JP2018156768A - Secondary battery reuse judgment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of determining whether or not a secondary battery can be reused. A determination system (3) includes a determination device (300) that controls an inverter (310) and a converter (320) configured to charge and discharge an assembled battery (10). The determination device 300 relates to (1) the full charge capacity of the assembled battery 10, the leaving period T in which the secondary battery is left without being charged and discharged, and the SOC and the temperature Tb of the assembled battery 10 during the leaving period T. Information is acquired, and (2) the standing resistance Rh indicating the increase amount of the internal resistance of the assembled battery 10 in the standing period T is estimated using the above information, and (3) the standing resistance Rh is determined according to the refresh condition determined by the standing resistance Rh. The inverter 310 and the converter 320 are controlled to execute refresh charge/discharge for reducing Rh, and (4) the internal resistance R of the battery pack 10 is estimated after execution of the refresh charge/discharge, and the estimated internal resistance R is It is determined whether or not the assembled battery 10 can be reused. [Selection diagram] Fig. 4

Description

  The present disclosure relates to a secondary battery reuse determination system, and more particularly to a technique for determining whether or not a recovered secondary battery can be reused.

  An electric vehicle such as a hybrid vehicle and an electric vehicle is equipped with an assembled battery for traveling. This assembled battery deteriorates as time passes or the mileage increases. For example, when the battery pack is discarded, the battery pack is removed from the electric vehicle and collected, and it is determined whether or not the battery pack can be reused according to the progress of the deterioration.

  Various techniques have been proposed for this determination method. For example, Japanese Patent Laying-Open No. 2014-020818 (Patent Document 1) is a technique for determining whether or not an assembled battery can be reused by using the open voltage, internal resistance value, and full charge capacity of the assembled battery as evaluation parameters. Disclose.

JP, 2014-020818, A JP 2011-247841 A JP 2010-04-5002 A

  Generally, in the determination of reuse of an assembled battery, an internal resistance is used as one of parameters for evaluating the progress of deterioration of the assembled battery (see, for example, Patent Document 1). More specifically, when the internal resistance of the assembled battery is less than a predetermined threshold value, it is determined that the assembled battery can be reused. When the internal resistance of the assembled battery is equal to or greater than the threshold value, the assembled battery is determined. It is determined that the battery cannot be reused.

  Here, when the assembled battery is left without being charged / discharged (for example, when it is left for several hours to several tens of hours or more), a phenomenon may occur in which the internal resistance of the assembled battery increases with time. It is known. Hereinafter, the increase in the internal resistance is also referred to as “standing resistance”.

  The inventor paid attention to the influence of neglected resistance in the determination of reuse of the assembled battery. The neglected resistance is not necessarily maintained once it occurs, but is reduced according to the state of charge (SOC) change after the assembled battery is left (that is, after charging and discharging of the assembled battery). Can be resolved). If this is not taken into consideration, it may not be possible to accurately determine whether or not the assembled battery can be reused.

  The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to recycle the assembled battery in a reuse determination system that determines whether or not the collected assembled battery (secondary battery) can be reused. It is to improve the accuracy of determining whether or not it can be used.

  A system according to an aspect of the present disclosure is a secondary battery reuse determination system that determines whether or not a recovered secondary battery can be reused. The reuse determination system includes a charge / discharge device configured to be able to charge / discharge a secondary battery, and a control device that controls the charge / discharge device. The control device includes (1) the full charge capacity of the secondary battery, the leaving period in which the secondary battery is left without being charged / discharged, the SOC (State Of Charge) and the temperature of the secondary battery during the leaving period, (2) Estimating the neglected resistance indicating the increase in the internal resistance of the secondary battery during the neglected period using the information, and (3) reducing the neglected resistance according to the conditions determined by the neglected resistance (4) The internal resistance of the secondary battery is estimated after execution of the refresh charge / discharge, and the internal resistance of the secondary battery is estimated using the estimated internal resistance. It is determined whether or not the secondary battery can be reused.

  Although the details will be described later, according to the above configuration, the neglected resistance of the secondary battery is estimated using various information (the above (1) and (2)). Then, refresh charge / discharge is executed according to the neglected resistance ((3) above). Thus, after the neglected resistance is sufficiently reduced (eliminated), in other words, it is possible to determine whether or not the secondary battery can be reused in a state where the influence of the neglected resistance is reduced (excluded) (the above (4) )). Therefore, it is possible to improve the accuracy of determining whether or not the secondary battery can be reused.

  According to the present disclosure, in the reuse determination system that determines whether or not the collected secondary battery can be reused, it is possible to improve the determination accuracy of whether or not the secondary battery can be reused.

It is a conceptual diagram for demonstrating reuse of a vehicle-mounted assembled battery. It is a figure which shows an example of a structure of each cell contained in an assembled battery. FIG. 2 is a circuit block diagram schematically showing a configuration of a determination system shown in FIG. 1. It is a flowchart for demonstrating the reuse method of the assembled battery in this Embodiment. It is a figure for demonstrating the relationship between the leaving period T of an assembled battery, and the leaving resistance Rh. It is a figure for demonstrating the relationship between the capacity deterioration rate of an assembled battery, and the leaving resistance Rh. It is a conceptual diagram which shows an example of the map in this Embodiment. It is a figure for demonstrating the determination method of the refresh condition of an assembled battery.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment]
In the embodiment described below, as an example of reusing a secondary battery, a case where an in-vehicle assembled battery is reused will be described. However, in the present disclosure, the use of the secondary battery that is a determination target of whether reuse is possible is not limited to in-vehicle use. Furthermore, the “secondary battery” according to the present disclosure is not limited to the assembled battery, and may be in the state of a single battery (cell).

<Reuse of in-vehicle assembled batteries>
FIG. 1 is a conceptual diagram for explaining the reuse of an in-vehicle assembled battery. Referring to FIG. 1, vehicle 1 is a hybrid vehicle, an electric vehicle, or a fuel vehicle. An assembled battery 10 for traveling is mounted on the vehicle 1. The assembled battery 10 is, for example, an assembled battery of a lithium ion secondary battery, and includes a plurality of cells 11 (see FIG. 2). The assembled battery 10 is removed from the vehicle 1 and collected at a dealer (dealer) or a repair shop.

  It is determined by the determination system 3 whether or not the collected battery pack 10 can be reused. The assembled battery determined to be reusable is mounted on another vehicle 2A or reused as a stationary assembled battery in the factory 2B. The usage of the stationary assembled battery is not particularly limited, and may be used in a house or a store. On the other hand, the assembled battery determined to be recyclable is recycled to recycle the material.

  The reuse of assembled batteries is roughly classified into reuse and rebuild. In the case of reuse, the collected assembled battery is shipped as a reuse product as it is after undergoing a shipping inspection. In the case of rebuilding, for example, the collected assembled battery is once disassembled into single cells. Among the disassembled unit cells, the unit cells that can be used as they are are combined to produce a new assembled battery. The newly manufactured assembled battery is shipped as a rebuilt product after undergoing a shipping inspection. In the embodiment described below, the reuse of the assembled battery includes reuse and rebuild.

<Configuration of assembled battery>
FIG. 2 is a diagram illustrating an example of the configuration of each cell 11 included in the assembled battery 10. The upper surface of the case 111 of the cell 11 is sealed with a lid 112. The lid body 112 is provided with a positive electrode terminal 113 and a negative electrode terminal 114. One end of each of the positive terminal 113 and the negative terminal 114 protrudes from the lid 112 to the outside. The other end of each of the positive electrode terminal 113 and the negative electrode terminal 114 is electrically connected to an internal positive electrode terminal and an internal negative electrode terminal (both not shown) inside the case 111.

  An electrode body 115 is accommodated inside the case 111 (in FIG. 2, the case 111 is seen through and indicated by a broken line). The electrode body 115 is formed, for example, by winding a positive electrode sheet 116 and a negative electrode sheet 117 that are stacked via a separator 118 into a cylindrical shape.

  The positive electrode sheet 116 includes a current collector foil and a positive electrode active material layer (a layer including a positive electrode active material, a conductive material, and a binder) formed on the surface of the current collector foil. Similarly, the negative electrode sheet 117 includes a current collector foil and a negative electrode active material layer (a layer including a negative electrode active material, a conductive material, and a binder) formed on the surface of the current collector foil. The separator 118 is provided in contact with both the positive electrode active material layer and the negative electrode active material layer. Electrode body 115 (positive electrode active material layer, negative electrode active material layer and separator 118) is impregnated with an electrolytic solution.

As materials for the positive electrode sheet 116, the negative electrode sheet 117, the separator 118, and the electrolytic solution, various conventionally known materials can be used. As an example, nickel is used for the positive electrode active material of the positive electrode sheet 116. The positive electrode active material further includes at least one of other metals such as cobalt, manganese, and aluminum in addition to nickel. The positive electrode active material may be lithium nickelate (LiNiO ₂ ). For the negative electrode sheet 117, for example, carbon is used. For the separator 118, for example, polyolefin is used. The electrolytic solution includes an organic solvent, lithium ions, and an additive.

  However, the material of the component of the cell 11 is not limited to the above material. Moreover, it is not essential that the electrode body 115 is a wound body, and the electrode body 115 may be a laminated body that is not wound. Furthermore, although the example of a square battery is shown in FIG. 2, the shape of each cell 11 can be made into arbitrary shapes, for example, a cylindrical battery may be sufficient.

<Leave battery pack>
In general, in the determination of reuse of an assembled battery, an internal resistance is used as one of parameters for evaluating the progress of deterioration of the assembled battery. More specifically, when the internal resistance of the assembled battery is less than a predetermined threshold (for example, Rth described later), it is determined that the assembled battery can be reused, and the internal resistance of the assembled battery is equal to or greater than the threshold. In this case, it is determined that the assembled battery cannot be reused.

  In the assembled battery 10, when the assembled battery 10 is left without being charged / discharged, a phenomenon may occur in which the internal resistance of the assembled battery 10 increases with time. This increase in internal resistance is referred to as “standing resistance Rh”.

  The inventor paid attention to the influence of the leaving resistance Rh in the determination of reuse of the assembled battery. If the leaving resistance Rh occurs once, the state is not necessarily maintained, but is reduced (cancelled) according to the SOC change mode after the leaving of the assembled battery 10 (that is, after the charging / discharging of the assembled battery 10 is started). Can be done. If this is not taken into consideration, it may not be possible to accurately determine whether or not the assembled battery 10 can be reused.

  Therefore, in the present embodiment, the leaving resistance Rh is estimated from various information by using the determination system 3. Furthermore, “refresh charge / discharge”, which is charge / discharge for reducing (eliminating) the standing resistance Rh, is executed in accordance with the condition determined by the estimated standing resistance Rh. Then, after the charging resistance Rh is sufficiently reduced (or eliminated) by executing this refresh charge / discharge, it is determined whether or not the assembled battery 10 can be reused. Thereby, as will be described below, the determination accuracy of whether or not the assembled battery 10 can be reused can be improved.

  FIG. 3 is a circuit block diagram schematically showing the configuration of the determination system 3 shown in FIG. Referring to FIG. 3, determination system 3 is configured such that assembled battery 10 collected from vehicle 1 can be installed. The determination system 3 includes a determination device 300, an inverter 310, a converter 320, a voltage sensor 330, a current sensor 340, and a temperature sensor 350.

  Inverter 310 responds to a command from determination device 300, converts AC power supplied from external power source (for example, system power source) 4 </ b> A into DC power, and charges assembled battery 10.

  Converter 320 performs voltage conversion of DC power discharged from battery pack 10 in response to a command from determination device 300, and supplies it to external load 4B. The external load 4B consumes power supplied from the assembled battery 10. The inverter 310 and the converter 320 correspond to a “charge / discharge device” according to the present disclosure.

  The voltage sensor 330 detects the voltage Vb of the assembled battery 10 (which may be a module including each cell 11 or a plurality of cells 11). The current sensor 340 detects the current Ib input / output to / from the assembled battery 10. The temperature sensor 350 detects the temperature Tb of the assembled battery 10. Each sensor outputs a signal indicating the detection result to the determination device 300.

  Although not shown, the determination device (control device) 300 includes a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output interface. The Based on the signals from the sensors, the determination device 300 estimates the degree of progress of the assembled battery 10 (including the neglected resistance Rh) by causing the CPU to read out and execute a program stored in the ROM in advance in the RAM. At the same time, refresh charge / discharge (refresh amount and refresh count) of the battery pack 10 is controlled.

  More specifically, the determination apparatus 300 includes a data acquisition unit 301, a charge / discharge control unit 302, a neglect resistance estimation unit 303, a refresh condition determination unit 304, a reusability determination unit 305, and a display unit 306. including.

  The data acquisition unit 301 receives signals from the respective sensors (the voltage sensor 330, the current sensor 340, and the temperature sensor 350), and various data (information) related to the assembled battery 10, more specifically, full charge of the assembled battery 10. Data regarding the capacity, the leaving period T in which the assembled battery 10 is left without being charged and discharged, and the temperature Tb and SOC of the assembled battery during the leaving period T is acquired. Details of the method of acquiring each data will be described later. The data acquisition unit 301 outputs the acquired data to the charge / discharge control unit 302 and the leaving resistance estimation unit 303.

  The charge / discharge control unit 302 controls charge / discharge (including refresh charge / discharge) of the assembled battery 10. More specifically, the charge / discharge control unit 302 controls the inverter 310 so that the assembled battery 10 is charged while monitoring the signal from each sensor, or the converter 320 so that the assembled battery 10 is discharged. To control.

  The neglected resistance estimating unit 303 estimates the neglected resistance Rh of the assembled battery 10 based on the data acquired by the data acquiring unit 301. Details of this estimation method will also be described later.

  The refresh condition determining unit 304 determines a refresh charge / discharge condition (also referred to as a refresh condition) according to the neglected resistance Rh estimated by the neglected resistance estimating unit 303. Here, the refresh conditions are the charge / discharge amount of the refresh charge / discharge (the charge amount when executing the refresh charge and the discharge amount when executing the refresh discharge), and the number of the refresh charge / discharge (when executing the refresh charge). At least one of the number of times of charging and the number of times of discharging when executing the refresh discharge). Instead of the charge / discharge amount of the refresh charge / discharge, the SOC change width of the assembled battery 10 due to the refresh charge / discharge may be used. The refresh condition determination unit 304 outputs the determined refresh condition to the charge / discharge control unit 302. The charge / discharge control unit 302 performs refresh charge / discharge according to the refresh condition determined by the refresh condition determination unit 304.

  The reusability determination unit 305 determines whether or not the assembled battery 10 after the refresh charge / discharge is performed by the charge / discharge control unit 302 can be reused. Details of this determination method will also be described later. The determination result by the reusability determination unit 305 is output to the display unit 306.

  The display unit 306 is realized by a display, for example, and displays the determination result by the reusability determination unit 305. The operator can confirm the determination result of the assembled battery 10 displayed on the display unit 306 and finally determine whether the assembled battery 10 is to be reused (reused or rebuilt) or recycled.

<Reuse flow>
FIG. 4 is a flowchart for explaining a method of reusing assembled battery 10 in the present embodiment. This flowchart is shown from a main routine (not shown) when the determination device 300 is installed in the assembled battery 10 collected from the vehicle 1 and a determination start button (not shown) provided on the determination device 300 is operated. Called and executed. Each step (hereinafter abbreviated as “S”) included in this flowchart is basically realized by software processing by the determination apparatus 300, but dedicated hardware (electrical circuit) created in the determination apparatus 300 is used. ).

  At the start of execution of this flowchart, data of the assembled battery 10 (more specifically, the SOC at the time when the assembled battery 10 was removed) during the period in which the assembled battery 10 was mounted on the vehicle 1 was obtained by a dealer engineer. It is acquired from the vehicle 1.

  In S10, the determination apparatus 300 calculates the full charge capacity C1 of the assembled battery 10. Since a known method can be used as a method for calculating the full charge capacity C1, detailed description will not be repeated. Since the full charge capacity in the initial state of the assembled battery 10 is known, the determination apparatus 300 determines the capacity deterioration rate (the current full charge based on the full charge capacity in the initial state) from the full charge capacity C1 of the assembled battery 10. (Capacity ratio) is further calculated.

  In S <b> 20, the determination apparatus 300 acquires a leaving period T that is a period in which the assembled battery 10 is left without being charged / discharged. For example, the neglect period T can be acquired as follows. It is considered that charging / discharging of the assembled battery 10 is performed on the travel route until the vehicle 1 is brought into the dealer, and charging / discharging of the assembled battery 10 is not performed after the vehicle 1 is brought into the dealer. Therefore, a dealer engineer records the time when the vehicle 1 is brought into the dealer, and inputs this time as the start time of leaving the assembled battery 10. Thereafter, the assembled battery 10 is removed from the vehicle 1 at the dealer and stored in a storage location such as a warehouse. And the determination apparatus 300 is installed in the assembled battery 10, and the time (the present time) when the above-mentioned determination start button provided in the determination apparatus 300 was operated is acquired as a leaving end time. In this case, the period between the leaving start time and the leaving end time can be set as the leaving period T.

  In S30, the determination apparatus 300 calculates the SOC of the battery pack 10 during the leaving period T. As an example, the average SOC of the SOC at the time when the assembled battery 10 is removed and the SOC at the current time can be used as the SOC of the assembled battery 10 during the leaving period T. The SOC at the current time may be the SOC of the battery pack 10 during the leaving period T.

  In S40, the determination apparatus 300 acquires the temperature Tb of the battery pack 10 during the leaving period T. For example, while the assembled battery 10 is removed from the vehicle 1 and stored in a storage place, the temperature Tb of the assembled battery 10 during the leaving period T can be acquired by attaching a temperature logger (not shown) to the assembled battery 10. Or you may use the environmental temperature (for example, average temperature) of the storage place of the assembled battery 10 as the temperature Tb of the assembled battery 10. FIG.

  In S50, the determination apparatus 300 estimates the left resistance Rh of the assembled battery 10 based on the data acquired in the processes of S10 to S40. This estimation method will be described below.

  FIG. 5 is a diagram for explaining the relationship between the leaving period T of the assembled battery 10 and the leaving resistance Rh. In FIG. 5, the horizontal axis represents the root of the battery module 10 leaving period T, and the vertical axis represents the battery resistance Rh of the battery pack 10 (which may be the rate of increase of the internal resistance due to the battery resistance Rh). .

  The leaving resistance Rh of the assembled battery 10 increases as the leaving period T of the assembled battery 10 becomes longer. More specifically, when plotted on a semilogarithmic graph having a logarithmic scale on the horizontal axis, the standing resistance Rh of the assembled battery 10 increases linearly as shown in FIG. Such a relationship is obtained in advance by experiment for each combination (SOC, Tb) of the SOC and temperature Tb of the battery pack 10 during the leaving period.

  FIG. 6 is a diagram for explaining the relationship between the capacity deterioration rate of the battery pack 10 and the leaving resistance Rh. In FIG. 6, the horizontal axis represents the capacity deterioration rate of the assembled battery 10, and the vertical axis represents the leaving resistance Rh of the assembled battery 10.

  When the deterioration of the assembled battery 10 progresses and the capacity deterioration rate of the assembled battery 10 increases, the leaving resistance Rh of the assembled battery 10 may change. For example, in the example shown in FIG. 6, the leaving resistance Rh of the assembled battery 10 increases as the capacity deterioration rate of the assembled battery 10 increases. The relationship as shown in FIG. 6 can also be obtained in advance by experiments. A map MP is prepared based on the relationship shown in FIGS. 5 and 6 and stored in a memory (not shown) of the determination apparatus 300.

  FIG. 7 is a conceptual diagram showing an example of the map MP in the present embodiment. As shown in FIG. 7, in the map MP, the increasing rate of the leaving resistance Rh corresponding to the combination (SOC, Tb) of the SOC of the battery pack 10 and the temperature Tb during the leaving period (the slope of each straight line shown in FIG. 5). Is equivalent to each capacity maintenance rate of the battery pack 10. Therefore, by referring to this map MP, the increasing rate of the leaving resistance Rh is calculated from the SOC, temperature Tb and capacity maintenance rate of the assembled battery 10, and the leaving period T (leaving period T The standing resistance Rh can be estimated by multiplying by the power root of T).

  Returning to FIG. 4, in S <b> 60, the determination apparatus 300 determines whether the neglected resistance Rh estimated in S <b> 50 is equal to or greater than a predetermined reference value. If leaving resistance Rh is equal to or greater than the reference value (YES in S60), determination device 300 advances the process to S70 and determines the refresh condition for battery pack 10.

  FIG. 8 is a diagram for explaining a method for determining the refresh condition of the battery pack 10. In FIG. 8, the horizontal axis indicates the number of refresh charges / discharges of the assembled battery 10, and the vertical axis indicates the standing resistance Rh of the assembled battery 10.

  When the charge / discharge amount (change width of SOC) of fresh charge / discharge in the assembled battery 10 is the same, as shown in FIG. 8, the leaving resistance Rh is reduced as the number of fresh charge / discharge increases. Although not shown, when the number of times of refresh charge / discharge of the assembled battery 10 is the same, if the charge / discharge amount of fresh charge / discharge increases, the neglected resistance Rh is reduced. Accordingly, the refresh condition of the assembled battery 10, that is, the charge / discharge amount and the number of times of charge / discharge of the fresh charge / discharge in the assembled battery 10 are determined according to the size of the leaving resistance Rh to be reduced (value estimated in S50). Is done. For example, the result of the experiment result shown in FIG. 8 performed under a plurality of conditions can be mapped, and a condition such that the leaving resistance Rh is less than a predetermined value can be determined as the refresh condition.

  Returning to FIG. 4 again, in S80, the determination apparatus 300 performs the refresh charge / discharge of the battery pack 10 in accordance with the refresh condition determined in S70. When the neglect resistance Rh is less than the reference value in S60 (NO in S60), the determination apparatus 300 skips the processes of S70 and S80 and advances the process to S90.

  In S90, the determination apparatus 300 calculates the internal resistance R and the full charge capacity C2 of the assembled battery 10. Since a known method can be used for calculating internal resistance R and full charge capacity C2, detailed description will not be repeated.

  In S100 to S120, the determination device 300 determines whether or not the assembled battery 10 can be reused. Specifically, when internal resistance R of battery pack 10 is less than threshold value Rth and full charge capacity C2 of battery pack 10 is greater than or equal to threshold value Cth (YES in S100), determination device 300 is Then, it is determined that the assembled battery 10 can be reused (reused or rebuilt) (S110). On the other hand, when internal resistance R of battery pack 10 is equal to or greater than threshold value Rth, or when full charge capacity C2 of battery pack 10 is less than threshold value Cth (NO in S100), determination device 300 determines that the assembled battery 10 is not reusable (not suitable for reuse) (S120). It is desirable to recycle the assembled battery 10 determined to be unsuitable for reuse.

  As described above, according to the present embodiment, the neglected resistance Rh of the battery pack 10 is estimated by the processes of S10 to S50, and the refresh condition corresponding to the estimated neglected resistance Rh is determined (S70). ). Then, after the leaving resistance Rh is sufficiently reduced (eliminated) by refresh charging / discharging (S80), it is determined whether or not the assembled battery 10 can be reused in the processing of S100 to S120. As a result, if the neglected resistance Rh is eliminated by refresh charging / discharging, the assembled battery 10 is restarted on the assumption that the internal resistance R is equal to or higher than the threshold value Rth even though the internal resistance of the assembled battery 10 is actually sufficiently low. It is prevented that it is erroneously determined that it cannot be used. Therefore, it is possible to improve the accuracy of determining whether or not the assembled battery 10 can be reused.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present disclosure is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  1, 2A vehicle, 2B factory, 3 judgment system, 4A external power source, 4B external load, 10 assembled battery, 11 cell, 111 case, 112 lid, 113 positive terminal, 114 negative terminal, 115 electrode body, 116 positive sheet, 117 negative electrode sheet, 118 separator, 300 determination device, 301 data acquisition unit, 302 charge / discharge control unit, 303 neglected resistance estimation unit, 304 refresh condition determination unit, 305 reusability determination unit, 306 display unit, 310 inverter, 320 converter 330 voltage sensor, 340 current sensor, 350 temperature sensor.

Claims (1)

A secondary battery reuse determination system for determining whether or not a recovered secondary battery can be reused,
A charging / discharging device configured to be capable of charging / discharging the secondary battery;
A control device for controlling the charge / discharge device,
The control device includes:
Information on the full charge capacity of the secondary battery, the leaving period in which the secondary battery is left without being charged / discharged, and the SOC (State Of Charge) and temperature of the secondary battery during the leaving period Acquired,
Estimating the neglected resistance indicating the increase in the internal resistance of the secondary battery during the neglected period using the information,
In accordance with conditions determined by the neglected resistance, the charge / discharge device is controlled to perform refresh charge / discharge, which is charge / discharge for reducing the neglected resistance,
A secondary battery reuse determination system that estimates an internal resistance of the secondary battery after execution of the refresh charge / discharge and determines whether or not the secondary battery can be reused using the estimated internal resistance.

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