Battery system and electric vehicle

Abstract

To enable estimation of the degree of deterioration of a replaced battery using frequency data when the battery is replaced.SOLUTION: A battery ECU updates the frequency data (Fig. 3(B)) for an area including the battery temperature TB and SOC as parameters, and estimates the degree of deterioration (amount of deterioration) from frequency data and a deterioration coefficient (Fig. 3(A)) which increases as the temperature TB increases. When the battery is replaced, the battery ECU obtains an estimate of the full charge capacity of the replaced battery, and calculates the degree of deterioration of the replaced battery from the difference from the full charge capacity of a new battery. Then, new frequency data (Fig. 3(C)) is created based on the degree of deterioration. The new frequency data is created as frequency data F for an area where the temperature TB is high and the SOC is high, and other areas are set to null (NULL).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a battery system and an electric vehicle.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2023-109010 (Patent Document 1) discloses a technique for restoring the amount of battery degradation when a battery ECU that calculates the integrated damage amount of a battery mounted on a vehicle is replaced. In this Patent Document 1, it is stated that the amount of battery degradation can be appropriately restored without being affected by the communication time of information received from the EFI ECU.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The battery deteriorates more as the battery temperature is higher. Therefore, in some cases, the degree of battery degradation (damage amount, degradation amount) is estimated using the frequency distribution (history) of the battery temperature and applying Arrhenius' law. In this case, the higher the frequency of the high-temperature state, the greater the degree of battery degradation (the promotion of battery degradation).

[0005] The frequency distribution of the battery temperature is the history of the battery temperature during the usage period of the battery. Hereinafter, the data of this history is also referred to as frequency data. As the usage period of the battery becomes longer, the amount of this data increases.

[0006] The control device for estimating the degree of degradation (the battery ECU in Patent Document 1) is not replaced, and the battery may be replaced. In this case, since the frequency data stored in the memory of the control device is the frequency data of the battery before replacement, the degree of degradation of the battery after replacement cannot be estimated using this frequency data.

[0007] The present disclosure is to enable the estimation of the degree of deterioration of a battery after replacement by using frequency data when the battery is replaced.

Means for Solving the Problem

[0008] The battery system of the present disclosure is a battery system including a battery, a temperature sensor that detects the battery temperature which is the temperature of the battery, and a control device that estimates the degree of deterioration of the battery. The control device estimates the degree of deterioration by using the frequency data of the battery temperature and a deterioration coefficient set such that the higher the battery temperature, the faster the deterioration rate. The frequency data is configured to be stored in the memory of the control device. When the battery is replaced, the control device acquires an estimated value of the full charge capacity of the battery after replacement, and calculates the degree of deterioration of the battery after replacement based on the full charge capacity at the time of the new battery and the estimated value of the full charge capacity. The control device is configured to create new frequency data such that the frequency data becomes the degree of deterioration of the battery after replacement, and estimate the degree of deterioration by using the new frequency data and the deterioration coefficient.

[0009] According to this configuration, the control device estimates the degree of deterioration by using the frequency data of the battery temperature and a deterioration coefficient set such that the higher the battery temperature, the faster the deterioration rate. The frequency data is stored in the memory of the control device.

[0010] When the battery is replaced, the degree of deterioration of the battery after replacement cannot be estimated by using the frequency data stored in the memory.

[0011] According to this configuration, when the battery is replaced, the control device acquires an estimated value of the full charge capacity of the battery after replacement, calculates the degree of deterioration of the battery after replacement based on the full charge capacity at the time of the new battery and the estimated value of the full charge capacity, and creates new frequency data such that the frequency data becomes the degree of deterioration of the battery after replacement. Then, the control device estimates the degree of deterioration by using the new frequency data and the deterioration coefficient. Since the new frequency data is created as data corresponding to the degree of deterioration of the battery after replacement, the degree of deterioration of the battery after replacement can be estimated by using the new frequency data and the deterioration coefficient.

[0012] Preferably, the control device may create new frequency data such that the frequency data in a region where the deterioration rate is equal to or higher than a predetermined value becomes the degree of deterioration of the battery after replacement.

[0013] According to this configuration, the new frequency data is created such that the frequency data in a region where the deterioration rate is equal to or higher than a predetermined value becomes the degree of deterioration of the battery after replacement. Since the deterioration rate is set to increase as the battery temperature increases, the region where the new frequency data is created is, for example, a high temperature region equal to or higher than a predetermined temperature. Batteries are generally used less frequently on the lower temperature side than in the normal use temperature range and on the higher temperature side than in the normal use temperature range. Therefore, since the usage frequency in the high temperature region where the new frequency data is created is low, it is possible to prevent the memory area from overflowing in the control device after replacement. Further, the deterioration coefficient is set such that the deterioration rate increases as the battery temperature increases. For this reason, in the low temperature region (region where the deterioration rate is slow) of the battery temperature, rather than creating frequency data such that it becomes the degree of deterioration of the battery after replacement, creating frequency data such that it becomes the degree of deterioration of the battery after replacement in the high temperature region (region where the deterioration rate is equal to or higher than a predetermined value) results in a smaller amount of data. Therefore, it is possible to prevent the memory area of the control device from overflowing after the battery is replaced.

[0014] Preferably, the frequency data may be the history of the battery temperature and the state of charge (SOC) of the battery.

[0015] The deterioration rate of the battery varies depending on the SOC. For example, deterioration is likely to be promoted in the high SOC region. According to this configuration, the frequency data is the history of the battery temperature and the SOC of the battery, and since the degree of deterioration is estimated in consideration of the SOC, the estimation accuracy of the degree of deterioration can be improved.

[0016] Preferably, the control device may be configured to store the frequency data in the non-volatile memory of the control device when the battery system stops.

[0017] According to this configuration, since the frequency data is stored in the non-volatile memory of the control device when the system stops, it is possible to suppress the erasure of the frequency data even when the power of the control device is lost.

[0018] The electric vehicle of the present disclosure is an electric vehicle equipped with the above battery system.

[0019] According to this configuration, even after the battery is replaced, it is possible to estimate the degree of deterioration of the battery mounted on the vehicle.

Advantages of the Invention

[0020] According to the present disclosure, when the battery is replaced, the degree of deterioration of the battery after replacement can be estimated using the frequency data.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0022] 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 their description will not be repeated.

[0023] FIG. 1 is an overall configuration diagram of an electric vehicle 1 equipped with a battery system S according to the present embodiment. In the present embodiment, the electric vehicle 1 is, for example, an electric vehicle. The electric vehicle 1 may be a plug-in hybrid vehicle equipped with an internal combustion engine and a battery. The electric vehicle 1 includes a motor generator (MG) 10 that is a rotary electric machine, a power transmission gear 20, drive wheels 30, a power control unit (PCU) 40, a system main relay (SMR) 50, a battery 100, a monitoring unit 200, a battery ECU (Electronic Control Unit) 300 that is an example of a control device, and a control ECU 500.

[0024] MG10 is, for example, an embedded structure permanent magnet synchronous motor (IPM motor), and has a function as an electric motor (motor) and a function as a generator. The output torque of MG10 is transmitted to the drive wheels 30 via a power transmission gear 20 configured to include a speed reducer, a differential device, and the like.

[0025] During braking of the electric vehicle 1, MG10 is driven by the drive wheels 30, and MG10 operates as a generator. Thereby, MG10 also functions as a braking device that performs regenerative braking for converting the kinetic energy of the electric vehicle 1 into electric power. The regenerative power generated by the regenerative braking force in MG10 is stored in the battery 100.

[0026] PCU40 is a power conversion device that converts power bidirectionally between MG10 and the battery 100. PCU40 includes, for example, an inverter and a converter that operate based on a control signal from the control ECU 500.

[0027] The SMR50 is electrically connected to the power line connecting the battery 100 and the PCU40. When the SMR50 is closed (ON) in response to a control signal from the control ECU500, power can be transferred between the battery 100 and the PCU40. On the other hand, when the SMR50 is opened (OFF) in response to a control signal from the control ECU500, the electrical connection between the battery 100 and the PCU40 is interrupted.

[0028] The battery 100 stores electric power for driving the MG10. The battery 100 is a rechargeable DC power source (secondary battery), and is a battery pack in which a plurality of single cells (battery cells) 100a are electrically connected in series. The battery 100 corresponds to the "battery" of the present disclosure. The single cell 100a may be composed of, for example, a lithium ion battery.

[0029] The monitoring unit 200 includes a voltage sensor 210, a current sensor 220, and a temperature sensor 230. The voltage sensor 210 detects the voltage VB of the battery 100. The current sensor 220 detects the current IB input to and output from the battery 100. When the battery 100 is discharging, the current IB has a negative (-) value, and when the battery 100 is charging, the current IB has a positive (+) value. The temperature sensor 230 detects the temperature TB of the battery 100. The temperature TB corresponds to an example of the "battery temperature" of the present disclosure. Each sensor outputs its detection result to the battery ECU300.

[0030] The electric vehicle 1 is provided with an inlet 60, and the battery 100 can be externally charged using a charging facility (EVSE: Electric Vehicle Supply Equipment) 400. The inlet 60 is configured to be connectable to a connector 420 provided at the tip of the charging cable 410 of the EVSE 400. The inlet 60 is electrically connected to a power line that is connected to the battery 100 via a charging circuit 70. In the present embodiment, when the SMR 50 is closed, the inlet 60 and the battery 100 are connected and external charging becomes possible. Note that the charging circuit 70 may include a charging relay. Also, the inlet 60 (charging circuit 70) may be connected to the power line between the battery 100 and the SMR 50 via a charging relay, and the external charging of the battery 100 may be configured to be possible when the charging relay is closed.

[0031] The battery ECU 300 includes a CPU (Central Processing Unit) 301 and a memory 302. The memory 302 includes a RAM (e.g., SRAM (Static Random Access Memory)) and a non-volatile memory (e.g., EEROM (Electrically Erasable Programmable Read-Only Memory)). The data stored in the RAM is lost when the power supply to the RAM stops (when the power of the battery ECU 300 is lost). The non-volatile memory does not lose the stored data even when the power supply stops (even when the power of the battery ECU 300 is lost). The battery ECU 300 estimates the SOC of the battery 100 using the signal received from the monitoring unit 200 and outputs it to the control ECU 500. Also, the battery ECU 300 estimates the degree of deterioration of the battery 100 and outputs it to the control ECU 500. The battery ECU 300 and the control ECU 500 may be connected, for example, by a CAN (Controller Area Network). In the present embodiment, the battery system S is composed of the battery 100, the monitoring unit 200, the battery ECU 300, the control ECU 500, etc.

[0032] The control ECU 500 includes a CPU 501 and a memory 502. Similar to the memory 302, the memory 502 includes a RAM and a non-volatile memory. Based on the signals received from the battery ECU 300, signals from various sensors (not shown) (for example, an accelerator opening signal, a vehicle speed signal, etc.), and information such as maps and programs stored in the memory 502, the control ECU 500 controls each device so that the electric vehicle 1 reaches a desired state.

[0033] Figure 2 is a flowchart showing an example of battery degradation estimation processing executed in the battery ECU 300. This flowchart is executed when the power switch (ignition switch) 250 is turned ON and the battery system S becomes ON. When the power switch 250 is turned ON and the battery system S becomes ON, in step (hereinafter, steps are abbreviated as "S") 10, the temperature TB and SOC of the battery 100 are acquired. The temperature TB may be a detection signal of the temperature sensor 230. The SOC may be calculated and acquired from the SOC-OCV (Open Circuit Voltage) characteristics of the battery 100 using the voltage VB detected by the voltage sensor 210.

[0034] In S11, frequency data is updated based on the temperature TB and SOC obtained in S10. FIG. 3 is a diagram for explaining the degradation coefficient and frequency data in the present embodiment. FIG. 3(A) is a diagram for explaining the degradation coefficient described later, and FIG. 3(B) is a diagram for explaining the frequency data updated in S11. In FIG. 3(B), the vertical axis represents the temperature TB [°C], and the horizontal axis represents the SOC [%]. In the present embodiment, the frequency data is the cumulative time of the time when the battery 100 exists in each region in a two-dimensional map with the temperature TB and SOC as parameters. For example, the temperature TB may be in the range of -40°C to +60°C, and the SOC may be in the range of 1% to 100%. Also, in each region, the interval of the temperature TB may be 1°C, or 2°C, or 5°C, and the interval of the SOC may be 1%, or 2%, or 5%. Further, the cumulative time may be, for example, in units of 1 minute. In S11, the time in the region corresponding to the temperature TB and SOC obtained in S10 is integrated (cumulated), and the frequency data is updated. The frequency data is stored in the SRAM of the memory 302 and is updated at any time when S11 is processed.

[0035] In the subsequent S12, the amount of deterioration ΔQ of the battery 100 is calculated. The amount of deterioration ΔQ is the amount of deterioration of the capacity [Ah] of the battery 100 (capacity deterioration amount), and corresponds to an example of the "degree of deterioration" in the present disclosure. The amount of deterioration ΔQ is calculated based on the frequency data updated in S11 and the deterioration coefficient. FIG. 3(A) is a diagram for explaining the deterioration coefficient, where the vertical axis is the temperature TB and the horizontal axis is the SOC. In the present embodiment, the deterioration coefficient is the capacity deterioration rate [% / Hr]. Since the higher the temperature TB and the higher (larger) the SOC, the more the deterioration of the battery 100 is promoted, the deterioration coefficient is set such that the higher the temperature TB and the higher the SOC, the faster the capacity deterioration rate. In S12, the frequency data (cumulative time) in each region is multiplied by the deterioration coefficient (capacity deterioration rate) to obtain the capacity deterioration amount in each region, and the sum thereof is calculated as the amount of deterioration ΔQ. Note that it is known that the capacity deterioration of the battery 100 (battery) follows the square root rule (capacity deterioration is proportional to the square root of time or the number of cycles), and the deteriorated capacity of each region may be obtained from the frequency data (cumulative time) and the deterioration coefficient using the square root rule.

[0036] In S13, it is determined whether the battery system S has changed from ON to OFF. When the power switch 250 is operated from ON to OFF, it is determined that the battery system S has changed from ON to OFF, and the process proceeds to S14. If there is no operation of the power switch 250, a negative determination is made and the process returns to S10, and the processes from S10 to S13 are repeatedly executed. The processes from S10 to S13 may be performed at predetermined intervals.

[0037] In S14, after writing the frequency data updated in S11 into the non-volatile memory of the memory 302, the process proceeds to S15. Note that the frequency data stored in the non-volatile memory of the memory 302 is used for the return of the frequency data, for example, when the power line is removed from the output terminal of the auxiliary battery that is the power source of the battery ECU 300 during the maintenance of the electric vehicle 1 or the like, and the frequency data stored in the SRAM of the memory 302 is lost.

[0038] In S15, after transmitting the amount of deterioration ΔQ calculated in S12 to the control ECU 500, this routine is terminated. The control ECU 500 writes (stores) the received amount of deterioration ΔQ in the non-volatile memory of the memory 502.

[0039] In the battery system S, the battery 100 may be replaced. The frequency data stored in the memory 302 (SRAM, non-volatile memory) of the battery ECU 300 is the frequency data of the battery 100 before replacement. Therefore, when the battery 100 is replaced, the amount of deterioration ΔQ of the battery 100 after replacement cannot be calculated using the frequency data stored in the memory 302. In the present embodiment, when the battery 100 is replaced, new frequency data is created so that the amount of deterioration ΔQ of the battery 100 after replacement can be calculated.

[0040] FIG. 4 is a flowchart showing an example of a battery replacement process executed in the battery ECU 300. This flowchart is executed when the IG switch (power switch) 250 is turned on and the battery ECU 300 is activated. In S20, it is determined whether there has been a battery replacement. For example, when the control ECU 500 receives an exchange signal from the service tool ST used by the operator who replaces the battery 100, it may be determined that there has been a battery replacement. Also, when the identification number (ID) of the battery 100 stored in the non-volatile memory of the memory 302 or the memory 502 is different from the identification number of the battery 100, it may be determined that there has been a battery replacement. Alternatively, when the SOC at the time of the IG switch OFF operation stored in the non-volatile memory of the memory 302 or the memory 502 is different from the SOC at the time of the ON operation of the IG switch 250 by a predetermined value or more, it may be determined that there has been a battery replacement. When there has been a battery replacement, the process proceeds to S21, and when there has been no battery replacement, this routine is terminated.

[0041] In S21, the frequency data stored in the memory 302 is reset. In the present embodiment, the frequency data stored in the SRAM and the non-volatile memory of the memory 302 is reset. The reset of the frequency data may be performed, for example, so that the frequency data becomes a null state. Also, frequency data corresponding to the amount of deterioration ΔQ assumed when the new battery 100 is used for 10 years may be prepared in advance and used as the frequency data after reset.

[0042] In the subsequent S22, an estimated full charge capacity Ca of the battery 100 after replacement is obtained. The method for obtaining the estimated full charge capacity Ca may be any method. For example, when an operator who replaces the battery 100 operates the service tool ST to notify the completion of the replacement work of the battery 100, the battery ECU 300 discharges the battery 100 so that the SOC of the battery 100 after replacement becomes equal to or less than a predetermined value (for example, 3%). When the SCO becomes equal to or less than the predetermined value, the discharge is stopped, and when a time required to eliminate the polarization of the battery 100 has elapsed, external charging is started using the EVSE 400, and the charging current is integrated. The external charging may be CCCV (Constant Current Constant Voltage) charging or CC (Constant Current) charging. Then, when the battery 100 is fully charged (when the charging termination current or the charging termination voltage is reached), the charging is stopped. Then, after leaving it for a predetermined time, the estimated full charge capacity Ca of the battery 100 after replacement is calculated from the SOC at the start of charging, the SOC at full charge, the amount of charging power, etc., obtained from the SOC-OCV characteristics. In S22, the estimated full charge capacity Ca calculated in this way may be obtained.

[0043] In S23, the amount of deterioration ΔQ of the battery 100 after replacement is calculated. In the memory 302 of the battery ECU 300, the full charge capacity Cs of the battery 100 at the time of being new (at the time of manufacture, at the time of factory shipment) is stored in advance. For example, the full charge capacity Cs may be the specification value (design value) of the battery 100. In S23, the amount of deterioration ΔQ is calculated as the difference between the full charge capacity Cs and the estimated full charge capacity Qa (ΔQ = Cs - Ca). (When the amount of deterioration ΔQ is handled as a negative value, it may be calculated from ΔQ = Ca - Cs.) In the subsequent S24, frequency data is created based on the amount of deterioration ΔQ calculated in S23, and this routine ends. In the present embodiment, the frequency data is created such that the frequency data in the region where the deterioration coefficient (capacity deterioration rate) is the largest becomes the amount of deterioration ΔQ. For example, when the temperature TB is the highest and the SOC is the largest (the region where the deterioration coefficient is the largest), the frequency data F in this region is calculated as F = ΔQ / S, where S is the deterioration coefficient of this region. Then, as shown in FIG. 3(C), the frequency data of this region is set to F, the frequency data of other regions is set to NULL, and new frequency data is created. The new frequency data is stored in the SRAM of the memory 302. (At this time, the new frequency data may be stored in the non-volatile memory of the memory 302 as well.) Thereafter, the new frequency data is updated in S11 of the battery deterioration estimation process (FIG. 2).

[0044] According to this embodiment, the battery ECU 300 estimates the degradation amount ΔQ using the temperature TB, the frequency data of the SOC, and the degradation coefficient set such that the higher the temperature TB, the faster the degradation rate (capacity degradation rate). When the battery 100 is replaced, the battery ECU 300 acquires the estimated value Ca of the full charge capacity of the battery 100 after replacement, and calculates the degradation amount ΔQ of the battery 100 after replacement based on the full charge capacity Cs at the time of the new battery 100 and the estimated value Ca of the full charge capacity. Then, new frequency data is created such that the frequency data becomes the degradation amount ΔQ of the battery 100 after replacement. Then, the battery ECU 300 estimates the degradation amount ΔQ (degree of degradation) using the new frequency data and the degradation coefficient. Since the new frequency data is created as data corresponding to the degradation amount ΔQ of the battery 100 after replacement, the degradation amount ΔQ of the battery 100 after replacement can be estimated using the new frequency data and the degradation coefficient.

[0045] FIG. 5 is a diagram showing the relationship between the temperature TB and the frequency (cumulative time). In FIG. 5, the vertical axis represents the frequency (cumulative time), and the horizontal axis represents the temperature TB. As shown in FIG. 5, the battery 100 is generally used less frequently on the lower temperature side and the higher temperature side than the normal use temperature range.

[0046] In this embodiment, the new frequency data is created such that the frequency data in the region where the temperature TB is high and the degradation coefficient is the largest (the region where the capacity degradation rate is the largest) becomes the degradation amount ΔQ. When the degradation coefficient in this region is S, the frequency data F in this region is F = ΔQ / S, and the frequency data in other regions is set to NULL. Since the larger the degradation coefficient, the smaller the frequency data F becomes, the data amount is smaller than creating frequency data from the degradation amount ΔQ in the region where the degradation coefficient is small (the region where the capacity degradation rate is slow). Also, after that (after the battery 100 is replaced), the temperature TB becomes high, and the frequency existing in the region where the degradation coefficient is the largest is also small. Thereby, it is possible to suppress the frequency data from overflowing after the battery 100 is replaced.

[0047] In the above embodiment, in S24 (FIG. 4), the frequency data F of the region where the temperature TB is the highest and the SOC is the largest (the region where the deterioration coefficient is the largest) was calculated based on the deterioration amount ΔQ, and new frequency data was created. However, the frequency data created based on the deterioration amount ΔQ does not necessarily have to be in the region where the temperature TB is the highest and the SOC is the largest (the region where the deterioration coefficient is the largest). For example, in the region where the temperature TB is the second highest and the SOC is the second largest, the frequency data f calculated based on the deterioration amount ΔQ is calculated, and as shown in FIG. 3(C), the frequency data of the region is set to f, and the frequency data of other regions is set to null.

[0048] Also, the frequency data f1 and f2 are calculated such that the value obtained by adding the deterioration amount calculated from the frequency data f1 of the region where the temperature TB is the highest and the SOC is the second largest and the deterioration amount calculated from the frequency data f2 of the region where the temperature TB is the second highest and the SOC is the largest becomes the deterioration amount ΔQ. As shown in FIG. 3(C), the frequency data of the region is set to f1 and f2, and the frequency data of other regions is set to null. In the present disclosure, the "region where the deterioration rate is equal to or higher than a predetermined value" may be, for example, any of the top 10% regions where the capacity deterioration rate is high (the deterioration coefficient is large).

[0049] In the above embodiment, the frequency data was the cumulative time of the time during which the battery 100 existed in each region in the two-dimensional map with the temperature TB and the SOC as parameters. However, the frequency data may be the cumulative time with only the temperature TB as a parameter. Also, the frequency data does not have to be the cumulative time as long as it is a history corresponding to the time during which the battery 100 existed in that region.

[0050] In addition, when the root rule is used to determine the degree of deterioration (deterioration amount ΔQ) of the battery 100, the capacity deterioration rate decreases as the usage time of the battery 100 elapses and the degree of deterioration increases. According to the present embodiment, the deterioration amount ΔQ of the battery 100 after replacement is calculated, and new frequency data is created from the deterioration amount ΔQ. Therefore, since the new frequency data is created as data considering the usage time of the battery 100 (the usage time from when it was new to the present), even after the battery ECU 300 is replaced, the degree of deterioration (deterioration amount ΔQ) can be accurately estimated.

[0051] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0052] 1 Electric vehicle, 10 Motor generator (MG), 20 Drive transmission gear, 30 Drive wheels, 40 PCU, 50 SMR, 60 Inlet, 70 Charging circuit, 100 Battery, 100a Single cell, 200 Monitoring unit, 210 Voltage sensor, 220 Current sensor, 230 Temperature sensor, 300 Battery ECU, 301 CPU, 302 Memory, 400 EVSE, 420 Connector, 500 Control ECU, 501 CPU, 502 Memory, S Battery system.

Claims

1. A battery system comprising a battery, a temperature sensor that detects a battery temperature which is the temperature of the battery, and a control device that estimates a degree of deterioration of the battery, wherein the control device estimates the degree of deterioration using frequency data of the battery temperature and a deterioration coefficient set such that the higher the battery temperature, the faster the deterioration rate, and the frequency data is configured to be stored in a memory of the control device, when the battery is replaced, the control device, acquires an estimated value of the full charge capacity of the battery after replacement, calculates the degree of deterioration of the battery after replacement based on the full charge capacity at the time of the new battery and the estimated value of the full charge capacity, creates new frequency data such that the frequency data becomes the degree of deterioration of the battery after replacement, and is configured to estimate the degree of deterioration using the new frequency data and the deterioration coefficient. A battery system.

2. The control device, creates new frequency data such that the frequency data in a region where the deterioration rate is equal to or higher than a predetermined value becomes the degree of deterioration of the battery after replacement. The battery system according to claim 1.

3. The frequency data is a history of the battery temperature and the state of charge (SOC) of the battery. The battery system according to claim 1 or claim 2.

4. The control device is configured to store the frequency data in a non-volatile memory of the control device when the battery system stops. The battery system according to claim 3.

5. An electric vehicle equipped with the battery system according to claim 4.

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