DESC:SYSTEM AND METHOD TO DETERMINE HEALTH OF BATTERY PACK
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202321006470 filed on 01/02/2023, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure relates to a system to determine the health of battery pack. Furthermore, the present disclosure relates to a method to determine the health of battery pack.
BACKGROUND
Nowadays, the energy storage systems that includes battery packs, have become the main power source for various mobility applications including electric energy buffers, electric vehicles and electric ships due to the exhibition of characteristics including environmental protection, higher energy density and larger cycle life. The health and performance of the battery packs is decided by a key parameter i.e. State of Health (SoH). The SoH takes into account various factors including charge acceptance, internal resistance, voltage and self-discharge. The SoH is the percentage ratio of the present charge capacity of the battery pack to the charge capacity of fresh battery pack of same ratings and chemistry. The state of health (SOH) on comparison with the service time, reflects the service conditions of a battery pack. The magnitude of SoH determines the degradation/aging of the battery pack with time in terms of charge capacity. The state of health (SOH) is a crucial parameter in assessing the longevity and reliability of the battery packs. With the time, the charge capacity of the batter pack fades, whether in use or not, due to change in structure and composition of the batter pack material. The knowledge of SoH provides insights into the internal behavior of the battery pack and deciding for the process of optimization of battery pack in term of extending the cycle life and safe use. Thus, the SOH of the battery pack is developed as an area of interest for the research purposes.
In energy storage systems, the SoH influences the range and overall efficiency of the battery pack and thus the knowledge of SoH is essential for monitoring the health and performance of the battery packs. The determination of SOH ensures the reliable energy storage, efficient power delivery, and optimal performance over the life span of the energy storage system. In applications including an uninterruptible power supply (UPS), the knowledge of the state-of-health (SOH) of an operating battery pack is required to ensure reliable operation of the electrical system. Since, the demand for energy storage systems is growing, the accurate and efficient methods for assessing the health of battery packs have become crucial. In energy storage and electric power systems, the determination of State of Health (SOH) of battery packs is a key parameter to decide the performance, safety, and longevity.
Conventional method of determination of SoH of battery pack involves consideration of capacity loss by comparing the charge capacity of the fully charged battery pack during charge and discharge cycles, with the battery's initial rated charge capacity. Another method involves the measurement of change in open circuit voltage during charge and discharge cycles. However, the abovesaid methods involve the consideration of individual factors including current, voltage, cycles and fails to represent accurately the internal health of the battery. Moreover, the abovesaid methods are time consuming in providing the results of measurement of SoH.
Another method involves the measurement of count of the charging-discharging cycles of the battery pack. However, the method involves consideration of number of cycles only and fails to exactly determine the state of health. Moreover, the battery needs to put out of service during the measurement. Moreover, the charge cycles of the battery packs used in the high voltage energy storage systems are not complete and hence inaccurate. Thus, the state of health of the battery pack determined using the cycle count would not be accurate.
Thus, there exists a need for system and method to determine health of battery pack that overcomes one or more problems as set forth above.
SUMMARY
An object of the present disclosure is to provide a battery management system (BMS) to determine the health of battery pack used in high voltage energy storage system.
Another object of the present disclosure is to provide a method of determining state of health of at least one battery pack used in high voltage energy storage system.
In accordance with the first aspect of the present disclosure, there is provided a battery management system with integrated state of health determination of at least one battery pack. The battery management system comprises at least one current source, at least one voltage measurement circuit and a control unit. At least one current source is connected to the at least one battery pack. At least one voltage measurement circuit is connected to the at least one battery pack. The control unit is communicably coupled with the at least one current source and the at least one voltage measurement circuit. The control unit is configured to instruct the at least one current source to generate a periodic signal, receive a measured voltage of the periodic signal from the at least one voltage measurement circuit, determine impedance of the at least one battery pack based on the measured voltage of the periodic signal and determine the state of health of the at least one battery pack based on the determined impedance of the at least one battery pack.
The present disclosure provides a battery management system with integrated state of health determination of at least one battery pack. The system as disclosed in the present disclosure is advantageous in terms of providing for greater accuracy in determination of state of health. The disclosed system facilitates the early detection of abnormal conditions in battery pack including overheating or voltage irregularities by real time determination of the state of health in minimum time duration. The disclosed system provides the earliest detection of degradation of battery pack, by consuming a smaller duration of time during determination. The system as disclosed in the present disclosure efficiently utilizes the input energy to arrangement by determining the state of health at predetermined time intervals of operation of battery pack instead of continuous determination of sate of health. The disclosed system provides a simple process of determination of state of health by involving processing of predefined relations. The battery management system of the present disclosure is advantageous in terms of accurately determining state of health of the battery pack employed in the energy storage solution where the conventional method of counting charge cycles are not effective in determining the state of health of the battery pack.
In accordance with the second aspect of the present disclosure, there is provided a method of determining state of health of at least one battery pack. The method comprises generating a periodic signal, by at least one current source, measuring voltage of the periodic signal, by at least one voltage measurement circuit, determining impedance of the at least one battery pack based on the measured voltage of the periodic signal and determining the state of health of the at least one battery pack based on the determined impedance of the at least one battery pack.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates a block diagram of a battery management system with integrated state of health determination of at least one battery pack, in accordance with an aspect of the present disclosure.
FIG. 2 illustrates a flow chart of a method of determining state of health of at least one battery pack, in accordance with another aspect of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a system and method to determine health of battery pack and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings which are shown by way of illustration-specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “battery management system” refer to an electronic system for managing proper functioning of the plurality of battery cells in the battery pack. The battery management system monitors and regulates the charging and discharging of battery packs. The battery management system monitors the battery's voltage, current, temperature, and other parameters to ensure that it is operating within its safe operating area.
As used herein, the terms ‘battery pack’ refer to the component of the system that includes assembly of cells connected together in series or/and parallel. The battery pack is integrated within a common housing or enclosure and configured to function collectively as a bigger energy storage unit. The battery pack may include various types of cells including cylindrical cells, prismatic cells, pouch cells, coin cells or any customised shape cells. The cells includes electrodes and electrolyte and during charging and discharging of the battery packs, the ions and the charge propagation between the electrodes through the electrolyte and external circuit respectively, to carry out the transformation among the electrical and chemical energy. The battery pack further comprises electronic components such as battery management system.
As used herein, the terms ‘current source’ refers to a power source used in the system for generating a current signal of a particular frequency to pass through the terminals of a battery pack. The current signal is a periodic signal and includes alternating current signal. The periodic signal is independent of changes in resistance of battery pack or fluctuations in input voltage of current source. The periodic signal is characterized by amplitude, frequency and phase. The current source includes operational amplifier. The periodic signal induces ionic migration within the electrolyte of the battery pack. The ions move back and forth in the electrolyte in response to the changing direction of the periodic signal.
As used herein, the terms ‘voltage measurement circuit’ refers to the electronic circuit that is used in the system to measure the voltage of the periodic signal. The circuit measures the voltage of the periodic signal in response to the periodic signal. The circuit includes high-precision voltage dividers, differential amplifiers, or other sensing components. The voltage measurement circuit employs sensors or probes including dividers, to measure the voltage across the battery pack. The amplifier is used in the circuit to amplify the voltage to a suitable level to enable capturing of even small variations in voltage. The measured voltage that is an analog voltage is converted into a digital voltage to examine the amplitude and phase of the voltage.
As used herein, the terms ‘control unit’ refers to an electronic device that is provided in system to control the operations of the current source and the voltage measurement circuit. The control unit instructs the current source to pass through the periodic signal to the battery pack. The control unit controls the amplitude and phase of the periodic signal. The unit directs the current source to adjust to provide the periodic signal with desired amplitude and phase at predefined frequency to pass through the battery pack. The unit instruct the voltage measurement circuit the circuit to measure the voltage of the periodic signal at the output i.e. terminals of the battery pack. The measured voltage of the periodic signal is the response of the battery pack to the periodic signal. The unit instructs the circuit to transfer the measured voltage. The unit receives the measured voltage. The control unit includes one or more processors, microcontrollers, or programmable logic devices programmed or configured to execute control algorithms, logic, or instructions. The control unit further includes memory storage for storing control algorithms, software and data.
As used herein, the term “memory module” refers to a physical module in the battery management system to store a predefined relation between impedance and state of health of the battery pack. It is to be understood that the predefined relation includes the inverse relation or/and other mathematical relationship between impedance and state of health of the battery pack.
As used herein, the term ‘communicably coupled’ refers to a bi-directional connection between the various components of the system. The bi-directional connection between the control unit and the current source of the system enables the exchange of data between the control unit and the current source. Similarly, the bi-directional connection between the control unit and voltage measurement circuit enables the exchange of data between the control unit and voltage measurement circuit.
Figure 1, in accordance with an embodiment, describes a battery management system 100 with integrated state of health determination of at least one battery pack 102. The battery management system 100 comprises at least one current source 104, at least one voltage measurement circuit 106 and a control unit 108. At least one current source 104 is connected to the at least one battery pack 102. At least one voltage measurement circuit 106 is connected to the at least one battery pack 102. The control unit 108 is communicably coupled with the at least one current source 104 and the at least one voltage measurement circuit 106. The control unit 108 is configured to instruct the at least one current source 104 to generate a periodic signal, receive a measured voltage of the periodic signal from the at least one voltage measurement circuit 106, determine impedance of the at least one battery pack 102 based on the measured voltage of the periodic signal and determine the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102.
The present disclosure provides a battery management system 100 with integrated state of health determination of at least one battery pack 102. The system 100 as disclosed in the present disclosure is advantageous in terms of providing for greater accuracy in determination of state of health. The disclosed system 100 facilitates the early detection of abnormal conditions in battery pack 102 including overheating or voltage irregularities by real time determination of the state of health in minimum time duration. The disclosed system provides the earliest detection of degradation of battery pack 102, by consuming a smaller duration of time during determination. The system 100 as disclosed in the present disclosure efficiently utilizes the input energy to arrangement by determining the state of health at predetermined time intervals of operation of battery pack 102 instead of continuous determination of state of health. The disclosed system provides a simple process of determination of state of health of battery pack 102 by involving processing of predefined relations. The system 100 as disclosed in the present disclosure provides for efficient utilization of energy of the battery pack by avoiding the degradation of the battery pack 102 during determination of state of health. The battery management system 100 of the present disclosure is advantageous in terms of accurately determining state of health of the battery pack 102 employed in the energy storage solution where the conventional method of counting charge cycles are not effective in determining the state of health of the battery pack 102.
In an embodiment, the generated periodic signal is a current signal having a predefined frequency. It is to be understood that the current signal is passed through the terminals of the battery pack 102 as the input to the battery pack 102, to generate the corresponding response of the periodic signal from the terminals as output of the battery pack 102. Beneficially, the magnitude of the predefined frequency of the periodic signal affects the rate of electrochemical process i.e ions migration at the electrode-electrolyte interface and consequent charge transfer to the terminals within the battery pack 102. The greater the magnitude of the predefined frequency, larger will be the rate of electrochemical processes within the battery pack 102. Beneficially, the current signal as an input is more sensitive to electrochemical process. It is to be understood that the electrochemical process produces the flow of the charge across the terminals of battery pack 102.
In an embodiment, the predefined frequency of the periodic signal is defined based on chemistry of the at least one battery pack 102. It is to be understood that the predefined frequency is defined based on the electrochemical processes and physical characteristics of the battery pack 102. Preferably, for lithium-ion battery pack 102, the predefined frequency of the periodic signal for state of health determination is 1kHz. Beneficially, the predefined frequency of the periodic signal is defined to enable the occurrence of the electrochemical processes within the battery pack 102. The electrochemical processes within the battery pack 102 includes the ions propagation at the electrode-electrolyte interfaces the diffusion phenomena of ions within the electrode materials. The physical characteristics of the battery pack 102 includes geometry of the cell within the battery pack 102.
In an embodiment, at least one current source 104 is configured to generate the periodic signal, upon receiving instruction from the control unit 108, and wherein the generated periodic signal passes through the at least one battery pack 102. It is to be understood that the control unit 108 instructs the current source 104 to generate the periodic signal. The periodic signal passes through the terminals of the battery pack 102 that are connected with the current source 104.
In an embodiment, at least one voltage measurement circuit 106 is configured to measure the voltage of the periodic signal at the output of the at least one battery pack 102. It is to be understood that the voltage measurement circuit 106 remains connected across the output i.e. terminals of the battery pack 102 to measure the voltage of the periodic signal across the battery pack 102. Beneficially, the flow of the charge establishes the voltage across the terminals of battery pack 102. The voltage measurement circuit 106 is directed by the control unit 108 to send the measured voltage of the periodic signal to the control unit 108. The control unit 108 receives the value of periodic signal from the current source 104 as the control unit 108 and the current source 104 are communicably coupled. The control unit 108 based on the measured voltage and the received value of periodic signal determine impedance of the battery pack 102. The control unit 108 processes the measured voltage and the periodic signal to determine the impedance of the battery pack 102. The processing may include the mathematical operation that includes Ohm’s law relation, between the measured voltage and the periodic signal. The determined impedance of the battery pack 102 includes internal resistance of the battery pack 102.
In an embodiment, the battery management system 100 comprises a memory module 110 communicably coupled to the control unit 108, and wherein the memory module 110 is configured to store a predefined relation between impedance and state of health of the at least one battery pack 102. It is to be understood that the predefined relation includes the inverse relation or/and other mathematical relation. Beneficially, the memory module 110 enables the storing of a predefined relation between impedance and state of health of battery pack 102. It is to be understood that the control unit 108 receives predefined relation between impedance and state of health of the at least one battery pack 102.
In an embodiment, the control unit 108 determines the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102 and the predefined relation between impedance and state of health of the at least one battery pack 102. Beneficially, based on the determined impedance of the battery pack 102, the predefined relation is processed by the control unit 108 to determine the state of health of the battery pack 102. It is to be understood that the determined impedance of the at least one battery pack 102 is compared with predefined relation between impedance and state of health of the at least one battery pack 102 to determine the state of health of the at least one battery pack 102.
In the exemplary embodiment, when the state of health of a lithium ion battery pack 102 is required to be determined, the control unit 108 instruct the current source 104 to generate a periodic signal of 1 kHz frequency. The periodic signal passes through the terminals of battery pack 102. The voltage measurement circuit 106 measures the voltage of the periodic signal at the output of the battery pack 102. The control unit 108 receives the measured voltage from the voltage measurement circuit 106. The control unit 108 receives the value of periodic signal from the current source 104. The control unit 108 processes the measured voltage of the periodic signal and the received value of the periodic signal to determine impedance of battery pack 102. The control unit 108 processes the predefined relation between impedance and state of health of battery pack 102 based on the determined impedance of the battery pack 102, to determine the state of health of the battery pack 102.
In an embodiment, the battery management system 100 comprises at least one current source 104, at least one voltage measurement circuit 106 and a control unit 108. At least one current source 104 is connected to the at least one battery pack 102. At least one voltage measurement circuit 106 is connected to the at least one battery pack 102. The control unit 108 is communicably coupled with the at least one current source 104 and the at least one voltage measurement circuit 106. The control unit 108 is configured to instruct the at least one current source 104 to generate a periodic signal, receive a measured voltage of the periodic signal from the at least one voltage measurement circuit 106, determine impedance of the at least one battery pack 102 based on the measured voltage of the periodic signal and determine the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102. Furthermore, the generated periodic signal is a current signal having a predefined frequency. Furthermore, the predefined frequency of the periodic signal is defined based on chemistry of the at least one battery pack 102. Furthermore, at least one current source 104 is configured to generate the periodic signal, upon receiving instruction from the control unit 108, and wherein the generated periodic signal passes through the at least one battery pack 102. Furthermore, at least one voltage measurement circuit 106 is configured to measure the voltage of the periodic signal at the output of the at least one battery pack 102. Furthermore, the battery management system 100 comprises a memory module 110 communicably coupled to the control unit 108, and wherein the memory module 110 is configured to store a predefined relation between impedance and state of health of the at least one battery pack 102. Furthermore, the control unit 108 determines the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102 and the predefined relation between impedance and state of health of the at least one battery pack 102.
Figure 2, in accordance with another aspect, describes a method 200 of determining state of health of at least one battery pack 102. The method 200 starts at step 202 and completes at step 208. At step 202, the method 200 comprises generating a periodic signal, by at least one current source 104. At step 204, the method 200 comprises measuring voltage of the periodic signal, by at least one voltage measurement circuit 106. At step 206, the method 200 comprises determining impedance of the at least one battery pack 102 based on the measured voltage of the periodic signal. At step 208, the method 200 comprises determining the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102.
In an embodiment, the method 200 comprises passing the periodic signal through the at least one battery pack 102 and measuring the voltage of the periodic signal at the output of the at least one battery pack 102.
In an embodiment, the method 200 comprises determining the state of health of the at least one battery pack 102 based on the determined impedance of the at least one battery pack 102 and the predefined relation between impedance and state of health of the at least one battery pack 102.
In an embodiment, the method 200 comprises generating periodic signal as a current signal having a predefined frequency.
In an embodiment, the method 200 comprises defining of the predefined frequency of the periodic signal based on chemistry of the at least one battery pack 102.
In an embodiment, the method 200 comprises configuring of the current source 104 to generate the periodic signal, upon receiving instruction from the control unit 108, and wherein the generated periodic signal passes through the at least one battery pack 102.
In an embodiment, the method 200 comprises storing a predefined relation between impedance and state of health of the at least one battery pack 102 via memory module 110.
It would be appreciated that all the explanations and embodiments of system 100 also apply mutatis-mutandis to the method 200.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art
,CLAIMS:We Claim:
1. A battery management system (100) with integrated state of health determination of at least one battery pack (102), the battery management system (100) comprises:
- at least one current source (104), connected to the at least one battery pack (102);
- at least one voltage measurement circuit (106), connected to the at least one battery pack (102); and
- a control unit (108) communicably coupled with the at least one current source (104) and the at least one voltage measurement circuit (106), wherein the control unit (108) is configured to:
- instruct the at least one current source (104) to generate a periodic signal;
- receive a measured voltage of the periodic signal from the at least one voltage measurement circuit (106);
- determine impedance of the at least one battery pack (102) based on the measured voltage of the periodic signal; and
- determine the state of health of the at least one battery pack (102) based on the determined impedance of the at least one battery pack (102).
2. The battery management system (100) as claimed in claim 1, wherein the generated periodic signal is a current signal having a predefined frequency.
3. The battery management system (100) as claimed in claim 2, wherein the predefined frequency of the periodic signal is defined based on chemistry of the at least one battery pack (102).
4. The battery management system (100) as claimed in claim 1, wherein the at least one current source (104) is configured to generate the periodic signal, upon receiving instruction from the control unit (108), and wherein the generated periodic signal passes through the at least one battery pack (102).
5. The battery management system (100) as claimed in claim 1, wherein the at least one voltage measurement circuit (106) is configured to measure the voltage of the periodic signal at the output of the at least one battery pack (102).
6. The battery management system (100) as claimed in claim 1, wherein the battery management system (100) comprises a memory module (110) communicably coupled to the control unit (108), and wherein the memory module (110) is configured to store a predefined relation between impedance and state of health of the at least one battery pack (102).
7. The battery management system (100) as claimed in claim 1, wherein the control unit (108) determines the state of health of the at least one battery pack (102) based on the determined impedance of the at least one battery pack (102) and the predefined relation between impedance and state of health of the at least one battery pack (102).
8. A method (200) of determining state of health of at least one battery pack (102), wherein the method (200) comprises:
- generating a periodic signal, by at least one current source (104);
- measuring voltage of the periodic signal, by at least one voltage measurement circuit (106);
- determining impedance of the at least one battery pack (102) based on the measured voltage of the periodic signal; and
- determining the state of health of the at least one battery pack (102) based on the determined impedance of the at least one battery pack (102).
9. The method (200) as claimed in claim 8, wherein the method (200) comprises passing the periodic signal through the at least one battery pack (102) and measuring the voltage of the periodic signal at the output of the at least one battery pack (102).
10. The method (200) as claimed in claim 8, wherein the method (200) comprises determining the state of health of the at least one battery pack (102) based on the determined impedance of the at least one battery pack (102) and the predefined relation between impedance and state of health of the at least one battery pack (102).