Method and apparatus for early warning of battery capacity drop

Abstract

This invention provides a method and apparatus for early warning of battery capacity drop, relating to the field of battery control calculation. The method includes: determining a battery capacity change value based on the ratio between the battery capacity change rate in the current detection cycle and the battery capacity change rate in the previous detection cycle, wherein the battery capacity change rate is calculated using battery degradation parameters and the number of battery cycles within the detection cycle; calculating the battery degradation slope in the current detection cycle when the battery capacity change value indicates an abnormal battery state; and outputting a battery drop warning signal based on the degradation duration period when the battery degradation slope in the current detection cycle indicates an abnormal battery degradation. This solves the technical problem of long time consumption in related technologies for predicting battery capacity drop.

Description

Technical Field

[0001] This invention relates to the field of battery control technology, and more specifically, to a method and apparatus for early warning of a sudden drop in battery capacity. Background Technology

[0002] Capacity degradation is an inevitable physical process throughout the entire life cycle of a battery. However, some batteries may suddenly experience a sharp drop in capacity during use, known as "capacity plunge." This phenomenon occurs in the middle and late stages of the battery's cycle life. It manifests as a sudden drop in the battery's usable capacity within a few charge-discharge cycles without any obvious warning signs. This can easily lead to safety risks such as a sudden reduction in range, abnormal charging, and thermal runaway.

[0003] In related technologies, battery degradation detection methods mainly include: simple threshold-based detection methods, data-driven machine learning models, and simulation models based on electrochemical mechanisms. Threshold-triggered methods often trigger alarms by setting a battery capacity threshold, but this method is a "post-event response" and cannot provide early warnings. Capacity degradation often begins in an accelerated decay phase before the threshold is triggered, and by the time the system alarms, the battery has already suffered irreversible damage, leaving no window for intervention. Data-driven models, while showing good fitting capabilities for capacity trends in laboratory environments, heavily rely on massive amounts of historical cyclic data (typically requiring thousands of complete charge-discharge cycles) for training, resulting in extremely poor generalization ability under small sample sizes and non-standard operating conditions in real vehicles (such as urban commuting, low-temperature environments, and frequent fast charging). Simulation models based on electrochemical mechanisms, such as single-particle models and pseudo-two-dimensional models, can simulate capacity decay mechanisms from a physical perspective, but they are computationally complex and time-consuming. Furthermore, these models heavily depend on precise material parameters (such as diffusion coefficients and reaction rate constants), which dynamically drift with battery aging, temperature, and state of charge, making actual calibration difficult and leading to significant error accumulation. Summary of the Invention

[0004] The main objective of this invention is to provide a method and apparatus for early warning of battery capacity drop, so as to solve the technical problem that the battery capacity drop prediction method in the related art is time-consuming.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for early warning of battery capacity drop is provided, comprising: determining a battery capacity change value based on the ratio between the battery capacity change rate in the current detection cycle and the battery capacity change rate in the previous detection cycle, wherein the battery capacity change rate is calculated using a battery degradation parameter and the number of battery cycles within the detection cycle; calculating a battery degradation slope in the current detection cycle when the battery capacity change value indicates an abnormal battery state; and outputting a battery drop warning signal based on the degradation duration period when the battery degradation slope in the current detection cycle indicates an abnormal battery degradation.

[0006] According to another aspect of the present invention, a battery capacity drop warning device is also provided, comprising: a battery capacity detection unit, configured to determine a battery capacity change value based on the ratio between the battery capacity change rate in the current detection period and the battery capacity change rate in the previous detection period, wherein the battery capacity change rate is calculated using a battery degradation parameter and the number of battery cycles within the detection period; a battery degradation calculation unit, configured to calculate the battery degradation slope in the current detection period when the battery capacity change value indicates an abnormal battery state; and a battery drop warning unit, configured to output a battery drop warning signal based on the degradation duration period when the battery degradation slope in the current detection period indicates an abnormal battery degradation.

[0007] By applying the technical solution of this invention, the capacity change rate of the battery during the charge-discharge cycle can be calculated and the trend of the degradation slope can be derived. A degradation trend assessment can be completed after a single charge-discharge cycle without waiting for a complete cycle or long-term data accumulation, thus shortening the battery capacity drop prediction cycle. By calculating the battery capacity degradation slope and its change rate in real time, the accelerated degradation trend can be identified in advance, and an early warning signal can be issued. When the ratio of the capacity change rate exceeds the threshold, the battery degradation slope is calculated instead of immediately triggering an alarm. This focuses on abnormal states with a continuous trend, reflects the true capacity degradation rate, reduces monitoring blind spots caused by vehicles not being driven for long periods of time while charging, effectively supports charging strategy optimization and current limiting intervention, significantly reduces the risk of thermal runaway, extends battery life, and improves vehicle operation safety and user trust. This solves the technical problem of long time consumption in battery capacity drop prediction methods in related technologies. Attached Figure Description

[0008] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0009] Figure 1 This is a flowchart of an optional early warning method for battery capacity drop according to this application;

[0010] Figure 2 This is a flowchart of an optional online prediction and calculation method for the capacity drop of automotive batteries according to an embodiment of the present invention; and

[0011] Figure 3 This is a graph showing the relationship between an optional cycle number (Cycle) and the available battery life (RSOH) according to an embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram of an optional early warning device for a rapidly decreasing battery capacity according to an embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0015] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0016] To facilitate understanding of the present invention by those skilled in the art, some terms or nouns involved in the various embodiments of the present invention are explained below:

[0017] A Battery Management System (BMS) is used to monitor, protect, and balance the operating status of individual cells in a power battery pack, ensuring system safety and stable performance.

[0018] State of Health (SOH) is a key indicator used to assess the degree of battery aging and remaining lifespan, representing the percentage of a battery's current actual capacity relative to its nominal capacity in its new condition.

[0019] State of Charge (SOC) indicates the percentage of a battery's current remaining charge relative to its current usable capacity, and is used to monitor battery charge and discharge levels in real time.

[0020] Available range, or R for short, refers to the estimated range that the battery can support the vehicle's driving distance under its current health condition. It is a key parameter for users to perceive battery performance.

[0021] This invention is applicable to automotive power battery control scenarios, such as online health monitoring and safety early warning scenarios for automotive lithium-ion batteries. It enables early prediction of battery capacity degradation without requiring additional hardware, relying on massive historical data, or increasing computational load. It calculates the battery capacity degradation slope and its rate of change in real time using existing BMS signals, identifies accelerated degradation trends in advance, and issues early warning signals. This effectively supports charging strategy optimization and current limiting intervention, significantly reduces the risk of thermal runaway, extends battery life, and improves vehicle operation safety and user trust.

[0022] To achieve the above objectives, according to one aspect of the present invention, a method for early warning of sudden drop in battery capacity is provided. Figure 1 This is a flowchart of an optional early warning method for a sudden drop in battery capacity according to an embodiment of the present invention, such as... Figure 1 As shown, the early warning method for battery capacity drop includes steps S101 to S103. The present invention will be described in detail below with reference to each implementation step.

[0023] Step S101 determines the battery capacity change value based on the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle. The battery capacity change rate is calculated using the battery degradation parameter and the number of battery cycles within the detection cycle.

[0024] Optionally, the step of determining the battery capacity change value based on the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle includes: if the battery is in a discharge state, calculating the battery capacity change rate of the previous detection cycle based on the battery degradation change rate of the previous detection cycle and the number of cycles in the previous detection cycle; calculating the battery capacity change rate of the current detection cycle based on the battery degradation change rate of the current detection cycle and the number of cycles in the current detection cycle; and calculating the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle to obtain the battery capacity change value.

[0025] It should be noted that the battery degradation rate is obtained by the difference between the SOH value at the end of the previous test cycle and the SOH value at the end of the cycle before that. The number of cycles is calculated by combining the driving mileage, available range, and the average SOH value of two adjacent cycles. This helps to normalize the capacity degradation to the contribution level of each complete charge-discharge cycle, thereby eliminating the interference of different driving behaviors on the degradation rate assessment. Furthermore, the battery capacity change rate for the current test cycle is calculated based on the battery degradation rate for the current test cycle and the number of cycles within the current test cycle. It can be understood that the SOH degradation for the current test cycle is also obtained by the difference between the SOH at the end of this discharge and the end of the previous discharge. The number of cycles is deduced from the driving mileage of the current cycle and the average SOH values ​​of the current and previous cycles, so that the calculation of the capacity change rate is synchronized with the actual vehicle usage conditions, which helps to reflect the dynamic aging trend of the battery in real operating conditions.

[0026] Optionally, the step of calculating the battery capacity change rate of the previous detection cycle based on the battery degradation change rate and the number of cycles in the previous detection cycle includes: obtaining battery usable range parameters and battery capacity; if the battery is in a discharging state, obtaining the discharge current and vehicle mileage, battery state of charge data at the start of discharge, and battery state of charge data at the end of discharge; obtaining battery state of charge data from the previous detection cycle, and calculating the battery capacity parameters of the previous detection cycle based on the battery state of charge data and battery capacity; and calculating the battery capacity parameters based on the discharge current, battery capacity, and historical detection data. The battery capacity parameters of the current test cycle are compared with those of the previous test cycle to determine the battery degradation rate of the previous test cycle. The historical test cycle refers to the historical cycles prior to the previous test cycle. Based on the battery capacity, usable battery range parameters, battery state of charge (SOC) data from the previous test cycle, SOC data at the start of discharge, SOC data at the end of discharge, and vehicle mileage from the previous test cycle, the number of cycles in the previous test cycle is determined. Based on the battery degradation rate of the previous test cycle and the number of cycles in the previous test cycle, the battery capacity change rate of the previous test cycle is calculated.

[0027] It should be noted that the available battery range parameter can be provided by the vehicle system, reflecting the theoretical driving distance that the battery can support in a brand new state. The battery capacity is the factory nominal value. Both serve as a benchmark reference for capacity calculation, which helps to establish a physical relationship between driving range and capacity consumption.

[0028] Furthermore, if the battery is in a discharge state, the system acquires the discharge current, vehicle mileage, battery state of charge (SOC) data at the start and end of discharge. The discharge current is used to calculate the actual amount of electricity released, the mileage is used to estimate the external performance of battery energy consumption, and the SOC data at the start and end of discharge (i.e., the SOC value) are used to calculate the relative change in battery SOC within that cycle. These data sources all come from existing sensors in the BMS, and data acquisition can be achieved without adding new hardware.

[0029] It should be noted that the battery capacity parameter is obtained by dividing the actual amount of electricity discharged during the discharge period by the range of SOC change within that cycle. In other words, the actual usable capacity is inferred from the difference between the integrated current and SOC, avoiding direct reliance on the nominal capacity and helping to dynamically adapt to changes in internal resistance and coulombic efficiency caused by battery aging. Furthermore, the battery degradation rate for the previous testing cycle can be determined based on the discharge current, battery capacity, battery capacity parameters from historical testing cycles, and the battery capacity parameters from the previous testing cycle. This means the battery degradation rate is obtained through the difference in capacity parameters between two adjacent testing cycles.

[0030] Additionally, it should be noted that the number of battery cycles can be estimated by the ratio of driving mileage to average available range. The average available range is obtained by weighting the current and previous cycle's State of Health (SOH). This coupling of physical driving behavior with battery health helps eliminate cycle count deviations caused by inconsistent SOC ranges or temperature fluctuations. Furthermore, the battery capacity change rate of the previous testing cycle can be calculated based on the battery degradation change rate and the number of cycles in the previous testing cycle. It can be understood that the battery capacity change rate is the average capacity degradation per cycle, obtained by dividing the degradation change rate by the number of cycles. This normalization process makes the degradation trends comparable under different driving habits or driving environments, helping to construct a stable and traceable degradation slope sequence.

[0031] Optionally, the step of determining the battery degradation rate in the previous detection cycle based on the discharge current, battery capacity, battery capacity parameters from historical detection cycles, and battery capacity parameters from the previous detection cycle includes: acquiring battery state of charge (SOC) change data from the start of discharge to the previous detection cycle to obtain first battery SOC change data; acquiring battery SOC change data from the end of discharge to the previous detection cycle to obtain second battery SOC change data; calculating the difference between the first and second battery SOC change data to obtain a first battery SOC difference; acquiring battery SOC change data from the start of discharge to historical detection cycles to obtain third battery SOC change data; acquiring battery SOC change data from the end of discharge to historical detection cycles to obtain fourth battery SOC change data; calculating the difference between the third and fourth battery SOC change data to obtain a second battery SOC difference; and calculating the battery degradation rate in the previous detection cycle based on the first battery SOC difference, the second battery SOC difference, the battery capacity, and the discharge current.

[0032] When acquiring the battery state of charge (SOC) change data from the end of discharge to the end of the previous detection cycle to obtain the second battery SOC change data, it can be understood that this data reflects the SOC change from the current discharge termination point to the end of the previous detection cycle. It is used to define the effective coverage range of the previous detection cycle in the current discharge process and avoid capacity calculation offset caused by the non-coincidence of the detection cycle boundary and the discharge boundary.

[0033] Then the difference in the state of charge of the first battery can be calculated. It should be noted that this difference represents the actual discharge range participated in during the previous detection cycle, which helps to eliminate the interference of incomplete discharge range on capacity decay assessment.

[0034] Furthermore, battery state-of-charge (SOC) change data is acquired from the start of discharge to the end of the historical detection cycle to obtain the third battery SOC change data; battery SOC change data is acquired from the end of discharge to the end of the historical detection cycle to obtain the fourth battery SOC change data. It can be understood that the third battery SOC change data describes the change in SOC from the current discharge start point to the end of the historical detection cycle, used to construct a historical capacity reference benchmark corresponding to the previous cycle, providing time-aligned input for calculating the difference in the rate of decay. The fourth battery SOC change data is used to define the coverage of the historical detection cycle in the current discharge process, ensuring structural consistency between the capacity calculation boundaries of the historical cycle and the current cycle, which helps improve the temporal consistency of the rate of decay calculation.

[0035] Furthermore, the difference between the state of charge change data of the third battery and the state of charge change data of the fourth battery is calculated to obtain the state of charge difference of the second battery. It can be understood that this difference reflects the range of charge change that participated in the discharge within the historical detection cycle, and together with the state of charge difference of the first battery, it constitutes the basis of capacity change in two adjacent detection cycles.

[0036] Optionally, the step of determining the number of cycles in the previous detection cycle based on battery capacity, available battery range parameters, battery state of charge data from the previous detection cycle, battery state of charge data at the start of discharge, battery state of charge data at the end of discharge, and vehicle mileage from the previous detection cycle includes: calculating a first charge decay parameter in the previous detection cycle based on a first battery state of charge difference, battery capacity, and discharge current; calculating a second charge decay parameter in the previous detection cycle based on a second battery state of charge difference, battery capacity, and discharge current; and calculating the number of cycles in the previous detection cycle based on the first and second charge decay parameters, combined with the available battery range parameters and vehicle mileage from the previous detection cycle.

[0037] It should be noted that the first charge decay parameter is obtained by multiplying the difference in state of charge (SOC) of the first battery by the battery capacity. It is used to characterize the theoretical discharge capacity corresponding to the SOC change in the previous detection cycle. The discharge current can be used to verify the rationality of this capacity integration, which helps to build a capacity assessment basis consistent with actual energy consumption. Furthermore, the second charge decay parameter reflects the discharge energy contribution corresponding to the historical detection cycles. Its calculation method is consistent with the first charge decay parameter. Together, they constitute a reference for capacity changes in adjacent cycles, which helps to eliminate single-point estimation deviations caused by the misalignment of the detection cycle and the discharge boundary.

[0038] Furthermore, the number of cycles within the previous detection period can be calculated. It should be noted that the number of cycles is obtained by dividing the mileage by the average available range, which is estimated from the average SOH value reflected by the first and second charge decay parameters. This method dynamically couples the vehicle's actual driving behavior with the battery capacity decay state, facilitating continuous and adaptive estimation of the equivalent cycle count in scenarios without complete charge-discharge cycle markers. Furthermore, this cycle count calculation method avoids reliance on assumptions of a fixed SOC range or fixed depth of discharge, allowing the cycle count to automatically adjust with battery aging, temperature changes, and user driving modes, thus improving the accuracy and adaptability of subsequent capacity change rate normalization calculations.

[0039] Optionally, the step of determining the battery capacity change value based on the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle includes: acquiring charging current, charging time, battery state of charge data at the start of charging, and battery state of charge data at the end of charging, while the detected battery state is in a charging state; determining the battery degradation change rate of the previous detection cycle based on the charging current, battery capacity, battery capacity parameters from historical detection cycles, and battery capacity parameters from the previous detection cycle; and determining the battery degradation change rate of the previous detection cycle based on the battery capacity, battery available range parameters, and battery state of charge of the previous detection cycle. The battery state-of-charge (SOC) data at the start of charging, the battery SOC data at the end of charging, and the vehicle mileage of the previous testing cycle are used to determine the number of cycles in the previous testing cycle. Based on the battery degradation rate and the number of cycles in the previous testing cycle, the battery capacity change rate of the previous testing cycle is calculated. Based on the battery degradation rate and the number of cycles in the current testing cycle, the battery capacity change rate of the current testing cycle is calculated. The ratio between the battery capacity change rate of the current testing cycle and the battery capacity change rate of the previous testing cycle is calculated to obtain the battery capacity change value.

[0040] It should be noted that the charging current and charging time are used to calculate the input capacity through integration. The battery state-of-charge (SOC) data at the start and end of charging are used to determine the charge change range during this charging process. This set of data can be collected in real time by the BMS without the need for additional sensors, which helps maintain the continuity and consistency of capacity estimation under charging conditions. Furthermore, the battery degradation rate is obtained by the difference in capacity parameters between two adjacent detection cycles. The capacity parameters are inferred from the input capacity and SOC change during charging, making capacity estimation independent of the discharge process. In addition, in this invention, the capacity change rate is obtained by dividing the degradation rate by the number of cycles. This normalization process makes the degradation performance comparable under different charging intensities, charging durations, or charging frequencies, which helps to construct a stable degradation slope sequence suitable for charging-dominated scenarios.

[0041] Furthermore, in this invention, the battery capacity change rate of the current detection cycle can be calculated based on the battery degradation change rate of the current detection cycle and the number of cycles within the current detection cycle. It should be noted that the calculation logic of the capacity change rate of the current detection cycle is completely symmetrical with that of the previous detection cycle. Its degradation change rate is also obtained by the difference between the current and historical capacity parameters. The number of cycles is calculated based on the same driving and SOH correlation model, ensuring seamless connection of the algorithm when switching between charging and discharging states.

[0042] Optionally, the step of determining the battery degradation rate of the previous detection cycle based on the charging current, battery capacity, battery capacity parameters from historical detection cycles, and battery capacity parameters from the previous detection cycle includes: acquiring battery state of charge (SOC) change data from the start of charging to the previous detection cycle to obtain fifth SOC change data; acquiring battery SOC change data from the end of charging to the previous detection cycle to obtain sixth SOC change data; calculating the difference between the fifth and sixth SOC change data to obtain a third SOC difference; acquiring battery SOC change data from the start of charging to historical detection cycles to obtain seventh SOC change data; acquiring battery SOC change data from the end of charging to historical detection cycles to obtain eighth SOC change data; calculating the difference between the seventh and eighth SOC change data to obtain a fourth SOC difference; and calculating the battery degradation rate of the previous detection cycle based on the third SOC difference, the fourth SOC difference, the battery capacity, and the charging current.

[0043] It should be noted that the fifth battery state-of-charge (SOC) change data reflects the cumulative change in SOC from the current charging start time to the end time of the previous detection cycle. This helps establish a temporal correlation between the charging process and the detection cycle boundary, aligning capacity estimation with actual charging behavior on the time axis. Furthermore, the sixth battery SOC change data characterizes the SOC change range extending from the current charging end time to the end time of the previous detection cycle. This is used to define the charge range covered by the previous detection cycle during the current charging process, helping to avoid capacity estimation errors caused by misalignment between the detection cycle boundary and the charging boundary.

[0044] Then, the difference between the state of charge change data of the fifth battery and the state of charge change data of the sixth battery is calculated to obtain the state of charge difference of the third battery. It should be noted that the state of charge difference of the third battery describes the actual SOC change during the previous detection cycle. As the core input for capacity calculation, it helps to eliminate the interference of non-effective charging intervals on the degradation assessment and improve the local accuracy of capacity change estimation.

[0045] Additionally, it's understandable that the seventh battery state-of-charge (SOC) change data describes the total SOC change from the current charging start point to the end of the historical testing cycle, providing a time-aligned reference for constructing the capacity benchmark for the historical cycle. The eighth battery SOC change data is used to determine the coverage area of ​​the historical testing cycle during the current charging process. Its structure is symmetrical with the sixth battery SOC change data, helping to ensure that the capacity assessment of the historical and current cycles has consistent boundary definitions in the time dimension.

[0046] Step S102: When the battery capacity change value indicates an abnormal battery status, calculate the battery degradation slope for the current detection cycle.

[0047] It should be noted that when the ratio of the battery capacity change rate reaches or exceeds a preset threshold (e.g., 1.1 or 1.2), it indicates that the capacity decay rate per unit cycle has accelerated significantly. At this time, the calculation of the decay slope is initiated. This slope is obtained by dividing the difference between the capacity change rate of the current cycle and the previous cycle by the corresponding cycle increment, which helps to quantify the instantaneous trend of accelerated decay.

[0048] Step S103: If the battery degradation slope in the current detection cycle indicates that the battery degradation is abnormal, output a battery drop warning signal according to the degradation duration cycle.

[0049] Optionally, the step of outputting a battery drop warning signal based on the degradation duration period when the battery degradation slope in the current detection cycle indicates an abnormality in battery degradation includes: if the battery is in a discharge state, and the battery degradation slope in the current detection cycle is less than or equal to a preset degradation rate threshold, recording the degradation duration period; determining whether the battery degradation slope in the current detection cycle belongs to a predetermined degradation stability range; if the battery degradation slope in the current detection cycle belongs to the predetermined degradation stability range and the degradation duration period is greater than a first degradation cycle threshold, outputting a current limiting signal, wherein the current limiting signal is used to reduce the battery current, and the value range of the first degradation cycle threshold is 2-5 times; if the battery degradation slope in the current detection cycle exceeds the predetermined degradation stability range and the degradation duration period is greater than a second degradation cycle threshold, outputting a battery drop warning signal, wherein the value range of the second degradation cycle threshold is 3-7 times.

[0050] If the battery degradation slope in the current detection period indicates an abnormality in battery degradation, a battery plunge warning signal is output based on the degradation duration period. For example, a negative change in the degradation slope (i.e., the slope is consistently less than zero) reflects an accelerating degradation rate. If the battery degradation slope in the current detection period falls within a predetermined stable degradation range (this predetermined stable degradation range can be set by the user, for example, defined as [S1, S2], where S1 and S2 can be customized, for example, S1 is defined as -0.0001 and S2 as 0), and the degradation duration period is greater than a first degradation period threshold (this first degradation period threshold can be defined as Tac1, and the specific value of Tac1 can be set by the user, for example, set to 3 times), a current limiting signal is output. If the battery degradation slope in the current detection period exceeds the predetermined stable degradation range (e.g., less than S1), and the degradation duration period is greater than a second degradation period threshold (this first degradation period threshold can be defined as Tac2, and the specific value of Tac2 can be set by the user, for example, set to 5 times), a battery plunge warning signal is output. This mechanism filters out instantaneous fluctuations through trend persistence, helping to form a stable warning basis before a real plunge event occurs.

[0051] It should be noted that when the battery degradation slope in the current detection cycle is less than or equal to the preset degradation rate threshold, the degradation slope may be negative, indicating that the capacity degradation rate is accelerating. Continuously recording the number of detection cycles below the threshold helps to build a cumulative observation window for the degradation trend and avoids misjudgments triggered by single-point abnormal fluctuations. When the battery degradation slope in the current detection cycle falls within the predetermined stable degradation range and the degradation duration is greater than the first degradation cycle threshold, a current limiting signal is output. It should be noted that when the slope is in the medium acceleration range and continuously exceeds the specified cycle threshold, a current limiting command is output, which can reduce the discharge current, for example, limiting the discharge current to 90% of its original value. By reducing the electrochemical reaction rate, the side reaction process is slowed down, which helps to delay the evolution of accelerated aging mechanisms such as lithium dendrite growth or interface film thickening.

[0052] Optionally, the step of outputting a battery drop warning signal based on the degradation duration period when the battery degradation slope in the current detection cycle indicates an abnormality in battery degradation includes: if the battery is in a charging state, and the battery degradation slope in the current detection cycle is greater than or equal to a preset degradation rate threshold, recording the degradation duration period; determining whether the battery degradation slope in the current detection cycle belongs to a predetermined degradation stability range; if the battery degradation slope in the current detection cycle belongs to the predetermined degradation stability range and the degradation duration period is greater than a third degradation cycle threshold, outputting a current limiting signal, wherein the current limiting signal is used to reduce the battery current, and the value range of the third degradation cycle threshold is 2-5 times; if the battery degradation slope in the current detection cycle exceeds the predetermined degradation stability range and the degradation duration period is greater than a fourth degradation cycle threshold, outputting a battery drop warning signal, wherein the value range of the fourth degradation cycle threshold is 3-7 times.

[0053] It should be noted that the positive value of the battery degradation slope in the charging state reflects the accelerated trend of capacity loss per unit cycle. This battery degradation slope is calculated by the difference of the capacity change rate in the charging cycle. Recording the number of detection cycles that are continuously higher than the threshold helps to capture the implicit aging acceleration caused by lithium deposition, increased interface side reactions, etc., even under conditions without discharge behavior.

[0054] Furthermore, it is determined whether the battery degradation slope of the current detection cycle belongs to the predetermined degradation stability range. It can be understood that the predetermined degradation stability range can be defined as the slope range of [S1, S2]. By dividing the range, the degradation process can be classified and identified in a hierarchical manner, which helps to initiate gentle intervention in the early stage and avoid frequent false alarms or insufficient response caused by a single threshold trigger.

[0055] For example, during the charging process, if the battery degradation slope in the current detection cycle indicates an abnormality in battery degradation, a battery drop warning signal is output based on the degradation duration. For example, a negative change in the degradation slope (i.e., the slope is consistently less than zero) reflects an accelerating degradation rate. If the battery degradation slope in the current detection cycle falls within a predetermined stable degradation range (this predetermined stable degradation range can be set by the user, for example, defined as [S1, S2], where S1 and S2 can be customized, for example, S1 is defined as -0.0001 and S2 as 0), and the degradation duration is greater than the third degradation cycle threshold (this third degradation cycle threshold can be defined as Tac3, and the specific value of Tac3 can be set by the user, for example, set to 3 times), a current limiting signal is output. If the battery degradation slope in the current detection cycle exceeds the predetermined stable degradation range (for example, less than S1), and the degradation duration is greater than the fourth degradation cycle threshold (this fourth degradation cycle threshold can be defined as Tac4, and the specific value of Tac4 can be set by the user, for example, set to 5 times), a battery drop warning signal is output.

[0056] It should be noted that when the slope remains in the medium acceleration range for an extended period and exceeds the third threshold Tac3 (i.e., the battery degradation slope in the current detection cycle is within the predetermined degradation stability range, and the degradation duration is greater than the third degradation cycle threshold, an output current limiting signal is generated), an output current limiting command is issued to reduce the charging current, for example, by lowering the charging current to 90% of its original value. This operation slows down electrolyte decomposition and byproduct accumulation by reducing the reaction kinetic rate, which helps to delay factors such as lithium metal deposition under high SOC.

[0057] By applying the technical solution of this invention, the degradation slope trend can be derived by calculating the capacity change rate of the battery during the charge-discharge cycle. A degradation trend assessment can be completed after a single charge-discharge cycle, without waiting for a complete cycle or long-term data accumulation. This significantly shortens the battery capacity drop prediction cycle. Without requiring additional hardware, relying on massive historical data, or increasing computational load, the battery capacity degradation slope and its rate of change are calculated in real time using existing BMS signals. This allows for early identification of accelerated degradation trends and the issuance of warning signals. When the capacity change rate ratio exceeds a threshold, the battery degradation slope is calculated instead of immediately triggering an alarm. This focuses on abnormal states with persistent trends, reflecting the true capacity degradation rate, reducing monitoring blind spots caused by vehicles not being driven for extended periods while charging. It effectively supports charging strategy optimization and current limiting intervention, significantly reduces the risk of thermal runaway, extends battery life, and improves vehicle operational safety and user trust. This solves the technical problem of long time consumption in battery capacity drop prediction methods in related technologies.

[0058] The present invention will now be described with reference to a specific embodiment.

[0059] This invention proposes an online prediction method for battery capacity drop. By detecting and calculating the slope of SOH change and the direction of slope change during charging and discharging cycles, the future trend of battery capacity change can be identified, and battery capacity drop can be predicted. Figure 2 This is a flowchart of an optional online prediction and calculation method for the capacity drop of automotive batteries according to an embodiment of the present invention, such as... Figure 2 As shown, it includes:

[0060] Step 1: Record basic data: available range R (corresponding to the battery available range parameters mentioned above), available depth of discharge range DOD_ava, battery capacity Q0, and initial SOH value (i.e., initial battery capacity value).

[0061] Step 2: Determine the current state. If it is discharging, record the discharge current I, discharge time t, vehicle mileage W, SOC1 at the start of discharge, SOC2 at the end of discharge, and SOH value at the end of the detection period T. The initial SOH value for the first detection cycle T is 1.

[0062] Step 3: Record the battery capacity parameters from the previous testing cycle. :

[0063]

[0064] Step 4: Record the SOH decay rate (i.e., the battery decay rate change rate in the previous detection cycle) during the previous detection cycle:

[0065]

[0066] Step 5: Detect the number of cycles within period T-1. The following formula can be used to calculate (corresponding to the calculation of the number of cycles in the previous detection period):

[0067]

[0068] Step 6, Number of loops The following formula can be used for calculation:

[0069]

[0070] Step 7, SOH change rate in the previous detection period T-1 The following formula can be used to calculate (corresponding to the calculation of the battery capacity change rate in the previous detection cycle):

[0071]

[0072] Step 8: Calculate the current detection cycle. :

[0073]

[0074] Step 9: Calculate the decay of SOH in the current detection cycle:

[0075]

[0076] Step 10: Detect the number of cycles within the current detection period T. The following formula can be used for calculation:

[0077]

[0078] Figure 3 This is a graph showing the relationship between an optional cycle number (Cycle) and the available battery life (RSOH) according to an embodiment of the present invention, such as... Figure 3 As shown, this illustrates the process of battery capacity degradation.

[0079] Step 11, Number of cycles The following formula can be used for calculation:

[0080]

[0081] Step 12: Detect the rate of change of SOH, Kd, ​​during the current detection period T. This can be calculated using the following formula:

[0082]

[0083] Step thirteen, if This is a normal phenomenon.

[0084] like It is necessary to calculate and determine the rate of change of the decay slope. .

[0085] The rate of change of the attenuation slope is as follows: .

[0086] like This indicates that the decay rate is slowing down, which is normal. This indicates that the decay rate is accelerating, and getting faster and faster. At this point, if... (corresponding to the predetermined attenuation stability range mentioned above), and the duration is greater than Tac1 (corresponding to the first attenuation period threshold mentioned above (set to 2-5 times), such as 3 times), then the current needs to be limited to 0.9 of the original value. If the battery degradation slope of the current detection cycle exceeds the predetermined degradation stability range, and the duration is greater than Tac2 (corresponding to the second degradation cycle threshold mentioned above (set to 3-7 times), such as 5 times), then a battery drop warning will be issued.

[0087] Optionally, S1 can be -0.0001 and S2 can be 0.

[0088] Step fourteen: If it is charging, record the charging current I, the charging time t, the SOC1 at the start of charging, and the SOC2 at the end of charging.

[0089] Step 15: Record the data from the previous testing cycle. :

[0090]

[0091] Step 16: Record the data from the previous testing cycle. Attenuation:

[0092]

[0093] Step 17: Record the number of cycles in the previous testing period. The following formula can be used for calculation:

[0094]

[0095] Step 18, Number of cycles The following formula can be used for calculation:

[0096]

[0097] Step 19: Record the rate of change of SOH in the previous detection cycle. The following formula can be used for calculation:

[0098]

[0099] Step 20: Calculate the current... :

[0100]

[0101] Step 21, calculate the current SOH decay:

[0102]

[0103] Step 22: Detect the number of cycles within period T. The following formula can be used for calculation:

[0104]

[0105] Step 23, Number of loops The following formula can be used for calculation:

[0106]

[0107] Step 24, the rate of change of SOH Kc during the detection period T can be calculated using the following formula:

[0108]

[0109] Step 25, if This is a normal phenomenon.

[0110] like Then it is necessary to calculate and determine the rate of change of the decay slope. .

[0111] in, .

[0112] like This indicates that the decay rate is slowing down, which is normal. This indicates that the decay rate is accelerating, and getting faster and faster. At this point, if... If the duration is greater than Tac3 (corresponding to the third decay period threshold mentioned above (the value range is set to 2-5 times), for example, set to 3 times), then the current needs to be limited to 0.9 of the original value. If the battery degradation slope in the current detection cycle exceeds the predetermined degradation stability range, and the duration is greater than Tac4 (corresponding to the fourth degradation cycle threshold mentioned above (the value range is set to 3-7 times), for example, set to 5 times), then a battery drop warning will be issued.

[0113] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: by independently calculating the battery capacity change rate per unit cycle in the charging and discharging cycles, and dynamically evaluating based on the ratio and slope trend of the change rate in adjacent cycles, early, online, and low-latency prediction of battery capacity drop is achieved. It does not require large-scale historical data training, solving complex electrochemical models, or dedicated impedance measurement hardware. It only uses conventional current, SOC, mileage, and time data that can be obtained by the BMS to complete the real-time analysis of the degradation trend, significantly reducing the consumption of computing resources.

[0114] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: By introducing a continuous monitoring mechanism for the attenuation slope, combined with graded interval judgment and incremental period threshold, misjudgments caused by current fluctuations, SOC sampling errors, or short-term operating condition changes are effectively filtered out. This ensures that the warning signal is triggered only when the attenuation trend stabilizes and accelerates for a continuous period exceeding the set time window, thus improving the stability and reliability of the prediction results. It can continuously monitor the capacity degradation trend in both discharging and charging modes, avoiding the monitoring failure problem of traditional methods under charging conditions and expanding the effective monitoring window.

[0115] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: The early warning mechanism adopts a stepped response strategy. When the attenuation slope is in the medium acceleration range and the duration is relatively long, the current limiting operation is automatically triggered to slow down the electrochemical side reaction process. When the slope enters the violent acceleration range and continues to exceed a higher threshold, the low-pressure warning is output. This not only achieves a smooth transition from prevention to alarm, but also provides an operable intervention opportunity for the vehicle control strategy, which helps to delay battery performance failure and improve system safety and service life.

[0116] The invention will now be described in conjunction with another alternative embodiment.

[0117] Figure 4 This is a schematic diagram of an optional battery capacity reduction warning device according to an embodiment of the present invention, as shown below. Figure 4As shown, the battery capacity drop warning device includes: a battery capacity detection unit 41, a battery attenuation calculation unit 42, and a battery drop warning unit 43.

[0118] The battery capacity detection unit 41 is used to determine the battery capacity change value based on the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle. The battery capacity change rate is calculated using the battery degradation parameter and the number of battery cycles within the detection cycle.

[0119] The battery degradation calculation unit 42 is used to calculate the battery degradation slope of the current detection cycle when the battery capacity change value indicates that the battery status is abnormal.

[0120] The battery drop warning unit 43 is used to output a battery drop warning signal according to the duration of the degradation when the battery degradation slope in the current detection cycle indicates that there is an abnormality in battery degradation.

[0121] Optionally, the battery capacity detection unit includes: a first battery capacity change rate calculation module, used to calculate the battery capacity change rate of the previous detection cycle based on the battery degradation change rate of the previous detection cycle and the number of cycles in the previous detection cycle if the battery is in a discharge state; a second battery capacity change rate calculation module, used to calculate the battery capacity change rate of the current detection cycle based on the battery degradation change rate of the current detection cycle and the number of cycles in the current detection cycle; and a battery capacity calculation module, used to calculate the ratio between the battery capacity change rate of the current detection cycle and the battery capacity change rate of the previous detection cycle to obtain the battery capacity change value.

[0122] Optionally, the first battery capacity change rate calculation module includes: a battery parameter acquisition submodule, used to acquire battery available range parameters and battery capacity; a battery charge data acquisition submodule, used to acquire discharge current and vehicle mileage, battery charge data at the start of discharge, and battery charge data at the end of discharge if the battery is in a discharge state; a battery capacity acquisition submodule, used to acquire battery charge data from the previous detection cycle, and calculate battery capacity parameters for the previous detection cycle based on the battery charge data and battery capacity from the previous detection cycle; and a first battery degradation change rate determination submodule, used to determine the battery capacity based on discharge current, battery capacity, and battery capacity from historical detection cycles. The system uses parameters and battery capacity parameters from the previous testing cycle to determine the battery degradation rate of the previous testing cycle. Historical testing cycles refer to cycles prior to the previous testing cycle. A first cycle count determination submodule determines the number of cycles within the previous testing cycle based on battery capacity, available battery range parameters, battery state-of-charge (SOC) data from the previous testing cycle, SOC data at the start of discharge, SOC data at the end of discharge, and vehicle mileage from the previous testing cycle. A first battery capacity change rate calculation submodule calculates the battery capacity change rate of the previous testing cycle based on the battery degradation rate and the number of cycles within the previous testing cycle.

[0123] Optionally, the first battery degradation rate determination submodule includes: a first battery state of charge (SOC) change data acquisition submodule, used to acquire battery SOC change data from the start of discharge to the previous detection cycle, to obtain first battery SOC change data; a second battery SOC change data acquisition submodule, used to acquire battery SOC change data from the end of discharge to the previous detection cycle, to obtain second battery SOC change data; a first SOC difference calculation submodule, used to calculate the difference between the first battery SOC change data and the second battery SOC change data, to obtain the first battery SOC difference; and a third battery SOC change data acquisition submodule, used to acquire data from the end of discharge to the previous detection cycle, to obtain the battery SOC change data from the start of discharge to the previous detection cycle, to obtain second battery SOC change data; a first SOC difference calculation submodule, used to calculate the difference between the first battery SOC change data and the second battery SOC change data, to obtain the first battery SOC difference; and a third battery SOC change data acquisition submodule, used to acquire data from the start of discharge to the previous detection cycle, to obtain the battery SOC change data from the start of discharge to the previous detection cycle, to obtain second battery SOC change data; a first battery SOC difference calculation submodule, used to calculate the difference between the first battery SOC change data and the second battery SOC change data, to obtain first battery SOC difference; and a third battery SOC change data acquisition submodule, used to acquire data from the start of discharge to the previous detection cycle, to obtain second battery SOC change ... The battery state-of-charge (SOC) change data from the start of discharge to the historical detection cycle is used to obtain the third battery SOC change data; the fourth battery SOC change data acquisition submodule is used to acquire the battery SOC change data from the end of discharge to the historical detection cycle to obtain the fourth battery SOC change data; the second SOC difference calculation submodule is used to calculate the difference between the third battery SOC change data and the fourth battery SOC change data to obtain the second battery SOC difference value; the battery degradation rate calculation submodule is used to calculate the battery degradation rate of the previous detection cycle based on the first battery SOC difference value, the second battery SOC difference value, the battery capacity, and the discharge current.

[0124] Optionally, the first cycle count determination submodule includes: a first charge decay parameter calculation submodule, used to calculate the first charge decay parameter in the previous detection cycle based on the first battery state of charge difference, battery capacity, and discharge current; a second charge decay parameter calculation submodule, used to calculate the second charge decay parameter in the previous detection cycle based on the second battery state of charge difference, battery capacity, and discharge current; and a first cycle count calculation submodule, used to calculate the cycle count in the previous detection cycle based on the first and second charge decay parameters in the previous detection cycle, combined with the battery available range parameter and the vehicle mileage in the previous detection cycle.

[0125] Optionally, the battery drop warning unit includes: a first attenuation duration recording module, used to record the attenuation duration if the battery is in a discharge state and the battery attenuation slope in the current detection period is less than or equal to a preset attenuation rate threshold; a first judgment module, used to judge whether the battery attenuation slope in the current detection period belongs to a predetermined attenuation stability range; a first current limiting signal output module, used to output a current limiting signal when the battery attenuation slope in the current detection period belongs to the predetermined attenuation stability range and the attenuation duration is greater than the first attenuation period threshold, wherein the current limiting signal is used to reduce the battery current, and the value range of the first attenuation period threshold is 2-5 times; and a first battery drop warning signal output module, used to output a battery drop warning signal when the battery attenuation slope in the current detection period exceeds the predetermined attenuation stability range and the attenuation duration is greater than the second attenuation period threshold, wherein the value range of the second attenuation period threshold is 3-7 times.

[0126] Optionally, the battery capacity detection unit includes: a battery state-of-charge (SOC) data acquisition module, used to acquire charging current, charging time, and battery SOC data at the start of charging and at the end of charging when the detected battery state is in a charging state; a battery degradation rate determination module, used to determine the battery degradation rate in the previous detection cycle based on charging current, battery capacity, battery capacity parameters from historical detection cycles, and battery capacity parameters from the previous detection cycle; and a cycle count determination module, used to determine the cycle count based on battery capacity, battery available range parameters, battery SOC data from the previous detection cycle, battery SOC data at the start of charging, and battery SOC data at the end of charging. The battery state-of-charge data and the vehicle mileage of the previous testing cycle are used to determine the number of cycles in the previous testing cycle; the first battery capacity change rate calculation module is used to calculate the battery capacity change rate of the previous testing cycle based on the battery degradation change rate and the number of cycles in the previous testing cycle; the first battery capacity change rate calculation module is used to calculate the battery capacity change rate of the current testing cycle based on the battery degradation change rate and the number of cycles in the current testing cycle; the battery capacity change value calculation module is used to calculate the ratio between the battery capacity change rate of the current testing cycle and the battery capacity change rate of the previous testing cycle to obtain the battery capacity change value.

[0127] Optionally, the battery degradation rate determination module includes: a fifth battery state of charge (SOC) change data acquisition submodule, used to acquire battery SOC change data from the start of charging to the previous detection cycle, to obtain fifth battery SOC change data; a sixth battery SOC change data acquisition submodule, used to acquire battery SOC change data from the end of charging to the previous detection cycle, to obtain sixth battery SOC change data; a third battery SOC difference calculation submodule, used to calculate the difference between the fifth battery SOC change data and the sixth battery SOC change data, to obtain third battery SOC difference; and a seventh battery SOC change data acquisition submodule, used to acquire data from the end of charging to the previous detection cycle, to obtain battery SOC change data. The system acquires battery state of charge (SOC) change data from the start of charging to the historical detection cycle, resulting in the seventh battery SOC change data; the eighth battery SOC change data acquisition submodule acquires battery SOC change data from the end of charging to the historical detection cycle, resulting in the eighth battery SOC change data; the fourth battery SOC difference calculation submodule calculates the difference between the seventh and eighth battery SOC change data, resulting in the fourth battery SOC difference value; and the battery degradation rate calculation submodule calculates the battery degradation rate of the previous detection cycle based on the third battery SOC difference value, the fourth battery SOC difference value, the battery capacity, and the charging current.

[0128] Optionally, the battery degradation warning unit further includes: a second degradation duration module, used to record the degradation duration if the battery is in a charging state and the battery degradation slope in the current detection period is greater than or equal to a preset degradation rate threshold; a second judgment module, used to determine whether the battery degradation slope in the current detection period belongs to a predetermined degradation stability range; a second current limiting signal output module, used to output a current limiting signal when the battery degradation slope in the current detection period belongs to the predetermined degradation stability range and the degradation duration is greater than a third degradation cycle threshold, wherein the current limiting signal is used to reduce the battery current, and the value range of the first degradation cycle threshold is 2-5 times; and a second battery degradation warning signal output module, used to output a battery degradation warning signal when the battery degradation slope in the current detection period exceeds the predetermined degradation stability range and the degradation duration is greater than a fourth degradation cycle threshold, wherein the value range of the second degradation cycle threshold is 3-7 times.

[0129] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0130] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0131] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for early warning of sudden drop in battery capacity, characterized in that, include: The battery capacity change value is determined based on the ratio between the battery capacity change rate in the current testing cycle and the battery capacity change rate in the previous testing cycle. The battery capacity change rate is calculated using the battery degradation parameter and the number of battery cycles within the testing cycle. When the battery capacity change value indicates an abnormal battery state, calculate the battery degradation slope for the current detection cycle; If the battery degradation slope in the current detection cycle indicates an abnormality in battery degradation, a battery depletion warning signal is output based on the degradation duration cycle.

2. The early warning method for battery capacity drop according to claim 1, characterized in that, The steps for determining the battery capacity change value based on the ratio between the battery capacity change rate in the current testing cycle and the battery capacity change rate in the previous testing cycle include: If the battery is in a discharging state, the battery capacity change rate of the previous detection cycle is calculated based on the battery degradation change rate and the number of cycles in the previous detection cycle. The battery capacity change rate for the current testing period is calculated based on the battery degradation rate and the number of cycles within the current testing period. The battery capacity change value is obtained by calculating the ratio between the battery capacity change rate in the current detection cycle and the battery capacity change rate in the previous detection cycle.

3. The early warning method for battery capacity drop according to claim 2, characterized in that, The steps for calculating the battery capacity change rate in the previous testing cycle, based on the battery degradation rate and the number of cycles in the previous testing cycle, include: Get battery available range parameters and battery capacity; If the battery is in a discharging state, acquire the discharge current and vehicle mileage, as well as the battery state of charge data at the start of discharge and at the end of discharge. Obtain the battery state of charge data from the previous detection cycle, and calculate the battery capacity parameters for the previous detection cycle based on the battery state of charge data from the previous detection cycle and the battery capacity. Based on the discharge current, the battery capacity, the battery capacity parameters of the historical detection cycle and the battery capacity parameters of the previous detection cycle, the battery degradation rate of the previous detection cycle is determined, wherein the historical detection cycle is the historical cycle prior to the previous detection cycle. Based on the battery capacity, battery available range parameters, battery state of charge data from the previous detection cycle, battery state of charge data at the start of discharge, battery state of charge data at the end of discharge, and vehicle mileage from the previous detection cycle, the number of cycles in the previous detection cycle is determined. The battery capacity change rate of the previous detection cycle is calculated based on the battery degradation change rate of the previous detection cycle and the number of cycles in the previous detection cycle.

4. The early warning method for battery capacity drop according to claim 3, characterized in that, The step of determining the battery degradation rate in the previous detection cycle based on the discharge current, the battery capacity, the battery capacity parameters of the historical detection cycle, and the battery capacity parameters of the previous detection cycle includes: Acquire battery state-of-charge change data from the start of discharge to the previous detection cycle to obtain the first battery state-of-charge change data; The battery state of charge change data from the end of discharge to the previous detection cycle is obtained to obtain the second battery state of charge change data. Calculate the difference between the first battery state of charge change data and the second battery state of charge change data to obtain the first battery state of charge difference; The battery state of charge change data from the start of discharge to the historical detection cycle is obtained to obtain the third battery state of charge change data. Obtain the battery state of charge change data from the end of discharge to the historical detection cycle to obtain the fourth battery state of charge change data; Calculate the difference between the state of charge change data of the third battery and the state of charge change data of the fourth battery to obtain the state of charge difference of the second battery. Based on the difference in state of charge of the first battery, the difference in state of charge of the second battery, the battery capacity, and the discharge current, the battery degradation rate of the previous detection cycle is calculated.

5. The early warning method for battery capacity drop according to claim 4, characterized in that, The step of determining the number of cycles in the previous testing cycle based on the battery capacity, available battery range parameters, battery state of charge data from the previous testing cycle, battery state of charge data at the start of discharge, battery state of charge data at the end of discharge, and vehicle mileage from the previous testing cycle includes: Based on the first battery state of charge difference, the battery capacity, and the discharge current, calculate the first charge decay parameter in the previous detection cycle; Based on the difference in the state of charge of the second battery, the battery capacity, and the discharge current, the second charge decay parameter in the previous detection cycle is calculated. Based on the first charge decay parameter and the second charge decay parameter in the previous testing cycle, combined with the battery's available range parameter and the vehicle's mileage in the previous testing cycle, the number of cycles in the previous testing cycle is calculated.

6. The early warning method for battery capacity drop according to claim 1, characterized in that, When the battery degradation slope in the current detection period indicates an abnormality in battery degradation, the step of outputting a battery drop warning signal based on the degradation duration period includes: If the battery is in a discharging state, and the battery degradation slope in the current detection cycle is less than or equal to a preset degradation rate threshold, the degradation duration cycle is recorded. Determine whether the battery degradation slope of the current detection cycle belongs to the predetermined degradation stability range; If the battery degradation slope in the current detection cycle falls within a predetermined degradation stability range, and the degradation duration is greater than a first degradation cycle threshold, a current limiting signal is output. The current limiting signal is used to reduce the battery current, and the first degradation cycle threshold ranges from 2 to 5 times. If the battery degradation slope in the current detection cycle exceeds the predetermined degradation stability range, and the degradation duration is greater than the second degradation cycle threshold, a battery drop warning signal is output, wherein the value of the second degradation cycle threshold is in the range of 3-7 times.

7. The early warning method for battery capacity drop according to claim 1, characterized in that, The steps for determining the battery capacity change value based on the ratio between the battery capacity change rate in the current testing cycle and the battery capacity change rate in the previous testing cycle include: When the battery is detected to be in a charging state, the charging current, charging time, battery state of charge data at the start of charging, and battery state of charge data at the end of charging are acquired. Based on the charging current, battery capacity, battery capacity parameters from historical testing cycles, and battery capacity parameters from the previous testing cycle, the battery degradation rate of the previous testing cycle is determined. Based on the battery capacity, battery available range parameters, battery state of charge data from the previous detection cycle, battery state of charge data at the start of charging, battery state of charge data at the end of charging, and vehicle mileage from the previous detection cycle, the number of cycles in the previous detection cycle is determined. Based on the battery degradation rate of the previous detection cycle and the number of cycles in the previous detection cycle, calculate the battery capacity change rate of the previous detection cycle. The battery capacity change rate for the current testing period is calculated based on the battery degradation rate and the number of cycles within the current testing period. The battery capacity change value is obtained by calculating the ratio between the battery capacity change rate in the current detection cycle and the battery capacity change rate in the previous detection cycle.

8. The early warning method for battery capacity drop according to claim 7, characterized in that, The step of determining the battery degradation rate in the previous detection cycle based on the charging current, the battery capacity, the battery capacity parameters of the historical detection cycle, and the battery capacity parameters of the previous detection cycle includes: Acquire the battery state of charge change data from the start of charging to the previous detection cycle to obtain the fifth battery state of charge change data; Obtain the battery state of charge change data from the end of charging to the previous detection cycle to obtain the sixth battery state of charge change data; The difference between the state of charge change data of the fifth battery and the state of charge change data of the sixth battery is calculated to obtain the state of charge difference of the third battery; Obtain battery state of charge change data from the start of charging to the historical detection cycle to obtain the seventh battery state of charge change data; Obtain the battery state of charge change data from the end of charging to the historical detection cycle to obtain the eighth battery state of charge change data; Calculate the difference between the state of charge change data of the seventh battery and the state of charge change data of the eighth battery to obtain the state of charge difference of the fourth battery; Based on the difference in state of charge of the third battery, the difference in state of charge of the fourth battery, the battery capacity, and the charging current, the battery degradation rate of the previous detection cycle is calculated.

9. The early warning method for battery capacity drop according to claim 1, characterized in that, When the battery degradation slope in the current detection period indicates an abnormality in battery degradation, the step of outputting a battery drop warning signal based on the degradation duration period includes: If the battery is in a charging state, and the battery degradation slope in the current detection cycle is greater than or equal to a preset degradation rate threshold, the degradation duration cycle is recorded. Determine whether the battery degradation slope of the current detection cycle belongs to the predetermined degradation stability range; If the battery degradation slope in the current detection cycle falls within a predetermined degradation stability range, and the degradation duration is greater than the third degradation cycle threshold, a current limiting signal is output. The current limiting signal is used to reduce the battery current, and the value of the third degradation cycle threshold ranges from 2 to 5 times. If the battery degradation slope in the current detection cycle exceeds the predetermined degradation stability range, and the degradation duration is greater than the fourth degradation cycle threshold, a battery drop warning signal is output, wherein the value of the fourth degradation cycle threshold is in the range of 3-7 times.

10. A warning device for rapidly decreasing battery capacity, characterized in that, include: A battery capacity detection unit is used to determine the battery capacity change value based on the ratio between the battery capacity change rate in the current detection cycle and the battery capacity change rate in the previous detection cycle, wherein the battery capacity change rate is calculated using battery degradation parameters and the number of battery cycles within the detection cycle. A battery degradation calculation unit is used to calculate the battery degradation slope of the current detection cycle when the battery capacity change value indicates that the battery state is abnormal. The battery degradation warning unit is used to output a battery degradation warning signal based on the degradation duration period when the battery degradation slope in the current detection period indicates that there is an abnormality in battery degradation.

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