Battery management device, battery management method

Abstract

To provide a technique which enables quick diagnosis of battery deterioration speed.SOLUTION: A battery management device of the present invention is configured to specify a first period and a subsequent second period during an idle period, and estimate battery temperature-dependent battery deterioration rate on the basis of a ratio of a first change in voltage during the first period and a second change in the voltage during the second period.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a technology for managing the state of a battery. [Background technology]

[0002] Technologies for diagnosing battery degradation have been developed, including those for estimating the SOH (State of Health) and internal resistance. Furthermore, technologies for shortening the time required for diagnosis have also been developed. For example, there is a method for estimating the degradation state using the change over time in battery voltage when the battery is in a resting state.

[0003] The following Patent Document 1 aims to "make it easier to determine the deterioration of a zinc battery," and describes a technology in which "a method for determining the deterioration of a zinc battery according to one embodiment includes an acquisition step of acquiring a voltage transition of a fully charged zinc battery in a resting state, a calculation step of calculating the degree of voltage drop of the zinc battery based on the voltage transition, and a determination step of determining the deterioration of the zinc battery based on the degree of voltage drop" (see abstract). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-003218 Summary of the Invention [Problem to be solved by the invention]

[0005] The remaining life of a battery is one of the important diagnostic items. One example of a method for diagnosing the remaining life is to estimate the rate at which the battery has deteriorated (deterioration mode) from the start of operation to the present time, and then estimate the remaining life based on the estimated deterioration rate. It would also be desirable to shorten the time required to diagnose the remaining life as much as possible. However, in prior art such as Patent Document 1, while techniques for diagnosing the deterioration state and the like in a short time have been considered, techniques for diagnosing the remaining life in a short time have not been considered. Furthermore, in order to diagnose the remaining life, for example, it is necessary to estimate the deterioration rate, but no techniques for estimating this in a short time have been considered.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique that can diagnose the rate of deterioration of a battery in a short period of time. [Means for solving the problem]

[0007] The battery management device of the present invention identifies a first period in a rest period and a subsequent second period, and estimates the rate of battery deterioration based on the battery temperature based on the ratio between a first change in voltage in the first period and a second change in voltage in the second period. [Effects of the Invention]

[0008] The battery management device according to the present invention can diagnose the rate of deterioration of a battery in a short period of time. Other objects, configurations, effects, etc. of the present invention will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration example of a battery storage system. [Figure 2] FIG. 2 is an equivalent circuit diagram of a storage battery. [Figure 3] 10 is a graph showing an example of the change over time in the voltage output by the battery during a rest period. [Figure 4] FIG. 1 is a diagram showing storage deterioration of a battery. [Figure 5] FIG. 10 is a diagram illustrating the relationship between battery temperature and deterioration rate. [Figure 6] FIG. 4 is a diagram showing the relationship between each value described in FIG. 3 and SOH. [Figure 7] 4 is a flowchart illustrating a procedure for the battery management device to estimate a deterioration mode of a battery. [Figure 8] FIG. 1 is a graph showing cycle deterioration of a battery. [Figure 9] FIG. 10 is a diagram illustrating the relationship between battery temperature and deterioration rate. [Figure 10] FIG. 4 is a diagram showing the relationship between each value described in FIG. 3 and SOH. [Figure 11] 4 is a flowchart illustrating a procedure for the battery management device to estimate a deterioration mode of a battery. [Figure 12] FIG. 10 is a configuration diagram of a battery system 1 according to a third embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of operation of the battery management device 13. [Figure 14] FIG. 10 is a diagram showing another example of operation of the battery management device 13. [Figure 15] This is an example of the results of a trial calculation of the economic value of a battery. DETAILED DESCRIPTION OF THE INVENTION

[0010] <First Embodiment> Figure 1 is a schematic diagram showing an example of the configuration of a storage battery system. The storage battery system is composed of a battery system made up of one or more storage batteries and a battery management device that manages the battery system. In the following, the battery is assumed to be a storage battery.

[0011] The battery system includes a battery module. The battery module is composed of one or more sub-modules. The sub-module has a battery cell and a group of sensors. The group of sensors may include, for example, a voltage sensor that measures the output voltage of the battery cell, a temperature sensor that measures the temperature of the battery cell, and a current sensor that measures the output current of the battery cell. The temperature sensor may be composed of, for example, a thermocouple. The detection unit acquires the measurement results from the sensor and transmits them to a battery management module (BMU). The BMU outputs measurement data describing the measurement results to the battery management unit.

[0012] The battery management device includes a detector that acquires measurement data, a processor that manages the battery status, and a memory that stores the data. The processor estimates the battery status using the measurement data acquired from the BMU. For example, as described below, it can estimate the remaining battery life (or the rate of deterioration used to estimate the remaining battery life).

[0013] Figure 2 is an equivalent circuit diagram of a storage battery. The equivalent circuit of a storage battery can be described by internal resistance, negative electrode equivalent circuit, positive electrode equivalent circuit, diffusion resistance, etc. The negative electrode equivalent circuit and positive electrode equivalent circuit can be described as an RC equivalent circuit with a time constant. Generally, the time constant of the negative electrode is smaller than the time constant of the positive electrode. In other words, the negative electrode responds faster. The diffusion resistance component occurs at a slower time than the positive electrode.

[0014] Figure 3 is a graph showing an example of the change over time in the voltage output by a battery during a rest period. The top part of Figure 3 shows the change over time in the battery voltage during a rest period after a discharge operation. The bottom part of Figure 3 shows the change over time in the battery voltage during a rest period after a charge operation. ΔVa is the change over time caused mainly by the response of the internal resistance and negative electrode, which respond relatively quickly. ΔVb is the change over time caused mainly by the response of the positive electrode and diffusion resistance, which respond relatively slowly. The period during which ΔVa occurs is called the first period (time length Δt1), and the period during which ΔVb occurs is called the second period (time length Δt2).

[0015] The degradation mode (degradation rate) of a battery may affect the response speed of the battery's components. This may cause changes in ΔVa / Δt1, ΔVb / Δt2, the ratio between ΔVa and ΔVb, etc., in Figure 3. In other words, since there is a correlation between the battery degradation mode and these values, it is believed that the battery degradation mode can be estimated based on these values. The battery management device according to the present invention utilizes this fact to estimate the battery degradation mode. Specific methods are described below.

[0016] Fig. 4 shows the storage degradation of a battery. Degradation progresses even when the battery is stored without being used. As a result of testing in this invention, it was found that when a battery is stored at a certain SOC (State of Charge) and a certain temperature, the battery deteriorates depending on the SOC and temperature.

[0017] The left side of Figure 4 shows the progression of deterioration when a battery with an SOC of C1% (e.g., less than 80%) is stored at battery temperatures T1, T2, and T3. For example, the battery temperatures are T1 = 5°C, T2 = 25°C, and T3 = 45°C. At each temperature, the longer the storage period, the more deterioration progresses, and the higher the temperature, the faster the deterioration rate.

[0018] The right side of Figure 4 shows the progression of degradation when a battery with an SOC of C2% (e.g., 80% or higher) is stored at battery temperatures T1, T2, and T3. Compared to the left side of Figure 4, it can be seen that the rate of degradation is particularly fast at temperature T3. In other words, the rate of degradation (degradation mode) is thought to be correlated with both battery temperature and SOC.

[0019] Figure 5 illustrates the relationship between battery temperature and degradation rate. As shown in Figure 4, the degradation rate (the downward slope in Figure 4, i.e., the rate of decrease in SOH over the number of days) tends to increase as the battery temperature increases. This slope is relatively small (slope A) when the battery is stored at a low SOC, but is relatively large (slope B) when the battery is stored at a high SOC. This can also be seen from the steep slope at temperature T3 on the right side of Figure 4.

[0020] According to Figure 5, a certain temperature serves as the boundary between the degradation rate of slope A and slope B. Furthermore, the degradation rate differs depending on whether the SOC is relatively small (e.g., C1%) or relatively large (e.g., C2%). In other words, it is possible to estimate the degradation rate based on a certain temperature threshold and SOC threshold.

[0021] FIG. 6 shows the relationship between the values ​​explained in FIG. 3 and SOH. For both ΔVa and ΔVb, the time rate of change (dVdt1 = ΔVa / Δt1, dVdt2 = ΔVb / Δt2) decreases as the SOH decreases. In a degradation mode with a high degradation rate (e.g., slope B in FIG. 5, corresponding to a high SOC and high battery temperature), the SOH is likely to decrease more significantly even with the same time rate of change. In other words, the graph is likely to pass through the area enclosed by the dotted line in the middle of FIG. 6.

[0022] Let's consider the ratio between dVdt1 and dVdt2. When the degradation rate is relatively slow, dVdt1 and dVdt2 are as shown by the solid lines in Figure 6. When the degradation rate is faster than this, the dVdt2 graph is considered to pass through the dotted area in the middle of Figure 6. In this case, if dVdt1 and dVdt2 corresponding to the same SOH value are obtained, dVdt2 will be smaller than the value shown by the solid line in Figure 6. In other words, when comparing cases where the degradation rate is fast and slow, the dVdt2 value corresponding to the same dVdt1 value will be smaller when the degradation rate is fast. This corresponds to the graph shifting to the left in the bottom part of Figure 6.

[0023] Thus, when the ratio of dVdt1 to dVdt2 is plotted as shown in the lower part of Figure 6, if the ratio is above the upper threshold of the graph, it can be assumed that degradation has progressed in a mode with a fast degradation rate. Conversely, if the plot is below the upper threshold, it can be assumed that degradation has progressed in a mode with a slow degradation rate. In this embodiment, the battery degradation mode is estimated based on this principle. If the ratio is below the lower threshold, it can be assumed that the degradation rate is even slower.

[0024] FIG. 7 is a flowchart explaining the procedure by which the battery management device estimates the deterioration mode of a battery. This flowchart can be executed by a calculation unit provided in the battery management device. This flowchart estimates the deterioration mode of a stored battery based on the principle explained above. Each step in FIG. 7 will be explained below.

[0025] The calculation unit acquires ΔVa, Δt1, ΔVb, and Δt2 described in FIG. 3 from, for example, the BMU. The calculation unit calculates the time change rate of the battery voltage (dVdt1=ΔVa / Δt1, dVdt2=ΔVb / Δt2). The calculation unit calculates the ratio Ratio of dVdt1 to dVdt2. If Ratio is above a threshold, it estimates that the battery degradation rate slope is B (a degradation mode in which the degradation rate is relatively fast). If Ratio is below the threshold, it estimates that the battery degradation rate slope is A (a degradation mode in which the degradation rate is relatively slow).

[0026] The calculation unit estimates the temperature and SOC at which the battery was stored based on the estimated degradation mode. First, based on the estimated degradation mode, it can estimate whether the slope of the degradation rate relative to temperature change is slope A or B in Figure 5 (in other words, whether the SOC is C1 or C2). This corresponds to identifying whether the battery deteriorated in the left or right degradation mode in Figure 4.

[0027] The calculation unit estimates the activation energy Ea of the battery. By estimating the degradation mode using the above procedure, it is possible to estimate whether the battery has deteriorated in the left or right degradation mode shown in Figure 4. This makes it possible to estimate the relationship between SOH / number of days (or number of cycles) / temperature, as shown in Figure 4. By substituting this temperature into, for example, the Arrhenius equation, the activation energy can be calculated. Since there is roughly a one-to-one correspondence between activation energy and degradation mode, the relationship between the activation energy for that degradation mode can be entered in advance in a data table, and the activation energy corresponding to the estimated degradation mode can be obtained from that data table.

[0028] The calculation unit obtains the number of times the battery has been charged or discharged from the BMU. Alternatively, the calculation unit obtains the amount of decrease in full charge capacity due to one charge or discharge from the BMU and compares this with the current full charge capacity (i.e., the current SOH) to estimate the number of times the battery has been charged or discharged. The calculation unit further estimates the SOH using any known method. For example, the SOH can be estimated by referring to data describing the correspondence between dVdt1 and SOH, the correspondence between dVdt2 and SOH, or a combination thereof.

[0029] The calculation unit uses the estimated SOH and the number of charge / discharge cycles to estimate the temperature T1 at which the battery has been stored. For example, the temperature at which the battery has been stored can be estimated by applying the current SOH and the number of charge / discharge cycles (or converting this to the number of days elapsed) to the relationship shown in Figure 4. If there is no point where the data points in Figure 4 match the acquired SOH / number of days, the data points in Figure 4 can be supplemented.

[0030] The calculation unit calculates the battery degradation acceleration by applying the estimated temperature T1 and activation energy to the Arrhenius equation. The reference temperature T2 is set to 298 K, for example. Through the above procedure, the battery management device can estimate the battery degradation mode and degradation acceleration. The calculation unit outputs the estimation result in an appropriate format.

[0031] <First embodiment: Summary> The battery management device according to this embodiment estimates the deterioration rate based on the battery temperature based on the first and second changes in the battery voltage during the rest period. The first and second changes appear relatively quickly after the end of the charge / discharge operation, so the deterioration rate can be estimated within a short time.

[0032] <Embodiment 2> FIG. 8 is a diagram showing the cycle degradation of a battery. T1 to T3 are the same as in FIG. 4. In the first embodiment, storage degradation of a battery was described, but a battery also degrades with each charge / discharge cycle. In principle, the higher the temperature, the faster the degradation rate (the amount of reduction in SOH due to one charge / discharge cycle). However, depending on the battery characteristics, the degradation rate may be faster than normal if the battery is not operated at a low temperature below the upper C-rate limit. The graph of temperature T1 in FIG. 8 shows this. In the second embodiment of the present invention, a method for estimating the degradation rate in such a case will be described. The configurations of the battery system and battery management device are the same as those of the first embodiment.

[0033] FIG. 9 is a diagram illustrating the relationship between battery temperature and degradation rate. The upper part of FIG. 9 shows the upper C-rate limit that the battery must comply with. In this example battery, an upper C-rate limit that must be complied with during battery charge / discharge operations is specified for each battery temperature. The lower part of FIG. 9 shows the relationship between battery temperature and degradation rate, similar to FIG. 5. However, unlike FIGS. 4 to 5, the degradation rate is the rate at which SOH decreases with increasing cycle count.

[0034] As in Figure 5, when the SOC is relatively small (e.g., C1%), the slope of the degradation rate versus temperature change is C. When the battery temperature is below 25°C, the slope increases to D2 if the C-rate limit is not observed. Further deviations from the C-rate limit increase the slope to D1.

[0035] FIG. 10 is a diagram showing the relationship between each value explained in FIG. 3 and SOH. As in FIG. 6, the area where the degradation rate slope is steep is indicated by a dotted line. For example, as explained in FIG. 9, when a battery is operated in a low-temperature environment of 25°C or less, if the upper C-rate limit is not observed, the degradation rate will increase. This is shown by the dotted line area in FIG. 10. In the lower part of FIG. 10, the area where dVdt2 / dVdt1 is greater than the threshold value includes areas corresponding to the two degradation modes explained in FIG. 9 (slope D1 and D2).

[0036] In the lower part of Figure 10, an upper threshold (and a lower threshold, if necessary) similar to that in the lower part of Figure 6 is set in a coordinate space with dVdt2 / dVdt1 on the vertical axis and dVdt2 on the horizontal axis. Alternatively, the vertical axis may be dVdt1, as in the lower part of Figure 6. In other words, as long as it is possible to clearly distinguish which degradation mode (D1 or D2) applies when dVdt2 / dVdt1 exceeds the upper threshold, either vertical axis is acceptable; these are merely different forms of expression.

[0037] Fig. 11 is a flowchart illustrating the procedure for the battery management device to estimate the deterioration mode of a battery. In addition to the flowchart described in the first embodiment, a step is added to select whether the slope of the deterioration rate when Ratio exceeds a threshold value is D1 or D2 (the slope of the deterioration rate described in Fig. 9). When Ratio exceeds the threshold value, the calculation unit determines whether the deterioration rate is D1 or D2 according to the distance between Ratio and the threshold value. For example, if the distance is relatively large, it is D1, and if the distance is small, it is D2. The rest is the same as in the first embodiment.

[0038] <Embodiment 2: Summary> The battery management device according to this embodiment estimates the degradation mode of a battery whose degradation rate increases if the C-rate upper limit is not observed in a low-temperature environment based on the deviation between dVdt2 / dVdt1 and a threshold value. This makes it possible to estimate the degradation rate of a battery having such degradation characteristics in a low-temperature environment in a short time, as in the first embodiment.

[0039] <Third Embodiment> Fig. 12 is a configuration diagram of a battery system 1 according to a third embodiment of the present invention. The battery system 1, battery controller (BMU) 12, and battery management unit 13 are the same as those shown in Fig. 1. The battery system 1 has a host controller 11, battery controller (BMU) 12, and battery management unit 13. The host controller 11 outputs operation instructions to the battery via the battery controller 12. The battery controller 12 controls the battery modules in accordance with the instructions. The battery management unit 13 has a detection unit 131 that acquires measurement data from the battery controller 12, a calculation unit 132 that diagnoses the battery using the methods described in the first and second embodiments, and a storage unit 133 that stores data used by the calculation unit 132.

[0040] 13 is a diagram showing an example of operation of the battery management device 13. The detection unit 131 acquires measurement values ​​or their history, such as battery voltage, battery temperature, battery current, C rate, and SOC, of ​​each battery module (or battery cell) from the BMU, and records these in the storage unit 133. The calculation unit 132 uses this data to estimate the battery degradation mode and degradation acceleration using the methods described in the first and second embodiments. This makes it possible to monitor whether the degradation mode of each battery is being maintained appropriately.

[0041] For example, when transmitting power generated by a power generation system including a battery system over a power company's power transmission network, a power transmission plan may be created in advance the day before the power transmission and sent to the power company, and the battery capacity may be diagnosed within a short time just before the start of power transmission on the day of the power transmission. In such a case, the diagnostic method according to the present invention is useful in that it can complete the diagnosis in a short time. Furthermore, by storing the battery temperature history in the memory unit 133, it is also useful that there is no need to estimate the empirical temperature T1 in FIG. 7 or FIG. 11 (it is sufficient to use the average value of the temperature history as T1).

[0042] FIG. 14 is a diagram showing another example of operation of the battery management device 13. The battery management device 13 is connected to a charger via a cloud system or the like. The charger is a device that charges the battery mounted on the vehicle. The detection unit 131 acquires measurement data such as the battery voltage and battery temperature of the battery mounted on the vehicle via the charger (or via a measuring instrument connected to the vehicle). The calculation unit 132 uses the measurement data to diagnose the battery's degradation mode, degradation acceleration, remaining life, etc. This makes it possible to estimate the economic value of the vehicle or the battery mounted on the vehicle.

[0043] Figure 15 shows an example of the results of a trial calculation of the economic value of a battery. The calculation unit 132 calculates the SOH, degradation acceleration, and a ranking of the economic value based on these for each battery using the procedure described in the above embodiment, and outputs the results. The ranking is, for example, an overall evaluation based on a combination of the SOH and degradation acceleration. The output format may be data describing these, or may be output via an output medium such as a display.

[0044] For batteries with a low evaluation (or a high rate of deterioration), the calculation unit 132 may charge them with restrictions on the charge current and the state of charge after the charging operation so as not to accelerate deterioration. It is desirable to perform diagnosis of the rate of deterioration, etc., during a period when no charging or discharging operation is being performed. This is the same for all of Figures 13 and 14.

[0045] <Modifications of the present invention> The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0046] In the above embodiment, the ratio between dVdt1 (ΔVa) and dVdt2 (ΔVb) is used to estimate the rate of battery deterioration. In addition, a similar time change rate after ΔVb may be further used to perform a more detailed diagnosis.

[0047] In the above embodiment, the start point of ΔVb is later than the start point of ΔVa, and the end point of ΔVb is later than the end point of ΔVa. As long as this relationship is maintained, for example, Δt1 (first period) and Δt2 (second period) may partially overlap.

[0048] In the above embodiments, the detection unit 131 and the calculation unit 132 can be configured by hardware such as a circuit device that implements their functions, or can be configured by a calculation device such as a CPU (Central Processing Unit) executing software that implements their functions. [Explanation of symbols]

[0049] 13:Battery management device 131: Detection unit 132: Arithmetic section 133: Storage section

Claims

1. A battery management device for managing the state of a battery, a detection unit that acquires a detected value of the voltage output by the battery; a calculation unit that estimates the state of the battery; Equipped with the calculation unit identifies a first period in a pause period after the battery has finished a charging operation or a discharging operation, and a second period in the pause period that starts after a start time of the first period and ends after an end time of the first period; the calculation unit identifies a first change in the voltage during the first period and a second change in the voltage during the second period; The calculation unit estimates a deterioration rate of the battery, which is dependent on the temperature of the battery, based on a ratio between the first change and the second change. A battery management device characterized by:

2. The battery comprises: a first component that causes the voltage to change according to a first time constant; a second component causing the voltage to change according to a second time constant greater than the first time constant; Equipped with the calculation unit uses a period in which the voltage changes according to the first time constant as the first period; The calculation unit uses a period during which the voltage changes according to the second time constant as the second period.

2. The battery management device according to claim 1.

3. the battery has a first degradation mode in which the battery degrades at a first degradation rate when a temperature of the battery is below a temperature threshold or a state of charge of the battery is below a state of charge threshold; the battery has a degradation mode in which the battery degrades at a degradation rate greater than the first degradation rate when the temperature of the battery is equal to or greater than the temperature threshold and the state of charge of the battery is equal to or greater than the state of charge threshold; The battery management device according to claim 1, wherein the calculation unit estimates, based on the ratio, whether the battery has deteriorated in the first deterioration mode or in a deterioration mode having a deterioration rate greater than that of the first deterioration mode.

4. the battery has a characteristic of deteriorating in a stored state at the first deterioration rate or at a deterioration rate greater than the first deterioration rate, depending on a temperature of the battery in the stored state and a state of charge of the battery in the stored state; The battery estimates, based on the ratio, whether the battery deteriorated in the first deterioration mode or in a deterioration mode with a deterioration rate greater than that of the first deterioration mode in a past storage state.

4. The battery management device according to claim 3.

5. the calculation unit estimates the activation energy of the battery in a past storage state based on the ratio; the calculation unit estimates the temperature of the battery based on a deterioration state of the battery; The calculation unit estimates a deterioration acceleration of the battery using the estimated activation energy and the estimated temperature.

5. The battery management device according to claim 4.

6. The calculation unit estimates a deterioration state of the battery, the calculation unit acquires the number of times the battery has performed a charging operation or a discharging operation, or estimates the number of times using the estimated deterioration state and an amount of capacity reduction of the battery due to one charging operation or one discharging operation; The battery management device according to claim 5 , wherein the calculation unit estimates the temperature of the battery using the number of times and the estimated deterioration state.

7. the calculation unit obtains a relationship between the deterioration state, the number of times or the elapsed time since the start of operation of the battery, and the temperature of the battery; The calculation unit estimates the temperature of the battery by applying the estimated deterioration state and the number of times or the elapsed time to the relationship.

7. The battery management device according to claim 6.

8. The calculation unit estimates the degradation state using a correspondence relationship between the first change and the degradation state or a correspondence relationship between the second change and the degradation state.

7. The battery management device according to claim 6.

9. the battery has a third degradation mode in which the battery degrades at a third degradation rate at a temperature equal to or higher than a reference temperature; the battery has a fourth degradation mode in which, when a charge operation or a discharge operation is performed at a C rate equal to or higher than a C rate threshold at a temperature lower than the reference temperature, the battery degrades at a fourth degradation rate higher than the third degradation rate; The calculation unit estimates whether the battery has deteriorated in the third deterioration mode or the fourth deterioration mode based on the ratio.

2. The battery management device according to claim 1.

10. the calculation unit calculates a distance between the ratio and a threshold value on a two-dimensional coordinate interval of the ratio and the second change amount; The calculation unit estimates the magnitude of the deterioration rate in the fourth deterioration mode according to the magnitude of the distance.

10. The battery management device according to claim 9.

11. The battery management device according to claim 1 , a memory unit for storing data describing the temperature history of the battery and the state of charge history of the battery; Equipped with The calculation unit estimates the deterioration acceleration of the battery using the temperature history described in the data. A battery system characterized by:

12. The battery management device according to claim 1 , a charger for charging the battery; Equipped with The calculation unit controls at least one of a charging current from the charger to the battery or a charging state of the battery after being charged by the charger, in accordance with the estimated deterioration rate, so as to suppress deterioration of the battery being charged by the charger. A battery system characterized by:

13. The calculation unit estimates the deterioration rate of the battery during a period when the charger does not perform a charging operation.

13. The battery system according to claim 12.

14. The battery management device according to claim 5 , a memory unit that stores data describing the deterioration state of the battery and the deterioration acceleration of the battery; Equipped with The calculation unit classifies the performance of the battery according to the estimated deterioration state and the estimated deterioration acceleration, and records the result in the data. A battery system characterized by:

15. A battery management method in which a process for managing a battery state is carried out by a processor, the processor comprising: obtaining a detected value of the voltage output from the battery; estimating the state of the battery; and In the estimating step, the processor identifies a first period in a rest period after the battery has finished a charging operation or a discharging operation, and a second period in the rest period that starts after a start time of the first period and ends after an end time of the first period; In the estimating step, the processor identifies a first change in the voltage during the first time period and a second change in the voltage during the second time period; In the estimating step, the processor estimates a deterioration rate of the battery, which is dependent on the temperature of the battery, based on a ratio between the first change and the second change. A battery management method characterized by:

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