A circuit management method for achieving voltage equalization

Abstract

The present invention relates to the technical field of circuit management, and specifically discloses a circuit management method for realizing voltage balancing, wherein an electric energy performance test is performed on each retired lithium battery, and a plurality of retired lithium batteries are randomly arranged according to the electric energy performance to form a battery pack, and the retired lithium batteries in each battery pack are connected to a balancing circuit through a wire to form each battery module; in each battery module, a battery detection unit is arranged, and the battery detection unit is respectively connected to each retired lithium battery in the battery module to detect the voltage of each retired lithium battery in each battery module in real time; the voltage of each retired lithium battery in each battery module is analyzed, and the voltage difference of the retired lithium batteries in each battery module is evaluated; and a balancing strategy for each battery module is formulated, until the voltage difference of all retired lithium batteries in each battery module is within a voltage difference allowable threshold range, the balancing operation is stopped, and the battery stability rate of the retired lithium batteries is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit management, and relates to a circuit management method for realizing voltage balancing. Background Art

[0002] At a time when the global energy landscape is transforming and clean energy technology is advancing rapidly, lithium-ion batteries have become the preferred energy storage solution for electric vehicles, renewable energy storage, and portable electronic devices, thanks to their advantages such as a lifespan far exceeding that of ordinary batteries, low self-discharge rate, and high energy density. However, although the battery life is long, it will eventually come to an end, especially for electric vehicles, which have extremely high performance requirements for batteries. When the actual capacity of the battery drops below 80%, it no longer meets the vehicle use standards and needs to be replaced. Retired batteries with a capacity between 20% and 80% are suitable for reuse and application in other scenarios.

[0003] The reason why the irrational use of retired lithium batteries poses a safety hazard is that after multiple charge and discharge cycles, their internal physical and chemical properties have changed with the aging process. This change leads to the inconsistency of retired lithium batteries and the decline of internal parameters, which affects their safety and stability during the cascade utilization process. The existing traditional lithium battery management system mainly protects the properties of new batteries, and does not give full consideration to the protection needs of batteries in the cascade utilization link; at the same time, the inconsistency and performance decline of retired lithium batteries also seriously affect their safety and stability during the reuse process. Summary of the invention

[0004] In view of the above problems in the prior art, the present invention provides a circuit management method for achieving voltage balancing, which is used to solve the above technical problems.

[0005] In order to achieve the above purpose and other purposes, the technical solution adopted by the present invention is as follows:

[0006] In one aspect, the present invention provides a circuit management method for achieving voltage balancing, the method comprising the following steps:

[0007] Conducting an electric energy performance test on each retired lithium battery, and randomly arranging multiple retired lithium batteries according to their electric energy performance to form a battery pack, and connecting the retired lithium batteries in each battery pack through wires and a balancing circuit to form each battery module;

[0008] In each battery module, a battery detection unit is provided, and the battery detection unit is respectively connected to each retired lithium battery in the battery module, and is used to detect the voltage of each retired lithium battery in each battery module in real time;

[0009] Analyze the voltage of each retired lithium battery in each battery module and evaluate the voltage difference of retired lithium batteries in each battery module;

[0010] According to the voltage difference of retired lithium batteries in each battery module, a balancing strategy for each battery module is formulated until the voltage difference of all retired lithium batteries in each battery module is within the voltage difference allowable threshold range, and then the balancing operation is stopped.

[0011] As a further improvement of the present invention, the electric energy performance test is performed on each retired lithium battery, and the specific test logic is:

[0012] The electric energy performance is divided into battery remaining capacity and battery internal resistance;

[0013] Perform multiple discharge tests on each retired lithium battery to obtain the test battery capacity value of each retired lithium battery corresponding to each discharge test, and then calculate the remaining battery capacity of each retired lithium battery by average calculation;

[0014] When each retired lithium battery is not connected to a load, use a multimeter to measure the open circuit voltage of each retired lithium battery. Connect a load with a known resistance value to both ends of each retired lithium battery. When the load is connected, use a multimeter to measure the voltage across both ends of each retired lithium battery, thereby calculating the battery internal resistance of each retired lithium battery. , k is the serial number of each retired lithium battery, is the resistance value of the known resistance load, is the voltage across the kth retired lithium battery when the load is connected, is the open circuit voltage of the kth retired lithium battery.

[0015] As a further improvement of the present invention, the voltage of each retired lithium battery in each battery module is detected in real time, and the specific detection process is as follows:

[0016] The battery detection unit is used to collect the voltage signals at both ends of each retired lithium battery in each battery module, and the collected voltage signals are converted into digital signals through ADC. The digital signals of each retired lithium battery in each battery module are calculated to obtain the voltage of each retired lithium battery in each battery module. , i is the number of each battery module, i=1,2,...N, j is the number of each retired lithium battery in the battery module, j=1,2,...M, is the voltage signal across the jth retired lithium battery in the i-th battery module, is the resolution of the ADC, is the output digital value of the ADC.

[0017] As a further improvement of the present invention, the voltage of each retired lithium battery in each battery module is analyzed, and the specific analysis logic is:

[0018] Calculate the average voltage in each battery module , M is the total number of retired lithium batteries in the battery module;

[0019] Calculate the voltage standard deviation of each battery module ;

[0020] Based on the formula , evaluate the voltage difference of retired lithium batteries in each battery module ,in, is the maximum voltage difference of retired lithium batteries in the i-th battery module, where , is the maximum voltage value of the retired lithium battery in the i-th battery module, is the minimum voltage value of the retired lithium battery in the i-th battery module.

[0021] As a further improvement of the present invention, the balancing strategy includes two modes: active balancing and passive balancing.

[0022] As a further improvement of the present invention, a balancing strategy for each battery module is formulated, and the specific formulation logic is as follows:

[0023] Obtaining the set voltage difference threshold and the voltage difference of retired lithium batteries in each battery module;

[0024] If the voltage difference of retired lithium batteries in a battery module is less than the set voltage difference threshold, it is determined that the battery module requires passive balancing, otherwise it is determined that the battery module requires active balancing.

[0025] As a further improvement of the present invention, each battery module that needs active balancing is redefined as each active balancing battery module, and is numbered 1,2,...g,...G in sequence;

[0026] The average voltage of each active balancing battery module is selected from the average voltage of each battery module, and recorded as the target voltage of each active balancing battery module. ;

[0027] According to the battery internal resistance of each retired lithium battery, the battery internal resistance of each retired lithium battery in each active balancing battery module is obtained. , thereby calculating the first balancing current of each retired lithium battery in each active balancing battery module , is the voltage of the jth retired lithium battery in the gth active balancing battery module, is the equalization coefficient, which is used to adjust the equalization speed and prevent over-equalization;

[0028] The battery detection unit is used to detect the single temperature of each retired lithium battery in each active balancing battery module in real time, and then the first balancing current of each retired lithium battery in each active balancing battery module is temperature corrected, and the second balancing current of each retired lithium battery in each active balancing battery module is calculated. , is the cell temperature of the jth retired lithium battery in the gth active balancing battery module, is the reference temperature of the retired lithium battery. is the temperature correction coefficient;

[0029] Calculate the health status of each retired lithium battery in each active balancing battery module , perform health status correction on the second balancing current of each retired lithium battery in each active balancing battery module, and calculate the third balancing current of each retired lithium battery in each active balancing battery module ;

[0030] Finally, the comprehensive analysis obtains the balancing current of each retired lithium battery in each active balancing battery module. , is the maximum allowable balancing current.

[0031] As a further improvement of the present invention, each battery module that requires passive balancing is redefined as each passive balancing battery module, and is numbered 1, 2, ... h, ... H in sequence;

[0032] The first balancing current of each retired lithium battery in each passive balancing battery module is calculated in the same way as the first balancing current of each retired lithium battery in each active balancing battery module. ;

[0033] The average voltage of each passive balancing battery module is selected from the average voltage of each battery module, and is recorded as the target voltage of each passive balancing battery module. ;

[0034] Comprehensive analysis of the balancing time of each retired lithium battery in each passive balancing battery module , is the remaining capacity of the jth retired lithium battery in the hth passive balancing battery module, is the voltage of the jth retired lithium battery in the hth passive balancing battery module;

[0035] The balancing circuit of each passive balancing battery module is started to consume the single-cell excess energy of each retired lithium battery in each passive balancing battery module according to the balancing time of each retired lithium battery in each passive balancing battery module and the first balancing current.

[0036] As described above, the circuit management method for realizing voltage balancing provided by the present invention has at least the following beneficial effects:

[0037] The present invention provides a circuit management method for realizing voltage balancing, which tests the electric energy performance of each retired lithium battery, and randomly arranges a plurality of retired lithium batteries according to the electric energy performance to form a battery pack, and connects the retired lithium batteries in each battery pack through a wire and a balancing circuit to form each battery module; in each battery module, a battery detection unit is arranged, and the battery detection unit is respectively connected to each retired lithium battery in the battery module to detect the voltage of each retired lithium battery in each battery module in real time; the voltage of each retired lithium battery in each battery module is analyzed to evaluate the voltage difference of the retired lithium batteries in each battery module; a balancing strategy for each battery module is formulated until the voltage difference of all retired lithium batteries in each battery module is within the voltage difference allowable threshold range, and the balancing operation is stopped. Through monitoring and balancing operations, it can be ensured that the battery pack works in a safer state; at the same time, when the voltage difference of the batteries in the battery pack is small, the stress concentration in the battery cycle process can be reduced, the battery aging can be slowed down, and the service life of the entire battery pack can be extended; the battery pack after balancing can more effectively utilize the residual electric energy of each battery, improve the overall energy output efficiency of the battery pack, and reduce energy waste. Ultimately, voltage balancing can ensure that the battery pack is more stable and reliable during output, reducing performance fluctuations caused by voltage imbalance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0039] Figure 1 It is a schematic diagram of the connection of each step of the method of the present invention. DETAILED DESCRIPTION

[0040] The above contents in combination with the implementation of the present invention are merely examples and explanations of the concept of the present invention. The technical personnel in the relevant technical field may make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention. Example

[0041] See also Figure 1 As shown, a circuit management method for realizing voltage balancing comprises the following steps:

[0042] Conducting an electric energy performance test on each retired lithium battery, and randomly arranging multiple retired lithium batteries according to their electric energy performance to form a battery pack, and connecting the retired lithium batteries in each battery pack through wires and a balancing circuit to form each battery module;

[0043] According to a preferred embodiment, the electric energy performance test is performed on each retired lithium battery, and the specific test logic is:

[0044] The electric energy performance is divided into battery remaining capacity and battery internal resistance;

[0045] Perform multiple discharge tests on each retired lithium battery to obtain the test battery capacity value of each retired lithium battery corresponding to each discharge test, and then calculate the remaining battery capacity of each retired lithium battery by average calculation;

[0046] (S1) Each retired lithium battery cell is fixed on a lithium battery fixture, and the fixture is placed in a constant temperature box to simulate a constant ambient temperature, and the ambient temperature is set to 25°C.

[0047] (S2) The working steps of the battery charge and discharge tester are configured to the constant current constant voltage (CC / CV) charging mode, the charging rate is set to 1C, and the charging cut-off voltage is set to 4.2V and the cut-off current is set to 0.1A. After charging is completed, the battery is left for one hour.

[0048] (S3) The battery charge and discharge tester is configured with a constant current discharge step, a discharge rate of 1C, and a cut-off voltage of 2.75V. After the battery is discharged to the cut-off voltage, the discharge is stopped and the battery is left for one hour.

[0049] (S4) The battery charge and discharge tester is configured to cycle step (S2) to step (S4) multiple times.

[0050] The battery charge and discharge tester will automatically record the capacity charged and discharged in the charge and discharge cycle, and take the average value of the discharge capacity of each discharge test. If the error between each discharge capacity and the average value is within 2%, the average value can be regarded as the remaining battery capacity of each retired lithium battery.

[0051] When each retired lithium battery is not connected to a load, use a multimeter to measure the open circuit voltage of each retired lithium battery. Connect a load with a known resistance value to both ends of each retired lithium battery. When the load is connected, use a multimeter to measure the voltage across both ends of each retired lithium battery, thereby calculating the battery internal resistance of each retired lithium battery. , k is the serial number of each retired lithium battery, is the resistance value of the known resistance load, is the voltage across the kth retired lithium battery when the load is connected, is the open circuit voltage of the kth retired lithium battery.

[0052] In each battery module, a battery detection unit is provided, and the battery detection unit is respectively connected to each retired lithium battery in the battery module, and is used to detect the voltage of each retired lithium battery in each battery module in real time;

[0053] According to a preferred embodiment, the voltage of each retired lithium battery in each battery module is detected in real time, and the specific detection process is as follows:

[0054] The battery detection unit is used to collect the voltage signals at both ends of each retired lithium battery in each battery module, and the collected voltage signals are converted into digital signals through ADC. The digital signals of each retired lithium battery in each battery module are calculated to obtain the voltage of each retired lithium battery in each battery module. , i is the number of each battery module, i=1,2,...N, j is the number of each retired lithium battery in the battery module, j=1,2,...M, is the voltage signal across the jth retired lithium battery in the i-th battery module, is the resolution of the ADC, is the output digital value of the ADC.

[0055] Analyze the voltage of each retired lithium battery in each battery module and evaluate the voltage difference of retired lithium batteries in each battery module;

[0056] According to a preferred embodiment, the voltage of each retired lithium battery in each battery module is analyzed, and the specific analysis logic is:

[0057] Calculate the average voltage in each battery module , M is the total number of retired lithium batteries in the battery module;

[0058] Calculate the voltage standard deviation of each battery module ;

[0059] Based on the formula , evaluate the voltage difference of retired lithium batteries in each battery module ,in, is the maximum voltage difference of retired lithium batteries in the i-th battery module, where , is the maximum voltage value of the retired lithium battery in the i-th battery module, is the minimum voltage value of the retired lithium battery in the i-th battery module.

[0060] According to the voltage difference of retired lithium batteries in each battery module, a balancing strategy for each battery module is formulated until the voltage difference of all retired lithium batteries in each battery module is within the voltage difference allowable threshold range, and then the balancing operation is stopped.

[0061] The battery module includes a balancing circuit, which includes multiple balancing modules, each of which is connected to each retired lithium battery in the battery module. The balancing module transfers or consumes electric energy through the current converter and the current transmission line according to the instructions of the control unit to achieve voltage balancing.

[0062] According to a preferred embodiment, the balancing strategy includes two modes: active balancing and passive balancing.

[0063] According to a preferred embodiment, a balancing strategy for each battery module is formulated, and the specific formulation logic is as follows:

[0064] Obtaining the set voltage difference threshold and the voltage difference of retired lithium batteries in each battery module;

[0065] If the voltage difference of retired lithium batteries in a battery module is less than the set voltage difference threshold, it is determined that the battery module requires passive balancing, otherwise it is determined that the battery module requires active balancing.

[0066] According to a preferred embodiment, each battery module that needs active balancing is redefined as each active balancing battery module, and is numbered 1,2,...g,...G in sequence;

[0067] The average voltage of each active balancing battery module is selected from the average voltage of each battery module, and recorded as the target voltage of each active balancing battery module. ;

[0068] According to the battery internal resistance of each retired lithium battery, the battery internal resistance of each retired lithium battery in each active balancing battery module is obtained. , thereby calculating the first balancing current of each retired lithium battery in each active balancing battery module , is the voltage of the jth retired lithium battery in the gth active balancing battery module, is the equalization coefficient, which is used to adjust the equalization speed and prevent over-equalization;

[0069] The battery detection unit is used to detect the single temperature of each retired lithium battery in each active balancing battery module in real time, and then the first balancing current of each retired lithium battery in each active balancing battery module is temperature corrected, and the second balancing current of each retired lithium battery in each active balancing battery module is calculated. , is the cell temperature of the jth retired lithium battery in the gth active balancing battery module, is the reference temperature of the retired lithium battery. is the temperature correction coefficient;

[0070] Calculate the health status of each retired lithium battery in each active balancing battery module , perform health status correction on the second balancing current of each retired lithium battery in each active balancing battery module, and calculate the third balancing current of each retired lithium battery in each active balancing battery module ;

[0071] Finally, the comprehensive analysis obtains the balancing current of each retired lithium battery in each active balancing battery module. , is the maximum allowable balancing current.

[0072] According to a preferred embodiment, each battery module that requires passive balancing is redefined as each passive balancing battery module, and is numbered 1, 2, ... h, ... H in sequence;

[0073] The first balancing current of each retired lithium battery in each passive balancing battery module is calculated in the same way as the first balancing current of each retired lithium battery in each active balancing battery module. ;

[0074] The average voltage of each passive balancing battery module is selected from the average voltage of each battery module, and is recorded as the target voltage of each passive balancing battery module. ;

[0075] Comprehensive analysis of the balancing time of each retired lithium battery in each passive balancing battery module , is the remaining capacity of the jth retired lithium battery in the hth passive balancing battery module, is the voltage of the jth retired lithium battery in the hth passive balancing battery module;

[0076] The balancing circuit of each passive balancing battery module is started to consume the single-cell excess energy of each retired lithium battery in each passive balancing battery module according to the balancing time of each retired lithium battery in each passive balancing battery module and the first balancing current.

[0077] The present invention provides a circuit management method for realizing voltage balancing, which tests the electric energy performance of each retired lithium battery, and randomly arranges a plurality of retired lithium batteries according to the electric energy performance to form a battery pack, and connects the retired lithium batteries in each battery pack through a wire and a balancing circuit to form each battery module; in each battery module, a battery detection unit is arranged, and the battery detection unit is respectively connected to each retired lithium battery in the battery module to detect the voltage of each retired lithium battery in each battery module in real time; the voltage of each retired lithium battery in each battery module is analyzed to evaluate the voltage difference of the retired lithium batteries in each battery module; a balancing strategy for each battery module is formulated until the voltage difference of all retired lithium batteries in each battery module is within the voltage difference allowable threshold range, and the balancing operation is stopped. Through monitoring and balancing operations, it can be ensured that the battery pack works in a safer state; at the same time, when the voltage difference of the batteries in the battery pack is small, the stress concentration in the battery cycle process can be reduced, the battery aging can be slowed down, and the service life of the entire battery pack can be extended; the battery pack after balancing can more effectively utilize the residual electric energy of each battery, improve the overall energy output efficiency of the battery pack, and reduce energy waste. Ultimately, voltage balancing can ensure that the battery pack is more stable and reliable during output, reducing performance fluctuations caused by voltage imbalance.

[0078] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0079] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0080] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0081] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circuit management method for achieving voltage balancing, characterized in that: include: Conducting an electric energy performance test on each retired lithium battery, and randomly arranging multiple retired lithium batteries according to their electric energy performance to form a battery pack, and connecting the retired lithium batteries in each battery pack through wires and a balancing circuit to form each battery module; In each battery module, a battery detection unit is provided, and the battery detection unit is respectively connected to each retired lithium battery in the battery module, and is used to detect the voltage of each retired lithium battery in each battery module in real time; Analyze the voltage of each retired lithium battery in each battery module and evaluate the voltage difference of retired lithium batteries in each battery module; According to the voltage difference of retired lithium batteries in each battery module, a balancing strategy for each battery module is formulated, and the balancing operation is stopped when the voltage difference of all retired lithium batteries in each battery module is within the voltage difference allowable threshold range; The balancing strategy includes active balancing and passive balancing; Formulate a balancing strategy for each battery module. The specific logic is as follows: Obtaining the set voltage difference threshold and the voltage difference of retired lithium batteries in each battery module; If the voltage difference of retired lithium batteries in a battery module is less than the set voltage difference threshold, it is determined that the battery module needs passive balancing, otherwise it is determined that the battery module needs active balancing; Redefine each battery module that needs active balancing as each active balancing battery module, and number them 1, 2, ...g, ...G in sequence; The average voltage of each active balancing battery module is selected from the average voltage of each battery module, and recorded as the target voltage of each active balancing battery module. ; According to the battery internal resistance of each retired lithium battery, the battery internal resistance of each retired lithium battery in each active balancing battery module is obtained. , thereby calculating the first balancing current of each retired lithium battery in each active balancing battery module , is the voltage of the jth retired lithium battery in the gth active balancing battery module, is the equalization coefficient, which is used to adjust the equalization speed and prevent over-equalization; The battery detection unit is used to detect the single temperature of each retired lithium battery in each active balancing battery module in real time, and then the first balancing current of each retired lithium battery in each active balancing battery module is temperature corrected, and the second balancing current of each retired lithium battery in each active balancing battery module is calculated. , is the cell temperature of the jth retired lithium battery in the gth active balancing battery module, is the reference temperature of the retired lithium battery. is the temperature correction coefficient; Calculate the health status of each retired lithium battery in each active balancing battery module , perform health status correction on the second balancing current of each retired lithium battery in each active balancing battery module, and calculate the third balancing current of each retired lithium battery in each active balancing battery module ; Finally, the comprehensive analysis obtains the balancing current of each retired lithium battery in each active balancing battery module. , is the maximum allowable balancing current; Redefine each battery module that needs passive balancing as each passive balancing battery module, and number them 1, 2, ...h, ...H in sequence; The first balancing current of each retired lithium battery in each passive balancing battery module is calculated in the same way as the first balancing current of each retired lithium battery in each active balancing battery module. ; The average voltage of each passive balancing battery module is selected from the average voltage of each battery module, and is recorded as the target voltage of each passive balancing battery module. ; Comprehensive analysis of the balancing time of each retired lithium battery in each passive balancing battery module , is the remaining capacity of the jth retired lithium battery in the hth passive balancing battery module, is the voltage of the jth retired lithium battery in the hth passive balancing battery module; The balancing circuit of each passive balancing battery module is started to consume the single-cell excess energy of each retired lithium battery in each passive balancing battery module according to the balancing time of each retired lithium battery in each passive balancing battery module and the first balancing current.

2. A circuit management method for realizing voltage balancing according to claim 1, characterized in that: Conduct electrical performance tests on retired lithium batteries. The specific test logic is as follows: The electric energy performance is divided into battery remaining capacity and battery internal resistance; Perform multiple discharge tests on each retired lithium battery to obtain the test battery capacity value of each retired lithium battery corresponding to each discharge test, and then calculate the remaining battery capacity of each retired lithium battery by average calculation; When each retired lithium battery is not connected to a load, use a multimeter to measure the open circuit voltage of each retired lithium battery. Connect a load with a known resistance value to both ends of each retired lithium battery. When the load is connected, use a multimeter to measure the voltage across both ends of each retired lithium battery, thereby calculating the battery internal resistance of each retired lithium battery. , k is the serial number of each retired lithium battery, is the resistance value of the known resistance load, is the voltage across the kth retired lithium battery when the load is connected, is the open circuit voltage of the kth retired lithium battery.

3. A circuit management method for realizing voltage balancing according to claim 1, characterized in that: Real-time detection of the voltage of each retired lithium battery in each battery module. The specific detection process is as follows: The battery detection unit is used to collect the voltage signals at both ends of each retired lithium battery in each battery module, and the collected voltage signals are converted into digital signals through ADC. The digital signals of each retired lithium battery in each battery module are calculated to obtain the voltage of each retired lithium battery in each battery module. , i is the number of each battery module, i=1,2,...N, j is the number of each retired lithium battery in the battery module, j=1,2,...M, is the voltage signal across the jth retired lithium battery in the i-th battery module, is the resolution of the ADC, is the output digital value of the ADC.

4. A circuit management method for realizing voltage balancing according to claim 1, characterized in that: The voltage of each retired lithium battery in each battery module is analyzed. The specific analysis logic is as follows: Calculate the average voltage of each battery module , M is the total number of retired lithium batteries in the battery module; Calculate the voltage standard deviation of each battery module ; Based on the formula , evaluate the voltage difference of retired lithium batteries in each battery module ,in, is the maximum voltage difference of retired lithium batteries in the i-th battery module, where , is the maximum voltage value of the retired lithium battery in the i-th battery module, is the minimum voltage value of the retired lithium battery in the i-th battery module.

Images