Self-discharge detection method, detection device and detection system thereof

Abstract

The present application discloses a self-discharge detection method, a detection device and a detection system thereof. The detection method comprises: connecting a plurality of cells to be tested in parallel to perform voltage balancing; when the voltage between the cells to be tested reaches a preset balancing level, removing the electrical connection between the cells to be tested; leaving the cells to be tested from which the electrical connection is removed to stand for a preset first time; after the first time, reconnecting a plurality of cells to be tested in parallel and connecting a current detection device to each cell to be tested; judging whether the current reading of the current detection device meets the preset detection standard; if so, determining that the cell to be tested connected to the current detection device is a normal self-discharge cell; if not, determining that the cell to be tested connected to the current detection device is an abnormal self-discharge cell. Compared with the traditional K value detection method, the method of detecting current readings has a higher resolution and significantly shortens the detection time.

Description

Technical Field

[0001] The present application relates to the field of self-discharge characteristic detection of battery cells, and specifically to a self-discharge detection method, a detection device and a detection system thereof. Background Art

[0002] Due to limitations in process scale, process level, and single-cell voltage, current power cell energy storage systems used in large-scale equipment like electric vehicles typically consist of a series or parallel connection of multiple cells. To avoid energy shortfalls, high self-discharge consistency is required within the same power cell energy storage system.

[0003] Therefore, screening out abnormally self-discharging cells is a crucial step in the manufacturing process of power cell energy storage systems. Currently, a common screening method involves measuring the K value of the cell (i.e., measuring the cell's voltage drop per unit time). However, this method is time-consuming and cannot effectively meet the needs of screening for abnormal self-discharging in existing large-capacity cells. Summary of the Invention

[0004] In view of the above problems, the present application provides a self-discharge detection method, a detection device and a detection system thereof, which can effectively overcome at least some of the defects of traditional detection methods.

[0005] In a first aspect, the present application provides a self-discharge detection method. The self-discharge detection method includes: connecting a plurality of cells to be tested in parallel to perform voltage balancing; when the voltage between the cells to be tested reaches a preset balancing level, removing the electrical connection between the cells to be tested; leaving the cells to be tested from which the electrical connection is removed to stand for a preset first time; after the first time, reconnecting the plurality of cells to be tested in parallel and connecting a current detection device to each cell to be tested; determining whether the current reading of the current detection device meets a preset detection standard; if so, determining that the cell to be tested connected to the current detection device is a normal self-discharging cell; if not, determining that the cell to be tested connected to the current detection device is an abnormal self-discharging cell.

[0006] In the technical solution of the embodiments of the present application, after a suitable rest period, the cells to be tested are reconnected in parallel and the current readings obtained from each cell can well represent the relative self-discharge levels among the cells to be tested. Consequently, cells with abnormal self-discharge can be screened out from the parallel-connected cells to be tested. Compared to traditional K-value detection methods, this current reading has a higher resolution and significantly shortens the overall detection time required.

[0007] In some embodiments, the steps of reconnecting several cells to be tested in parallel and connecting a current detection device to each cell to be tested specifically include: connecting the negative poles of several cells to be tested through wires, and connecting a current detection device to the positive pole of each cell to be tested; wherein, when the current flows out of the positive pole of the cell to be tested, the current reading of the current detection device is positive. The steps of judging whether the current reading of the current detection device meets the preset detection standard specifically include: when the current reading is greater than zero, determining that the current reading meets the preset detection standard; when the current reading is less than zero and the absolute value is less than the preset current threshold, determining that the current reading meets the preset detection standard; when the current reading is less than zero and the absolute value is greater than or equal to the preset current threshold, determining that the current reading does not meet the preset detection standard.

[0008] The technical solution of the embodiments of this application provides a specific connection method for the current detection device, a specific definition of the current reading, and a corresponding judgment method. Based on this judgment method, cells with abnormal self-discharge can be easily and quickly screened out by comparing the current reading with the current threshold.

[0009] In some embodiments, the self-discharge detection method further comprises the step of generating a preset detection standard based on previously acquired battery cell self-discharge detection data. The above technical solution provides a method for generating detection standards using existing battery cell self-discharge detection data. The detection standards thus obtained are highly representative and applicable, and can be reused in subsequent self-discharge anomaly detection, effectively improving battery cell detection efficiency.

[0010] In some embodiments, the above-mentioned step of generating the preset current threshold based on the previously obtained battery cell self-discharge detection data specifically includes: performing a voltage drop test on a number of sample battery cells to determine the self-discharge rate of each sample battery cell; connecting a number of sample battery cells in parallel to perform voltage balancing; when the sample battery cells connected in parallel reach a preset balance level, removing the electrical connection between the sample battery cells; leaving the electrically disconnected sample cells to stand for a preset first time; after the first time, connecting a current detection device to each sample battery cell and obtaining a current reading of the current detection device; among the number of sample battery cells, determining the sample battery cell whose self-discharge rate is the same as the preset self-discharge rate standard as the reference battery cell; and determining the absolute value of the current reading of the current detection device connected to the reference battery cell as the current threshold.

[0011] In the technical solution of the present application, a batch of sample cells is subjected to both the voltage drop test and the aforementioned self-discharge test to determine the correlation between the two test methods. This allows the current threshold corresponding to the self-discharge test to be determined based on the commonly used self-discharge rate standard, facilitating its use and implementation in production operations.

[0012] In some embodiments, the self-discharge detection method further includes determining whether the voltages between the cells to be tested have reached a preset level of balance after a preset second time has elapsed for the cells to be tested connected in parallel. In the above technical solution, a method is provided for determining whether the voltages between the cells to be tested have reached a preset level of balance based on the length of time the cells to be tested have been connected in parallel. This method for determining whether the voltages of the cells to be tested have reached a preset level of balance is easy to implement and simple to operate.

[0013] In a second aspect, the present application provides a self-discharge detection device. The self-discharge detection device includes: a detection module for determining whether the voltage between the parallel-connected cells to be tested has reached a preset balance level and whether the electrically disconnected cells to be tested have been at rest for a preset first time; a current acquisition module for obtaining a current reading of a current detection device; after the voltage between the parallel-connected cells to be tested has reached a preset balance level and has been at rest for a first time, the current detection device is connected to each parallel-connected cell to be tested; a judgment module for determining whether the current reading meets a preset detection standard; if so, determining that the cell to be tested connected to the current detection device is a normal self-discharging cell; if not, determining that the cell to be tested connected to the current detection device is an abnormal self-discharging cell.

[0014] In the technical solution of the embodiments of the present application, after multiple balanced cells have been left to rest for a period of time, the detection device measures the current reading of the branch circuit containing each cell. This current reading effectively represents the relative self-discharge levels among the cells under test. Compared to traditional K-value detection methods, this current reading has a higher resolution and significantly shortens the overall detection time.

[0015] In some embodiments, the self-discharge detection device further includes a detection standard setting module. This detection standard setting module is configured to generate a preset detection standard based on previously acquired battery cell self-discharge detection data. In the above technical solution, the detection standard generated by the detection standard setting module using existing battery cell self-discharge detection data is highly representative and applicable, and can be reused in subsequent self-discharge anomaly detection, effectively improving battery cell detection efficiency.

[0016] In a third aspect, the present application provides an electronic device comprising: a processor and a processor in communication with the processor; and a memory storing computer program instructions, which, when called by the processor, cause the processor to execute the self-discharge detection method described above.

[0017] In the technical solution of the embodiments of this application, the electronic device uses the current readings of each branch as detection data. These current readings can effectively represent the relative self-discharge levels among the cells under test, allowing cells with abnormal self-discharge to be screened out. Compared to traditional K-value detection methods, this significantly shortens the overall detection time.

[0018] In a fourth aspect, the present application provides a non-volatile computer storage medium, wherein the non-volatile computer storage medium stores computer program instructions, so that when the computer program instructions are called by a processor, the self-discharge detection method described above is executed.

[0019] In the technical solution of the present embodiment, the current readings obtained from each branch circuit are used as test data. These current readings can well represent the relative self-discharge levels among the cells under test. This allows cells with abnormal self-discharge to be identified among the cells under test, which are connected in parallel.

[0020] In a fifth aspect, the present application provides a self-discharge detection system. The self-discharge detection system includes: a voltage balancing device, a cell resting device, a current detection device, and a control device. Among them, the voltage balancing device is configured to: connect a number of cells to be tested in parallel for voltage balancing; the cell resting device is configured to: after the voltages of the cells to be tested reach a preset level of balance, remove the connection between the cells to be tested and let them rest; the current detection device is configured to: after the cells to be tested have finished resting, connect the cells to be tested to obtain the corresponding current reading; the control device is configured to: execute the above-mentioned self-discharge detection method and screen out cells with abnormal self-discharge among the cells to be tested.

[0021] In the technical solution of the embodiments of the present application, the current reading of each tested cell, obtained after a period of rest, is used as test data. Because the current reading at this time can well represent the relative self-discharge levels among the tested cells, it can be used as test data to screen out cells with abnormal self-discharge among the tested cells.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0024] Figure 1 This is a schematic structural diagram of a self-discharge detection system according to some embodiments of the present application;

[0025] Figure 2 A flow chart of a self-discharge detection method according to some embodiments of the present application;

[0026] Figure 3 This is a method flow chart of step S205 of some embodiments of the present application, illustrating a method for screening self-discharge anomalies using a current threshold as a detection criterion;

[0027] Figure 4 A flow chart of a self-discharge detection method according to some other embodiments of the present application;

[0028] Figure 5 This is a flow chart of a method for generating a current threshold value in some embodiments of the present application, illustrating a method for determining the current threshold value through detection results of sample cells;

[0029] Figure 6 This is a schematic diagram of voltage balancing results in some embodiments of the present application, showing how the voltage difference between two parallel-connected battery cells changes with the parallel connection time;

[0030] Figure 7 This is a functional block diagram of a self-discharge detection device according to some embodiments of the present application;

[0031] Figure 8 This is a functional block diagram of a self-discharge detection device according to some other embodiments of the present application;

[0032] Figure 9 Schematic diagram of an electronic device according to some embodiments of the present application. DETAILED DESCRIPTION

[0033] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0035] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0036] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0038] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0039] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0040] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0041] Currently, the typical method for screening for abnormal self-discharge in battery cells is to test the K values ​​of multiple cells (i.e., the voltage drop of the cell per unit time). Cells with K values ​​significantly greater than normal, or with K values ​​significantly different from other cells, are then identified as having abnormal self-discharge.

[0042] There are other methods for screening abnormal self-discharge of battery cells. After a long period of voltage balancing of multiple battery cells, the net inflow current of each battery cell is calculated based on the fact that the sum of the self-discharge current and external discharge current of the battery is equal to determine the self-discharge situation of the battery cell, thereby screening for abnormal self-discharge of the battery cell.

[0043] The applicant has noted that measuring the K value of a battery cell takes a long time. In particular, for larger-capacity power cells, the voltage drop generated in a short period of time is very weak, making it difficult to detect using instrumentation. Accurately measuring the voltage drop can only be achieved after the cell has been allowed to rest for an extended period.

[0044] Screening for self-discharge anomalies by detecting the net inflow current requires a long voltage balancing period to ensure consistent state of charge across multiple cells. Furthermore, multiple connections and disconnections are required to determine the net inflow current for each cell, making the overall process complex.

[0045] To address the aforementioned time-consuming self-discharge detection issue, the applicant has provided a technical solution for detecting abnormal self-discharge in battery cells based on static leakage current. "Static leakage current" refers to the current flowing through each branch of a battery cell, obtained by sampling it using a current detection device after connecting multiple cells to be tested in parallel after voltage equalization and resting.

[0046] Compared to voltage drop detection, current detection has higher resolution and can distinguish minute differences between cells due to self-discharge characteristics, thus significantly shortening the required rest time.

[0047] Compared to methods that measure the net inflow current of a cell, static leakage current detection directly measures the relative current between all parallel cells, eliminating the need for repeated disconnection and connection operations, simplifying the process. Furthermore, since static leakage current detection involves no calculation steps and doesn't require a specific reference point, the requirement for voltage consistency between cells is relatively low, significantly shortening the required voltage balancing time.

[0048] To fully illustrate the specific application scenarios of this application, the following description uses 16 parallel-connected battery cells as an example. Of course, those skilled in the art will appreciate that, based on the same principles and concepts, the self-discharge detection system of the embodiment of this application can also be applied to other self-discharge anomaly detection of different numbers and types of battery cells.

[0049] See also Figure 1 , Figure 1 Schematic diagram of a self-discharge detection system according to some embodiments of the present application. The self-discharge detection system includes a voltage equalization device 110 , a cell resting device 120 , a leakage current detection device 130 , and a control device 140 .

[0050] The voltage equalization device 110 is a device for making multiple cells B under test reach a balanced state. It can be implemented by wires or any other suitable type of electrical connection components, as long as it can achieve parallel connection between multiple cells. For example, Figure 1 Connect the wires as shown.

[0051] The cell resting device 120 is used to disconnect the cells B under test from each other and allow them to rest for a certain period of time to demonstrate their self-discharge characteristics. In this embodiment, the term "resting device" is used for convenience, but it can be implemented in any suitable manner and is not limited to a physical device. For example, it can be a specific placement location or storage space that is sufficient to accommodate the cells B under test.

[0052] The current detection device 130 is a data acquisition device used to collect data on the current flowing through the branch circuit where each cell B to be tested resides. It can be any suitable type of current detection instrument, as long as it has sufficient current detection accuracy. In some embodiments, a high-precision current detection device with minimal internal resistance can be used.

[0053] Each branch where the battery cell B to be tested is located can be provided with a corresponding current detection device 130 to detect the leakage current of the battery cell B to be tested on the branch. Figure 1 As shown, corresponding to the 16 cells to be tested connected in parallel, 16 current detection devices 130 may be provided.

[0054] In some embodiments, the current detection device 130 may be connected between the positive electrode of the battery cell B to be tested and the parallel connection node N of the battery cell B to be tested. Thus, when the current flows out of the positive electrode of the battery cell B to be tested, the current reading of the current detection device 130 is positive, and when the current flows into the parallel connection node N, the current reading of the current detection device 130 is negative.

[0055] Of course, the current detection device 130 can also adjust its placement position and provide corresponding current readings according to actual needs without being limited to Figure 1 shown.

[0056] The control device 140 can be an electronic computing device with logical operation capabilities, including but not limited to a server or industrial computer. It can establish a communication connection with the current detection device 130 via wired or wireless means, thereby receiving the current readings collected by the current detection device 130 and determining whether the tested battery cell B has abnormal self-discharge based on the current readings.

[0057] During operation, the positive and negative electrodes of multiple cells B under test are connected separately through the voltage balancing device 110 for voltage balancing. When the voltages of the cells B under test reach a predetermined level of voltage balancing, the electrical connections between the cells B under test are disconnected and the cells are placed in the cell resting device 120 for a suitable period of time.

[0058] After a suitable resting time, multiple cells B to be tested are connected in parallel again (for example Figure 1 16 cells to be tested as shown), and the current flowing through each cell B to be tested is collected through the current detection device 130.

[0059] The control device 140 receives and determines whether the current readings obtained by the current detection device 130 meet a preset detection standard (such as a preset current threshold), and determines those cells to be tested whose current readings do not meet the preset detection standard as abnormal self-discharge cells.

[0060] One of the advantages of the embodiments of the present application is that in the traditional voltage drop test process, since the voltage drop of the battery cell to be tested changes extremely little in a short period of time, it can only be effectively detected and identified after a long period of accumulation of static time.

[0061] However, slight changes in the voltage drop between cells under test can be identified and distinguished using the aforementioned static leakage current detection method. In other words, static leakage current has a higher resolution. Therefore, the static leakage current detection method used in this application to screen cells with abnormal self-discharge can significantly shorten the required static time compared to measuring the voltage drop of the cells under test.

[0062] According to some embodiments of the present application, Figure 2 This is a flow chart of a self-discharge detection method according to some embodiments of the present application. The self-discharge detection method can be executed by the self-discharge detection system described above. Figure 2 , the self-discharge detection method includes:

[0063] S201 , connecting several cells to be tested in parallel to perform voltage balancing.

[0064] The "cell under test" refers to a completed energy storage component that requires self-discharge anomaly testing to ensure the consistency of its self-discharge characteristics. It can be a single cell or a cell assembly consisting of multiple cells.

[0065] "Voltage balancing" means making the voltages between the cells to be tested as consistent as possible, that is, improving the voltage consistency of the cells to be tested to eliminate the impact caused by voltage differences that exist before the test.

[0066] S202 : When the voltages between the cells to be tested reach a preset equilibrium level, disconnect the electrical connections between the cells to be tested.

[0067] The "preset balance level" refers to the voltage consistency requirement between the cells to be tested. The specific determination method can be determined according to actual needs.

[0068] When the voltages between the cells under test reach a predetermined equilibrium, they are considered to have the same state of charge. Using this as the starting point for comparing the self-discharge characteristics of the cells under test can better eliminate any differences that existed before testing.

[0069] “Removal” refers to disconnecting the electrical connections between multiple cells to be tested so that the multiple cells to be tested will not be affected by each other.

[0070] S203 , leaving the electrically disconnected battery cell to be tested at rest for a preset first time.

[0071] The "first time" is a time value set by the technician based on the actual needs. In the static state, different cells under test will release their stored electricity according to their respective self-discharge characteristics, causing their own voltage to change.

[0072] S204 , after the first time has elapsed, reconnecting a plurality of cells to be tested in parallel and connecting a current detection device to each cell to be tested.

[0073] The “connected current detection device” means connecting the current detection device to the branch where each battery cell to be tested is located to reflect the magnitude of the current flowing through the branch. Any suitable type of connection method can be selected according to the actual needs, such as Figure 1 The current sensing device is connected as shown.

[0074] As described above, during the static process, due to the different self-discharge characteristics of the cells under test, the amount of electricity released per unit time will also vary. After the initial accumulation of these differences, they can be reflected in the voltage differences between the cells under test.

[0075] Please continue reading Figure 1 Because there are slight voltage differences between the cells to be tested, after reconnecting them in parallel, the voltage differences between the cells to be tested will generate corresponding currents in each branch. By connecting a current detection device and detecting the current flowing through each branch, the voltage differences between the cells to be tested can be identified.

[0076] S205: Determine whether the current reading of the current detection device meets the preset detection standard. If yes, execute step S206; if not, execute step S207.

[0077] The "testing standard" is a screening criterion determined by technicians based on the test results of cells from the same batch or type. It is used to determine whether the current reading of the tested cell is closer to that of a cell with abnormal self-discharge or a cell with normal self-discharge.

[0078] As described above, the current reading represents the self-discharge of the cell after the voltage equalization and rest phases. For simplicity, in the present embodiment, this current reading may also be referred to as "rest leakage current."

[0079] S206 , determining that the battery cell to be tested, which is connected to the current detection device, is a normal self-discharging battery cell.

[0080] Among them, when the preset test standards are met, it shows that based on existing historical experience, the battery cell to be tested is likely to be a battery cell with normal self-discharge and can pass the test.

[0081] S207 , determining that the battery cell to be tested, which is connected to the current detection device, is a battery cell with abnormal self-discharge.

[0082] Among them, when the preset detection standards are not met, it shows that based on existing historical experience, it can basically be considered that the self-discharge characteristics of the battery cell to be tested are closer to those of the battery cell with abnormal self-discharge, and there is abnormal self-discharge.

[0083] One advantage provided by the embodiments of the present application is the use of static leakage current as a screening criterion for abnormal cell self-discharge. Compared to traditional voltage drop testing methods, static leakage current has higher resolution. Only a short static time is required to distinguish subtle voltage differences between the tested cells due to differences in self-discharge characteristics, effectively shortening the time required for self-discharge detection.

[0084] According to some embodiments of the present application, optionally, refer to Figure 3 , Figure 3 The present invention provides a flow chart of a method for determining whether a current reading meets a preset detection standard. Figure 1 As shown, when the negative electrodes of the multiple cells to be tested are connected by wires and the positive electrode of each cell to be tested is connected to a current detection device, the above step S205 specifically includes the following steps:

[0085] S2051. Determine whether the current reading is greater than zero. If so, execute step S2052; if not, execute step S2053.

[0086] Among them, when the set current flows out from the positive electrode of the battery cell to be tested, the current reading of the current detection device is positive. It can be understood that when using Figure 1 In the connection shown, a positive current reading indicates that the voltage of the cell under test is greater than the voltage at the parallel node. This indicates that the voltage drop of the cell under test is small and its self-discharge is low.

[0087] S2052. Determine whether the current reading meets the preset detection standard.

[0088] S2053: Determine whether the absolute value of the current reading is greater than or equal to a preset current threshold. If so, execute step S2054; if not, execute step S2052.

[0089] A negative current reading indicates that the voltage of the cell under test is lower than the voltage at the parallel node. This indicates a larger voltage drop and a higher degree of self-discharge. Furthermore, a larger absolute value of the current reading indicates a greater difference between the voltage of the cell under test and the voltage at the parallel node. This indicates that the greater the voltage drop, the greater the self-discharge.

[0090] Based on this, a suitable current threshold can be set to determine whether the self-discharge level of the battery cell to be tested is too large and should be determined as an abnormal self-discharge battery cell.

[0091] S2054: Determine whether the current reading does not meet the preset detection standard.

[0092] One of the advantages of the embodiments of the present application is that, based on the specific connection method of the current detection device and the specific definition of the current reading, a corresponding current reading judgment method is provided, so that battery cells with abnormal self-discharge can be easily and quickly screened out.

[0093] It should be noted that based on the current reading judgment principle disclosed in the embodiment of the present application, those skilled in the art can also adjust, replace or delete one or more judgment steps in the detection standard according to different actual conditions (such as changes in the connection position of the current detection device), and are not limited to the embodiments of the present application. Figure 3 shown.

[0094] According to some embodiments of the present application, optionally, refer to Figure 4 , Figure 4 The self-discharge detection method provided in some other embodiments of the present application may further include:

[0095] S208: Generate a preset detection standard based on the previously obtained battery cell self-discharge detection data.

[0096] The "cell self-discharge test data" is the test results related to self-discharge characteristics obtained by conducting a series of self-discharge test experiments on sample cells. The specific self-discharge test data used can be determined based on actual needs, such as the specific test standards used.

[0097] One advantage of the present invention is that it provides a method for generating test standards using existing sample cell self-discharge test data as sample data. The test standards thus obtained are highly representative and applicable, and can be reused in subsequent self-discharge anomaly detection, effectively improving cell detection efficiency.

[0098] According to some embodiments of the present application, optionally, refer to Figure 5 , Figure 5 Flowchart of the method for determining the test standard provided in the embodiment of the present application. The method for determining the test standard specifically includes:

[0099] S2081. Perform a voltage drop test on several sample battery cells to determine the self-discharge rate of each sample battery cell.

[0100] The "self-discharge rate" refers to the voltage drop per unit time of a static battery cell. This can be determined through traditional voltage drop testing methods, such as voltage balancing and long-term static testing of the battery cells. The specific methods of voltage drop testing are well known to those skilled in the art and will not be detailed here.

[0101] S2082. Connect several sample cells in parallel to perform voltage balancing.

[0102] Here, "sample cells" refer to cells with similar characteristics to the cells to be tested, such as cells of the same type produced in the same batch or on the same production line. It is understood that sample cells are representative and can be considered as samples for sampling and testing of the cells to be tested. In this embodiment, they are referred to as "sample cells."

[0103] S2083: When the voltages between the sample cells reach a preset equilibrium level, disconnect the electrical connection between the sample cells.

[0104] S2084: Leave the sample battery cell, which has been electrically disconnected, to rest for a preset first time.

[0105] S2085: After the first time has passed, connect each sample battery cell to a current detection device and obtain a current reading of the current detection device.

[0106] Among them, in steps S2082 to S2085, the same self-discharge detection method as that of the battery cell to be tested is adopted for the sample battery cells to obtain their corresponding static leakage currents.

[0107] S2086. Determine, among the plurality of sample cells, a sample cell having a self-discharge rate that is the same as a preset self-discharge rate standard as a reference cell.

[0108] The "self-discharge rate standard" is a standard value determined by technicians based on actual needs. It can be determined based on specific needs (such as production indicators required by customers).

[0109] It should be noted that the above “same” means that the self-discharge rate of the sample battery cell is roughly the same as the self-discharge rate standard but not absolutely the same. The difference between the two is allowed to fluctuate within a specific percentage range, such as 1%.

[0110] S2087. Determine the absolute value of the current reading of the current detection device connected to the reference battery cell as the current threshold.

[0111] As described above, the sample cells are subjected to a voltage drop test to obtain their self-discharge rates, and the self-discharge detection method provided in the embodiment of the present application is used to obtain their static leakage currents.

[0112] Therefore, the correspondence between the self-discharge rate and the static leakage current can be determined based on the sample data provided by the sample cells. Based on this correspondence, the preset self-discharge rate can be converted into a corresponding current threshold to complete the screening of self-discharge anomalies in the test cells.

[0113] One of the advantages of the embodiments of the present application is that the corresponding relationship between the self-discharge rate and the static leakage current is obtained by simultaneously performing a voltage drop test and the above-mentioned self-discharge test on a batch of sample cells.

[0114] Therefore, the current threshold corresponding to the self-discharge detection can be determined based on the commonly used self-discharge rate standard, which is convenient for use and implementation in production operations.

[0115] In some embodiments, optionally, please continue to refer to Figure 4 ,Apart from Figure 2 In addition to the steps shown, the self-discharge detection method may further include, after the above step S201:

[0116] S2011: After a preset second time period has elapsed, determine whether the voltages between the cells to be tested have reached a preset balance level.

[0117] The preset second time is set by technicians based on actual conditions such as the capacity and type of the battery cells, and represents the length of time required for the parallel connection of the battery cells to be tested to reach the required degree of balance.

[0118] For example, if subsequent testing results reveal that the missed or over-missed rates for tested cells exceed expectations, the initial testing time can be appropriately extended. The "missed rate" refers to the percentage of tested cells with abnormal self-discharge that were not screened out due to overly loose screening criteria. The "over-missed rate" refers to the percentage of tested cells with normal self-discharge that were incorrectly screened out due to overly strict screening criteria.

[0119] One of the advantages of the embodiments of the present application is that the method of determining whether the voltage between the two reaches a preset balance level based on the length of time the battery cells to be tested are connected in parallel is easy to implement and simple to operate, and can be well applied in actual detection.

[0120] According to some embodiments of the present application, optionally, the second time can be set to a value between 4 hours and 10 hours.

[0121] Among them, for the second time, as the time for voltage balancing of the cells to be tested continues to increase, the consistency of the voltage values ​​between the cells to be tested will be higher, and the voltage difference between the cells to be tested will be smaller. Figure 6 As shown in the figure, as the balancing time increases, the voltage difference between parallel cells will gradually decrease. The smaller the voltage difference between the cells to be tested, the more accurate the self-discharge anomaly screening results will be.

[0122] However, as a necessary step in the self-discharge abnormality detection, the longer the potential equalization time is, the longer the time required for the self-discharge abnormality detection of the battery cell is.

[0123] Therefore, in the process of implementing this application, it was surprisingly discovered that setting the second time to a value between 4 hours and 10 hours can well balance the needs of the above two aspects, and can shorten the detection time as much as possible while ensuring that the voltage consistency between the battery cells to be tested can meet the detection needs.

[0124] Several specific examples are provided below to fully illustrate the self-discharge detection method and the specific implementation of each step of the self-discharge detection method according to the embodiment of the present application.

[0125] Example 1:

[0126] 1) Potential equalization: Use on 16 fresh cells to be tested Figure 1 The potential equalization device 110 shown performs potential equalization for 10 hours.

[0127] 2) Standing: After 10 hours of potential equalization, remove the parallel connection between the cells to be tested and then stand the 16 cells to be tested for 6 hours.

[0128] 3) Connect the current detection device: Connect the negative poles of the 16 cells to be tested through wires, and connect a current detection device to the positive pole of each cell to be tested, and obtain the current reading of each current detection device.

[0129] The current detection device can be a high-precision current detection device with a current detection accuracy of ±1uA and an internal resistance of 50mΩ. The current reading is the static leakage current of the battery cell under test.

[0130] 4) Determine the current threshold: Use other cells from the same batch as sample cells and perform the voltage drop test and the above test steps to obtain the voltage drop and static leakage current of the sample cells.

[0131] Assume that according to actual requirements, a K value greater than 0.02mV / h is considered an abnormal self-discharge cell (i.e., the self-discharge rate standard is 0.02mV / h). At this time, among the sample cells, the static leakage current of the sample cell with a self-discharge rate closest to 0.02mV / h can be selected as the current threshold.

[0132] The above step 4) can be performed in advance to detect and obtain the required current threshold value. The obtained current threshold value is pre-stored in a specific memory for the control device to call.

[0133] 5) Screening for abnormal self-discharge cells: When the static leakage current of the cell under test is greater than zero, the cell under test is determined to be a normal self-discharge cell. When the static leakage current of the cell under test is less than zero, determine whether its absolute value is greater than or equal to the current threshold determined in step 4). If so, the cell under test is determined to be an abnormal self-discharge cell; otherwise, the cell under test is determined to be a normal self-discharge cell.

[0134] Example 2:

[0135] 1) Potential equalization: Use on 16 fresh cells to be tested Figure 1 The potential equalization device 110 shown performs potential equalization for a potential equalization time of 4 hours.

[0136] 2) Standing: After 4 hours of potential equalization, remove the parallel connection between the cells to be tested and then stand the 16 cells to be tested for 6 hours.

[0137] 3) Connect the current detection device: Connect the negative poles of the 16 cells to be tested through wires, and connect a current detection device to the positive pole of each cell to be tested, and obtain the current reading of each current detection device.

[0138] The current detection device can be a high-precision current detection device with a current detection accuracy of ±1uA and an internal resistance of 50mΩ. The current reading is the static leakage current of the battery cell under test.

[0139] 4) Determine the current threshold: Use other cells from the same batch as sample cells and perform the voltage drop test and the above test steps to obtain the voltage drop and static leakage current of the sample cells.

[0140] Assume that according to actual requirements, a K value greater than 0.02mV / h is considered an abnormal self-discharge cell (i.e., the self-discharge rate standard is 0.02mV / h). At this time, among the sample cells, the static leakage current of the sample cell with a self-discharge rate closest to 0.02mV / h can be selected as the current threshold.

[0141] The above step 4) can be performed in advance to detect and obtain the required current threshold value. The obtained current threshold value is pre-stored in a specific memory for the control device to call.

[0142] 5) Screening for abnormal self-discharge cells: When the static leakage current of the cell under test is greater than zero, the cell under test is determined to be a normal self-discharge cell. When the static leakage current of the cell under test is less than zero, determine whether its absolute value is greater than or equal to the current threshold determined in step 4). If so, the cell under test is determined to be an abnormal self-discharge cell; otherwise, the cell under test is determined to be a normal self-discharge cell.

[0143] One advantage of the embodiments of the present application is that by detecting the static leakage current of the battery cell instead of the voltage drop of the battery cell, the high resolution can significantly reduce the static time required for the battery cell to be tested. Moreover, this detection method does not require the equipment to be connected for a long time; only a single connection is required to obtain the current detection value of the battery cell after the static state, which can greatly save equipment costs and simplify the detection operation.

[0144] According to some embodiments of this application, please refer to Figure 7 , Figure 7 The self-discharge detection device 700 of the embodiment of the present application includes: a detection module 710 , a current acquisition module 720 and a judgment module 730 .

[0145] Among them, the detection module 710 is used to determine whether the voltage between the parallel-connected cells to be tested has reached a preset balance level and whether the electrically disconnected cells to be tested have been left to rest for a preset first time. The current acquisition module 720 is used to obtain the current reading of the current detection device; after the voltage between the cells to be tested has reached a preset balance level and has been left to rest for a first time, the current detection device is connected to each parallel-connected cell to be tested. The judgment module 730 is used to determine whether the current reading meets the preset detection standard; if so, it is determined that the cell to be tested connected to the current detection device is a normal self-discharging cell; if not, it is determined that the cell to be tested connected to the current detection device is an abnormal self-discharging cell.

[0146] During operation, the detection module 710 determines, based on time detection and other methods, whether the battery cell under test has reached a preset level of balance and has completed its rest period. The current acquisition module 720 obtains the current readings of the current detection device connected after the battery cell under test has reached the preset level of balance and has rested for a sufficient period of time, and provides them to the judgment module 730. Based on the received current readings, the judgment module 730 sorts them by magnitude and determines whether each current reading meets the preset detection criteria. Finally, the judgment module 730 screens the battery cells under test for abnormal self-discharge based on the judgment results.

[0147] One advantage of the present embodiment is that the detection device measures the current reading of each branch of the battery cell. This current reading can well represent the relative self-discharge levels of the tested cells and has a high resolution. Compared to traditional K value detection methods, the static time can be significantly shortened.

[0148] According to some embodiments of the present application, optionally, refer to Figure 8 , Figure 8 Another embodiment of the present application provides a self-discharge detection device. Figure 7In addition to the functional modules shown, it also includes: a detection standard setting module 740.

[0149] The detection standard setting module 740 is used to generate a preset detection standard based on previously acquired battery cell self-discharge detection data. In this embodiment of the present application, a method for generating detection standards using existing battery cell self-discharge detection data is provided. This detection standard, determined based on sample data, can be reused for self-discharge anomaly detection across the same batch of battery cells, effectively improving battery cell detection efficiency.

[0150] According to some embodiments of the present application, optionally, the detection standard setting module 740 is specifically used to: perform a voltage drop test on a number of sample battery cells to determine the self-discharge rate of each sample battery cell; connect a number of sample battery cells in parallel to perform voltage balancing; when the sample battery cells connected in parallel reach a preset balance level, remove the electrical connection between the sample battery cells; let the sample battery cells from which the electrical connection is removed stand for a preset first time; after the first time, connect a current detection device to each sample battery cell and obtain a current reading of the current detection device; among the number of sample battery cells, determine the sample battery cell whose self-discharge rate is the same as the preset self-discharge rate standard as the reference battery cell; determine the absolute value of the current reading of the current detection device connected to the reference battery cell as the current threshold.

[0151] In this embodiment, by simultaneously performing the voltage drop test and the aforementioned self-discharge test on a batch of sample cells, a corresponding relationship between the test results of the two test methods is obtained. This allows the corresponding current threshold to be determined based on commonly used self-discharge rate standards, facilitating its use and implementation in production operations. Furthermore, this current threshold can be reused across the same batch or type of cells under test, improving detection efficiency.

[0152] According to some embodiments of the present application, optionally, the above-mentioned judgment module 730 is specifically used to: when the current reading is greater than zero, determine that the current reading meets the preset detection standard; when the current reading is less than zero and the absolute value is less than a preset current threshold, determine that the current reading meets the preset detection standard; when the current reading is less than zero and the absolute value is greater than or equal to the preset current threshold, determine that the current reading does not meet the preset detection standard.

[0153] The negative and positive electrodes of several cells to be tested are connected by wires, and a current detection device is connected between the positive electrode of each cell to be tested and the parallel connection node. When current flows from the positive electrode of the cell to be tested, the current detection device reads a positive current. This embodiment provides a specific method for screening cells with abnormal self-discharge. Based on this screening method, cells with abnormal self-discharge can be easily and quickly screened out by current readings.

[0154] According to some embodiments of the present application, the detection module 710 is optionally configured to determine that the parallel-connected cells have reached equilibrium after a predetermined second time has elapsed. This second time can be determined by a technician based on actual needs. In this embodiment, a method for determining whether equilibrium has been achieved based on the length of time the cells have been connected in parallel is provided, which is easy to implement and simple to operate.

[0155] It should be noted that in the embodiments of the present application, the functional modules of the self-discharge detection device are divided according to the method steps to be performed. In some embodiments, one or more functional modules (such as the detection module, current acquisition module, judgment module, and threshold setting module) in the self-discharge detection device of the embodiments of the present application can be split into more functional modules based on actual needs to perform the corresponding method steps. In other embodiments, one or more functional modules in the self-discharge detection device of the embodiments of the present application can be integrated into fewer functional modules to perform the corresponding method steps.

[0156] According to some embodiments of this application, please refer to Figure 9 , Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may be a control device or any other suitable type of electronic computing platform for executing the above self-discharge detection method, and its specific implementation is not limited here.

[0157] The electronic device may include a processor 910 , a communication interface 920 , a memory 930 , and a communication bus 940 .

[0158] The processor 910, communication interface 920, and memory 930 communicate with each other via a communication bus 940. The communication interface 920 is used to connect to other devices (e.g., a current detection device). The processor 910 is used to call a program 950 to execute one or more steps of the self-discharge detection method described in the above embodiment or to implement one or more functional modules of the self-discharge detection device described in the above embodiment. Specifically, the program 950 may include program code or computer operating instructions.

[0159] In this embodiment, depending on the type of hardware used, processor 910 can be a central processing unit, other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0160] The memory 930 is used to store the program 950. The memory 930 may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory.

[0161] The present application also provides a computer-readable storage medium. The computer-readable storage medium may be a non-volatile computer-readable storage medium. The computer-readable storage medium stores a computer program.

[0162] When executed by a processor, the computer program implements one or more steps of the self-discharge detection method described in the above embodiment or implements one or more functional modules of the self-discharge detection device described in the above embodiment. A complete computer program product is embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing the computer program disclosed in the embodiments of this application.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A self-discharge detection method, characterized in that: include: Connect several cells to be tested in parallel to balance the voltage; When the voltage between the battery cells to be tested reaches a preset balance level, removing the electrical connection between the battery cells to be tested; leaving the electrically disconnected battery cell to be tested to stand for a preset first time; After the first time has passed, reconnecting the plurality of cells to be tested in parallel and connecting each cell to be tested to a current detection device; Determine whether the current reading of the current detection device meets the preset detection standard; the current reading refers to the static leakage current of the battery cells to be tested flowing through each branch after multiple battery cells to be tested are connected in parallel after voltage equalization and static state, which is used to indicate the relative self-discharge degree between the multiple battery cells to be tested; If so, determining that the battery cell to be tested connected to the current detection device is a normal self-discharging battery cell; If not, determining that the battery cell to be tested connected to the current detection device is a battery cell with abnormal self-discharge; The step of reconnecting the plurality of cells to be tested in parallel and connecting each cell to be tested to a current detection device specifically comprises: connecting the negative electrodes of the plurality of cells to be tested via a wire, and connecting the positive electrode of each cell to be tested to a current detection device; wherein when current flows out of the positive electrode of the cell to be tested, the current reading of the current detection device is positive; The determining whether the current reading of the current detection device meets the preset detection standard specifically includes: when the current reading is greater than zero, determining that the current reading meets the preset detection standard; when the current reading is less than zero and the absolute value is less than a preset current threshold, determining that the current reading meets the preset detection standard; When the current reading is less than zero and the absolute value is greater than or equal to a preset current threshold, it is determined that the current reading does not meet the preset detection standard.

2. The self-discharge detection method according to claim 1, wherein: The method further comprises: The preset detection standard is generated according to the previously obtained battery cell self-discharge detection data.

3. The self-discharge detection method according to claim 2, wherein: The step of generating the preset detection standard based on the previously obtained cell self-discharge detection data specifically includes: Performing a voltage drop test on a plurality of sample battery cells to determine the self-discharge rate of each of the sample battery cells; Connecting a plurality of the sample cells in parallel to perform voltage balancing; When the sample cells connected in parallel reach voltage equilibrium, removing the electrical connection between the sample cells; leaving the electrically disconnected sample battery cell to rest for a preset first time; After the first time has passed, connecting each of the sample cells to a current detection device and obtaining a current reading of the current detection device; Among the plurality of sample cells, determining a sample cell having a self-discharge rate that is the same as a preset self-discharge rate standard as a reference cell; An absolute value of a current reading of a current detection device connected to the reference battery cell is determined as the current threshold.

4. The self-discharge detection method according to any one of claims 1 to 3, characterized in that: The method further comprises: When a preset second time has passed for the plurality of cells to be tested that are connected in parallel, it is determined that the voltages between the cells to be tested reach a preset balance level.

5. A self-discharge detection device, characterized in that: include: A detection module is used to determine whether the parallel-connected cells to be tested have reached equilibrium and whether the electrically disconnected cells to be tested have been left idle for a preset first time; A current acquisition module, used to obtain current readings of a current detection device; The current detection device is connected to the positive electrode of each parallel-connected battery cell to be tested after the voltage between the battery cells to be tested reaches a preset balance and the battery cells have been left at rest for a first time; when current flows out of the positive electrode of the battery cell to be tested, the current reading is positive. The current reading refers to the static leakage current of the battery cells to be tested flowing through each branch after the multiple battery cells to be tested are connected in parallel after voltage balance and rest, and is used to characterize the relative self-discharge degree between the multiple battery cells to be tested; A judgment module is used to judge whether the current reading meets a preset detection standard; if so, determine that the battery cell to be tested connected to the current detection device is a normal self-discharging battery cell; if not, determine that the battery cell to be tested connected to the current detection device is an abnormal self-discharging battery cell; The judgment module is specifically configured to determine that the current reading meets the preset detection standard when the current reading is greater than zero; and to determine that the current reading meets the preset detection standard when the current reading is less than zero and the absolute value is less than a preset current threshold; When the current reading is less than zero and the absolute value is greater than or equal to a preset current threshold, it is determined that the current reading does not meet the preset detection standard.

6. The self-discharge detection device according to claim 5, characterized in that: Also includes: The detection standard setting module is used to generate the preset detection standard according to the previously obtained battery cell self-discharge detection data.

7. An electronic device, characterized in that: include: A processor and a memory in communication with the processor; the memory stores computer program instructions, and when the computer program instructions are called by the processor, the processor executes the self-discharge detection method according to any one of claims 1 to 4.

8. A non-volatile computer storage medium, characterized in that The non-volatile computer storage medium stores computer program instructions, so that when the computer program instructions are called by a processor, the self-discharge detection method according to any one of claims 1 to 4 is executed.

9. A self-discharge detection system, characterized in that: include: A voltage balancing device is configured to: connect a plurality of cells to be tested in parallel for voltage balancing; A cell resting device, wherein the cell resting device is configured to: after the voltages of a plurality of cells to be tested reach a preset equilibrium level, remove the connections between the cells to be tested and allow them to rest; A current detection device, wherein the current detection device is configured to: connect the battery cell to be tested to obtain a corresponding current reading after the battery cell to be tested has been allowed to rest; the current reading refers to the static leakage current of the battery cell to be tested flowing through each branch after the multiple battery cells to be tested are connected in parallel after voltage equalization and rest, and is used to indicate the relative self-discharge degree between the multiple battery cells to be tested; A control device, wherein the control device is configured to: execute the self-discharge detection method according to any one of claims 1 to 4, and screen out abnormal self-discharge cells among the plurality of cells to be tested.

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