System and method for acquiring characteristics of secondary battery

Abstract

A battery characteristic acquisition system (10) comprises: a charging control unit (21), a measuring unit (22), a storage unit (33), and a characteristic curve creation unit (321). The charging control unit (21) charges a battery (90). The measuring unit (22) measures the OCV of the battery (90) before the start of charging and the charge capacity value charged from the start of charging to the completion of charging by full charging, and calculates the SOC at the start of charging by subtracting the measured charge capacity value from the full charge capacity of the secondary battery. The storage unit (33) stores the OCV and the SOC for a plurality of times. The characteristic curve creation unit (321) creates an SOC-OCV curve of the battery (90) by using the OCV and remaining capacity for a plurality of times.

Description

[Technical field]

[0001] The present invention relates to a technique for obtaining an SOC-OCV characteristic curve of a secondary battery. [Background technology]

[0002] Patent Document 1 describes a battery pack that calculates the degree of deterioration of a secondary battery. The battery pack in Patent Document 1 calculates the internal resistance of the secondary battery, and calculates the rate of increase in the internal resistance as the degree of deterioration of the secondary battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4389910 specification Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1, a method of determining the degree of deterioration of a secondary battery from only the internal resistance provides only an index representing one of the various deterioration factors of the secondary battery, and does not accurately determine the deterioration state of the secondary battery.

[0005] As a method capable of accurately determining the deterioration level of a secondary battery, a method using the SOC-OCV characteristic curve of the secondary battery is known.

[0006] However, with the conventional methods, it takes a lot of time and effort to obtain the SOC-OCV characteristic curve of a secondary battery.

[0007] Therefore, an object of the present invention is to easily obtain the SOC-OCV characteristic curve of a secondary battery. [Means for solving the problem]

[0008] A secondary battery characteristic acquisition system according to an embodiment of the present invention includes a charge control unit, a measurement unit, a storage unit, and a characteristic curve creation unit. The charge control unit has a first mode in which the secondary battery is intermittently charged, and a second mode in which the secondary battery is continuously charged, and selects either the first mode or the second mode to charge the secondary battery. The measurement unit measures the OCV of the secondary battery and the capacity from the start of charging in the first mode, and calculates the remaining capacity at each measured OCV. The storage unit stores the OCV and remaining capacity for multiple times. The characteristic curve creation unit creates a remaining capacity-OCV curve of the secondary battery using the OCV and remaining capacity for multiple times. Furthermore, after the OCV from 0 to 100% capacity is finally collected, the remaining capacity is converted to SOC to complete the SOC-OCV curve.

[0009] The charge control unit performs charging in the first mode in a range in which the terminal voltage and the SOC are not stored, and performs charging in the second mode in a range in which the terminal voltage and the SOC are stored.

[0010] In this configuration, continuous charging is performed in the range where data (terminal voltage and SOC) for creating the characteristic curve have been measured or calculated, and intermittent charging is performed while measuring the terminal voltage in the range where data (terminal voltage and SOC) for creating the characteristic curve have not been measured or calculated. This makes it possible to shorten the charging time for each charge while still measuring a large amount of data for creating the characteristic curve. Therefore, the SOC-OCV characteristic curve of the secondary battery can be easily obtained. Effect of the Invention

[0011] According to the present invention, the SOC-OCV characteristic curve of a secondary battery can be easily obtained. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a functional block diagram showing a configuration of a battery characteristics acquisition system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing an example of a method for acquiring characteristics of a secondary battery according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a flowchart showing intermittent charging. [Figure 4] FIG. 4 is a graph showing an example of the relationship between the SOC and the charging opportunity in the first embodiment. [Diagram 5] FIG. 5 shows an example of an SOC-OCV curve in the first embodiment. [Figure 6] FIG. 6 is a functional block diagram showing a configuration of a battery characteristics acquisition system according to the second embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing an example of a method for acquiring characteristics of a secondary battery according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a graph showing an example of the relationship between the SOC and the charging opportunity in the second embodiment. [Figure 9] FIG. 9 shows an example of an SOC-OCV curve in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [First embodiment] A secondary battery characteristic acquisition technique according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a functional block diagram showing the configuration of a battery characteristic acquisition system according to the first embodiment of the present invention.

[0014] As shown in Fig. 1, a battery characteristic acquisition system 10 includes a charging device 20 and a management device 30. The battery characteristic acquisition system 10 corresponds to the "secondary battery characteristic acquisition system" of the present invention. This system is applied, for example, to a system for renting equipment equipped with a battery (secondary battery) 90. In this case, the charging device 20 is provided, for example, at an agency that rents the equipment, and the management device 30 is provided at a management company or the like that manages the rental of the equipment. Note that the system can be applied not only to equipment equipped with the battery 90, but also to a rental system for the battery 90 alone.

[0015] (Charging device 20) The charging device 20 includes a charging control unit 21, a measuring unit 22, a communication unit 23, and a charging terminal 290. Although not shown, the charging device 20 receives power from a commercial power source or the like.

[0016] The charging control unit 21 charges the battery 90 connected to the charging terminal 290. Specifically, the charging control unit 21 continuously supplies power to the battery 90 until the battery 90 is fully charged in accordance with a predetermined charging condition. At this time, the charging control unit 21 acquires identification information (individual identification information) from the battery 90.

[0017] The measurement unit 22 measures the terminal voltage of the secondary battery. More specifically, the measurement unit 22 measures the voltage and OCV (open circuit voltage) of the battery 90 during charging.

[0018] The measurement unit 22 measures the charging capacity value from the start of charging to the completion of charging due to full charging. More specifically, the measurement unit 22 measures the current from the start of charging to full charging and the time from the start of charging to full charging, and calculates the charging capacity value from these.

[0019] The measurement unit 22 calculates the SOC before charging by subtracting the charging capacity value from the full charge capacity of the charged battery 90. The full charge capacity can be found by referring to the identification number of the battery 90 acquired by the charging control unit 21, for example.

[0020] The communication unit 23 receives the identification number from the charging control unit 21 and the OCV and SCO from the measurement unit 22, associates the identification number, OCV, and SOC of the battery 90 with each other, and transmits them to the communication unit 31 of the management device 30.

[0021] The charging control unit 21 and the measurement unit 22 execute the above-mentioned processing each time the battery 90 is charged (each time a request to charge the battery 90 is received from the user), and the communication unit 23 links and transmits the identification number, OCV, and SOC of the battery 90.

[0022] (Management device 30) The management device 30 includes a communication unit 31 , a calculation unit 32 , and a storage unit 33 .

[0023] The communication unit 31 receives the identification number, OCV, and SOC of the battery 90 from the communication unit 23 of the charging device 20, and outputs them to the storage unit 33. The communication unit 31 outputs these to the storage unit 33 every time it receives them.

[0024] The storage unit 33 stores the identification number, OCV, and SOC from the communication unit 31 in association with each other. The storage unit 33 stores these data in sequence each time they are input from the communication unit 31. In this way, the storage unit 33 stores the identification number, OCV, and SOC of the battery 90 for the number of times it has been charged up to now. In other words, if charging has been performed multiple times, the storage unit 33 stores the OCV and SOC for multiple times corresponding to this number of times in association with the identification number of the battery 90.

[0025] The calculation unit 32 includes a characteristic curve creation unit 321 and a determination unit 322. The calculation unit 32 is realized by, for example, an arithmetic processing device such as a personal computer.

[0026] The characteristic curve creation unit 321 uses the OCV and SOC for a plurality of times to calculate a characteristic curve of the battery 90. More specifically, the characteristic curve creation unit 321 uses the OCV and SOC for a plurality of times to calculate a SOC-OCV curve of the battery 90. For example, the characteristic curve creation unit 321 may combine the calculation of the OCV with a method of estimating the OCV from a transition curve.

[0027] The secondary battery characteristic acquisition technique using the above-mentioned configuration will be described with reference to the drawings. In summary, in the secondary battery characteristic acquisition technique according to this embodiment, when the battery 90 is charged multiple times by the charging device 20, the management device 30 calculates the remaining capacity-OCV curve using data obtained during these multiple charging times. At this time, the charging device 20 and the management device 30 do not acquire the OCV if there is a range for which the remaining capacity-OCV curve has already been calculated. On the other hand, the charging device 20 and the management device 30 additionally calculate the remaining capacity-OCV curve for a range (unmeasured range) different from the range for which the remaining capacity-OCV curve has already been calculated. Then, the charging device 20 and the management device 30 calculate the entire remaining capacity-OCV curve by combining these.

[0028] FIG. 2 is a flowchart showing an example of a method for acquiring characteristics of a secondary battery according to the first embodiment of the present invention.

[0029] As shown in FIG. 2, an agency equipped with a charging device 20 lends a fully charged battery 90 to a user (S21) and receives the used battery 90 (S22).

[0030] The charging device 20 acquires the unmeasured range. The unmeasured range is a range in which a pair of the OCV and the remaining capacity is not stored. The charging device 20 determines whether the voltage measured at the start of the current charging, i.e., the current OCV, is within the unmeasured range (S23).

[0031] Specifically, in the case of an initial charge (first charge), the charging device 20 determines that the OCV is within the unmeasured range regardless of the current OCV value.

[0032] In the case of the second or subsequent charge, if the state at the time of this return is within a range in which a pair of OCV and remaining capacity has not been obtained in previous charges, the charging device 20 determines that it is within the unmeasured range. In other words, if the OCV before the start of this charge is lower than the lowest OCV stored, the charging device 20 determines that it is within the unmeasured range.

[0033] On the other hand, if the current remaining capacity is within the range for which a pair of OCV and remaining capacity was obtained in a previous charge, the charging device 20 determines that it is outside the unmeasured range (within the measured range). In other words, if the OCV before the start of the current charge is equal to or higher than the lowest OCV stored, the charging device 20 determines that it is outside the unmeasured range. Note that while the OCV cannot be measured directly during charging, if it is within the measured range, the relationship between the charging voltage and OCV is already known. Therefore, the OCV can be estimated from the charging voltage based on this relationship and determined to be outside the unmeasured range.

[0034] The charging device 20 (charging control unit 21) has a plurality of charging modes. More specifically, the charging device 20 has a first mode in which the charging device 20 charges the battery 90 intermittently and a second mode in which the charging device 20 charges the battery 90 continuously.

[0035] If the battery is within the unmeasured range (S23: YES), the charging device 20 performs charging (intermittent charging) in the first mode (S24).

[0036] Charging in the first mode (intermittent charging) is specifically performed as follows: Figure 3 is a flowchart showing the intermittent charging.

[0037] The charging device 20 continuously charges for a short period for measurement (S241). The charging device 20 stops charging, electrically opens the terminals of the battery 90 (S242), and maintains the electrically open state until a stabilization time (the time until the voltage stops changing and becomes stable) has elapsed (S243: NO).

[0038] After the stabilization time has elapsed (S243: YES), the charging device 20 measures the open circuit voltage (OCV) (S244).

[0039] The charging device 20 repeats this short-time charging for measurement (S241), electrical opening of the terminals (S242), and OCV measurement (S244) until the end of the unmeasured range (S25: NO). The end of the unmeasured range can be detected by the point in time when the OCV measured in S244 becomes equal to or higher than the OCV measured previously.

[0040] By carrying out such processing, the OCV can be measured while charging little by little, so that many pairs of different OCVs and remaining capacity can be obtained.

[0041] When the unmeasured range ends (S25: YES), the charging device 20 performs charging in the second mode (continuous charging) (S26). At this time, the charging device 20 does not measure the OCV.

[0042] The charging device 20 continues charging (continuous charging) in the above-mentioned second mode (S26) until the battery is fully charged (S27: NO).

[0043] When the battery 90 is fully charged (S27: YES), the charging device 20 calculates the remaining capacity for each measured OCV (S28), and transmits the set of the OCV and remaining capacity to the management device 30, linking them to the identification information of the battery 90 (S29).

[0044] The management device 30 calculates the remaining capacity-OCV curve of the battery 90 using the multiple sets of OCV and remaining capacity received and stored from the charging device 20. Furthermore, the management device 30 calculates the SOC-OCV curve of the battery 90 using the SOC calculated from the capacity and remaining capacity of the battery 90.

[0045] (Explanation using concrete examples) FIG. 4 is a graph showing an example of the relationship between SOC and charging opportunity in the first embodiment. In FIG. 4, since the full charge capacity is not known until all the data is collected, the SOC cannot be calculated and is stored as the remaining capacity, but for the sake of simplicity, the horizontal axis shows SOC and the vertical axis shows charging opportunity. A circle indicates a fully charged state, and a triangle indicates SOC before charging starts. The voltage V1-V5 accompanying the triangle indicates the OCV at that time. C1A, C2A, and C5A indicate charging capacity values ​​in intermittent charging, and C2N, C3N, C4N, and C5N indicate charging capacity values ​​in continuous charging.

[0046] In the first charge, the pair of OCV and remaining capacity is not stored. Therefore, in the first charge, the entire range to be charged is an unmeasured range. The charging device 20 measures the OCV (V1) before charging starts, and performs intermittent charging while measuring the OCV in the first mode. When the battery is fully charged, the charging device 20 calculates the charging capacity value C1A and calculates the remaining capacity at each OCV.

[0047] As a result, during the first charge, pairs of SOC and OCV can be obtained in a short measurement cycle for the range from SOC 70% to SOC 100%.

[0048] In the second charge, the range from SOC 70% to SOC 100% is the measured range, so the range where the SOC is lower than 70% (the range where the OCV is smaller than V1) is the unmeasured range.

[0049] The charging device 20 measures the OCV (V2) before the start of charging, and because V2 is lower than V1, it determines that it is within the unmeasured range. Therefore, in the second charge, the charging device 20 first performs intermittent charging while measuring the OCV in the first mode.

[0050] The charging device 20 performs intermittent charging in the first mode, and when it detects that the unmeasured range has ended, it switches from the first mode to the second mode and performs continuous charging without measuring the OCV. That is, the charging device 20 performs intermittent charging in the first mode, and when the OCV reaches V1 (when the SOC reaches 70%), it switches from the first mode to the second mode and performs continuous charging without measuring the OCV. The second mode does not open the terminals, does not allow the stabilization time to elapse, and does not measure the OCV, so it can charge faster than the first mode even with the same charging voltage and charging current as the first mode.

[0051] Thereafter, when the battery is fully charged, the charging device 20 calculates a charging capacity value C2A in the first mode (intermittent charging) and a charging capacity value C2N in the second mode (continuous charging), and calculates the remaining capacity of each OCV obtained in the first mode.

[0052] As a result, in the second charge, a pair of remaining capacity and OCV can be obtained in a short measurement cycle for the range from SOC 20% to SOC 70%.

[0053] During the third charge, the range from SOC 20% to SOC 100% is the measured range, so the range where SOC is lower than 20% (the range where OCV is smaller than V2) is the unmeasured range.

[0054] The charging device 20 measures the OCV (V3) before the start of charging, and because V3 is higher than V2, it determines that it is outside the unmeasured range. Therefore, in the third charge, the charging device 20 performs continuous charging in the second mode until the battery is fully charged.

[0055] In the fourth charge, as in the third charge, the range from SOC 20% to SOC 100% is the measured range, so the range where SOC is lower than 20% (the range where OCV is smaller than V2) is the unmeasured range.

[0056] The charging device 20 measures the OCV (V4) before the start of charging, and because V4 is higher than V2, it determines that it is outside the unmeasured range. Therefore, in the fourth charge, the charging device 20 performs continuous charging in the second mode until the battery is fully charged.

[0057] During the fifth charge, as with the third and fourth charges, the range from SOC 20% to SOC 100% is the measured range, so the range where SOC is lower than 10% (the range where OCV is smaller than V2) is the unmeasured range.

[0058] The charging device 20 measures the OCV (V5) before the start of charging, and because V5 is lower than V2, it determines that it is within the unmeasured range. Therefore, in the fifth charge, the charging device 20 first performs intermittent charging while measuring the OCV in the first mode.

[0059] The charging device 20 performs intermittent charging in the first mode, and when it detects that the unmeasured range has ended, it switches from the first mode to the second mode and performs continuous charging without measuring the OCV. That is, the charging device 20 performs intermittent charging in the first mode, and when the OCV reaches V2 (when the SOC reaches 20%), it switches from the first mode to the second mode and performs continuous charging without measuring the OCV.

[0060] Thereafter, when the battery is fully charged, the charging device 20 calculates a charging capacity value C5A in the first mode (intermittent charging) and a charging capacity value C5N in the second mode (continuous charging), and calculates the remaining capacity of each OCV obtained in the first mode.

[0061] As a result, during the fifth charge, a set of remaining capacity and OCV can be obtained in a short measurement cycle for the range from SOC 0% to SOC 20%.

[0062] Then, by performing the above-mentioned processing, for multiple charges (charging requests), the OCV can be adjusted from SOC 0% to 100% (fully charged) in a total of five charges, covering the range from SOC 0% to SOC 100%, and the SOC can be calculated from the fully charged capacity and remaining capacity.

[0063] By carrying out such processing, the management device 30 can obtain the following set of data of SOC and OCV.

[0064] 5 shows an example of a remaining capacity-OCV curve in the first embodiment. In FIG. 5, the horizontal axis indicates SOC, and the vertical axis indicates OCV. Each black circle in FIG. 5 is the measurement data of OCV and SOC, as shown in FIG.

[0065] As shown by the black circles in Fig. 5, during intermittent charging, the SOC and OCV can be obtained at short intervals, which allows the management device 30 to calculate the SOC-OCV curve with higher accuracy.

[0066] Furthermore, by using the method of the first embodiment, in the second and subsequent charging operations, the pair of SOC and OCV is acquired at short intervals only in the range where the pair of SOC and OCV is not available. This allows faster charging in the range where the pair of SOC and OCV has already been acquired. Therefore, the battery characteristics acquisition system 10 can calculate the SOC-OCV curve with higher accuracy while preventing the charging time of the battery 90 from becoming undesirably long.

[0067] [Second embodiment] A secondary battery characteristic acquisition technique according to a second embodiment of the present invention will be described with reference to the drawings. The secondary battery characteristic acquisition technique according to the second embodiment differs from the secondary battery characteristic acquisition technique according to the first embodiment in that, under specific conditions, OCV and SOC are measured after discharging. Only the differences will be described below.

[0068] Fig. 6 is a functional block diagram showing a configuration of a battery characteristic acquisition system according to a second embodiment of the present invention. As shown in Fig. 6, a battery characteristic acquisition system 10A differs from the battery characteristic acquisition system 10 according to the first embodiment in that the battery characteristic acquisition system 10A includes a charge / discharge device 20A. The charge / discharge device 20A includes a charge / discharge control unit 21A.

[0069] The charge / discharge control unit 21A has a function (charging function) of the charge control unit 21 shown in the first embodiment, and further has a discharging function.

[0070] When measuring a pair of SOC and OCV, if a specific condition is satisfied, the charge / discharge control unit 21A performs discharge and then performs intermittent charging in the first mode for the SOC range in which the discharge was performed.

[0071] The management device 30 calculates the SOC-OCV curve of the battery 90 by using pairs of remaining capacity and OCV obtained by the measurement unit 22 for multiple charging operations by the charge / discharge control unit 21A and charging after discharging.

[0072] In the above description, intermittent charging is performed in the first mode after discharging, but OCV may be measured by performing intermittent discharging in the first mode for the same section.

[0073] (How to obtain battery characteristics) Fig. 7 is a flowchart showing an example of a method for acquiring characteristics of a secondary battery according to the second embodiment of the present invention. Note that in Fig. 7, description of charge control when discharge control is not performed is omitted, and charge control without additional discharge control is the same as in the first embodiment.

[0074] Charging / discharging device 20A acquires the unmeasured range from management device 30 (S31).

[0075] The charging / discharging device 20A measures the OCV before starting charging of the battery 90 that has been requested to be charged. When the discharge condition is satisfied (S320: YES), the charging / discharging device 20A discharges the battery 90 (S32).

[0076] Here, the discharge condition is either or both of the number of charges (number of requested charges) reaching a predetermined number and the OCV before the start of charging being equal to or lower than the discharge permission voltage. For example, when the discharge condition is the number of charges, the discharge condition is set to the fourth charge. When the discharge condition is the discharge permission voltage, the discharge condition is set to the OCV before the start of charging corresponding to an SOC of 20%. Furthermore, when the discharge condition is the number of charges and the discharge permission voltage, the discharge condition is set to the number of charges being equal to or higher than the fourth charge and the OCV before the start of charging corresponding to an SOC of 20%. Note that this is merely an example and is not limited to this.

[0077] After the charging / discharging device 20A reduces the SOC to 0% by discharging, it performs intermittent charging in the first mode for the unmeasured range (S33). Alternatively, the charging / discharging device 20A acquires data up to SOC 0% by intermittent discharging in the first mode.

[0078] The charging / discharging device 20A continues intermittent charging in the first mode (S33) until the unmeasured range ends (S34: NO).

[0079] When the unmeasured range ends (S34: YES), charging / discharging device 20A performs charging (continuous charging) in the second mode (S35). Charging / discharging device 20A performs charging (continuous charging) in the second mode (S35) until fully charged (S36: NO).

[0080] When the charging / discharging device 20A is fully charged (S36: YES), it calculates the remaining capacity for each measured OCV (S37), and transmits the set of the OCV and remaining capacity to the identification information of the battery 90, together with the identification information of the battery 90, to the management device 30 (S38).

[0081] The management device 30 calculates the SOC-OCV curve of the battery 90 using the sets of the OCV and remaining capacity for multiple times that are received from the charging device 20 and stored.

[0082] With such a configuration and processing, the battery characteristics acquisition system 10A can forcibly acquire a set of SOC and OCV by discharging, which could not be acquired by previous charging. At this time, by setting the above-mentioned discharge conditions, the battery characteristics acquisition system 10A does not unconditionally discharge, but only discharges when a specific condition is satisfied, thereby suppressing deterioration of the battery 90 due to discharge.

[0083] In particular, the battery characteristics acquisition system 10A discharges the battery 90 only when the SOC is in a low range, thereby further suppressing deterioration of the battery 90 due to discharge.

[0084] In addition, by setting the number of charges as the discharge condition, the battery characteristics acquisition system 10A can prevent the pair of remaining capacity and OCV from being unable to be acquired for an extended period of time, and can more reliably calculate an accurate remaining capacity-OCV curve.

[0085] (Explanation using concrete examples) Fig. 8 is a graph showing an example of the relationship between SOC and charging opportunity in the second embodiment. In Fig. 8, the horizontal axis indicates SOC, and the vertical axis indicates charging opportunity. A circle indicates a fully charged state, and a triangle indicates SOC before charging starts. Voltages V1-V4 and V4d accompanying the triangle indicate the OCV at that time. C1A, C2A, and C4A indicate charging capacity values ​​in intermittent charging, and C2N, C3N, and C4N indicate charging capacity values ​​in continuous charging.

[0086] The first, second and third charging operations are the same as those in the first embodiment described above (see FIG. 4), and the description thereof will be omitted.

[0087] In the fourth charge, as in the third charge, the range from SOC 20% to SOC 100% is the measured range, so the range where SOC is lower than 20% (the range where OCV is smaller than V2) is the unmeasured range.

[0088] The charging / discharging device 20A measures the OCV (V4) before the start of charging, and because V4 is lower than V2, it determines that it is within the unmeasured range. Furthermore, the charging / discharging device 20A discharges the battery 90 because this fourth charge satisfies the discharge condition (for example, the fourth charge and the OCV is lower than the OCV of SOC 20%).

[0089] After discharging to SOC 0%, the charger / discharger 20A measures the OCV (V4d). After that, the charger / discharger 20A first performs intermittent charging in the first mode while measuring the OCV.

[0090] The charging / discharging device 20A performs intermittent charging in the first mode, and when it detects that the unmeasured range has ended, it switches from the first mode to the second mode and performs continuous charging without measuring the OCV. That is, the charging / discharging device 20A performs intermittent charging in the first mode, and when the OCV reaches V2 (when the SOC reaches 20%), it switches from the first mode to the second mode and performs continuous charging without measuring the OCV.

[0091] Thereafter, when the charging / discharging device 20A is fully charged, it calculates the charging capacity value C4A in the first mode (intermittent charging) and the charging capacity value C4N in the second mode (continuous charging), and calculates the SOC at each OCV obtained in the first mode after discharging.

[0092] As a result, in the fourth charge, discharge is used, and pairs of SOC and OCV can be obtained in a short measurement cycle for the range from SOC 0% to SOC 20%.

[0093] This allows the battery characteristic acquisition system 10A to effectively utilize the discharge process and acquire pairs of SOC and OCV for the range from SOC 0% to SOC 100% (fully charged) in a short measurement cycle.

[0094] By carrying out such processing, the management device 30 can obtain the following set of data of SOC and OCV.

[0095] Fig. 9 shows an example of an SOC-OCV curve in the second embodiment. In Fig. 9, the horizontal axis indicates SOC, and the vertical axis indicates OCV. White circles and black circles in Fig. 9 indicate measurement data of OCV and SOC. White circles indicate measurement data obtained by using discharge. Black circles indicate measurement data obtained without using discharge (measurement data obtained by the same method as in the first embodiment).

[0096] 9, the SOC and OCV can be acquired at small intervals from SOC 0% to SOC 100%, allowing the management device 30 to calculate the SOC-OCV curve with higher accuracy.

[0097] Furthermore, by using the method of the second embodiment, the battery characteristics acquisition system 10A can acquire a set of SOC and OCV by discharging in a range that could not be acquired by multiple charging without discharging. This allows the battery characteristics acquisition system 10A to calculate the SOC-OCV curve with higher accuracy while preventing the number of charging times of the battery 90 from increasing significantly.

[0098] Furthermore, the battery characteristics acquisition system 10A can suppress deterioration of the battery 90 due to discharging by setting the OCV corresponding to the SOC at which discharging is permitted low. [Explanation of symbols]

[0099] 10, 10A: Battery characteristic acquisition system 20: Charging device 20A: Charge / discharge device 21: Charging control unit 21A: Charge / discharge control unit 22: Measuring part 23: Communications Department 30: Management device 31: Communications Department 32: Arithmetic section 33: Storage part 90: Battery 290: Charging terminal 321: Characteristic curve creation section 322: Judgment section

Claims

1. a charge control unit having a first mode for intermittently charging a secondary battery and a second mode for continuously charging the secondary battery, the charge control unit selecting either the first mode or the second mode to charge the secondary battery; a measurement unit that measures a terminal voltage of the secondary battery in the first mode and calculates a remaining capacity for each of the measured terminal voltages; a storage unit that stores the terminal voltage and the remaining capacity for a plurality of times; a characteristic curve creation unit that creates a remaining capacity-OCV curve of the secondary battery using the terminal voltages and remaining capacities of the multiple times; Equipped with The charging control unit is When the terminal voltage and the remaining capacity are not stored, charging is performed in the first mode. charging in the second mode within a range in which the terminal voltage and the remaining capacity are stored; A system for acquiring characteristics of secondary batteries.

2. A charge / discharge control unit including the charge control unit and performing charge control and discharge control, The charge / discharge control unit is If there is an unmeasured range of the terminal voltage and the remaining capacity, and the discharge permission condition is satisfied, After discharging the secondary battery, charging the unmeasured range in the first mode. The secondary battery characteristic acquisition system according to claim 1 .

3. The discharge permission condition is that the terminal voltage before the start of charging is equal to or lower than a discharge permission voltage. The secondary battery characteristic acquisition system according to claim 2 .

4. a charge control step of selecting a first mode for intermittently charging a secondary battery and a second mode for continuously charging the secondary battery and charging the secondary battery by selecting either the first mode or the second mode; a measurement step of measuring a terminal voltage of the secondary battery in the first mode and calculating a remaining capacity for each of the measured terminal voltages; a storage step of storing the terminal voltage and the remaining capacity a plurality of times; a characteristic curve calculation step of creating a remaining capacity-OCV curve of the secondary battery using the terminal voltages and remaining capacities of the multiple times; having The charging control step includes: When the terminal voltage and the remaining capacity are not stored, charging is performed in the first mode. charging in the second mode within a range in which the terminal voltage and the remaining capacity are stored; A method for obtaining characteristics of a secondary battery.

5. The charging control step includes a charge / discharge control step for performing charge control and discharge control, The charge / discharge control step includes: If there is an unmeasured range of the terminal voltage and the remaining capacity, and the discharge permission condition is satisfied, After discharging the secondary battery, charging the unmeasured range in the first mode. The method for acquiring characteristics of a secondary battery according to claim 4 .

6. The discharge permission condition is that the terminal voltage before the start of charging is equal to or lower than a discharge permission voltage. The method for acquiring characteristics of a secondary battery according to claim 5 .

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