage is data located at the midpoint between the open circuit voltage after charging and the voltage during discharging. By multiplying this intermediate value by the ratio of the charging current and the discharging current, a highly accurate stable open circuit voltage can be obtained with a simple procedure.

  According to the present invention, using an A / D converter with practical conversion accuracy, it is possible to obtain a highly accurate stable open circuit voltage with a small error from an actual measurement value in a relatively short time.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of a battery device as an example of the present embodiment. The battery device 101 supplies power to a portable electronic device such as a notebook personal computer.
The battery device 101 includes a battery main body 102 and a charge / discharge control unit 103 that provides a charge / discharge control function and a protection function. In FIG. 1, description of a protective function for detecting an abnormal state of the battery main body 102 and disconnecting the connection between the terminal and the battery main body 102 is omitted.
The battery main body 102 is formed by connecting cells 104 of a lithium ion secondary battery in series and parallel. That is, the first cell 104a in which two cells are connected in parallel and the second cell 104b in which two cells are connected in parallel are connected in series. The cell connection configuration is an example, and other connection configurations may be used.
Both terminals of the cell 104 are connected to voltage detection terminals T106, T107 and T108 of the microcomputer 105, respectively, and are used to measure the voltage between the terminals of the cell 104.
Further, a current detection resistor R110 is inserted between the negative pole of the battery main body 102 and the negative terminal T109. Similarly, both terminals of the current detection resistor R110 are connected to the current detection terminals T111 and T112 of the microcomputer 105 and used for current measurement.
The microcomputer 105 is further connected to the gates of a discharge FET 113 and a charge FET 114, respectively.
The discharge FET 113 is a switching element that is turned on when discharging from the cell 104 and forms a discharge path for discharging from the cell 104 to a load (not shown) via the plus terminal T115. On / off of the discharge FET 113 is controlled by a discharge control unit 209 (FIG. 2) described later.
The charging FET 114 is a switching element that is turned on when charging the cell 104 and forms a charging path that supplies the cell 104 with a charging current supplied from a charging circuit (not shown) to the plus terminal T115 and charges it. On / off of the charge FET 114 is controlled by a charge control unit 208 (FIG. 2) described later.
The above elements are also in the prior art.

The internal discharge control FET 116 and the discharge current limiting resistor R117 are connected between the minus terminal T109 from between the source of the charge FET 114 and the source of the discharge FET 113. The internal discharge control FET 116 is turned on by applying the same voltage as the source, that is, the ground potential, to the gate.
The internal discharge control FET 116 and the discharge current limiting resistor R117 are newly provided in this embodiment.
It is an element for performing internal discharge for a predetermined time necessary for calculating an open circuit voltage described later in the present embodiment.

FIG. 2 is a functional block diagram showing the internal functions of the microcomputer 105.
The first changeover switch 202 and the second changeover switch 203 are sequentially controlled by the control signal of the counter 204 when measuring the voltage between the terminals of the first cell 104a, the voltage between the terminals of the second cell 104b, and the current. Can be switched.
The counter 204 counts clocks generated from a clock source (not shown) and sequentially switches the first changeover switch 202 and the second changeover switch 203 according to the coefficient result.
The other ends of the first changeover switch 202 and the second changeover switch 203 are connected to the A / D converter 205.
When the first changeover switch 202 and the second changeover switch 203 are switched by the counter 204, the A / D converter 205 polls at about 100 msec, the voltage between the terminals of the first cell 104, the second cell 104. The terminal voltage and current (terminal voltage of the current detection resistor R110) are continuously converted to digital values.
The value digitally converted by the A / D converter 205 is written into the RAM 206.
That is, the counter 204, the first changeover switch 202, the second changeover switch 203, and the A / D converter 205 are connected to the voltage between the terminals of the first cell 104, the voltage between the terminals of the second cell 104, and current (current detection). The voltage between the terminals of the resistor R110 is polled at about 100 msec, continuously measured, and sequentially recorded in the RAM 206.

As the data of the voltage and current between the terminals of the cell 104 held in the RAM 206, the previous value and the current value are recorded.
The charge / discharge determination unit 207 determines whether the battery is currently being charged, discharged, or not connected to any device by looking at the direction of current.
The charge control unit 208 operates in response to the control signal that the charge / discharge determination unit 207 determines to be currently charging.
The discharge control unit 209 operates in response to the control signal determined by the charge / discharge determination unit 207 to be currently discharging.
The stable open circuit voltage measurement unit 210 receives the control signal determined by the charge / discharge determination unit 207 to be currently charged, counts the clock internally, and starts when a predetermined time has elapsed from the start of charging. The charge control unit 208, the discharge control unit 209, and the internal discharge control FET 116 are controlled.

[Mechanism for measuring stable open circuit voltage]
Hereafter, the mechanism which measures the stable open circuit voltage which is the objective of this embodiment is demonstrated.
Here, the stable open circuit voltage is a voltage between open terminals measured after a predetermined time is applied to the battery and the load is removed and a sufficient time has elapsed. This is an open-circuit voltage in a state where the chemical reaction inside the battery has settled and an equilibrium state has been reached.
FIG. 3 is a schematic graph schematically showing an operation flow of typical battery charging, charging stop, discharging, and charging, a battery terminal voltage that changes in accordance with the flow, and a change in charging / discharging current. It is. In the case of this example, the charging circuit connected to the battery device 101 performs constant current and constant voltage (CC / CV: Constant Current, Constant Voltage).
First, when CC / CV charging is performed on the battery, the voltage between the terminals of the battery and the charging current maintain a stable voltage value and current value when viewed macroscopically (t1).
Next, when the CC / CV charging is stopped, the current naturally becomes zero, but the voltage between the terminals of the battery rapidly decreases (t2), and then gradually converges to a stable voltage. This is the open circuit voltage OCV after charging.
Thereafter, when an appropriate load is connected to the battery, the battery is discharged (t4). In this discharge, the voltage suddenly drops at first and then converges to a constant voltage (t5). This is the stable discharge voltage CCV @ DHG. The discharge current at this time is CUR @ DHG.
Thereafter, when charging is started again (t6), the voltage between the terminals of the battery rapidly increases (t7).

Here, it is found from the measurement results described below that the stable open circuit voltage is a voltage located at approximately the midpoint between OCV and CCV @ DHG.
FIG. 4 is a graph obtained by measuring voltage and current when a charge / discharge experiment was performed on a lithium ion battery cell.
This measurement was performed by the following experiment.
Charging object: Lithium ion battery cell 1 discharge circuit: 4Ω constant resistance discharge circuit Charging condition: constant current constant voltage (CC / CV) Charging charge voltage: Maximum 4.2V
Charging current: Max 1.5A
Charging temperature: 25 ° C
As a test pattern, the pattern of charge (10 minutes) → discharge (5 seconds) → rest (3 hours) is repeated until full charge, and each time the charge ends (CUR @ CHG) and voltage (OCV), discharge It is the result of measuring the current (CUR @ DHG) and voltage (CCV @ DHG) just before the end, and the voltage just before termination (measured stable open circuit voltage (hereinafter “measured stable open circuit voltage”)).
FIG. 4 also plots the calculated stable open circuit voltage calculated using the calculation formula described later.

This graph is plotted from the right. Hereinafter, description will be given from the right side of the graph.
When the battery is almost empty, the measured stable open circuit voltage is slightly less than the intermediate value between OCV and CCV @ DHG (t11).
Thereafter, as charging progresses, the measured stable open circuit voltage increases. Accordingly, the charging current value CUR @ CHG gradually decreases (t12 to t13).
The charging current value CUR @ CHG sharply decreases around the time when the charging capacity of the battery has cut below 1 Ah (t14). The measured stable open circuit voltage rises and eventually becomes higher than the intermediate value between OCV and CCV @ DHG (t15).
At the end of charging, the charging current value CUR @ CHG is infinitely close to zero. At the same time, the measured stable open circuit voltage is very close to the OCV (t16).
For reference, FIG. 5 shows a graph of results obtained by performing the same measurement in an atmosphere at 5 ° C. Since CCV @ DHG has shown the low value, it turns out that the performance of a battery is not fully demonstrated. Nevertheless, the change in the measured stable open circuit voltage is almost the same as in FIG.

4 and 5 that the measured stable open circuit voltage is always between OCV and CCV @ DHG, and the measured stable open circuit voltage is between OCV and CCV @ DHG. There is a tendency to be biased according to changes in CUR @ CHG and CUR @ DHG.
Based on this observation, the following formula was established, and “calculated stable open circuit voltage” was plotted in FIGS. 4 and 5. As a result, it has been found that the difference between the calculated stable open circuit voltage and the measured stable open circuit voltage is extremely small as compared with the conventional measurement and calculation methods.

That is, the stable open circuit voltage can be calculated more accurately as compared with the prior art by performing the measurement for practicing Equation 1 during charging.
The discharge current is preferably in the range from half of the maximum charge current to the maximum charge current. This is because if the discharge current is too much or too little compared with the charge current, an appropriate ratio cannot be given to an intermediate value between OCV and CCV @ DHG.

FIG. 6 is an internal block diagram of the stable open circuit voltage measurement unit 210. In order to practice Formula 1, charge / discharge is controlled, necessary data is collected, and calculation is performed.
The RAM 602 is physically the same as the RAM 206 in FIG. 2, but has a different address. That is, the address space is different from the storage area existing in the RAM 206 of FIG. In this address space, a CUR @ CHG storage unit 603, an OCV storage unit 604, a CUR @ DHG storage unit 605, and a CCV @ DHG storage unit 606 are provided. These values are copied from each storage area of the RAM 206 in FIG.
The counter 607 counts clocks generated from a clock source (not shown). The charging / discharging determination unit 207 is activated by a determination result indicating that charging is in progress, and is reset by a determination result indicating that charging is completed.
The counter 607 outputs a control signal to the discharge control unit 209, the charge control unit 208, and the internal discharge control FET 116 as a result of the counting. Accordingly, the counter 204 controls the CUR @ CHG storage unit 603, the OCV storage unit 604, the CUR @ DHG storage unit 605, and the CCV @ DHG storage unit 606 of the RAM 602 to copy values from the RAM 206.
The stable open circuit voltage calculation unit 608 reads values from the CUR @ CHG storage unit 603, the OCV storage unit 604, the CUR @ DHG storage unit 605, and the CCV @ DHG storage unit 606 of the RAM 602, and executes Equation 1 to perform the stable open circuit. The voltage is calculated and output as data.

FIG. 7 is a flowchart showing a process flow of the stable open circuit voltage measurement unit 210.
When the process is started (S701), first, the determination result of the charge / discharge determination unit 207 is checked, and it is confirmed whether or not the battery is currently being charged (S702).
If charging is in progress, the timer 1 is started (S703), whether the timer 1 measures 10 minutes (S704), or whether the charging is interrupted by checking the determination result of the charge / discharge determination unit 207 ( S705) is confirmed. If charging is in progress, the loop processing is continued until 10 minutes have elapsed.
When 10 minutes have elapsed, since charging has been continued for 10 minutes, a process of measuring a stable open circuit voltage is executed (S706), and the process is repeated from the beginning (S707).

8 and 9 are flowcharts showing the flow of processing for measuring the stable open circuit voltage. This is the content of step S706 in FIG.
When the process is started (S801), first, the current current value of the RAM 206 is copied to the CUR @ CHG storage unit 603 (S802).
Next, the charging control unit 208 is controlled to turn off the charging FET 114 and stop charging (S802). Then, the timer 2 is activated (S804) and waits for a predetermined time (S805). Here, it is 1 second.
When the predetermined time has elapsed, the current voltage value of the first cell 104 and the current voltage value of the second cell 104 are copied from the RAM 206 to the OCV storage unit 604 (S806).
Next, the discharge control unit 209 is controlled to perform low voltage discharge, and the internal discharge control FET 116 is turned on (S807).
Then, the timer 3 is started (S808), and the elapse of a predetermined time is waited (S809). Here, it is 1 second.
When the predetermined time has elapsed, the current voltage value of the first cell 104 and the current voltage value of the second cell 104 are copied to the CCV @ DHG storage unit 606, and the current value is copied from the RAM 206 to the CUR @ DHG storage unit 605. (S910). At this point, the data necessary for the calculation process is finally ready.
The internal discharge control FET 116 is turned off (S911), and a stable open circuit voltage is calculated (S912). Thereafter, the charging is resumed (S913) and terminated (S914). In addition, the calculation process of the stable open circuit voltage of step S912 may be in any order.

  If the battery device 101 is continuously charged by the processes from FIG. 7 to FIG. 9, the stable open circuit voltage measurement process is performed every 10 minutes.

FIG. 10 is a block diagram showing the use of the stable open circuit voltage value obtained by this embodiment.
The stable open circuit voltage can be used as a basis for detecting an abnormal state of the battery cell 104.
The stable open circuit voltage of the cell 104 in the normal state is within a predetermined voltage range. When deviating from this voltage range, it can be determined that an abnormal state has occurred.
With a simple voltage between the terminals of the cell 104, the voltage fluctuates greatly each time the battery is charged / discharged, so that it is difficult to detect an abnormal state.
On the other hand, since the stable open circuit voltage depends only on the remaining capacity state and the deterioration state of the cell 104 itself, the voltage fluctuation is small as compared with the measurement of the voltage between terminals. That is, more precise abnormal state detection can be expected than the abnormal state detection by comparing the voltage between the terminals and the threshold value.
In FIG. 10, as a result of determining the abnormal state, the thermal fuse fusing FET 1006 is turned on, and the thermal fuse 1007 is blown.

As described above, the stable open circuit voltage depends only on the remaining capacity state and the deterioration state of the cell 104 itself. For this reason, it can be expected to measure the remaining capacity of the battery more precisely.
In FIG. 10, stable open circuit voltage data is transmitted to an external electronic device through the serial port T1008 of the microcomputer 105.
An external electronic device, such as a notebook personal computer, can receive this data and update the remaining battery capacity.
Further, the degree of deterioration of the battery can be calculated by recording capacity data immediately after the battery is manufactured in a non-illustrated nonvolatile memory in the microcomputer 1005. By knowing the degree of deterioration of the battery, the user can accurately grasp the replacement time of the battery.

The following application examples can be considered in the present embodiment.
(1) The equation for calculating the stable open circuit voltage is not limited to Equation 1 described above.
The following equation 2 can also calculate a stable open circuit voltage with substantially the same accuracy. Equation 2 is also an equation that uses a phenomenon in which the charging current (CUR @ CHG) decreases as it approaches full charge.

In the present embodiment, a technique for calculating a stable open circuit voltage of a battery has been disclosed.
The stable open circuit voltage must be measured by leaving it for a long time in an open state after charging. In normal use conditions, the stable open circuit voltage had to be roughly measured. Further, the conventional calculation method using the difference in open-circuit voltage requires high accuracy for the A / D converter, has a large error, and is not practical.
According to the stable open circuit voltage calculation method disclosed in the present embodiment, a high accuracy is not required for the A / D converter, and the error with the measured value is small in a relatively short time. Voltage data can be obtained.
Based on the stable open circuit voltage data, the abnormal state of the battery cell can be detected with higher accuracy than before.
Based on the stable open circuit voltage data, the remaining capacity of the battery cell can be calculated with higher accuracy than before.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and other modifications may be made without departing from the gist of the present invention described in the claims. It goes without saying that application examples are included.

1 is a block diagram of a battery device according to an embodiment of the present invention. FIG. It is a functional block diagram which shows the function inside a microcomputer. It is a typical graph which shows typically the flow of the operation | movement called the charge of a typical battery, charge stop, discharge, and charge, the voltage between the terminals of the battery which changes in connection with it, and the change of charging / discharging current. It is the graph which measured the voltage and electric current at the time of conducting charge / discharge experiment to a lithium ion battery cell. It is the graph which measured the voltage and electric current at the time of conducting charge / discharge experiment to a lithium ion battery cell. It is an internal block diagram of the stable open circuit voltage measurement part. It is a flowchart which shows the flow of a process of the stable open circuit voltage measurement part. It is a flowchart which shows the flow of the process which measures a stable open circuit voltage. It is a flowchart which shows the flow of the process which measures a stable open circuit voltage. It is a block diagram which shows the use of the stable open circuit voltage value obtained by this embodiment. It is a figure which shows the mechanism which calculates an equilibrium voltage by a prior art. It is the graph which compared the stable open circuit voltage calculation method by a prior art, and the measured stable open circuit voltage.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Battery apparatus, 102 ... Battery main-body part, 103 ... Charge / discharge control part, 104 ... Cell, 105 ... Microcomputer, T106, T107, T108 ... Voltage detection terminal, T109 ... Negative terminal, R110 ... Current detection resistance, T111, T112 ... Current detection terminal, 113 ... Discharge FET, 114 ... Charge FET, T115 ... Plus terminal, 116 ... Internal discharge control FET, R117 ... Discharge current limiting resistor, 202 ... First changeover switch, 203 ... Second changeover switch 204, 607 ... counter, 205 ... A / D converter, 206, 602 ... RAM, 207 ... charge / discharge determination unit, 208 ... charge control unit, 209 ... discharge control unit, 210 ... stable open circuit voltage measurement unit, 603 ... CUR @ CHG storage unit, 604... OCV storage unit, 605... CUR @ DHG storage , 606 ... CCV @ DHG storage unit, 608 ... stable open circuit voltage calculating unit

Claims (4)

A first step of detecting whether or not the battery is continuously charged for a predetermined time;
In the first step, a second step of obtaining a charging current;
After the first step and the second step, a third step of stopping charging and bringing the battery into a no-load state;
After the third step, waiting for the elapse of a predetermined time, and acquiring the open circuit voltage of the battery;
A fifth step of connecting a predetermined load to the battery after the fourth step, and further acquiring a discharge voltage and a discharge current of the battery after a predetermined time;
A method for calculating a stable open circuit voltage of a battery, comprising: a sixth step of calculating a stable open circuit voltage of the battery based on the charging current, the open circuit voltage, the discharge voltage and the discharge current. .   2. The battery according to claim 1, wherein the sixth step is a value obtained by adding an element of a ratio between the charging current and the discharging current to an intermediate value between the open-circuit voltage and the discharging voltage. Stable open circuit voltage calculation method. A voltage detector for detecting the voltage across the battery;
A current detector for detecting the current of the battery;
A memory for sequentially recording voltage data and current data obtained from the voltage detection unit and the current detection unit;
A charge / discharge determination unit that determines whether the battery is currently in a charged state, a discharged state, or a no-load state from current data recorded in the memory;
A stable open circuit voltage measuring unit that is connected to the memory and the charge / discharge determination unit and calculates a stable open circuit voltage of the battery based on the voltage data and the current data held in the memory;
A discharge control switch controlled by the stable open circuit voltage measurement unit;
An abnormal state detection unit that detects the abnormal state of the battery by comparing the stable open circuit voltage data obtained from the stable open circuit voltage measurement unit with a threshold value;
A battery device comprising: a protection mechanism control switch that obtains an output signal of the abnormal state detection unit and turns on a predetermined protection mechanism. A voltage detector for detecting the voltage across the battery;
A current detector for detecting the current of the battery;
A memory for sequentially recording voltage data and current data obtained from the voltage detection unit and the current detection unit;
A charge / discharge determination unit that determines whether the battery is currently in a charged state, a discharged state, or a no-load state from current data recorded in the memory;
A stable connected to the memory and the charge / discharge determination unit, and based on the voltage data and the current data held in the memory, calculates a stable open circuit voltage of the battery and outputs stable open circuit voltage data An open circuit voltage measurement unit;
A portable electronic device connected to a battery device, comprising a discharge control switch controlled by the stable open circuit voltage measurement unit,
An electronic apparatus, wherein the remaining capacity of the battery is recalculated based on the stable open circuit voltage data obtained from the stable open circuit voltage measurement unit.

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