Battery SOH calculation method
By storing calendar and cycle capacity decay fitting curves at different temperatures in a 12V battery, the aging decay of lithium-ion batteries can be calculated in real time, solving the problems of computational complexity and accuracy in existing technologies, and realizing real-time and accurate SOH estimation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-03
AI Technical Summary
Existing methods for calculating the state of harm (SOH) of lithium-ion batteries suffer from problems such as computational complexity, high requirements for computational power and data accuracy, and inability to achieve accurate evaluation under static conditions in 12V batteries.
By storing calendar and cycle capacity decay fitting curves at different temperatures, the aging decay of the battery in different temperature ranges is calculated in real time. A simplified Arrhenius formula is used for SOH updates, simplifying model requirements and reducing computational load.
It enables real-time and accurate SOH calculation in a 12V battery without the need for static conditions, reducing computational complexity and data processing costs, and improving the real-time performance and accuracy of the estimation.
Smart Images
Figure CN121784595A_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to the field of batteries, and more particularly to a method for calculating the State of Health (SOH) of a battery. [Background Technology]
[0002] Lithium-ion batteries, with their advantages of high energy density, light weight, long lifespan, fast charging, and greater environmental friendliness, are gradually replacing lead-acid batteries and becoming the preferred 12V battery for vehicles. The 12V battery is primarily responsible for powering on and off the vehicle and providing energy to handle sudden changes in vehicle load, ensuring the normal operation of the entire vehicle system. However, the State of Health (SOH) of a lithium-ion battery is crucial in the battery management system because the charge and discharge capabilities of batteries differ significantly at different SOH levels, making it a key indicator for measuring the degree of battery performance degradation. The SOH of a battery is typically equal to (current capacity / BOL capacity) × 100%, where BOL capacity refers to the capacity at the beginning of the battery's lifespan.
[0003] Therefore, accurately assessing the state of harmonics (SOH) of lithium batteries is an indispensable and crucial step in battery management systems to ensure stable battery performance and safety.
[0004] Currently, the State of Health (SOH) of lithium-ion batteries is mainly used for the management of power batteries, and the calculation methods are mainly as follows:
[0005] 1. Equivalent Circuit Method: This method involves detecting parameters such as cell voltage, current, and temperature, and calculating the battery's state of equilibrium (SOH) by establishing an equivalent circuit. This method requires building a complex model and demands high computational power and data accuracy.
[0006] 2. Voltage Characteristic Method: This method analyzes the voltage change curves during the charging and discharging process of lithium-ion batteries, selects key voltage points, and performs a long period of rest followed by full charging. The State of Harm (SOH) is calculated based on the difference in charge received by the new and old batteries at their current capacities. This method requires at least two consecutive hours of rest with a current less than 2A. However, 12V batteries do not have a completely static operating condition; they still have a certain output current even after the vehicle enters sleep mode and can be woken up at any time by functions such as Sentry Mode.
[0007] 3. Internal Resistance Method: This method infers the State of Health (SOH) value by measuring changes in the battery's internal resistance. The battery's internal resistance is significantly affected by external factors such as temperature, requiring consideration of multiple factors to accurately reflect the battery's health.
[0008] In summary, existing methods for calculating the state of harm (SOH) of lithium-ion batteries all have varying degrees of shortcomings. Therefore, it is necessary to propose an improved method for calculating the SOH of batteries. [Summary of the Invention]
[0009] To solve the above-mentioned technical problems, or at least partially solve them, embodiments of the present invention provide an improved method for calculating battery SOH.
[0010] According to one aspect of the present invention, embodiments of the present invention provide a method for calculating the state of equilibrium (SOH) of a battery. The method includes: after each update of the SOH of the battery, re-accumulating the calendar aging time of the battery in each of multiple temperature ranges in the current update cycle, and re-accumulating the cycle aging throughput of the battery in each of multiple temperature ranges in the current update cycle. Multiple calendar capacity decay fitting curves and multiple cycle capacity decay fitting curves at different temperatures are stored. The calendar capacity decay fitting curve at each temperature is obtained by fitting calendar aging data at the corresponding temperature, and the cycle capacity decay fitting curve at each temperature is obtained by fitting cycle aging data at the corresponding temperature. Each calendar capacity decay fitting curve at each temperature corresponds to a temperature range, and each cycle capacity decay fitting curve at each temperature corresponds to a temperature range. The battery in the current update cycle... The cycle aging throughput within each temperature range is the total charge accumulated by the battery during the charge and discharge process of the current update cycle within the corresponding temperature range. When the SOH of the battery needs to be updated, the calendar aging decay caused by the accumulated calendar aging time in the corresponding temperature range in the current update cycle is calculated based on the calendar capacity decay fitting curve at each temperature, and the cycle aging decay caused by the accumulated cycle aging throughput in the corresponding temperature range in the current update cycle is calculated based on the cycle capacity decay fitting curve at each temperature. The updated SOH of the battery is calculated based on the calendar aging decay caused by the accumulated calendar aging time in each temperature range in the current update cycle, the cycle aging decay caused by the accumulated cycle aging throughput in each temperature range in the current update cycle, and the current SOH of the battery.
[0011] Compared with existing technologies, this invention stores multiple calendar capacity decay fitting curves and multiple cycle capacity decay fitting curves at different temperatures. This allows for real-time calculation of the calendar aging decay caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle, based on the calendar capacity decay fitting curve at each temperature. It also allows for calculation of the cycle aging decay caused by the cumulative cycle aging throughput in the corresponding temperature range during the current update cycle, based on the cycle capacity decay fitting curve at each temperature. This enables the updating of the battery's State of Health (SOH), improving the real-time performance and accuracy of SOH estimation. [Attached Image Description]
[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:
[0013] Figure 1 This is a schematic flowchart of the battery SOH calculation method in one embodiment of the present invention;
[0014] Figure 2 This is a schematic diagram of the measurement and recording of calendar aging data at different temperatures in this invention;
[0015] Figure 3 This is a schematic diagram of the measurement and recording of cyclic aging data at different temperatures in this invention;
[0016] Figure 4 This is a schematic diagram of the cycle capacity decay fitting curve at the corresponding temperature, obtained by fitting a set of battery capacity decay data with cycle aging throughput.
[0017] Figure 5 The figure shows the simulation results obtained from a single-temperature simulation based on a calendar capacity decay fitting curve at 25℃.
[0018] Figure 6 The figure shows the simulation results obtained from multi-temperature simulations based on the calendar capacity decay fitting curves at different temperatures.
Detailed Implementation Methods
[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0021] Figure 1 This is a schematic flowchart of a battery SOH calculation method 100 according to one embodiment of the present invention. Figure 1 As shown, the battery SOH calculation method is used to cyclically update the SOH of the battery, and the method includes the following steps.
[0022] Step 110: After each update of the SOH of the battery, re-accumulate the calendar aging time of the battery in each of the multiple temperature ranges in the current update cycle, and re-accumulate the cycle aging throughput of the battery in each of the multiple temperature ranges in the current update cycle.
[0023] Multiple calendar capacity decay fitting curves and multiple cycle capacity decay fitting curves at different temperatures are stored. The calendar capacity decay fitting curve at each temperature is obtained by fitting the calendar aging data at the corresponding temperature, and the cycle capacity decay fitting curve at each temperature is obtained by fitting the cycle aging data at the corresponding temperature. The calendar capacity decay fitting curve at each temperature corresponds to a temperature range, and the cycle capacity decay fitting curve at each temperature corresponds to a temperature range. The cycle aging throughput of the battery in each temperature range during the current update cycle is the total amount of charge accumulated by the battery during the charge and discharge process of the current update cycle within the corresponding temperature range.
[0024] In one embodiment, calendar aging data at different temperatures needs to be obtained in advance. Figure 2 This is a schematic diagram illustrating the measurement and recording of calendar aging data at different temperatures in this invention. Figure 2 In the example shown, temperatures of 25°C, 35°C, 45°C, and 55°C were selected as test points for low temperature, medium temperature, high temperature, and extremely high temperature, respectively. The current SOH of the battery was recorded every 30 days during the calendar aging process until the SOH trend stabilized or fell below the lithium battery scrapping threshold (e.g., SOH below 75%). The SOH of the battery can be tested in the laboratory using various existing methods. Figure 2 The data does not provide the specific measured SOH, but instead uses √. The calendar aging data at each temperature includes multiple calendar aging records. Each calendar aging record includes: the current temperature, the calendar aging duration, and the SOH measured after the battery has undergone the stated calendar aging duration. The calendar aging duration is different for different calendar aging records.
[0025] In one embodiment, it is necessary to obtain cyclic aging data at different temperatures in advance. Figure 3 This is a schematic diagram illustrating the measurement and recording of cyclic aging data at different temperatures in this invention. Figure 3 In the example shown, the temperature points of 25℃, 35℃ and 45℃ were selected as the test points for low temperature, medium temperature and high temperature, respectively. The current SOH was recorded every 200 full charge and discharge cycles until the SOH trend stabilized or fell below the lithium battery scrapping threshold (e.g., SOH below 75%). Figure 3The data does not provide the specific measured SOH, but instead uses √. The cycle aging data at each temperature includes multiple cycle aging records, each of which includes the current temperature, the number of full charge-discharge cycles, and the SOH measured after the battery has undergone the stated number of full charge-discharge cycles.
[0026] The state-of-the-art (SOH) degradation of lithium-ion batteries and the cycle aging throughput (corresponding to the number of cycles) or calendar aging time satisfy the Arrhenius formula, which effectively reflects battery capacity degradation. The Arrhenius formula is as follows:
[0027]
[0028] In the formula: Y is the SOH decay amount, A is the pre-exponential factor, -Ea is the activation energy, R is the ideal gas constant, t is the temperature, x is the cyclic aging throughput or calendar aging time, and z is the power law factor.
[0029] Calendar capacity decay fitting curves (or calendar capacity decay formulas) at different temperatures are obtained by fitting calendar aging data at different temperatures. Cyclic capacity decay fitting curves (or cyclic capacity decay formulas) at different temperatures are obtained by fitting cyclic aging data at different temperatures.
[0030] Because the data is fitted separately at different temperatures, resulting in different decay curves for each temperature, this data processing and fitting method does not involve temperature changes.
[0031] We can combine t with other values to form a single value that needs to be fitted, thus the simplified Arrhenius formula becomes:
[0032] y = a * x b +c
[0033] In the formula: y is the SOH decay amount, a is the fitting coefficient, x is the cycle aging throughput or calendar aging duration, b is the power law factor, and c is the fitting constant term.
[0034] In other words, the fitted curves for calendar capacity decay and cycle capacity decay at each temperature are both:
[0035] y = a * x b +c (Formula 1)
[0036] The calendar capacity decay fitting curves corresponding to each temperature are obtained by fitting calendar aging data at the corresponding temperature, specifically a, b, and c.
[0037] Based on the cyclic aging data at the corresponding temperature, we obtain the corresponding a, b, and c curves for the cyclic capacity decay at each temperature.
[0038] by Figure 2 and Figure 3 Taking the example shown, the calendar capacity decay fitting curves at 25℃, 35℃, 45℃ and 55℃ will be obtained respectively, where each temperature corresponds to its own a, b and c; the cycle capacity decay fitting curves at 25℃, 35℃ and 45℃ will be obtained respectively, where each temperature corresponds to its own a, b and c.
[0039] Figure 4 The diagram shows the curves of the cycle capacity decay fitting curves at the corresponding temperature obtained by fitting a set of battery capacity decay (Capfadeper) and cycle aging throughput (Ah) data, proving that the above formula can well simulate battery aging and can be used as an empirical model for battery aging.
[0040] In one example, based on the calendar aging data of a certain brand of 12V lithium-ion battery in the laboratory, the MATLAB data fitting tool was used to fit the simplified formula (1) above to obtain the calendar capacity decay formula under 25℃ conditions, where a is 0.009405, b is 0.3166, and c is 0.00001909.
[0041] In another example, based on laboratory data of a certain brand of 12V lithium-ion battery, the MATLAB data fitting tool was used to fit the data according to the simplified formula (1) above, and the cycle capacity decay fitting curve under 25℃ was obtained, where a is 0.0002704, b is 0.7023, and c is -0.0006219. The battery aging SOH algorithm was built using Simulink.
[0042] For 12V lithium batteries, high-current charge and discharge processes mainly consider cycle aging, while full charge and dormancy periods consider calendar aging. The distinction between calendar aging and cycle aging is primarily based on current magnitude. Considering the application scenarios of 12V lithium batteries, calendar aging can be considered when the charge / discharge current is less than 2A.
[0043] In one specific embodiment, the calendar aging time of the battery in the current update cycle is accumulated within each of four temperature ranges: below 30°C, 30°C to 40°C, 40°C to 50°C, and above 50°C. The calendar aging time below 30°C corresponds to the calendar capacity decay formula at 25°C, the calendar aging time between 30°C and 40°C corresponds to the calendar capacity decay formula at 35°C, the calendar aging time between 40°C and 50°C corresponds to the calendar capacity decay formula at 45°C, and the calendar aging time above 50°C corresponds to the calendar capacity decay formula at 55°C.
[0044] In one specific embodiment, the cycle aging throughput of the battery in the current update cycle is re-accumulated in each of the three temperature ranges: below 30°C, 30°C to 40°C, and above 40°C. The cycle aging throughput below 30°C corresponds to the cycle capacity decay fitting curve at 25°C, the cycle aging throughput between 30°C and 40°C corresponds to the cycle capacity decay fitting curve at 35°C, and the cycle aging throughput above 40°C corresponds to the cycle capacity decay fitting curve at 45°C.
[0045] Step 120: When the SOH of the battery needs to be updated, calculate the calendar aging decay caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle based on the calendar capacity decay fitting curve at each temperature, and calculate the cycle aging decay caused by the cumulative cycle aging throughput in the corresponding temperature range during the current update cycle based on the cycle capacity decay fitting curve at each temperature.
[0046] Specifically, the battery's State of Health (SOH) is considered to need to be updated when the sum of the calendar aging times for each temperature range accumulated in the current update cycle reaches a predetermined duration, or when the sum of the cycle aging throughput for each temperature range accumulated in the current update cycle reaches a predetermined capacity. For example, the predetermined duration is 24 hours, and the predetermined capacity is the initial life capacity (BOL) of the battery. In this example, if the sum of the calendar aging times for each temperature range accumulated in the current update cycle reaches 24 hours—for instance, 8 hours for calendar aging below 30°C, 8 hours for calendar aging between 30°C and 40°C, 4 hours for calendar aging between 40°C and 50°C, and 4 hours for calendar aging above 50°C, totaling 24 hours—then the battery's SOH is considered to need to be updated.
[0047] If the sum of the cycle aging throughput accumulated in each temperature range during the current update cycle reaches the BOL capacity, for example, the cycle aging throughput below 30°C is 35% of the BOL, the cycle aging throughput between 30°C and 40°C is 35% of the BOL, the cycle aging throughput above 40°C is 30% of the BOL, and the total cycle aging throughput in each temperature range is BOL, then the SOH of the battery is considered to need to be updated.
[0048] In one specific embodiment, the calculation of calendar aging decay caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle, based on the calendar capacity decay fitting curve at each temperature, includes:
[0049] Calculate the calendar aging time of the corresponding temperature range equivalent to the current SOH of the battery. Taking a temperature range below 30°C as an example, calculate the equivalent calendar aging time below 30°C for the current SOH of the battery. It should be explained that when calculating the calendar aging decay caused by the cumulative calendar aging time below 30°C in the current update cycle, the influence of the current SOH of the battery needs to be considered. Therefore, it is necessary to calculate the equivalent calendar aging time below 30°C for the current SOH of the battery in order to complete the subsequent more accurate calculation.
[0050] Calculate the cumulative calendar aging time for the corresponding temperature range in the current update cycle. Calendar aging time corresponding to the temperature range equivalent to the current SOH of the battery. and Where ti represents the i-th temperature interval, n is the number of temperature intervals, and i is greater than or equal to 1 and less than or equal to n; that is...
[0051] Will By substituting the calendar capacity decay fitting curve at the corresponding temperature, the total calendar aging decay can be obtained. Will By substituting the calendar capacity decay fitting curve at the corresponding temperature, we obtain the calendar aging decay amount equivalent to the current SOH in the corresponding temperature range.
[0052] Overall calendar aging degradation Subtract the calendar aging degradation amount from the current SOH equivalent temperature range. Get the calendar aging decay amount caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle. Right now
[0053] In one specific embodiment, the calculation of the cycle aging decay caused by the cumulative cycle aging throughput in the corresponding temperature range during the current update cycle, based on the cycle capacity decay fitting curve at each temperature, includes:
[0054] Calculate the cycle aging throughput of the battery in the corresponding temperature range equivalent to its current state of equilibrium (SOH). Taking a temperature range below 30°C as an example, calculate the current SOH of the battery equivalent to the cycle aging throughput below 30°C. It should be explained that when calculating the cycle aging decay caused by the cumulative cycle aging throughput below 30°C in the current update cycle, the influence of the current SOH of the battery needs to be considered. Therefore, it is necessary to calculate the current SOH of the battery equivalent to the cycle aging throughput below 30°C in order to complete the subsequent more accurate calculation.
[0055] Calculate the cumulative aging throughput within the corresponding temperature range in the current update cycle. Cyclic aging throughput equivalent to the current SOH of the battery in the corresponding temperature range and Where ti represents the i-th temperature interval, n is the number of temperature intervals, and i is greater than or equal to 1 and less than or equal to n; that is...
[0056] Will By substituting the cycle capacity decay fitting curve at the corresponding temperature, the total cycle aging decay can be obtained. Will By substituting the cycle capacity decay fitting curve at the corresponding temperature, the equivalent cycle aging decay amount of the current SOH in the corresponding temperature range is obtained.
[0057] Overall cyclic aging degradation Subtract the current SOH equivalent cyclic aging degradation amount in the corresponding temperature range The amount of cyclic aging decay caused by the cumulative cyclic aging throughput in the corresponding temperature range during the current update cycle is obtained. Right now
[0058] Step 130: Calculate the updated SOH of the battery based on the calendar aging decay caused by the calendar aging duration accumulated in each temperature range in the current update cycle, the cycle aging decay caused by the cycle aging throughput accumulated in each temperature range in the current update cycle, and the current SOH of the battery.
[0059] Specifically, the updated SOH of the battery can be obtained by subtracting the calendar aging decay caused by the accumulated calendar aging time in each temperature range during the current update cycle and the cycle aging decay caused by the accumulated cycle aging throughput in each temperature range during the current update cycle from the current SOH of the battery.
[0060] After step 130, the process can return to step 110 to calculate the next update cycle until the SOH trend of the battery stabilizes or falls below the battery scrap threshold (e.g., SOH below 75%). During the first update cycle, the calendar aging time of the battery in each of the multiple temperature ranges is directly accumulated, as is the cycle aging throughput of the battery in each of the multiple temperature ranges in the current update cycle.
[0061] A single-temperature simulation of calendar aging at 25℃ was performed to verify the accuracy of the algorithm at that temperature. The simulation results are shown below. Figure 5The daily SOH decay rate is relatively high in the early stage, then gradually flattens out, and finally the SOH decreases to 75% at 3059 days, reaching the product's set EOL (End of Life), which is in line with the product design.
[0062] Considering the vehicle's operating conditions and the installation location of the 12V lithium battery, coupled simulations were performed on different temperature ranges of calendar aging, with the following percentages: low temperature: medium temperature: high temperature: extremely high temperature, accounting for 85%: 14%: 0.9%: 0.1% respectively. The results are shown in [Figure number missing]. Figure 6 SOH decreased to 75% in 1808 days, reaching the design EOL.
[0063] In one embodiment, the cumulative calendar aging time of the battery in each temperature range and the cumulative cycle aging throughput of the battery in each temperature range during each update cycle are stored in a non-volatile memory area. The state of equilibrium (SOH) of the battery is backed up to the non-volatile memory area, and the battery's SOH is backed up to the non-volatile memory area once every time it changes by a predetermined value. Specifically, the predetermined value is 2%, that is, a backup is performed every time the SOH changes by 2%. This allows for the calculation of the SOH over the entire life cycle, and also allows for the querying of the battery's usage records and the SOH calculation process at each stage.
[0064] The battery SOH calculation method of this invention can achieve one or more of the following beneficial effects:
[0065] 1. No need for continuous long-term static storage; calculations can be performed in real time.
[0066] 2. No need to build complex models, reducing computational load and lower CPU (Central Processing Unit) requirements;
[0067] 3. By adopting a data fitting method, the fitting formula is simplified while ensuring the accuracy of SOH throughout the entire life cycle, thus reducing the cost of data collection in the early stage;
[0068] 4. The storage scheme for SOH is optimized, and backup storage is performed every 2% change or when the controller is powered off to reduce the possibility of data loss.
[0069] The above describes a 12V battery, but it is clear that the battery SOH calculation method in this invention is not only applicable to 12V batteries, but also to batteries of other voltage values, such as 4V and 24V batteries. Furthermore, the battery SOH calculation method in this invention is not only applicable to lithium batteries, but also to other types of batteries.
[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.
[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for calculating the state of matter (SOH) of a battery, used for cyclically updating the SOH of a battery, characterized in that, It includes: After each update of the battery's SOH, the calendar aging time of the battery in each of the multiple temperature ranges in the current update cycle is re-accumulated, and the cycle aging throughput of the battery in each of the multiple temperature ranges in the current update cycle is re-accumulated. Multiple calendar capacity decay fitting curves and multiple cycle capacity decay fitting curves at different temperatures are stored. The calendar capacity decay fitting curve at each temperature is obtained by fitting the calendar aging data at the corresponding temperature, and the cycle capacity decay fitting curve at each temperature is obtained by fitting the cycle aging data at the corresponding temperature. The calendar capacity decay fitting curve at each temperature corresponds to a temperature range, and the cycle capacity decay fitting curve at each temperature corresponds to a temperature range. The cycle aging throughput of the battery in each temperature range in the current update cycle is the total amount of charge accumulated by the battery during the charge and discharge process in the corresponding temperature range in the current update cycle. When the SOH of the battery needs to be updated, the calendar aging decay amount caused by the cumulative calendar aging time in the corresponding temperature range in the current update cycle is calculated based on the calendar capacity decay fitting curve at each temperature, and the cycle aging decay amount caused by the cumulative cycle aging throughput in the corresponding temperature range in the current update cycle is calculated based on the cycle capacity decay fitting curve at each temperature. The updated SOH of the battery is calculated based on the calendar aging decay caused by the accumulated calendar aging time in each temperature range during the current update cycle, the cycle aging decay caused by the accumulated cycle aging throughput in each temperature range during the current update cycle, and the current SOH of the battery.
2. The battery SOH calculation method according to claim 1, characterized in that, The battery's State of Health (SOH) is considered to need to be updated when the sum of the calendar aging durations for each temperature range accumulated in the current update cycle reaches a predetermined duration, or when the sum of the cycle aging throughputs for each temperature range accumulated in the current update cycle reaches a predetermined capacity.
3. The battery SOH calculation method according to claim 1, characterized in that, The calendar capacity decay fitting curve and the cycle capacity decay fitting curve at each temperature are as follows: y=a*x b +c Where y is the SOH decay rate, a is the fitting coefficient, x is the cycle aging throughput or calendar aging duration, b is the power-law factor, and c is the fitting constant term. The calendar capacity decay fitting curves corresponding to each temperature are obtained by fitting calendar aging data at the corresponding temperature, specifically a, b, and c. Based on the cyclic aging data at the corresponding temperature, we obtain the corresponding a, b, and c curves for the cyclic capacity decay at each temperature.
4. The battery SOH calculation method according to claim 3, characterized in that, The calendar aging data at each temperature includes multiple calendar aging records. Each calendar aging record includes: the current temperature, the calendar aging duration, and the SOH measured after the battery has experienced the calendar aging duration. The calendar aging duration is different for different calendar aging records. The cycle aging data at each temperature includes multiple cycle aging records. Each cycle aging record includes the current temperature, the number of full charge-discharge cycles, and the SOH measured after the battery has undergone the full charge-discharge cycles.
5. The battery SOH calculation method according to claim 1, characterized in that, The cumulative calendar aging time of the battery in each temperature range during each update cycle, and the cumulative cycle aging throughput of the battery in each temperature range are stored in non-volatile memory. The state of energy (SOH) of the battery is backed up to a non-volatile storage area. The battery's SOH is backed up to the non-volatile storage area once every time it changes by a predetermined value.
6. The battery SOH calculation method according to claim 1, characterized in that, The calendar aging decay amount caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle is calculated based on the calendar capacity decay fitting curve at each temperature, including: Calculate the calendar aging time of the corresponding temperature range equivalent to the current SOH of the battery. Calculate the cumulative calendar aging time for the corresponding temperature range in the current update cycle. Calendar aging time corresponding to the temperature range equivalent to the current SOH of the battery. and Where ti represents the i-th temperature interval, n is the number of temperature intervals, and i is greater than or equal to 1 and less than or equal to n; that is... Will By substituting the calendar capacity decay fitting curve at the corresponding temperature, the total calendar aging decay can be obtained. Will By substituting the calendar capacity decay fitting curve at the corresponding temperature, we obtain the calendar aging decay amount equivalent to the current SOH in the corresponding temperature range. Overall calendar aging degradation Subtract the calendar aging degradation amount from the current SOH equivalent temperature range. Get the calendar aging decay amount caused by the cumulative calendar aging time in the corresponding temperature range during the current update cycle. Right now 7. The battery SOH calculation method according to claim 1, characterized in that, The amount of cycle aging decay caused by the cumulative cycle aging throughput in the corresponding temperature range during the current update cycle is calculated based on the fitted curve of cycle capacity decay at each temperature. Calculate the cycle aging throughput of the battery in the corresponding temperature range equivalent to its current state of equilibrium (SOH). Calculate the cumulative aging throughput within the corresponding temperature range in the current update cycle. Cyclic aging throughput equivalent to the current SOH of the battery in the corresponding temperature range and Where ti represents the i-th temperature interval, n is the number of temperature intervals, and i is greater than or equal to 1 and less than or equal to n; that is... Will By substituting the cycle capacity decay fitting curve at the corresponding temperature, the total cycle aging decay can be obtained. Will By substituting the cycle capacity decay fitting curve at the corresponding temperature, the equivalent cycle aging decay amount of the current SOH in the corresponding temperature range is obtained. Overall cyclic aging degradation Subtract the current SOH equivalent cyclic aging degradation amount in the corresponding temperature range The amount of cyclic aging decay caused by the cumulative cyclic aging throughput in the corresponding temperature range during the current update cycle is obtained.
8. The battery SOH calculation method according to claim 1, characterized in that, The updated SOH of the battery is obtained by subtracting the calendar aging decay caused by the accumulated calendar aging time in each temperature range during the current update cycle and the cycle aging decay caused by the accumulated cycle aging throughput in each temperature range during the current update cycle from the current SOH of the battery.