JP2009041998A - Method and device for detecting storage capacity of secondary cell, and the charger of secondary cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for detecting the storage capacity of a secondary cell which enable calculation of the storage capacity of the secondary cell in a short time at any time, not only at charging, and also at checking of a state of deterioration of the secondary cell from the storage capacity, and to provide a charger. <P>SOLUTION: An external voltage V<SB>a</SB>, equal to or larger than an electromotive force E, is impressed on the secondary cell 10, and a cell terminal voltage V<SB>ON</SB>at impression and a current J<SB>ON</SB>then are measured, respectively. The external voltage V<SB>a</SB>being cut off, an open-circuit cell terminal voltage V<SB>OFF</SB>of the secondary cell 10 is measured and the storage capacity Q of the secondary cell is determined by using the cell terminal voltage V<SB>ON</SB>, the above current J<SB>ON</SB>and the open-circuit cell terminal voltage V<SB>OFF</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a secondary battery storage capacity detection method, a secondary battery storage capacity detection device, and a secondary battery charger technology, and in particular, calculates the storage capacity of a currently used battery in a short time. The present invention relates to a secondary battery storage capacity detection method, a secondary battery storage capacity detection device, and a secondary battery charger technology.

Secondary batteries such as nickel cadmium batteries, nickel metal hydride batteries, and lithium ion batteries are batteries that can be used repeatedly by repeating discharge and charge cycles.
However, if the secondary battery is charged a plurality of times, the storage capacity of the secondary battery is reduced compared to the initial stage due to overcharge, deterioration of the electrolyte solution or electrode plate of the secondary battery, etc. As the battery deteriorates, the secondary battery can no longer be used.
Here, the deterioration due to charging and discharging of the secondary battery will be described using a lithium ion battery which is an example of the secondary battery.
The lithium ion battery is composed of an anode plate, a cathode plate, an electrolytic solution, and the like. At the time of discharge, lithium ions Li ⁺ and electrons e ⁻ are emitted from the cathode, and lithium ions Li ⁺ and electrons e ⁻ are absorbed at the anode. Lithium ion Li ⁺ is exchanged between the two electrodes via the electrolytic solution, and electrons are exchanged via the circuit, whereby a current flows through the circuit and is discharged.
On the other hand, at the time of charging, conversely, lithium ions Li ⁺ and electrons e ⁻ are emitted from the anode, and lithium ions Li ⁺ and electrons e ⁻ are absorbed at the cathode. Lithium ion Li ⁺ is exchanged between the two electrodes via the electrolytic solution, and electrons are exchanged via the circuit, whereby a current flows through the circuit and is charged.
In the process of discharging and charging, an internal resistance (internal impedance) is generated in the secondary battery. Possible causes of the internal resistance include an increase in resistance in lithium ion Li ⁺ electrophoresis, a decrease in reaction rate, a decrease in diffusion rate, and a decrease in the number of lithium ion Li ⁺ sites at the anode and cathode. The internal resistance increases due to repeated charging and discharging, and as a result, deterioration of the secondary battery proceeds.
Conventionally, the degree of deterioration of the secondary battery has been detected by measuring the temperature change rate of the secondary battery and comparing it with the temperature change of the non-degraded secondary battery (see Patent Document 1). . However, in the conventional method, it is necessary to continuously measure the temperature change for a long time, and when the temperature of the battery is measured, it may be affected by the outside air temperature, etc., and the degree of deterioration is detected with high accuracy. I couldn't. Further, although it can be detected whether or not it has deteriorated, it has not been possible to detect how much deterioration has progressed compared to a secondary battery that has not deteriorated.

Conventionally, in intermittent charging, the difference (difference voltage) between the open circuit battery terminal voltage released from the charging circuit and the maximum threshold voltage at full charge is detected, and the difference voltage is compared with a predetermined threshold value. And the technique which determines deterioration of a battery based on the comparison result is known (refer patent document 2). However, in the prior art, the deterioration of the battery is determined only at the time of intermittent charging, and the deterioration of the secondary battery is determined while using the secondary battery or after discharging using the secondary battery. I couldn't. In addition, the deterioration of the battery can be determined only by the comparison result with a predetermined threshold value, and the value of the storage capacity cannot be specifically confirmed.
Japanese Patent No. 3913443 Japanese Patent No. 3539123

  Therefore, in view of such problems, the present invention can calculate the storage capacity of the secondary battery in a short time at any time, not only at the time of charging, and can check the deterioration state of the secondary battery from the storage capacity. A storage capacity detection method, a secondary battery storage capacity detection device, and a secondary battery charger are provided.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, in the first aspect, to apply an electromotive force E more external voltage V _a to the secondary battery, the secondary battery of the applied when the battery terminal voltage V _ON is applied when the current J _ON and were respectively measured, the blocks the external voltage V _a, the secondary open circuit battery terminal voltage V _OFF measures the battery, using the the applied when the battery terminal voltage V _ON and applied during current J _ON and the open circuit battery terminal voltage V _OFF The storage capacity Q of the secondary battery represented by the following formula is calculated.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.

In claim 2, the current in the energy storage capacitance detection device for a secondary battery for detecting a battery capacity, voltage supply means for applying an electromotive force E more external voltage V _a to the secondary battery of the secondary battery, the secondary A voltage measuring means for measuring a battery terminal voltage of the battery, a current measuring means for measuring a current flowing through the secondary battery, a voltage switching means for switching an application state from the voltage supply means to the secondary battery, and a secondary battery A storage capacity calculation means for calculating the storage capacity, and when the external voltage is applied from the voltage supply means, the voltage measuring means applies a battery terminal voltage V _ON when the secondary battery is applied, and the current The measuring means measures the current J _ON when the secondary battery is applied, and switches the voltage switching means to cut off the external voltage applied to the secondary battery, thereby opening the open circuit battery terminal voltage V _{OFF of the} secondary battery. Measure The storage capacity detection means calculates the storage capacity Q of the secondary battery expressed by the following equation using the applied battery terminal voltage V _ON , applied current J _ON , and open circuit battery terminal voltage V _OFF. It is.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.

In claim 3, in the charger of the rechargeable battery to be charged by applying a voltage to the secondary battery, and voltage supply means for applying a force E more external voltage V _a to the secondary battery, the secondary battery Voltage measuring means for measuring the battery terminal voltage, current measuring means for measuring the current flowing through the secondary battery, voltage switching means for switching the application state from the voltage supply means to the secondary battery, and the storage capacity of the secondary battery A storage battery capacity calculating means for calculating the secondary battery, and when the secondary battery is charged, an external voltage is applied from the voltage supply means when the secondary battery is applied by the voltage measuring means. The voltage V _ON and the current J _ON when the secondary battery is applied are respectively measured by the current measuring means, and the external voltage applied to the secondary battery is cut off by switching the voltage switching means. Open circuit battery terminal voltage _{VO The FF} is measured, and the storage capacity calculation unit calculates the storage capacity Q of the secondary battery expressed by the following formula using the applied battery terminal voltage V _ON , the applied current J _ON , and the open circuit battery terminal voltage V _OFF. Is calculated.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.

  According to a fourth aspect of the invention, there is provided a soundness degree calculating means for calculating a soundness degree indicating a deterioration state with respect to the charge / discharge cycle of the secondary battery.

  According to a fifth aspect of the invention, there is provided display means for displaying a soundness level indicating a storage capacity of the secondary battery and a deterioration state with respect to a charge / discharge cycle of the secondary battery.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect, it is possible to calculate the current storage capacity of the secondary battery, which greatly changes depending on the usage history and the secular change, in a short time. Moreover, the storage capacity of the secondary battery can be calculated not only when fully charged, but also when the secondary battery is used or after the secondary battery has been discharged.

  In claim 2, it is possible to calculate in a short time the current storage capacity of a secondary battery that greatly changes due to usage history, secular change, it is possible to preset the replacement time of the battery from the current storage capacity, Suddenly, it is possible to prevent the battery from reaching the end of its life and becoming unusable.

  According to the third aspect of the present invention, in particular, in a device in which the secondary battery is always set in the charger, the device can be used in a planned manner by measuring how the storage capacity has changed from the initial storage capacity. . In addition, by measuring the current storage capacity, charging can be stopped before overcharging occurs.

  In Claim 4, optimal and sound battery management can be performed by monitoring the deterioration state of a battery.

  According to the fifth aspect, the storage capacity of the secondary battery can be easily grasped by measuring how the storage capacity of the secondary battery has changed and displaying it on the display unit.

Next, embodiments of the invention will be described.
1 is a circuit diagram of a storage capacity detection device, FIG. 2 is a block diagram of the storage capacity detection device, and FIG. 3 is a perspective view of the storage capacity detection device. 4A is a conceptual diagram showing the state of the secondary battery during discharging, FIG. 4B is a conceptual diagram showing the state of the secondary battery during charging, FIG. 5 is a conceptual diagram showing an equivalent circuit of the battery element, and FIG. Fig. 7 is a graph showing the relationship between the voltage of the secondary battery and time, Fig. 7 is a flowchart showing the flow of measurement of the current flowing through the secondary battery and the voltage of the secondary battery, and Fig. 8 is the current flowing through the secondary battery and the secondary battery. FIG. 9 is a flowchart of the battery voltage measurement flow, FIG. 9 is a circuit diagram of the charger, and FIG. 10 is a block diagram of the charger.

[Storage capacity detector]
A secondary battery storage capacity detection apparatus using the secondary battery storage capacity detection method will be described.
As shown in FIGS. 1 and 2, the storage capacity detection device 1 includes a circuit 2 for measuring an internal resistance R, and includes an external power source 12 as a voltage supply means and a voltmeter 13 as a voltage measurement means. From the ammeter 14 as the current measuring means, the circuit switch 15 as the voltage switching means for switching the application state to the secondary battery 10, the control device 16 as the storage capacity calculating means for calculating the storage capacity Q, the display unit 17, etc. Become. As shown in FIG. 2, a voltmeter 13 and an ammeter 14 are connected to the control device 16 on the input side, and a circuit switch 15 and a display unit 17 are connected to the output side.
As shown in FIG. 3, the storage capacity detection device 1 is provided with a lead 18 for connecting to a secondary battery whose current storage capacity Q is desired to be detected. The lead wire 18 is connected to the circuit 2 in the storage capacity detection device 1, and the secondary battery 10 is connected to the lead wire 18 by connecting the secondary battery 10 for which the current storage capacity Q is to be calculated. 2 can be connected.

  Next, a method for detecting the storage capacity Q of the secondary battery 10 using the storage capacity detection device 1 will be described.

[Principle of secondary battery]
First, the principle of the secondary battery 10 will be described using a lithium ion battery which is an example of the secondary battery 10. The electrochemical principle of other secondary batteries such as lead batteries and nickel metal hydride batteries is the same.

As shown in FIG. 4, the secondary battery 10 is composed of a cathode 21, an anode 22, an electrolyte solution 23, and the like. At the time of discharging, as shown in FIG. 4A, the anode 22 is higher than the cathode 21 having a higher ion potential. Lithium ions Li ⁺ and electrons e ⁻ are emitted to the anode, and lithium ions Li ⁺ and electrons e ⁻ are absorbed by the anode 22. At this time, the lithium ion Li ⁺ is exchanged between the two electrodes via the electrolytic solution 23, and the electron e ⁻ is exchanged via the circuit 24, whereby a current flows from the anode 22 to the cathode 21 in the circuit 24 and is discharged. The Rukoto.
On the other hand, at the time of charging, as shown in FIG. 4B, lithium ions Li ⁺ and electrons e ⁻ are emitted from the anode 22 whose ion potential has been increased by applying an external voltage to the cathode 21, and lithium ions are emitted from the cathode 21. Li ⁺ and electrons e ⁻ are absorbed. At this time, the lithium ion Li ⁺ is exchanged between the two electrodes via the electrolytic solution 23, and the electron e ⁻ is exchanged via the circuit 24, whereby a current flows from the cathode 21 to the anode 22 in the circuit 24, and the secondary The battery 10 is charged.

Next, the electromotive force E of the secondary battery 10 will be described. The electromotive force E means a battery terminal voltage when the secondary battery 10 is not connected to an external circuit and no current flows. That is, the electromotive force E is not the flow of lithium ions Li ⁺ or electrons e ⁻ , but an ion potential difference between the cathode 21 and the anode 22. Therefore, the ion potential difference is represented by the difference in the occupation ratio of the lithium ion Li ⁺ site between the cathode 21 and the anode 22.

Next, the storage capacity Q of the secondary battery 10 will be described. The storage capacity Q means the size of the space where the lithium ions Li ⁺ are stored in the cathode. That is, the large storage capacity Q means that the volumes of the cathode 21 and the anode 22 are large (the number of sites is large), the working surface is large, and the lithium ion Li ⁺ permeates into both electrodes quickly and often. Means.
The storage capacity Q decreases as the secondary battery 10 deteriorates. The deterioration of the secondary battery 10 means that the internal resistance (internal impedance) R increases and the lithium ion Li ⁺ does not contact the battery electrode and does not function. Possible causes of the increase in the internal resistance R include an increase in resistance in lithium ion Li ⁺ electrophoresis, a decrease in reaction rate, a decrease in diffusion rate, and a decrease in the number of lithium ion Li ⁺ sites at the anode and cathode. . The internal resistance R increases due to repeated charging and discharging, and as a result, the secondary battery 10 deteriorates.

[Relationship between storage capacity and internal resistance]
Next, the relationship between the storage capacity Q and the internal resistance (internal impedance) R will be described.
Assuming that the minute working surface element that forms a pair of the cathode 21 and the anode 22 is dS, the battery element can be represented by an equivalent circuit by this dS as shown in FIG.
Here, the conductance ρ, which means the ease of current flow in the circuit per unit action area, is r, where the resistance per unit area is r.
ρ = 1 / r
When the effective working area is S, the internal resistance R is
R = 1 / ∫ρdS = 1 / ρS = r / S
It is represented by In addition, the storage capacity Q of the entire area is q, where the electric capacity per unit area is q.
Q = ∫qdS = qS
It is represented by From the above formula,
QR = qr = K
The relationship is obtained. Here, K is a constant determined by the type of the secondary battery.
That is, in the same type of secondary batteries having different storage capacities Q, the value obtained by multiplying the storage capacities Q and the internal resistance R is constant. Therefore, a battery with a large storage capacity Q has a small internal resistance R in inverse proportion, As the internal resistance R increases, the storage capacity Q decreases in inverse proportion. Further, when the effective working area S decreases, the storage capacity Q decreases while the internal resistance R increases. Therefore, by calculating the internal resistance R, the storage capacity Q can be calculated using the value of K.

[Calculation of internal resistance]
Next, a method for calculating the internal resistance R using the storage capacity detection device 1 will be described.
Wherein by the circuit switch 15 when the "ON" secondary battery 10 and the power supply 12 is connected, has a configuration for applying an external voltage V _a to the secondary battery 10. The external voltage V needs to be higher than the open circuit battery terminal voltage V _{OFF of the} secondary battery 10 that measures the storage capacity Q.
Open circuit in the case where the case of the circuit switch 15 to "ON", i.e. applied when the battery terminal voltage V _ON and the applied time of the current J _ON when hanging the external voltage V _a, the circuit switch 15 to the "OFF" When the battery terminal voltage V is _OFF , the internal resistance R is
R = (V _ON −V _OFF ) / J _ON
It is represented by
From the above, the current storage capacity Q is
Q = K / R = K × J _ON / (V _ON −V _OFF )
Can be calculated.

[Method of measuring voltage and current]
Next, a method of measuring the applied battery terminal voltage V _ON , applied current J _ON , and open circuit battery terminal voltage V _OFF will be described with reference to FIGS.
First, a method of measuring the time of transition from the state where the external voltage V _a is not applied to a state in which the external voltage V _a is applied with reference to FIGS.
First, to measure the state of the circuit switch 15 is "OFF", i.e. the open-circuit battery terminal voltage V _OFF at the time the external voltage V _a is not applied T1 (see FIG. 6) by the voltmeter 13 (Step S10). Subsequently, to the circuit switch 15 to "ON" (step S20), the application time of the battery terminal voltage _{V ON} time external voltage _{V a} is applied T2 (see FIG. 6) by the voltmeter 13, applied The hourly current J _ON is measured by the ammeter 14 (step S30). Here, T2 is not a moment when an external voltage is applied V _a, which is a predetermined time t1 elapses after applying an external voltage V _a. Thereby, it becomes possible to measure the respective values at the time the shaking had subsided the value of the voltage and current generated at the moment of applying an external voltage V _a.
Next, a method for measuring the time of transition from the state where the external voltage V _a is applied to a state in which the external voltage V _a is not applied with reference to FIGS. 6 and 8.
First, the state of the circuit switch 15 is "ON", namely the external voltage V when _a is applied T3 the voltmeter 13 applied when the battery terminal voltage V _ON (see FIG. 6), upon application measuring the current _{J oN} by the ammeter 14 (step S110), subsequently, the circuit switch 15 in the "OFF" (step S120), when the external voltage _{V a} is not applied T4 (see FIG. 6) The open circuit battery terminal voltage V _OFF is measured by the voltmeter 13 (step S130). Here, T4 is not the moment of blocking the external voltage V _a, which is a predetermined time t2 elapses after the blocking the external voltage V _a. This makes it possible to measure the voltage at the time the shaking had subsided the value of the voltage and current generated at the moment of blocking the external voltage V _a. However, the voltage of the secondary battery, since gradually decreases from the moment of blocking the external voltage V _a, wherein the predetermined time t2 is required longer than the predetermined time t1.
By measuring the applied battery terminal voltage V _ON , applied current J _ON and open circuit battery terminal voltage V _OFF by the above-described method, the constant K is a constant value determined by the type of the secondary battery. The current storage capacity Q can be calculated. The constant K is, for example, 0.156 [Ah · Ω] if the secondary battery is a lithium ion battery.

  By configuring in this way, it is possible to measure the current storage capacity Q of the secondary battery 10 that changes greatly according to usage history and secular change in a short time, and the replacement time of the secondary battery can be determined from the current storage capacity Q. It can be set in advance, and it can be prevented that the secondary battery 10 suddenly reaches the end of its life and the device cannot be used or the memory disappears.

As described above, the power storage capacity detecting method for a secondary battery of the present embodiment, by applying a force E more external voltage V _a to the secondary battery, is applied and the applied time of the battery terminal voltage V _ON of the rechargeable battery measuring respectively the current J _ON time, to cut off the external voltage V _a, to measure the open-circuit battery terminal voltage V _OFF of the secondary battery, wherein the applied when the battery terminal voltage V _ON and applied during current J _ON The storage capacity Q of the secondary battery expressed by the following equation is calculated using the open circuit battery terminal voltage V _OFF .
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.
By configuring in this way, it is possible to calculate the current storage capacity of the secondary battery, which greatly changes depending on the usage history and the secular change, in a short time. Moreover, the storage capacity of the secondary battery can be calculated not only when fully charged, but also when the secondary battery is used or after the secondary battery has been discharged.

In addition, the storage capacity detection device 1 of the present embodiment is the same as the storage capacity detection device 1 of the secondary battery 10 that detects the current storage capacity of the secondary battery 10. _a power source 12 for applying _a , a voltmeter 13 for measuring a battery terminal voltage of the secondary battery 10, an ammeter 14 for measuring a current flowing through the secondary battery 10, and an application state from the power source 12 to the secondary battery a circuit switch 15 for switching the secondary battery becomes 10 and a control unit 16 which calculates the power storage capacity, with the external voltage V _a is applied from the power source 12, the voltmeter 13 by a secondary battery interrupting the application when the battery terminal voltage V _oN, by the ammeter 14 measures the application time of the current J _oN of the secondary battery, respectively, the external voltage V _a applied to the secondary battery by switching the circuit switches 15 Secondary power The open-circuit battery terminal voltage _{V OFF} of 10 is measured, by the control device 16, represented by the following equation using applied when the battery terminal voltage _{V ON,} applied during current _{J ON,} and the open-circuit battery terminal voltage _{V OFF} The storage capacity Q of the secondary battery is calculated.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.
By configuring in this way, it is possible to calculate the current storage capacity of a secondary battery that changes greatly due to usage history and secular change in a short time, and it is possible to preset the replacement time of the battery from the current storage capacity It is possible to prevent the sudden use of the device due to sudden battery life.

[Charger]
Next, the secondary battery charger 40 using the method for detecting the storage capacity of the secondary battery 10 will be described. This embodiment uses the same secondary battery storage capacity detection method as that of the first embodiment described above, and differs from the first embodiment in that such a detection method is adopted for the charger 40.
As shown in FIG. 9, the charger 40 performs charging by applying a voltage to the secondary battery 10 from the outside, and obtains the internal resistance R of the secondary battery 10 to obtain the secondary battery 10. The storage capacity Q of the battery 10 is calculated and displayed. The charger 40 includes a power supply 41 as voltage supply means, a voltmeter 42 as voltage measurement means, an ammeter 43 as current measurement means, a circuit switch 44 as voltage switching means for switching the application state to the secondary battery, A control device 45 serving as a storage capacity calculation unit that calculates the capacity, a display unit 46 serving as a display unit that displays the storage capacity, and a storage device 47 that stores the initial storage capacity are provided.
As shown in FIG. 10, a voltmeter 42 and an ammeter 43 are connected to the control device 45 on the input side, and a circuit switch 44 and a display unit 46 are connected to the output side. In addition, a storage device 47 is connected to the control device 45, and is configured to mutually input and output information.
It has been found that the internal resistance R takes a substantially constant value until the end of charging. At the end of charging, the internal resistance R generally increases with an irreversible chemical reaction. Therefore, if the charging rate is up to about 70%, the inherent internal resistance R of the secondary battery can be accurately calculated, so that the current storage capacity Q of the secondary battery 10 can be calculated.
To calculate the charge capacity Q of the rechargeable battery 10, the time the charge rate from the initial stage of charging is 70%, when the circuit switch 44 to "ON", i.e. it takes external voltage V _a measures applied when the battery terminal voltage V _oN when voltmeter 42 are, applied during the current J _oN measured by the ammeter 43, when the circuit switch 44 to "OFF", i.e. to cut off the external voltage V _a In this case, the open circuit battery terminal voltage V _OFF is measured by the voltmeter 42.

The storage capacity Q of the secondary battery 10 is calculated by temporarily switching the circuit switch 44 “ON” or “OFF” during charging. That is, during normal, by continuing continuously or intermittently applied from an external power source 41 external voltage V _a to the secondary battery 10 it was charged, "ON" of the circuit switch 44 at the time of calculation of the energy storage capacity Q By temporarily switching “OFF”, the applied battery terminal voltage V _ON , applied current J _ON and open circuit battery terminal voltage V _OFF are measured. As a result, in a device that always sets the secondary battery 10 in the charger 40, for example, an electric vehicle equipped with a charger, it is possible to sequentially measure how the storage capacity has changed from the beginning.

[Calculation of SOH (health level)]
Next, SOH (State Of Health) that is an index indicating the progress of deterioration of the secondary battery 10 will be described.
In the charger 40 of this embodiment, the control device 45 calculates SOH, which is a soundness level indicating a deterioration state with respect to the charge / discharge cycle of the secondary battery. The SOH is an index indicating the progress of deterioration of the battery, and is expressed as a ratio of the current storage capacity to the initial storage capacity. When the initial storage capacity is Q ₀ ,
SOH = (Q / Q ₀ ) × 100
Can be calculated.
That is, by calculating the initial storage capacity Q ₀ in advance, the SOH can be obtained from the current storage capacity Q.
In the charger 40, first, the initial storage capacity is determined from the values of the applied battery terminal voltage V _ON , applied current J _ON , and open circuit battery terminal voltage V _OFF measured when starting use of the secondary battery. Q ₀ is calculated, and the initial storage capacity Q ₀ is stored in the storage device 47. Then, a current storage capacity Q is calculated from values of the applied battery terminal voltage V _ON , applied current J _ON , and open circuit battery terminal voltage V _OFF measured after the secondary battery is used, and the storage device 47 The initial storage capacity Q ₀ is called, and the control device 45 calculates SOH.

With this configuration, the control device 45 of the charger 40 calculates the current storage capacity Q and SOH of the secondary battery, and outputs them to the display unit 46 for display. In addition to the storage capacity Q and SOH, the display unit 46 can also display the battery terminal voltage V _ON when applied and the open circuit battery terminal voltage V _OFF when the circuit switch is turned “OFF”. is there.

  The circuit can also be used for quality control of the battery in the secondary battery production process. That is, it is possible to prevent the outflow of defective products by detecting the storage capacity of the secondary battery before shipment.

As described above, the charger 40 of the secondary battery 10 according to the present embodiment is such that the secondary battery 10 is charged by applying a voltage to the secondary battery 10, and the secondary battery 10 has an electromotive force E or higher. A power source 41 for applying the external voltage Va, _a voltmeter 42 for measuring the battery terminal voltage of the secondary battery 10, an ammeter 43 for measuring the current flowing through the secondary battery 10, and the secondary battery from the power source 41. 10 is provided with a circuit switch 44 for switching the application state to the battery 10 and a control device 45 for calculating the storage capacity of the secondary battery 10. When the secondary battery 10 is charged, the external voltage V _{a is} supplied from the power source 41. Is applied, the voltmeter 42 measures the battery terminal voltage V _ON when the secondary battery 10 is applied, and the ammeter 43 measures the current J _ON when the secondary battery 10 is applied, and the circuit switch 44 to change the secondary battery Blocks the external voltage _{V a} applied to the 10 measures the open-circuit battery terminal voltage _{V OFF} of the secondary battery 10, by the control device 45, is applied when the battery terminal voltage _{V ON,} applied during current _{J ON} , And the open circuit battery terminal voltage V _OFF is used to calculate the storage capacity Q of the secondary battery expressed by the following equation.
Q = K × J _ON / (V _ON −V _OFF )
However, K is a constant determined by the type of battery. By configuring in this way, it is possible to determine how the storage capacity has changed from the initial storage capacity, especially in devices where secondary batteries are always set in the charger. By measuring, the device can be used in a planned manner. In addition, by measuring the current storage capacity, charging can be stopped before overcharging occurs.

The charger 40 includes a control device 45 that calculates a soundness level SOH indicating a deterioration state of the secondary battery 10 with respect to the charge / discharge cycle. By configuring in this way, optimal and sound battery management can be performed by monitoring the deterioration state of the battery.
The charger 40 includes a display unit 46 that displays a storage capacity Q of the secondary battery 10 and a soundness level SOH indicating a deterioration state with respect to a charge / discharge cycle of the secondary battery 10. By configuring in this way, it is possible to easily grasp the storage capacity of the secondary battery by measuring how the storage capacity of the secondary battery has changed and displaying it on the display unit.

The circuit diagram of a storage capacity detection apparatus. The block diagram of an electrical storage capacity detection apparatus. The perspective view of an electrical storage capacity detection apparatus. (A) The conceptual diagram which shows the state of the secondary battery at the time of discharge (b) The conceptual diagram which shows the state of the secondary battery at the time of charge. The conceptual diagram which shows the equivalent circuit of a battery element. The graph which shows the voltage of a secondary battery, and the relationship of time. The flowchart figure which shows the flow of a measurement of the electric current which flows into a secondary battery, and the voltage of a secondary battery. The flowchart figure which shows the flow of a measurement of the electric current which flows into a secondary battery, and the voltage of a secondary battery. The circuit diagram of a charger. The block diagram of a charger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacity detection apparatus 10 Secondary battery 12 External power supply 13 Voltmeter 14 Ammeter 15 Circuit switch 16 Control apparatus 40 Charger 41 External power supply 42 Voltmeter 43 Ammeter 44 Circuit switch 45 Control apparatus 46 Display part

Claims (5)

Apply an external voltage (V _a ) greater than the electromotive force (E) to the secondary battery, and measure the battery terminal voltage (V _ON ) and the applied current (J _ON ) when the secondary battery is applied,
_{Cut off the} external voltage (V _a ), measure the open circuit battery terminal voltage (V _OFF ) of the secondary battery,
Using the applied battery terminal voltage (V _ON ), applied current (J _ON ), and open circuit battery terminal voltage (V _OFF ) to calculate the storage capacity (Q) of the secondary battery expressed by the following equation: A method for detecting a storage capacity of a secondary battery.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery. In the secondary battery storage capacity detection device that detects the current storage capacity of the secondary battery,
Voltage supply means for applying an external voltage (V _a ) equal to or higher than the electromotive force (E) to the secondary battery;
Voltage measuring means for measuring the battery terminal voltage of the secondary battery;
Current measuring means for measuring the current flowing in the secondary battery;
Voltage switching means for switching the application state from the voltage supply means to the secondary battery;
A storage capacity calculation means for calculating the storage capacity of the secondary battery;
In a state where a voltage is applied from the voltage supply means, a battery terminal voltage (V _ON ) when the secondary battery is applied by the voltage measurement means, and a current (J _ON ) when the secondary battery is applied by the current measurement means Measure each
Switching the voltage switching means to cut off the voltage applied to the secondary battery, and measuring the open circuit battery terminal voltage (V _OFF ) of the secondary battery,
The storage capacity of the secondary battery expressed by the following equation using the battery terminal voltage (V _ON ) when applied, the current (J _ON ) when applied, and the open circuit battery terminal voltage (V _OFF ) by the storage capacity calculation means (Q) is calculated, The storage capacity detection apparatus of the secondary battery characterized by the above-mentioned.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery. In a secondary battery charger that charges a secondary battery by applying a voltage,
Voltage supply means for applying an external voltage (V _a ) equal to or higher than the electromotive force (E) to the secondary battery;
Voltage measuring means for measuring the battery terminal voltage of the secondary battery;
Current measuring means for measuring the current flowing in the secondary battery;
Voltage switching means for switching the application state from the voltage supply means to the secondary battery;
A storage capacity calculation means for calculating the storage capacity of the secondary battery;
When charging the secondary battery,
In a state where a voltage is applied from the voltage supply means, a battery terminal voltage (V _ON ) when the secondary battery is applied by the voltage measurement means, and a current (J _ON ) when the secondary battery is applied by the current measurement means Measure each
Switching the voltage switching means to cut off the voltage applied to the secondary battery, and measuring the open circuit battery terminal voltage (V _OFF ) of the secondary battery,
The storage capacity of the secondary battery expressed by the following equation using the battery terminal voltage (V _ON ) when applied, the current (J _ON ) when applied, and the open circuit battery terminal voltage (V _OFF ) by the storage capacity calculation means (Q) is calculated, The battery charger of the secondary battery characterized by the above-mentioned.
Q = K × J _ON / (V _ON −V _OFF )
Where K is a constant determined by the type of battery.   The charger for a secondary battery according to claim 3, further comprising a soundness calculation means for calculating a soundness level indicating a deterioration state with respect to a charge / discharge cycle of the secondary battery. The secondary battery charger according to claim 4, further comprising display means for displaying a storage capacity of the secondary battery and a soundness degree indicating a deterioration state with respect to a charge / discharge cycle of the secondary battery.

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