Staged high-precision lithium battery pack equalization repair method

Abstract

The invention provides a staged high-precision lithium battery pack equalization repair method in the technical field of lithium battery repair, which comprises the following steps of: S10, performing identity verification on equalization repair equipment through a visual interface; the method comprises the following steps of: acquiring input balance repair parameters including repair target voltage Vtarget, first repair current I1, second repair current I2, a repair voltage offset value Voffset and standing time T, and storing each balance repair parameter into a balance repair file, wherein the balance repair parameters comprise the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the standing time T; step S20, collecting the initial open-circuit voltage Voc1 of each single battery cell by the equalization repair equipment, and when the Voc1 is less than Vtarget-Voffset, executing large-current constant-current charging; when Vtarget-Voffset is more than or equal to Vtarget and Voc1 is less than Vtarget, performing low-current constant-current charging; when Vtarget is larger than or equal to Vtarget and Voc1 is smaller than Vtarget + Voffset, low-current constant-current discharging is executed; when the Voc1 is larger than or equal to the sum of the Vtarget and the Voffset, large-current constant-current discharging is executed; and step S30, disconnecting the charging and discharging loop of each single cell to complete equalization repair. The method has the advantages that the precision and the safety of lithium battery pack equalization repair are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery repair, and in particular to a phased high-precision lithium battery pack equalization repair method. Background Art

[0002] A lithium battery pack is composed of multiple single cells connected in series. Each single cell has a certain capacity. However, due to differences in cell materials, usage time, number of charge and discharge cycles, etc., the open circuit voltages of the single cells inside the lithium battery pack may be inconsistent.

[0003] When a lithium battery pack is charging, if any single cell reaches the upper voltage limit, charging must be stopped; when discharging, if any single cell reaches the lower voltage limit, discharging must be stopped. Therefore, inconsistent open circuit voltage will affect the capacity and service life of the lithium battery pack. When the maximum voltage and minimum voltage deviation of the single cells inside the lithium battery pack is too large, the lithium battery pack needs to be balanced and repaired.

[0004] Traditionally, external active balancing equipment (balancing repair equipment) is mainly used for balancing and repairing lithium battery packs. The active balancing equipment charges and discharges each single cell of the lithium battery pack, collects the open circuit voltage during the charging and discharging process in real time, and keeps the open circuit voltage of all single cells at the same level. However, there are the following disadvantages:

[0005] 1. Charging and discharging of single cells will produce polarization. For the same single cell, the greater the current during charging and discharging, the more obvious the polarization phenomenon; under the action of polarization voltage, the voltage of the single cell will float down during charging, and the voltage of the single cell will float up during discharging, which will affect the repair accuracy; although the constant voltage charging and discharging method with maximum current limitation can reduce the polarization effect, it cannot completely eliminate the polarization effect, and the cell voltage still fluctuates by 0 to 20mv; 2. During the equalization repair process, the open-circuit voltage of the single cell is collected with power, which makes the real cell voltage collection inaccurate, and the voltage displayed on the screen of the active equalization equipment is inaccurate, affecting the user experience; 3. There is no authority control for the setting of equalization repair parameters. The operator can arbitrarily configure the repair target voltage, repair current, etc. When the parameters are configured incorrectly, accidents such as overcharging and over-discharging of the cell are prone to occur.

[0006] Therefore, how to provide a phased high-precision lithium battery pack equalization repair method to improve the accuracy and safety of lithium battery pack equalization repair has become a technical problem that needs to be solved urgently. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a high-precision lithium battery pack equalization repair method in stages, so as to improve the accuracy and safety of the lithium battery pack equalization repair.

[0008] The present invention is implemented as follows: a phased high-precision lithium battery pack equalization repair method, comprising the following steps:

[0009] Step S10: After the equalization repair device performs identity authentication through the visual interface, it obtains input equalization repair parameters including the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the static time T, and saves each of the equalization repair parameters to the equalization repair file;

[0010] Step S20: The equalization repair device closes each charge and discharge loop based on the repair instruction obtained, collects the initial open circuit voltage Voc1 of each single cell of the lithium battery pack, and enters step S30 when Voc1<Vtarget-Voffset; enters step S60 when Vtarget-Voffset≤Voc1<Vtarget; enters step S70 when Vtarget≤Voc1<Vtarget+Voffset; enters step S40 when Voc1≥Vtarget+Voffset;

[0011] Step S30, the equalization repair equipment performs high-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0012] Step S40, the balancing and repairing equipment performs a large-current constant-current discharge on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0013] Step S50, the balancing and repairing device performs a static operation on the single cell, and collects the real-time current I3 and the real-time open circuit voltage Voc2;

[0014] Step S60, the equalization repair device performs low-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0015] Step S70, the balancing and repairing equipment performs a small constant current discharge on the single cell, collects the real-time current I 3, and collects the real-time open circuit voltage Voc2 in the no-load state;

[0016] Step S80: The equalization repair device disconnects the charge and discharge circuits of each single cell to complete the equalization repair of the lithium battery pack.

[0017] Furthermore, in step S10, the balancing and repairing device performs identity authentication through a visual interface as follows:

[0018] The balance repair device obtains the input account and password through a visual interface, and matches the account and password through a preset password table to perform identity authentication.

[0019] Furthermore, in step S10, the value range of the first repair current I1 is 0.1-5A; the value range of the second repair current I2 is 60-200mA; the value range of the repair voltage offset value Voffset is 0-15mV; and the value range of the standing time T is 10-120min.

[0020] Furthermore, the step S30 is specifically as follows:

[0021] The equalization repair device performs high-current constant-current charging on the single cell based on the first repair current I1, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0022] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≥Vtarget+Voffset, the high-current constant-current charging is terminated and the process goes to step S50.

[0023] Furthermore, the step S40 is specifically as follows:

[0024] Based on the first repair current I1, the balancing repair device performs a large-current constant-current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0025] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget-Voffset, the high-current constant-current discharge is terminated and the process goes to step S50.

[0026] Furthermore, the step S50 is specifically as follows:

[0027] The balancing and repairing device performs a static operation on the single cell based on the static time T, collects the real-time current I 3 and the real-time open circuit voltage Voc2, and displays the real-time current I 3 and the real-time open circuit voltage Voc2 on the display screen in real time;

[0028] When the static time T is reached, if Voc2=Vtarget, the balance repair device proceeds to step S80; if Voc2<Vtarget, the balance repair device proceeds to step S60; if Voc2>Vtarget, the balance repair device proceeds to step S70.

[0029] Furthermore, the step S60 is specifically as follows:

[0030] The equalization repair device performs low-current constant-current charging on the single cell based on the second repair current I2, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0031] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2 ≥ Vtarget, the low-current constant-current charging is terminated and the process goes to step S80.

[0032] Furthermore, the step S70 is specifically as follows:

[0033] Based on the second repair current I2, the balancing repair device performs a small constant current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0034] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget, ends the small current constant current discharge and enters step S80.

[0035] Furthermore, the step S80 is specifically as follows:

[0036] The equalization repair device disconnects the relays of the charge and discharge circuits of the single cells that have completed the equalization repair in sequence until the equalization repair of all the single cells is completed, so as to complete the equalization repair of the lithium battery pack.

[0037] Furthermore, the interleaved no-load state collects the real-time open circuit voltage Voc2 specifically as follows:

[0038] During the balancing repair process, the balancing repair equipment enters the no-load state every 10S, controls the output current of all charging and discharging circuits to zero, collects the real-time current I3, and when I3<10mA, delays 300mS and then collects the real-time open-circuit voltage Voc2.

[0039] The advantages of the present invention are:

[0040] After identity authentication through the visual interface, the input equalization repair parameters including the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the static time T are obtained, and each equalization repair parameter is saved in the equalization repair file; the equalization repair device closes each charging and discharging loop based on the obtained repair instruction, collects the initial open circuit voltage Voc1 of each single cell of the lithium battery pack, and when Voc1<Vtarget-Voffset, performs high-current constant-current charging; when Vtarget-Voffset≤Voc1<Vtarget, performs low-current constant-current charging; when Vtarget≤Voc1<Vtarget+Voffset, enters the execution of low-current constant-current discharge; when Voc1≥Vtarget+Voffset, performs high-current constant-current discharge; after executing high-current constant-current After charging or high-current constant-current discharge, a static operation is performed, and during the balanced repair process, the no-load state is entered every 10S to collect the real-time open-circuit voltage Voc2; that is, the balanced repair process of the lithium battery pack is divided into three stages: high-current constant-current charging and discharging, static, and low-current constant-current charging and discharging. High-current constant-current charging and discharging are performed based on the first repair current I1, and then static is performed to release the polarization voltage generated by the high-current constant-current charging and discharging. Finally, low-current constant-current charging and discharging are performed based on the second repair current I2 to complete the balanced repair. Since the value range of the second repair current I2 is 60-200mA, basically no polarization voltage is generated, and the real-time open-circuit voltage Voc2 is collected in the no-load state to ensure the collection accuracy, combined with identity authentication before balanced repair, it is prevented that unauthorized people set the balanced repair parameters at will, and the balanced repair parameters are saved to the balanced repair file to avoid power loss, which ultimately greatly improves the accuracy and safety of balanced repair of lithium battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0042] Figure 1 The present invention is a flowchart of a phased high-precision lithium battery pack equalization repair method. DETAILED DESCRIPTION

[0043] The technical solution in the embodiment of the present application has the following overall idea: the lithium battery pack balanced repair process is divided into three stages: high current constant current charge and discharge, static, and low current constant current charge and discharge. High current constant current charge and discharge are performed based on the first repair current I1, and then static is performed to release the polarization voltage generated by the high current constant current charge and discharge. Finally, low current constant current charge and discharge are performed based on the second repair current I2 to complete the balanced repair. Since the value range of the second repair current I2 is 60-200mA, basically no polarization voltage is generated, and the real-time open circuit voltage Voc2 is collected in a no-load state to ensure the collection accuracy. Combined with identity authentication before balanced repair, it is prevented that unauthorized people arbitrarily set balanced repair parameters, and the balanced repair parameters are saved to the balanced repair file to avoid power loss, thereby improving the accuracy and safety of balanced repair of the lithium battery pack.

[0044] Please refer to Figure 1 As shown, a preferred embodiment of a phased high-precision lithium battery pack equalization repair method of the present invention includes the following steps:

[0045] Step S10: After the balanced repair device performs identity authentication through the visual interface, it obtains the input balanced repair parameters including the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the static time T, and saves each of the balanced repair parameters to a balanced repair file to avoid losing the balanced repair parameters after the balanced repair device loses power;

[0046] Step S20, the balancing repair device closes each charge and discharge circuit based on the obtained repair instruction, collects the initial open circuit voltage Voc1 of each single cell of the lithium battery pack, and when Voc1<Vtarget-Voffset, enters step S30; when Vtarget-Voffset≤Voc1<Vtarget, enters step S60; when Vtarget≤Voc1<Vtarget+Voffset, enters step S70; when Voc1≥Vtarget+Voffset, enters step S40; each charge and discharge circuit of the balancing repair device is respectively connected to a single cell of the lithium battery pack, and each charge and discharge circuit is switched on and off by a relay;

[0047] Step S30, the equalization repair equipment performs high-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0048] Step S40, the balancing and repairing equipment performs a large-current constant-current discharge on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0049] Step S50, the balancing and repairing device performs a static operation on the single cell, and collects the real-time current I3 and the real-time open circuit voltage Voc2;

[0050] Step S60, the equalization repair device performs low-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state;

[0051] Step S70, the balancing and repairing device performs a small constant current discharge on the single cell, collects the real-time current I 3, and collects the real-time open circuit voltage Voc2 in the no-load state; that is, only the real-time current I 3 is collected in the balancing and repairing state, and the real-time open circuit voltage Voc2 is collected in the no-load state;

[0052] Step S80: The equalization repair device disconnects the charge and discharge circuits of each single cell to complete the equalization repair of the lithium battery pack.

[0053] In step S10, the balancing and repairing device performs identity authentication through a visual interface specifically as follows:

[0054] The balance repair device obtains the input account and password through a visual interface, and matches the account and password through a preset password table to perform identity authentication.

[0055] In the step S10, the value range of the first repair current I1 is 0.1-5A; the value range of the second repair current I2 is 60-200mA; the value range of the repair voltage offset value Voffset is 0-15mV; and the value range of the standstill time T is 10-120min.

[0056] In specific implementation, I2=I 1 / 5 is also limited. When the calculated result is exactly within 60-200mA, the calculated result is directly applied, otherwise a close current value is used; for example, when I2=5000mA, 5000mA / 5=1000mA, because 1000mA>200mA, the final I1=200mA.

[0057] The step S30 is specifically as follows:

[0058] The equalization repair device performs high-current constant-current charging on the single cell based on the first repair current I1, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0059] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≥Vtarget+Voffset, the high-current constant-current charging is terminated and the process goes to step S50.

[0060] During high-current constant-current charging, charging is terminated only when Voc2 ≥ Vtarget + Voffset, and Voffset offsets the partial voltage rise caused by polarization, thereby improving the efficiency of balanced repair.

[0061] The step S40 is specifically as follows:

[0062] Based on the first repair current I1, the balancing repair device performs a large-current constant-current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0063] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget-Voffset, the high-current constant-current discharge is terminated and the process goes to step S50.

[0064] During high-current constant-current discharge, the discharge is terminated when Voc2 ≤ Vtarget - Voffset, and Voffset offsets the partial voltage drop caused by the polarization phenomenon, thereby improving the balanced repair efficiency.

[0065] The step S50 is specifically as follows:

[0066] The balancing and repairing device performs a static operation on the single cell based on the static time T, collects the real-time current I 3 and the real-time open circuit voltage Voc2, and displays the real-time current I 3 and the real-time open circuit voltage Voc2 on the display screen in real time;

[0067] When the static time T is reached, if Voc2=Vtarget, the balance repair device proceeds to step S80; if Voc2<Vtarget, the balance repair device proceeds to step S60; if Voc2>Vtarget, the balance repair device proceeds to step S70.

[0068] The step S60 is specifically as follows:

[0069] The equalization repair device performs low-current constant-current charging on the single cell based on the second repair current I2, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0070] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2 ≥ Vtarget, the low-current constant-current charging is terminated and the process goes to step S80.

[0071] The step S70 is specifically as follows:

[0072] Based on the second repair current I2, the balancing repair device performs a small constant current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time;

[0073] The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget, ends the small current constant current discharge and enters step S80.

[0074] The step S80 is specifically as follows:

[0075] The equalization repair device disconnects the relays of the charge and discharge circuits of the single cells that have completed the equalization repair in sequence until the equalization repair of all the single cells is completed, so as to complete the equalization repair of the lithium battery pack.

[0076] The interleaved no-load state acquisition real-time open circuit voltage Voc2 is specifically:

[0077] During the balancing repair process, the balancing repair equipment enters the no-load state every 10S, controls the output current (charging current or discharging current) of all charging and discharging circuits to zero, collects the real-time current I3, and when I3 < 10mA, delays 300mS and then collects the real-time open-circuit voltage Voc2.

[0078] In summary, the advantages of the present invention are:

[0079] After identity authentication through the visual interface, the input equalization repair parameters including the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the static time T are obtained, and each equalization repair parameter is saved in the equalization repair file; the equalization repair device closes each charging and discharging loop based on the obtained repair instruction, collects the initial open circuit voltage Voc1 of each single cell of the lithium battery pack, and when Voc1<Vtarget-Voffset, performs high-current constant-current charging; when Vtarget-Voffset≤Voc1<Vtarget, performs low-current constant-current charging; when Vtarget≤Voc1<Vtarget+Voffset, enters the execution of low-current constant-current discharge; when Voc1≥Vtarget+Voffset, performs high-current constant-current discharge; after executing high-current constant-current After charging or high-current constant-current discharge, a static operation is performed, and during the balanced repair process, the no-load state is entered every 10S to collect the real-time open-circuit voltage Voc2; that is, the balanced repair process of the lithium battery pack is divided into three stages: high-current constant-current charging and discharging, static, and low-current constant-current charging and discharging. High-current constant-current charging and discharging are performed based on the first repair current I1, and then static is performed to release the polarization voltage generated by the high-current constant-current charging and discharging. Finally, low-current constant-current charging and discharging are performed based on the second repair current I2 to complete the balanced repair. Since the value range of the second repair current I2 is 60-200mA, basically no polarization voltage is generated, and the real-time open-circuit voltage Voc2 is collected in the no-load state to ensure the collection accuracy, combined with identity authentication before balanced repair, it is prevented that unauthorized people set the balanced repair parameters at will, and the balanced repair parameters are saved to the balanced repair file to avoid power loss, which ultimately greatly improves the accuracy and safety of balanced repair of lithium battery packs.

[0080] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A phased high-precision lithium battery pack equalization repair method, characterized in that: The steps include: Step S10: After the equalization repair device performs identity authentication through the visual interface, it obtains input equalization repair parameters including the repair target voltage Vtarget, the first repair current I1, the second repair current I2, the repair voltage offset value Voffset and the static time T, and saves each of the equalization repair parameters to the equalization repair file; Step S20: The equalization repair device closes each charge and discharge loop based on the repair instruction obtained, collects the initial open circuit voltage Voc1 of each single cell of the lithium battery pack, and enters step S30 when Voc1<Vtarget-Voffset; enters step S60 when Vtarget-Voffset≤Voc1<Vtarget; enters step S70 when Vtarget≤Voc1<Vtarget+Voffset; enters step S40 when Voc1≥Vtarget+Voffset; Step S30, the equalization repair equipment performs high-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state; Step S40, the balancing and repairing equipment performs a large-current constant-current discharge on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state; Step S50, the balancing and repairing device performs a static operation on the single cell, and collects the real-time current I3 and the real-time open circuit voltage Voc2; Step S60, the equalization repair device performs low-current constant-current charging on the single cell, collects the real-time current I 3, and collects the real-time open-circuit voltage Voc2 in the no-load state; Step S70, the balancing and repairing equipment performs a small constant current discharge on the single cell, collects the real-time current I 3, and collects the real-time open circuit voltage Voc2 in the no-load state; Step S80: The equalization repair device disconnects the charge and discharge circuits of each single cell to complete the equalization repair of the lithium battery pack.

2. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: In step S10, the balancing and repairing device performs identity authentication through a visual interface specifically as follows: The balance repair device obtains the input account and password through a visual interface, and matches the account and password through a preset password table to perform identity authentication.

3. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: In the step S10, the value range of the first repair current I1 is 0.1-5A; the value range of the second repair current I2 is 60-200mA; the value range of the repair voltage offset value Voffset is 0-15mV; and the value range of the standstill time T is 10-120min.

4. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S30 is specifically as follows: The equalization repair device performs high-current constant-current charging on the single cell based on the first repair current I1, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time; The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≥Vtarget+Voffset, the high-current constant-current charging is terminated and the process goes to step S50.

5. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S40 is specifically as follows: Based on the first repair current I1, the balancing repair device performs a large-current constant-current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time; The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget-Voffset, the high-current constant-current discharge is terminated and the process goes to step S50.

6. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S50 is specifically as follows: The balancing and repairing device performs a static operation on the single cell based on the static time T, collects the real-time current I 3 and the real-time open circuit voltage Voc2, and displays the real-time current I 3 and the real-time open circuit voltage Voc2 on the display screen in real time; When the static time T is reached, if Voc2=Vtarget, the balance repair device proceeds to step S80; if Voc2<Vtarget, the balance repair device proceeds to step S60; if Voc2>Vtarget, the balance repair device proceeds to step S70.

7. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S60 is specifically as follows: The equalization repair device performs low-current constant-current charging on the single cell based on the second repair current I2, collects the real-time current I3 every 1S during the charging process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time; The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2 ≥ Vtarget, the low-current constant-current charging is terminated and the process goes to step S80.

8. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S70 is specifically as follows: Based on the second repair current I2, the balancing repair device performs a small constant current discharge on the single cell, collects the real-time current I3 every 1S during the discharge process, collects the real-time open-circuit voltage Voc2 in the no-load state, and displays the real-time current I3 and the real-time open-circuit voltage Voc2 on the display screen in real time; The balancing repair device monitors the real-time open circuit voltage Voc2 in real time, and when Voc2≤Vtarget, ends the small current constant current discharge and enters step S80.

9. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The step S80 is specifically as follows: The equalization repair device disconnects the relays of the charge and discharge circuits of the single cells that have completed the equalization repair in sequence until the equalization repair of all the single cells is completed, so as to complete the equalization repair of the lithium battery pack.

10. A multi-stage high-precision lithium battery pack equalization repair method as claimed in claim 1, characterized in that: The interleaved no-load state acquisition real-time open circuit voltage Voc2 is specifically: During the balancing repair process, the balancing repair equipment enters the no-load state every 10S, controls the output current of all charging and discharging circuits to zero, collects the real-time current I3, and when I3<10mA, delays 300mS and then collects the real-time open-circuit voltage Voc2.

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