Battery pack repair method and system

Abstract

The present disclosure relates to the field of batteries. The battery pack repair method and system disclosed in the present disclosure are used to repair a battery pack including a plurality of cells connected in series. The repair method includes: voltage equalization of the battery pack in a repairable state; performing an abnormal cell replacement step, including: detecting whether there are abnormal cells with abnormal impedance among the plurality of cells after voltage equalization, and replacing the abnormal cells with normal cells. The battery pack repair method and system disclosed in the present disclosure can increase the service life of the battery pack, and has high repair efficiency and low cost.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a battery pack repair method and system. Background Art

[0002] In the related art, after a battery pack has been in operation for a period of time, for example, a battery pack for a two-wheeled vehicle, its operating performance will decline and its subsequent service life will be short. However, if such a battery pack is directly discarded, it will easily cause waste. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present disclosure is to provide a battery pack repair method and system, which can increase the service life of the battery pack and have high repair efficiency and low cost.

[0004] The battery pack repair method provided by the present disclosure is used to repair a battery pack including a plurality of battery cells connected in series, and the repair method includes: performing voltage equalization on the battery pack in a repairable state; executing an abnormal battery cell replacement step, including: detecting whether there are abnormal batteries with abnormal impedance among the plurality of battery cells after voltage equalization, and replacing the abnormal batteries with normal batteries.

[0005] According to some embodiments provided by the present disclosure, a method for detecting whether the battery pack is in a repairable state includes one of the following: 1) pre-checking whether a battery management system chip of the battery pack is damaged, and if not, collecting multiple voltage values ​​of multiple battery cells, and comparing whether a voltage difference between a maximum voltage value and a minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, determining that the battery pack is in the repairable state; 2) collecting multiple voltage values ​​of multiple battery cells, and comparing whether a voltage difference between a maximum voltage value and a minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, determining that the battery pack is in the repairable state.

[0006] According to some embodiments provided by the present disclosure, the voltage balancing includes at least one of active balancing and passive balancing; the balancing target of the voltage balancing includes: after voltage balancing, the voltage difference between the maximum voltage value and the minimum voltage value of the multiple voltage values ​​corresponding to the multiple battery cells is below the set voltage value.

[0007] According to some embodiments provided by the present disclosure, the detection of whether there is an abnormal battery cell with abnormal impedance among the multiple battery cells after voltage equalization includes: collecting multiple impedance values ​​corresponding to the multiple battery cells after voltage equalization, screening abnormal values ​​among the multiple impedance values, and determining that the battery cell corresponding to the abnormal value is the abnormal battery cell; and / or the normal battery cell includes: a new battery cell with normal impedance or the abnormal battery cell with normal impedance after maintenance.

[0008] According to some embodiments provided by the present disclosure, the collecting of multiple impedance values ​​corresponding to the multiple battery cells after voltage balancing includes: collecting a total working current in a circuit of multiple battery cells in series and a plurality of working voltages corresponding to the multiple battery cells, and determining the plurality of impedance values ​​based on the total working current, the plurality of working voltages and Ohm's law.

[0009] According to some embodiments provided by the present disclosure, it also includes: performing the voltage balancing and abnormal cell replacement steps on the replaced battery pack in a cycle until the impedance of each cell is normal under voltage balancing.

[0010] According to some embodiments provided by the present disclosure, it also includes: detecting the charge state of a battery pack in which each cell has normal impedance under voltage balancing after being fully charged, and determining whether the battery pack has been repaired to a preset qualified standard based on whether the charge state reaches a preset charge state.

[0011] The present disclosure also provides a battery pack repair system for repairing a battery pack including a plurality of battery cells connected in series, the repair system including: a battery balancing device for performing voltage balancing on the battery pack in a repairable state; an impedance detection device, disposed at a later stage of the balancing device, for detecting whether there are abnormal battery cells with abnormal impedance among the plurality of battery cells after voltage balancing; a replacement device, disposed at a later stage of the impedance detection device, for replacing the abnormal battery cells with normal battery cells; and a control device connected to the balancing device, the impedance detection device and the replacement device.

[0012] According to some embodiments provided by the present disclosure, it also includes: a pre-inspection device, the pre-inspection device includes: a first pre-inspection unit, used to detect whether the battery management system chip of the battery pack is damaged; and a second pre-inspection unit, arranged at the rear stage of the first pre-inspection unit, used to collect multiple voltage values ​​of the multiple battery cells, and compare whether the voltage difference value between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, it is determined that the battery pack is in a repairable state; or the pre-inspection device includes: a second pre-inspection unit, used to collect multiple voltage values ​​of the multiple battery cells, and compare whether the voltage difference value between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within the first preset range, and if so, it is determined that the battery pack is in a repairable state.

[0013] According to some embodiments provided by the present disclosure, the impedance detection device includes: a current detection unit, installed on a series circuit in which a plurality of the battery cells are connected in series, and used to detect the total working current of the battery cells; a plurality of voltage detection units, correspondingly connected in parallel at both ends of the plurality of the battery cells, and used to detect a plurality of working voltages of the plurality of the battery cells; an impedance analysis unit, respectively connected to the current detection unit and the plurality of voltage detection units, and used to determine a plurality of impedance values ​​according to the total working current and the plurality of working voltages; and / or a state of charge detection device, provided at a later stage of the replacement device and connected to the control device, the control device determining whether the battery pack is repaired to a preset qualified standard according to whether the state of charge of the battery pack reaches a preset state of charge.

[0014] Beneficial effects:

[0015] (1) The battery pack repair method and system disclosed in the present invention can repair the battery pack and increase the service life of the battery pack, and has high repair efficiency and low cost.

[0016] (2) The battery pack repair method and system disclosed in the present invention can balance the voltage and impedance of the multiple cells in the battery pack, and the repair effect is good.

[0017] (3) The battery pack repair method and system disclosed in the present invention are helpful in avoiding the mixing of unqualified battery packs among the repaired battery packs, and are helpful in ensuring the repair effect of the battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a repair process diagram of a battery pack repair method according to an embodiment of the present disclosure.

[0019] Figure 2 It is a repair process diagram of a battery pack repair method according to another embodiment of the present disclosure.

[0020] Figure 3 It is a schematic diagram of the layout of the battery pack repair system of the embodiment of the present disclosure.

[0021] Reference numerals:

[0022] Battery balancing device 11;

[0023] Impedance detection equipment 12;

[0024] Replacement device 13;

[0025] Control device 14;

[0026] Pre-inspection equipment 15

[0027] State of charge detection device 16;

[0028] Conveying equipment 800. DETAILED DESCRIPTION

[0029] The following is an explanation of the embodiments of the present disclosure by specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the information disclosed by the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in the present disclosure can also be modified or changed in various ways according to different viewpoints and application modules without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0030] In the related art, after a battery pack has been in operation for a period of time, for example, a battery pack for a two-wheeled vehicle, its operating performance will decline and its subsequent service life will be short. However, if such a battery pack is directly discarded, it will easily cause waste.

[0031] In view of this, the present disclosure provides a battery pack repair method and system, which can repair the battery pack, improve the working performance of the battery pack, and extend the service life of the battery pack.

[0032] The battery pack repair method is used to repair a battery pack, and the battery pack includes a plurality of battery cells connected in series. Each of the battery cells can work independently to provide electrical energy to the outside world. Optionally, the battery pack can be a two-wheeled vehicle battery pack, but it is understood that the battery pack described in the present disclosure includes but is not limited to this, and the battery pack can also be a four-wheeled vehicle battery pack or other battery packs having a plurality of the battery cells connected in series.

[0033] Figure 1 FIG. 1 is a schematic diagram of a repair process of a battery pack repair method according to an embodiment of the present disclosure. Figure 1 , the battery pack repair method comprises the following steps:

[0034] S10: Perform voltage equalization on the battery pack in a repairable state. The battery pack in a repairable state can be understood as the battery pack that is in a state of needing repair and can be repaired. Therefore, when repairing the battery pack, the present disclosure can first eliminate the battery packs with good working performance that do not need to be repaired, and eliminate the battery packs that cannot be repaired, thereby avoiding the situation in which it is discovered during the repair process that the battery pack does not need to be repaired or cannot be repaired, avoiding the waste of time and resources, and is conducive to improving the repair efficiency of the battery pack and reducing the repair cost.

[0035] Optionally, detecting whether the battery pack is in a repairable state includes step a: collecting multiple voltage values ​​of multiple battery cells, and comparing whether the voltage difference between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range. For example, the first preset range may be 3mV-5mV. Therefore, if the voltage difference is too small, it means that the battery pack is not damaged and can continue to work well without repair. If the voltage difference is too large, it means that major faults such as short circuit or open circuit may occur in the battery pack. When repairing the battery pack, each cable line needs to be checked one by one, which makes the repair difficult and has low repair value. Such battery packs can also be eliminated. Therefore, the above steps can eliminate battery packs with good working performance, battery packs that cannot be repaired, and battery packs with major faults and low repair value, so as to facilitate screening out battery packs that can be repaired with simple operations. ‌

[0036] Optionally, detecting whether the battery pack is in a repairable state further includes step b: before step a, detecting whether the battery management system chip of the battery pack is damaged. The battery management system chip is connected to the plurality of battery cells and is used to manage the plurality of battery cells. It is the core part of the battery pack and the part with higher cost. When the battery management system chip is damaged, the battery pack has little repair value and can be discarded.

[0037] For example, detecting whether the battery management system chip is damaged includes: sending an instruction to the battery management system chip, and determining whether the battery management system chip is damaged according to whether the battery management system chip responds to the instruction. Thus, after sending the instruction to the battery pack, if the battery management system chip responds to the instruction, it means that the battery management system chip is not damaged. If the battery management system chip cannot respond to the instruction, it means that the battery management system chip is damaged.

[0038] Optionally, the voltage equalization target includes: among the multiple voltage values ​​corresponding to the multiple battery cells, the voltage difference between the maximum voltage value and the minimum voltage value is below a set voltage value. For example, the set voltage value is lower than any value within the first preset range, for example, the set voltage value may be 2mV.

[0039] Optionally, the voltage equalization of the battery pack includes passive equalization. For example, the operation of the passive equalization includes connecting a balancing resistor and a conduction switch in parallel to the battery cell with high voltage. Thus, when the conduction switch is turned on, the charging current is shunted when passing through the balancing resistor, so that the charging current of the battery cell with high voltage is small, while the charging current of the battery cell with low voltage is large, thereby achieving voltage equalization of each battery cell. Of course, it can be understood that the voltage equalization may also include active equalization, and the operation of the active equalization includes setting an energy conversion device between the battery cell with high voltage and the battery cell with low voltage, and the energy conversion device includes energy storage elements such as capacitors and / or inductors. The energy conversion device can absorb the electricity of the battery cell with high voltage and send the electricity to the battery cell with low voltage, thereby achieving voltage equalization of each battery cell by continuously converting energy through the energy conversion device.

[0040] S20: Execute an abnormal cell replacement step, the abnormal cell replacement step comprising: detecting whether there is an abnormal cell with abnormal impedance among the multiple cells after voltage equalization, and replacing the abnormal cell with a normal cell. It can be understood that the impedance of the cell after voltage equalization refers to the total impedance of the cell after voltage equalization, for example, when the cell with high voltage is connected in parallel with the equalization resistor, the impedance of the cell after voltage equalization refers to the total resistance of the cell and the equalization resistor in parallel.

[0041] For the battery pack, the impedance of each cell should be kept as the same as possible after voltage equalization, otherwise the charging or discharging process of each cell will be different during charging or discharging, affecting the overall performance and life of the battery pack. Therefore, after voltage equalization, it is detected whether there is an abnormal cell in each cell whose impedance value is abnormal (obviously different) from other cells. When the abnormal cell exists, the abnormal cell is replaced with a normal cell with the same impedance value as other cells. Therefore, this step ensures that the impedance corresponding to each cell can be balanced after voltage equalization, so that the battery pack has a better repair effect, can repair the battery pack with good working performance, and extend the service life of the battery pack.

[0042] Optionally, the detection of whether there are abnormal cells with abnormal impedance among the multiple cells after voltage equalization includes: collecting multiple impedance values ​​corresponding to the multiple cells after voltage equalization, screening out abnormal values ​​among the multiple impedance values, and determining that the cell corresponding to the abnormal value is the abnormal cell. In other words, after obtaining the multiple impedance values ​​corresponding to the multiple cells after voltage equalization, if there is an abnormal value among the multiple impedance values, the cell corresponding to the abnormal value is the abnormal cell, and thus the abnormal cell is screened out. Conversely, if there is no abnormal value among the multiple impedance values, the abnormal cell does not exist among the multiple cells after voltage equalization.

[0043] For example, the screening can be implemented using an outlier screening algorithm. For example, after calculating the average value and standard deviation of multiple impedance values, each impedance value is compared with a comparison range formed according to the average value and the standard deviation. When the size of any impedance value is outside three times the standard deviation of the average value, the impedance value is determined to be the outlier, and the battery cell corresponding to the outlier is the abnormal battery cell. On the contrary, the impedance value is a normal value, and the battery cell impedance is normal. Of course, it can be understood that the outlier screening algorithm includes but is not limited to this, and other algorithms that can screen out outliers are also within the protection scope of the present disclosure.

[0044] Optionally, the acquisition of multiple impedance values ​​corresponding to the multiple battery cells after voltage equalization includes: acquiring the total working current and the working voltage of each battery cell in the series circuit of the multiple battery cells, and determining the multiple impedance values ​​according to the total working current, the multiple working voltages and Ohm's law. For example, the voltage across each battery cell after the total working current and voltage equalization is substituted into the formula for solving the resistance in Ohm's law, and the value obtained by the solution is the impedance value. Thus, according to the multiple working voltages, the total working current and Ohm's law, the impedance value corresponding to each battery cell after voltage equalization can be calculated.

[0045] Optionally, the normal battery cell includes a new battery cell with normal impedance or the abnormal battery cell with normal impedance after repair. In other words, after finding the abnormal battery cell, the abnormal battery cell can be replaced with a new battery cell with good function and normal impedance, or the abnormal battery cell can be sent for repair, and after the impedance value of the abnormal battery cell is repaired to normal, the repaired abnormal battery cell can be reinstalled.

[0046] Figure 2 FIG. 1 is a schematic diagram of a repair process of a battery pack repair method according to another embodiment of the present disclosure. Figure 2 , the battery pack repair method further includes the following steps:

[0047] S30: Cyclically performing the voltage balancing and abnormal cell replacement steps on the replaced battery pack until the impedance of each cell is normal under voltage balancing.

[0048] In other words, after performing the abnormal cell replacement step on the battery pack, the repair process of the battery pack can be looped back to the voltage equalization, and the abnormal cell replacement step can be performed again after the voltage equalization, and the impedance detection can be re-performed on the battery pack after the voltage equalization until there are no abnormal values ​​among the multiple impedance values ​​obtained by the impedance detection. The cycle is repeated to ensure that after the last abnormal cell replacement, there are no abnormal cells in the battery pack.

[0049] Optionally, see Figure 2 , the battery pack repair method further includes the following steps:

[0050] S40: Detecting the state of charge of the battery pack after it is fully charged and each cell has normal impedance under voltage balancing, and determining whether the battery pack is repaired according to whether the state of charge reaches a preset state of charge.

[0051] In other words, after the voltage equalization operation and abnormal cell replacement operation of the battery pack are completed, the battery pack is fully charged, and the state of charge of the battery pack after being fully charged is detected. When it is detected that the state of charge of the battery pack after being fully charged reaches the preset state of charge, it is determined that the repair effect of the battery pack reaches the preset qualified standard, and the battery pack can be collected and put into use again. When it is detected that the state of charge of the battery pack after being fully charged does not reach the preset state of charge, it is determined that the repair effect of the battery pack does not reach the preset qualified standard, and the battery pack can be discarded and recycled, and will no longer be put into use or repaired, which is conducive to avoiding the mixing of unqualified battery packs with the qualified battery packs, and is conducive to ensuring the repair effect of the battery pack.

[0052] Specifically, the state of charge of the battery pack after it is fully charged can be characterized by an SOC value, and the preset qualification standard includes that the SOC value of the battery pack after it is fully charged is greater than or equal to 90%. Therefore, when the SOC value of the battery pack after it is fully charged is greater than or equal to 90%, it is determined that the repair effect of the battery pack is good and the battery pack can continue to be put into use. When the detected SOC value of the battery pack after it is fully charged is less than 90%, the battery pack can be discarded and recycled and no longer put into use.

[0053] Figure 3 Schematic diagram of the arrangement of the battery pack repair system according to the embodiment of the present disclosure. Figure 3The battery pack repair system provided by the present disclosure includes a battery balancing device 11, an impedance detection device 12, a replacement device 13 and a control device 14. The battery balancing device 11 is used to perform voltage balancing on the battery pack in a repairable state. The impedance detection device 12 (such as an EIS impedance analysis device) is arranged at the rear stage of the battery balancing device 11, and is used to detect whether there are abnormal cells with abnormal impedance in the multiple cells after voltage balancing. The replacement device 13 (such as a multi-degree-of-freedom manipulator) is used to replace the abnormal cell with a normal cell. The control device 14 (such as an industrial computer) is connected to the battery balancing device 11, the impedance detection device 12 and the replacement device 13.

[0054] Understandably, Figure 3 The arrow on the dotted line indicates the conveying direction of the battery pack when it is conveyed. When the battery pack repair system of the present disclosure repairs the battery pack, the battery pack is conveyed by a conveying device 800 such as a conveyor belt, and passes through the station where the battery balancing device 11 is located, the station where the impedance detection device 12 is located, and the station where the replacement device 13 is located in sequence along the direction indicated by the arrow on the dotted line. The control device 14 controls the battery balancing device 11, the impedance detection device 12, and the replacement device 13 to perform voltage balancing operations and abnormal battery cell replacement operations on the battery pack in sequence, thereby repairing the battery pack and extending the service life of the battery pack.

[0055] Optionally, the impedance detection device 12 includes a current detection unit, a plurality of voltage detection units and an impedance analysis unit. The current detection unit is installed in a series circuit in which a plurality of the battery cells are connected in series, and is used to detect the total working current of the battery cells. The plurality of voltage detection units are connected in parallel at both ends of the plurality of battery cells, and are used to detect a plurality of working voltages of the plurality of battery cells. The impedance analysis unit is respectively connected to the current detection unit and the plurality of voltage detection units, and is used to determine a plurality of impedance values ​​corresponding to the plurality of battery cells according to the total working current and the plurality of working voltages.

[0056] See also Figure 3 , Figure 3 The arrow on the solid line pointing to the battery balancing device 11 indicates that the battery pack can be transported to the battery balancing device 11 by the replacement device 13 . Figure 3The arrow on the solid line pointing to the replacement device 13 indicates that the battery pack can be moved from the battery balancing device 11 to the replacement device 13. Optionally, the replacement device 13 may be a walkable multi-degree-of-freedom manipulator, which is used to cyclically transport the battery pack between the battery balancing device 11 and the impedance detection device 12 when the battery pack cyclically performs the voltage balancing and the abnormal cell replacement operations. Alternatively, a transport device passing through the impedance detection device 12 is provided between the replacement device 13 and the battery balancing device 11, such as a transport manipulator, which is used to cyclically transport the battery pack between the battery balancing device 11, the impedance detection device 12 and the replacement device 13 when the battery pack cyclically performs the voltage balancing and the abnormal cell replacement operations.

[0057] Optionally, see Figure 3 The battery pack repair system also includes a pre-inspection device 15.

[0058] In some examples, the pre-inspection device 15 includes a first pre-inspection unit and a second pre-inspection unit. The first pre-inspection unit is used to detect whether the battery management system chip of the battery pack is damaged. The second pre-inspection unit is arranged at the rear stage of the first pre-inspection unit, and is used to collect multiple voltage values ​​of multiple battery cells, and compare whether the voltage difference between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, it is determined that the battery pack is in a repairable state.

[0059] In some other examples, the pre-inspection device 15 only includes a second pre-inspection unit. The second pre-inspection unit is used to collect multiple voltage values ​​of the multiple battery cells, and compare whether the voltage difference between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, it is determined that the battery pack is in a repairable state.

[0060] Optionally, the battery pack repair system further includes a state of charge detection device 16. The state of charge detection device 16 is provided at a later stage of the replacement device 13 and is connected to the control device 14. The control device 14 determines whether the battery pack is repaired to a preset qualified standard according to whether the state of charge of the battery pack reaches a preset state of charge.

[0061] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure shall still be covered by the protection scope of the present disclosure.

Claims

1. A battery pack repair method, characterized in that: For repairing a battery pack comprising a plurality of cells connected in series, the repair method comprising: The method for detecting whether the battery pack is in a repairable state includes the following: 1) pre-checking whether the battery management system chip of the battery pack is damaged, if not damaged, collecting multiple voltage values ​​of multiple battery cells, and comparing whether the voltage difference between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, if so, determining that the battery pack is in the repairable state; 2) collecting multiple voltage values ​​of multiple battery cells, and comparing whether the voltage difference between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, if so, determining that the battery pack is in the repairable state; Performing voltage balancing on the battery pack in a repairable state; The abnormal cell replacement step is performed, including: detecting whether there are abnormal cells with abnormal impedance among the multiple cells after voltage equalization, and replacing the abnormal cells with normal cells; the detecting whether there are abnormal cells with abnormal impedance among the multiple cells after voltage equalization includes: collecting multiple impedance values ​​corresponding to the multiple cells after voltage equalization, screening abnormal values ​​among the multiple impedance values, and determining that the cell corresponding to the abnormal value is the abnormal cell; the normal cell includes: a new cell with normal impedance or the abnormal cell with normal impedance after repair; The state of charge of the battery pack after it is fully charged is detected in which each cell has normal impedance under voltage balancing, and whether the battery pack is repaired to a preset qualified standard is determined according to whether the state of charge reaches a preset state of charge.

2. The battery pack repair method according to claim 1, characterized in that: The voltage balancing includes at least one of active balancing and passive balancing; The voltage equalization target includes: after voltage equalization, the voltage difference between the maximum voltage value and the minimum voltage value of the multiple voltage values ​​corresponding to the multiple battery cells is below the set voltage value.

3. The battery pack repair method according to claim 1, characterized in that: The collecting of multiple impedance values ​​corresponding to the multiple battery cells after voltage balancing includes: collecting the total working current on the multiple battery cell series circuit and the multiple working voltages corresponding to the multiple battery cells, and determining the multiple impedance values ​​according to the total working current, the multiple working voltages and Ohm's law.

4. The battery pack repair method according to claim 1, characterized in that: Also includes: The voltage equalization and abnormal cell replacement steps are cyclically performed on the replaced battery pack until the impedance of each cell is normal under voltage equalization.

5. Battery pack repair system, characterized in that: For repairing a battery pack including a plurality of cells connected in series, the repair system comprises: A pre-inspection device, the pre-inspection device comprising: a first pre-inspection unit, used to detect whether the battery management system chip of the battery pack is damaged; and a second pre-inspection unit, provided at a later stage of the first pre-inspection unit, used to collect multiple voltage values ​​of the multiple battery cells, and compare whether the voltage difference value between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within a first preset range, and if so, determine that the battery pack is in a repairable state; or the pre-inspection device comprises: a second pre-inspection unit, used to collect multiple voltage values ​​of the multiple battery cells, and compare whether the voltage difference value between the maximum voltage value and the minimum voltage value among the multiple voltage values ​​is within the first preset range, and if so, determine that the battery pack is in a repairable state; A battery balancing device, used for performing voltage balancing on the battery pack in a repairable state; An impedance detection device, provided at a later stage of the equalization device, for detecting whether there is an abnormal cell with abnormal impedance among the plurality of cells after voltage equalization; A replacement device, provided at a later stage of the impedance detection device, for replacing the abnormal battery cell with a normal battery cell; A control device connected to the equalizing device, the impedance detecting device and the replacing device; A state of charge detection device is provided at a subsequent stage of the replacement device and is connected to the control device. The control device determines whether the battery pack is repaired to a preset qualified standard based on whether the state of charge of the battery pack reaches a preset state of charge.

6. The battery pack repair system according to claim 5, characterized in that: The impedance detection device includes: a current detection unit, installed on a series circuit of multiple battery cells connected in series, for detecting the total working current of the battery cells; multiple voltage detection units, correspondingly connected in parallel at both ends of the multiple battery cells, for detecting multiple working voltages of the multiple battery cells; an impedance analysis unit, respectively connected to the current detection unit and the multiple voltage detection units, for determining multiple impedance values ​​according to the total working current and the multiple working voltages.

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