Battery pack or battery module repairability calculation method, electronic device, and program

Abstract

The application discloses a battery pack or battery module repairable degree calculation method, the battery pack or battery module is fully charged, the maximum voltage value U_Cell_MAX of a single battery cell in the battery pack or battery module is obtained; the voltage value U_Cell_FastRate of the battery cell with the fastest voltage change rate in the battery pack or battery module is obtained; the battery internal resistance consistency differential pressure U_Diff_IR is U_Cell_MAX-U_Cell_FastRate, the battery internal resistance consistency loss Delta_1 is 1-U_Diff_IR / U_Intvl*100%, the voltage platform U_Intvl is a fixed constant, and the repairable degree R1 of the battery pack or battery module is Delta_1*Delta_Cor, wherein the coefficient Delta_Cor is a calibration coefficient.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and specifically relates to a method, electronic device and program for calculating the repairability of a battery pack or battery module. Background Technology

[0002] In the development of new energy technologies, batteries used for energy storage or power have become a crucial component. Because current energy storage and power batteries can store large amounts of energy, they are mostly composed of multiple battery modules or cells forming a battery pack. A battery module is composed of multiple individual cells connected in series and parallel. During use, differences in internal resistance, capacity, and aging can cause variations in the consistency between these modules or cells, thus affecting the usable capacity and charge / discharge performance of the entire battery pack. Summary of the Invention

[0003] The battery pack or battery module referred to in this invention refers to a battery pack or battery module among all rechargeable batteries whose discharge or charge voltage curve has a linear variation range. The repairability of the battery pack or battery module can be measured using the testing methods of this invention, and the battery pack or battery module includes, but is not limited to, ternary lithium and lithium iron phosphate batteries.

[0004] To address the problem of assessing and measuring the repairability of battery packs or battery modules, one embodiment of the present invention provides a method for calculating the repairability of battery packs or battery modules, comprising the following steps.

[0005] The battery pack or battery module is fully charged to obtain the maximum voltage value U_Cell_MAX of a single battery module or single cell.

[0006] Obtain the cell voltage value U_Cell_FastRate with the fastest voltage change rate in the battery pack or battery module;

[0007] Therefore, the uniform voltage difference due to the battery's internal resistance, U_Diff_IR, is equal to U_Cell_MAX - U_Cell_FastRate.

[0008] Battery internal resistance uniformity loss Delta_1 = 1 - U_Diff_IR * 1000 / U_Intvl * 100%,

[0009] Wherein, the voltage plateau U_Intvl is a fixed constant.

[0010] Therefore, the repairability of the battery pack or battery module is R1 = Delta_1 * Delta_Cor_1.

[0011] Among them, the coefficient Delta_Cor_1 is the calibration coefficient.

[0012] or,

[0013] The battery pack or battery module should be fully charged and discharged at least once. After fully charging, wait for the batteries to be fully balanced before discharging.

[0014] The voltage values ​​of the battery modules or cells contained in the battery pack or battery module are measured and calculated, including...

[0015] U_Diff_FastRate_Cell=U_STRT_FastRate_Cell - U_End_FastRate_Cell

[0016] U_Diff_AVRG_Cell=U_STRT_AVRG_Cell - U_End_AVRG_Cell

[0017] Delta_2=1- U_Diff_AVRG_Cell / U_Diff_FastRate_Cell *100%

[0018] The repairability of the battery pack R2 = (Delta_Total - Delta_2) * Delta_Cor_2,

[0019] in,

[0020] U_Diff_FastRate_Cell — The maximum voltage change rate of the battery module or cell, expressed in volts.

[0021] U_STRT_FastRate_Cell — Cut-off voltage on the battery module or cell, which can be expressed in "volts".

[0022] U_End_FastRate_Cell — The cutoff voltage of the battery module or cell, which can be expressed in volts.

[0023] U_Diff_AVRG_Cell — Average voltage change rate of the battery module or cell, expressed in volts.

[0024] U_STRT_AVRG_Cell — Average cutoff voltage of the battery module or cell, which can be expressed in "volts".

[0025] U_End_AVRG_Cell — Average cutoff voltage of the battery module or cell, which can be expressed in "volts".

[0026] Delta_2 – Battery capacity consistency loss, which can be expressed as a percentage.

[0027] Delta_Total – Total capacity loss, expressed as a percentage, refers to the percentage reduction in the actual capacity of the battery compared to its factory-supplied capacity under standard factory testing conditions.

[0028] Delta_Cor_2 — Calibration coefficient, which can be represented as a percentage. It is a coefficient used to correct the calculation results due to factors such as measurement error and / or temperature influence. Attached Figure Description

[0029] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example, not limitation, in which:

[0030] Figure 1 An example diagram of the full discharge voltage curve of a battery pack according to one embodiment of the present invention.

[0031] Figure 2 An example diagram of the full charge voltage curve of a battery pack according to one embodiment of the present invention. Detailed Implementation

[0032] Existing battery repair methods involve individually charging, discharging, or equalizing (i.e., mutual charging and discharging) the battery module and cells. These methods are referred to as equalization repair in this disclosure. The purpose of equalization repair is to maintain the voltage of the battery or cells at a consistent level, thereby restoring some usable capacity and performance. If equalization repair is ineffective, damaged cells can be replaced to restore capacity.

[0033] However, existing repair methods cannot determine the specific differences between the modules and cells within the battery pack, nor can they predict the repair outcome, i.e., the extent to which the battery pack can be repaired. Currently designed energy storage and power batteries require time-consuming and labor-intensive disassembly and repackaging, necessitating mechanical damage and sealing of the battery pack, making battery pack repair both difficult and costly. Therefore, it is necessary to calculate the repairability of the battery pack before disassembling and repairing it, thereby arriving at a reasonable solution within a minimal cost range: disassembly and repair, continued use, or recycling for secondary applications.

[0034] According to one or more embodiments, a method for calculating the repairability of a battery pack or battery module is achieved by measuring the capacity loss caused by the difference in internal resistance of the cells inside the battery pack, or by measuring the loss of battery internal resistance consistency.

[0035] Currently, most packaged battery packs cannot directly measure the internal resistance of their cells, thus making it impossible to directly measure internal resistance differences. The method disclosed herein indirectly measures internal resistance differences by monitoring changes in cell voltage. The principle is that if there is an internal resistance difference between cells, under the condition of connecting them in series with the same current, and assuming there are no design-related differences in the internal resistance of the terminals or battery pack connectors, Ohm's law states that the cell with higher internal resistance will experience a larger voltage drop. This will manifest as a change in cell voltage difference after a long period of charge-discharge cycles. By identifying this change pattern and using specific testing methods, the numerical value of the internal resistance difference between cells can be indirectly measured. This method is only applicable to battery packs with a high number of cycles and significant internal resistance differences. The specific measurement method is as follows:

[0036] First, by detecting the voltage change process of each cell or module during the discharge or charging process, the cell or module with the fastest voltage change rate is identified.

[0037] Then, with the battery pack balancing function off, the battery is charged. Among all the fully charged cells or modules, the maximum voltage value U_Cell_MAX is selected, and then the cell with the fastest voltage change rate U_Cell_FastRate in the battery pack at the same moment is selected.

[0038] Calculate U_Diff_IR= U_Cell_MAX-U_Cell_FastRate,

[0039] Delta_1 = 1 - U_Diff_IR / U_Intvl * 100%, or

[0040] Delta_1 = 1 - U_Diff_IR * 1000 / U_Intvl * 100%. Here, for unit conversion purposes, the volts are converted to millivolts, and the multiplier is 1000 in the calculation.

[0041] Among them, the voltage plateau U_Intvl is a fixed constant, which is determined by the battery material composition.

[0042] Then the repairability of the battery pack is R1 = Delta_1 * Delta_Cor_1.

[0043] The meanings of the parameters involved are as follows:

[0044] U_Cell_MAX — The highest voltage value of a single cell, which can be expressed in volts (V).

[0045] U_Cell_FastRate — The voltage value of the cell with the fastest voltage change rate among all cell strings in a battery pack or battery module, and the unit can be "volts, v".

[0046] Voltage change rate Delta_U_ChangeRate = (U2-U1) / t; where U2 is the cell voltage at the start of charging / discharging, U1 is the cell voltage at the end of charging / discharging, and t is the duration of the charging / discharging process.

[0047] U_Diff_IR — Voltage difference due to uniformity of battery internal resistance, expressed in volts (V).

[0048] Delta_1 — Battery internal resistance uniformity loss, which can be expressed as a percentage.

[0049] U_Intvl — Voltage plateau, expressed in millivolts (mV), is a fixed constant determined by the battery material composition. Here, the voltage plateau refers to the range during battery charging and discharging where the voltage change is not drastic and exhibits a certain linearity between a fully charged and partially discharged state.

[0050] Delta_Cor_1 — Calibration coefficient, expressed as a percentage. The calibration coefficient Delta_Cor is used to correct for deviations in the actual calculation due to measurement errors in the instrument control circuit, voltage fluctuations during battery charging and discharging, and temperature effects. When measuring the repairability of battery packs in batches, sampled battery packs can be disassembled and repaired to verify and compare the results with the actual measurements. The calibration coefficient can then be adjusted to ensure consistency between the battery repairability results and the actual results.

[0051] In this embodiment, the battery pack is composed of multiple battery cells or multiple battery modules, and the battery module is composed of multiple battery cells connected in series or in parallel. In this example, the multiple battery cells or multiple battery modules used to monitor the voltage difference need to be connected in series to ensure that the voltage value of each battery cell and module can reflect the true internal electrochemical voltage value of the battery cell. If the battery cells or modules are connected in parallel to monitor the voltage, the monitoring effect on consistency will be lost due to the mutual charging and discharging between the parallel battery cells or modules.

[0052] According to one or more embodiments, a second method for calculating the repairability of a battery pack or battery module is provided, which involves estimating the capacity consistency loss of the battery. The principle is that during the cyclic charging and discharging process, components such as the positive and negative electrode materials of the battery are continuously lost, leading to differences in capacity loss between cells. This difference causes the voltage change rate to vary among cells or series modules during full charging or discharging. While it's impossible to calculate the absolute capacity value of each cell or module by identifying and calculating this voltage change rate, it can be used to indirectly estimate the relative proportion difference in capacity between the cells. This portion of capacity difference loss cannot be repaired through equalization. By subtracting the capacity consistency loss of the cells or modules from the overall capacity loss of the battery pack, the degree of repairability of the battery pack can be determined.

[0053] This method of measurement requires at least one full charge and discharge cycle of the battery pack. After full charge, allow the batteries to fully equalize before discharging.

[0054] The rate of change of battery voltage during charging and discharging directly reflects the retention rate of the battery's internal capacity; the greater the rate of change, the lower the remaining capacity. The average voltage change rate is selected.

[0055] U_Diff_FastRate_Cell=U_STRT_FastRate_Cell - U_End_FastRate_Cell

[0056] U_Diff_AVRG_Cell=U_STRT_AVRG_Cell - U_End_AVRG_Cell

[0057] Delta_2=1- U_Diff_AVRG_Cell / U_Diff_FastRate_Cell *100%

[0058] Battery pack repairability R2 = (Delta_Total – Delta_2) * Delta_Cor_2;

[0059] The total capacity loss, Delta_Total, can be determined by calculating the cumulative capacity after multiple charge-discharge cycles of the battery, taking the average value, and then comparing it with the factory-set capacity.

[0060] Delta_Total = Average measured capacity / Factory capacity

[0061] The calibration coefficient Delta_Cor_2 is the coefficient used to correct the results in actual calculations due to measurement errors and temperature effects.

[0062] The meanings of the parameters involved are as follows:

[0063] U_Diff_FastRate_Cell — Maximum voltage change rate, expressed in volts.

[0064] U_STRT_FastRate_Cell — Cut-off voltage on the cell, which can be expressed in volts.

[0065] U_End_FastRate_Cell — The cell's cutoff voltage, which can be expressed in volts.

[0066] U_Diff_AVRG_Cell — Average voltage change rate, expressed in volts.

[0067] U_STRT_AVRG_Cell — Cut-off voltage on the cell, which can be expressed in volts.

[0068] U_End_AVRG_Cell — Cell cutoff voltage, which can be expressed in volts.

[0069] Delta_2 – Battery capacity consistency loss, which can be expressed as a percentage.

[0070] Delta_Total – Total capacity loss, expressed as a percentage, refers to the percentage reduction in the actual capacity of the battery compared to its factory-supplied capacity under standard factory testing conditions.

[0071] Delta_Cor_2 — Calibration coefficient, which can be represented as a percentage. It is a coefficient used to correct the calculation results due to factors such as measurement error and / or temperature influence.

[0072] The beneficial effect of this invention is that, without disassembling the battery pack, it can analyze the causes of capacity reduction during battery use through rapid detection methods and algorithms, confirm the proportion of each cause, and derive key data such as battery repairability. This allows battery pack asset owners to quickly determine the disposal plan for battery packs in operation and assess its economic viability. This method effectively improves the effectiveness and efficiency of battery pack repair and reduces the cost of investing in battery pack repair solutions.

[0073] To further illustrate the beneficial effects of this invention, a calculation example is given below.

[0074] The battery pack was selected for data analysis and discharge data verification. The battery is a power battery used in electric motorcycles. This battery type is a ternary lithium battery with the following basic parameters: nominal voltage 3.7V, factory capacity 62Ah, full charge voltage 4.2V, and depleted voltage 3.2V. The charge and discharge curves show obvious linear characteristics. Figure 1 This is the full discharge voltage curve of the battery pack, in volts, with a discharge current of 10A. Figure 2 The battery pack's full charge voltage curve is shown in volts, with a charging current of 7A. The charge / discharge test used 17 ternary lithium-ion cells connected in series, with a nominal voltage of 60V. Taking discharge as an example, there are upper inflection points of 70.5V and lower inflection points of 56.9V, which translate to a cell voltage of 4.147V to 3.347V. The voltage difference across this plateau is 0.8V, or 800mV.

[0075] During use, this battery pack exhibited significant capacity loss and insufficient range. The actual remaining capacity was 55.76Ah, compared to 89.94% of the factory capacity, which translates to a capacity loss of 10.06%. Therefore, a consistency analysis was conducted as follows.

[0076] According to the battery pack or battery module repairability calculation method, in the process of analyzing the internal resistance consistency loss of the battery pack, the battery pack is first fully charged with the equalization function turned off. The voltage of each cell is shown in Table 1. The maximum voltage value U_Cell_MAX (highest voltage of a single cell, volts) is 4.115V, and the cell with the fastest voltage change rate in the battery pack is U_Cell_FastRate = 4.105V. Therefore, U_Diff_IR (internal resistance consistency voltage difference, volts) is 10mV, and Delta_1 (internal resistance consistency loss, %) is 1.25%. Therefore, the repairability R1 of the battery pack can be calculated to be within 1.25%.

[0077] Table 1

[0078]

[0079] According to Method 2 for calculating the repairability of battery packs or battery modules, the capacity consistency loss of the battery pack is calculated. After the battery pack is fully charged, it is discharged to the cutoff voltage, and the voltage of each cell in the series is shown in Table 2.

[0080] Table 2

[0081]

[0082] Based on the data in Table 2, the average charge-discharge voltage difference is 746.12 mV. The cell closest to this value is selected as the 9th cell in the series, with an average voltage change rate difference of 747 mV. The maximum charge-discharge voltage difference is 814 mV, and the cell in the 6th cell in the series is selected.

[0083] U_Diff_FastRate_Cell (maximum voltage change rate, volts) = 814mV

[0084] U_Diff_AVRG_Cell (Average Voltage Change Rate, Voltage Difference, Volts) = 747 mV

[0085] Delta_2 (capacity consistency loss, %) = 1 - 747 / 814 * 100% = 8.23%

[0086] The total capacity loss obtained from previous charge-discharge tests is 10.06%. Subtracting Delta_2 (capacity consistency loss, %) and assuming a calibration coefficient of 1, the repairability R2 of the battery pack is found to be within 1.83%.

[0087] The following example further illustrates how to determine the repairability and cost-effectiveness of a battery pack.

[0088] As the results above show, the repairability of the battery pack or battery module calculated by Method 1 is 1.25%, and by Method 2 it is 1.83%. Here, repairability specifically refers to the possibility of battery equalization repair. Based on the battery pack's ex-factory price of 3600 yuan and the repairability, the added value after battery repair is no more than 65.9 yuan. Therefore, the results indicate that the proportion of battery capacity and health repaired through equalization is low, and it does not have the economic value of disassembling and equalizing.

[0089] As shown in the table of Method 2, the voltage change of cell number 6 is the largest, indicating that its voltage degradation is the most severe during battery pack use. Replacing this cell could be considered to restore the battery pack's capacity. Assuming a total labor and material cost of 500 yuan for cell replacement, the maximum added value after repairing the current 8.23% capacity consistency loss is 296 yuan. Compared to the labor and material costs, repairing the cell is not yet economically viable. If an added value greater than 500 yuan is required, dividing it by the battery pack price reveals that a capacity consistency loss of over 13.9% is needed for cell replacement to be economically viable for restoring battery pack capacity. This example fully demonstrates how to analyze the repairability of a battery pack and assess the effectiveness and economics of battery repair solutions.

[0090] It should be understood that in the embodiments of the present invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, the character " / " in this document generally indicates that the preceding and following associated objects have an "or" relationship.

[0091] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0092] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0093] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for calculating the repairability of a battery pack or battery module, characterized in that, Includes the following steps, The battery pack or battery module is charged, and after being fully charged, the maximum voltage value U_Cell_MAX among the voltage values ​​of a single battery module or a single cell in the battery pack is obtained. And obtain the voltage value U_Cell_FastRate, which is the voltage value with the fastest voltage change rate among the voltage values ​​of a single battery module or a single cell in the battery pack or battery module; Therefore, the uniform voltage difference due to the battery's internal resistance, U_Diff_IR, = U_Cell_MAX - U_Cell_FastRate. Battery internal resistance uniformity loss Delta_1 = 1 - U_Diff_IR / U_Intvl * 100%, Wherein, the voltage plateau U_Intvl is a fixed constant. Therefore, the repairability of the battery pack or battery module is R1 = Delta_1 * Delta_Cor_1. Among them, the coefficient Delta_Cor_1 is the calibration coefficient.

2. The repairability calculation method according to claim 1, characterized in that, Before charging, the voltage change process of each cell or battery module is detected during the discharge or charging process to identify the cell or battery module with the fastest voltage change rate.

3. The method according to claim 1, characterized in that, During the charging process, the equalization function of the battery pack or battery module is turned off.

4. The repairability calculation method according to claim 1, characterized in that, The value of the voltage plateau U_Intvl depends on the properties of the cell materials used in the battery pack or battery module. During the charging and discharging process of the battery pack or battery module, the voltage curve of the voltage plateau has obvious linear characteristics.

5. A method for repairing a battery pack or battery module, characterized in that, The repairability of the battery pack or battery module to be repaired is obtained according to the repairability calculation method of any one of claims 1 to 4. Based on the repair value of the battery pack or battery module, it is determined whether to disassemble and equalize the battery cells or battery modules therein for repair or to replace the damaged battery cells or battery modules.

6. An electronic device comprising a processor and a memory, the processor being configured to execute instructions stored in the memory, characterized in that, It is used to calculate the repairability of battery packs or battery modules. The processor performs all the steps of any one of the methods as claimed in claims 1 to 4.

7. A program product, characterized in that, It is used to perform the repairability calculation method for any of the battery packs or battery modules as described in claims 1 to 4.

8. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 4.

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