TECHNICAL FIELD
[0001] The present disclosure relates, in general, to electronic control unit (ECU) of a vehicle.
[0002] In particular, the present disclosure relates to method and system for determining state of health (SOH) of a battery based on position of the piston along with temperature of the battery, voltage drop, and state of charge of the battery.
BACKGROUND
[0003] Background description includes information that may be useful in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[0004] In vehicles, battery supplies power to all auxiliary electrical and electronic devices along with initial power during starting of the vehicle for engine cranking. Therefore, the battery plays important role in starting of the vehicle. When the battery is not healthy, it will not supply sufficient power to start the vehicle. Accordingly, an estimation is required to determine state of health (SOH) of the battery while use in the vehicle.
[0005] Existing systems do not estimate state of health (SOH) of the battery. The existing system indicates malfunction of the charging system with the help of alternator related errors and harness related errors. For estimation of battery health below methods are generally used:
[0006] 1. Electrochemical Impedance Spectroscopy (EIS): It measures the impedance of the battery in frequency domain to estimate the SOH. It uses dedicated setup to measure SOH.

[0007] 2. Charging and discharging method: Charging the battery to full capacity followed by complete discharge. After complete discharge compute the available capacity. But this method is not feasible in vehicles as the battery can't be fully discharged.
[0008] Above mentioned methods has several disadvantages as mentioned below:
[0009] 1. Dedicated setup requirement, it cannot be integrated on a vehicle.
[0010] 2. While estimating SOH, battery cannot be used.
[0011] 3. Additional setup cost will be required for SOH estimation.
[0012] US Patent 8111037B2 dated June 27, 2008 discloses a method for determining a battery's state of health. An initial battery voltage is measured after a first voltage drop during an initiation of an engine cranking phase. A battery voltage is monitored during the remainder of the engine cranking phase. A lowest battery voltage is determined during the remainder of the engine cranking phase. A determination is made if a voltage difference between the lowest battery voltage and the initial battery voltage at the initiation of the engine cranking phase is less than a voltage threshold. A low battery state-of-health is identified in response to the voltage difference being less than the voltage threshold.
[0013] Problem associated with US patent 8111037B2 is that the method uses threshold value which is based only on battery temperature and battery state of charge (SOC). The threshold value may give false indication of state of health (SOH) of the battery even when SOH of the battery is in good condition.
[0014] Therefore, there is need in the art to develop a method and a system that can determine the state of health (SOH) of the battery more accurately as compared to existing technologies by incorporating more robust factors.

OBJECTS OF THE DISCLOSURE
[0015] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0016] A general object of the present disclosure is to provide a method and a system for determining State of Health (SOH) of battery using piston position along with other existing factors.
[0017] An object of the present disclosure is to provide a method and a system for determining the SOH of the battery based on real time threshold values.
[0018] These and other objects and advantages of the present disclosure will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY
[0019] This summary is provided to introduce concepts related to a method and a system for determining state of health (SOH) of battery using piston position along with other parameters. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0020] The present disclosure relates to a method for determining state of health (SOH) of a battery in a vehicle based on real time threshold values. The method includes detecting first voltage drop (VI) during engine cranking phase and determining first voltage drop threshold voltage (Vthl) from a lookup table based on the first voltage drop (VI) of the battery; detecting second voltage drop (V2) during the engine cranking phase; and determining voltage difference (AV) between the first voltage drop (VI) and the second voltage drop (V2). The method further includes determining temperature and state of charge (SOC) of the battery before the engine cranking phase; determining SOC threshold voltage (Vthsoc)

from the lookup table based on the determined SOC of the battery; determining temperature threshold voltage (Vthtemp) from a lookup table based on the determined temperature (T) of the battery; determining piston position (P) before the engine cranking phase; determining piston position threshold voltage (Vthp) from a lookup table based on the determined piston position (P) of the engine; and calculating total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp). The method includes determining a low state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal).
[0021] In an aspect, the piston position (P) is detected by camshaft position (CKP) sensor and crankshaft position (CMP) sensors.
[0022] In an aspect, determining a good state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
[0023] The present disclosure further relates to a system implemented in an Electronic Control Unit to determine state of health (SOH) of a battery in a vehicle based on real time threshold values. The ECU comprises one or more processors coupled to a memory and a battery state of health (SOH) determination unit. The battery SOH determination unit configured to determine first voltage drop threshold voltage (Vthl) from a lookup table based on a first voltage drop (VI) of the battery during an engine cranking phase; determine second voltage drop (V2) during the engine cranking phase; determine voltage difference (AV) between the first voltage drop (VI) and the second voltage drop (V2); determine State of charge (SOC) threshold voltage (Vthsoc) from a lookup table based on a SOC of the battery before the engine cranking phase; determine temperature threshold voltage (Vthtemp) from a lookup table based on temperature (T) of the battery before the engine cranking phase; detect, by camshaft position (CKP) sensor and crankshaft position (CMP) sensors, piston position (P) before the engine cranking phase; determine piston position threshold voltage (Vthp) from a

lookup table based on the piston position (P) of the engine; calculate total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp); and determine a low state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal).
[0024] In an aspect, the battery SOH determination unit determines a good state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
[0025] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[0026] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0027] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in

accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:
[0029] Fig. 1 illustrates an electronic control unit (ECU) to determine state of health (SOH) of battery, in accordance with an embodiment of the present disclosure; and
[0030] Fig. 2 illustrates a method of determination of SOH of the battery using piston position, in accordance with an embodiment of the present disclosure;
[0031] Fig. 3a illustrates voltage profile of a healthy battery during engine cranking phase, in accordance with an embodiment of the present disclosure;
[0032] Fig. 3b illustrates voltage profile of an un-healthy battery during engine cranking phase, in accordance with an embodiment of the present disclosure;
[0033] Fig. 4a illustrates voltage profile with first voltage drop during engine cranking phase, in accordance with an embodiment of the present disclosure;
[0034] Fig. 4b illustrates voltage profile with state of charge of battery before the engine cranking phase, in accordance with an embodiment of the present disclosure;
[0035] Fig. 4c illustrates voltage profile with temperature of the battery before the engine cranking phase, in accordance with an embodiment of the present disclosure;
[0036] Fig. 4d illustrates voltage profile with piston position, in accordance with an embodiment of the present disclosure;
[0037] Fig. 4e illustrates voltage profile of a battery when piston is near to top dead center (TDC) before engine cranking phase, in accordance with an embodiment of the present disclosure; and

[0038] Fig. 4f illustrates voltage profile of a battery when piston is near to bottom dead center (BDC) before engine cranking phase, in accordance with an embodiment of the present disclosure.
[0039] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in a computer-readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION
[0040] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0041] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and/or

"including," when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0043] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0044] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0045] Definition of engine cranking phase: To start a vehicle at least a vehicle battery, a starter motor, and an ignition switch is required. When the ignition key is inserted within the ignition switch and turned to a start position, or start switch pressed to start condition in case of keyless vehicles, power energizes a solenoid coil within the starter which results in a starter pinion engaging a flywheel of an engine. The pinion of the starter motor drives the flywheel for starting the engine of the vehicle. When the engine is started, the ignition key or start switch (in keyless vehicles) is released and the pinion of the starter motor retracts from the flywheel thereby terminating the engine cranking phase.
[0046] Embodiments and/or implementations described herein relate to method and system for determining state of health (SOH) of battery during cranking of engine.

[0047] The present system for determining the state of health (SOH) of battery can be implemented or embedded in Electronic Control Unit (ECU). In another embodiment, a separate micro-controller can be provided to determine the SOH of the battery.
[0048] FIG. 1 illustrates exemplary components of an ECU 100, in accordance with some embodiments of the present disclosure. The ECU 100 can work as a central system to communicate with a plurality of electronic components provided in the vehicle including battery. The ECU 100 includes a processor(s) 102, an interface(s) 104, and a memory 106.
[0049] The processor(s) 102 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, logic circuitries, and/or any devices that manipulate data based on operational instructions.
[0050] Among other capabilities, the one or more processor(s) 102 are configured to fetch and execute computer-readable instructions and one or more routines stored in the memory 106. The memory 106 may store one or more computer-readable instructions or routines, which may be fetched and executed to determine SOH of battery. The memory 106 may include any non-transitory storage device including, for example, volatile memory such as RAM, or non¬volatile memory such as EPROM, flash memory, and the like.
[0051] The interface(s) 104 may include a variety of interfaces, for example, interfaces for data input and output devices referred to as I/O devices, storage devices, and the like. The interface(s) 104 may facilitate communication of the ECU 100 with various devices coupled, such as battery sensors to receive battery temperature, current, voltage, and determine state of charge (SOC), receive data from camshaft position sensor and crankshaft position sensor. The interface(s) 104 may also provide a communication pathway for one or more components of the ECU 100. Examples of such components include, but are not limited to, processing unit(s) 108 and data 112.

[0052] The processing unit(s) 108 may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing unit(s) 108. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing unit(s) 108 may be processor-executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing unit(s) 108 may include a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the processing unit(s) 108. In such examples, the ECU 100 may include the machine-readable storage medium storing the instructions and the processing resource to execute the instructions or the machine-readable storage medium may be separate but accessible to the ECU 100 and the processing resource. In other examples, the processing unit(s) 108 may be implemented by electronic circuitry.
[0053] In an aspect, the processing unit(s) 108 may include a battery state of health (SOH) determination unit 110. The processing unit(s) 108 may include other unit(s) which may implement functionalities that supplement applications or functions performed by the ECU 100 or the processing unit(s) 108.
[0054] Further, the data 112 may include data that is either stored or generated as a result of functionalities implemented by any of the components of the processing unit(s) 108. In some aspects, the data 112 may be stored in the memory 106 in the form of various data structures. Additionally, data 112 can be organized using data models, such as relational or hierarchical data models. The data 112 may store data, including temporary data and temporary files, generated by the processing unit(s) 108 for performing the various functions of the ECU 100.
[0055] The data 112 may store a plurality of lookup tables having threshold voltage values corresponding to different factors, such as lookup table based on

state of charge of battery, lookup table based on piston position, lookup table based on first voltage drop, lookup table based on battery temperature. The stored lookup tables provide runtime computation to the processing unit(s) 108 to perform the action to accurately determine the state of health (SOH) of the battery.
[0056] The ECU 100 is coupled with a plurality of sensors and auxiliary devices through the interface 104. The ECU 100 coupled with the battery and its sensors to receive battery temperature 201, battery voltage 202, and battery current 204. Further, the ECU 100 is coupled with the engine 203 and its sensors such as camshaft position sensor and crankshaft position sensor to determine position of the piston in the cylinder.
[0057] In operation, when an engine crank request is made by inserting the ignition key in ignition switch or start switch to start position in case of keyless vehicles to energize the starter to start the engine, the battery SOH determination unit 110 monitors the engine cranking request. Upon detection of the engine cranking request, the battery SOH determination unit 110 determines the battery health every time and generates an alarm when SOH of the battery is not good.
[0058] The present battery SOH determination unit 110 detects first voltage drop (VI) and second voltage drop (V2) during engine cranking phase and determines first voltage drop, piston position, state of charge of battery, and temperature of battery before the engine cranking phase.
[0059] Need of first voltage drop: referring fig. 4a, first dip voltage is used because the peak current of starter is very high, this might be equal to the lock-in current of starter motor (since initial rpm is zero). This is the case of high rate discharge from battery. The voltage dip in an unhealthy battery will be more as compared to a healthy battery as the chemistry is already deteriorated, hence it will not able to overcome to its normal state in short span. It is one of the indicators of battery health. Thus a higher threshold is applied to the batteries in

which the dip is higher. A threshold will be defined beyond which the battery will be judged with the above defined function.
[0060] Need of SOC of battery: referring fig. 4b, a battery with low SOC exhibits a behaviour similar to an unhealthy battery. But after charging it to full capacity, battery may recover to its original capacity. Thus while estimating SOH, SOC needs to be considered. If the battery is initially at poor SOC then mis-estimation may happen, hence to avoid mis-estimation this factor is taken into consideration. Threshold value of 0 is given to battery with SOC 100% and as the SOC decreases the threshold also decreases, this is done to make sure that a healthy battery with low SOC is not judged to be unhealthy because of low SOC. [0061] Need of Temperature of Battery: referring fig. 4c, a battery exhibits different characteristics at different temperature due to its chemistry. At higher temperature the battery is capable of supplying more current as compared to lower temperature. That is why a higher threshold is applied to the battery at higher temperature. This is done to prevent that the battery is not judged healthy at higher temperature even if the battery is unhealthy.
[0062] Need of comparison based on second dip voltage: The behavior of the battery after a high discharge current is directly linked to the battery's SOH. The second voltage dip while cranking is an indicator of the battery behavior after high discharge. The second voltage dip occurs when any of piston is in compression stroke as the torque requires is highest. After the high rate discharge (i.e., the first dip) a healthy battery can easily recover and thus AV will be more, on the other hand an unhealthy battery will not be able to recover and thus the AV will be lower as illustrates in figure 3a and 3b. Thus, a battery can be considered not good if AV is less than a threshold value which is determined using piston position, VI, SOC, and temperature of the battery.
[0063] Need of Piston Position: The cranking profile of any vehicle is dependent on three major factors, the starter characteristics, type of battery and the type of engine used. Currently, the systems focus only on the first two

parameters for estimating the SOH. The proposed system uses the input from the engine to improve the estimation and prevent any false negatives.
[0064] Case 1. Initial piston position is at or just before top dead center (TDC) (Close to 0 degree):
[0065] Referring to Fig. 4e, in this case the value of AV will be higher because of the following two reasons: 1. The time taken to reach the first compression stroke is higher the battery will have enough time to recover and thus the voltage drop will be less for the same amount of current. 2. The revolution per minute (rpm) of starter motor will be higher and thus the current consumption will be lower.
[0066] Case 2. Initial piston position is beyond BDC (>180degree):
[0067] Referring to Fig. 4f, in this case the value of AV will be less as compared to case 1 because of the following reasons: 1. The time taken to reach the first compression stroke is very less, thus the battery will not be able to recover fully after the high discharge, leading to a higher voltage drop. 2. The rpm of starter motor is lower and thus the current consumption will be higher.
[0068] Technical effect: Thus if the value of initial piston position is not taken into account, case 1 will be OK (i.e., healthy) while case 2 will be NG (i.e., not good or un-healthy) even when using the same battery in similar conditions. To prevent these false negative conditions, the initial piston position needs to be used for the estimation of SOH of the battery.
[0069] Fig. 4d illustrate exemplary explanation of relationship between the voltage and the piston position. By keeping the other conditions constant (i.e., battery temperature and SOC) the cranking profile will be recorded with the initial piston position at different rotor angles. Record AV at 0. After cranking at different rotor angles record AV, and plot the graph at different rotor angles.

[0070] Before the engine cranking phase, the battery SOH determination unit 110 determines the State of charge (SOC) threshold voltage (Vthsoc) from a lookup table based on a SOC of the battery and temperature threshold voltage (Vthtemp) from a lookup table based on temperature (T) of the battery. The battery SOH determination unit 110 also detects piston position (P) before the engine cranking phase by existing camshaft position (CKP) sensor and crankshaft position (CMP) sensors. Further, the battery SOH determination unit 110 determines piston position threshold voltage (Vthp) from a lookup table based on the detected piston position (P) of the engine before the engine cranking phase. In an implementation, the lookup tables for threshold voltages of SOC, temperature, and piston position may be stored in a single lookup table or individual lookup table may be provided.
[0071] The piston position is identified with the help of crank position sensor (alone or along with cam position sensor). Crank position sensor generates signal w.r.t rotation of crank rotor. Based on the pattern of crank sensor output (alone or along with cam sensor signal), cylinder position will be identified. Initial cylinder position (where starter was engaged to rotate the crank rotor) will be calculated based on number of crank rotor signals passed (in the starting cycle) until first identification point.
[0072] During the engine cranking phase, the battery SOH determination unit 110 detects first voltage drop (VI) and second voltage drop (V2) when the battery supplies current to the starter. Upon detecting the first voltage drop (VI), the battery SOH determination unit 110 determines the first voltage drop threshold voltage (Vthl) from a lookup table based on the first voltage drop (VI) of the battery. In an implementation, the second voltage drop (V2) is the lowest voltage drop during the engine cranking phase.
[0073] The battery SOH determination unit 110 determine/calculate the voltage difference (AV) between the first voltage drop (VI) and the second

voltage drop (V2) by subtracting second voltage drop (V2) from the first voltage drop (VI).
AV = V2 - VI
[0074] The battery SOH determination unit 110 determines first voltage drop threshold voltage (Vthl) from a lookup table based on the first voltage drop (VI) of the battery. The battery SOH determination unit 110 calculates total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp).
Vtotal = Vthl+Vthsoc+Vthtemp+Vthp
[0075] Upon calculating the total threshold voltage (Vtotal) and the voltage difference (AV), the battery SOH determination unit 110 compares the voltage difference (AV) with the total threshold voltage (Vtotal). The battery SOH determination unit 110 determine low/unhealthy state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal). The battery SOH determination unit 110 determines good/healthy state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
AV > Vtotal
[0076] If above comparison is true, the battery health is considered good, else battery health is considered bad. The battery SOH determination unit 110 gives a signal of battery state 205 defining health condition of the battery. In case battery health condition is not good or unhealthy, the ECU 100 may send a signal 206 to display device in instrument panel to indicate the battery unhealthy condition to user of the vehicle before the complete failure of the battery.
[0077] FIG. 2 illustrates a method 400 of determination of state of health (SOH) of the battery, according to an embodiment of the present disclosure. The order in which the method 400 is described is not intended to be construed as a

limitation, and any number of the described method blocks can be combined in any appropriate order to carry out the method 400 or an alternative method. Additionally, individual blocks may be deleted from the method 400 without departing from the scope of the subject matter described herein.
[0078] At block 402, the method 400 includes detecting first voltage drop (VI) during engine cranking phase.
[0079] At block 404, the method 400 includes determining first voltage drop threshold voltage (Vthl) from a lookup table based on the detected first voltage drop (VI) of the battery during the engine cranking phase.
[0080] At block 406, the method 400 includes detecting second voltage drop (V2) during the engine cranking phase.
[0081] At block 408, the method includes determining/calculating voltage difference (AV) between the first voltage drop (VI) and the second voltage drop by subtracting the second voltage drop (V2) from the first voltage drop (VI).
[0082] At block 410, the method includes determining state of charge (SOC) and temperature (T) of the battery before the engine cranking phase.
[0083] At block 412, the method includes determining SOC threshold voltage (Vthsoc) from a lookup table based on the SOC of the battery and determining temperature threshold voltage (Vthtemp) from a lookup table based on the temperature of the battery before the engine cranking phase.
[0084] At block 414, the method includes determining piston position (P) by the camshaft position (CKP) sensor and crankshaft position (CMP) sensors during the engine cranking phase.
[0085] At block 416, the method includes determining piston position threshold voltage (Vthp) from a lookup table based on the piston position (P) of the engine before the engine cranking phase.

[0086] At block 418, the method includes calculating total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp).
[0087] At block 420, the method includes determining an unhealthy state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal). The method further includes determine a healthy state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
[0088] In an embodiment, upon determining that battery health is not good and it needs replacement or repair, the battery SOH determination system generates an alarm that can be visual, audio or combination of both to the user of the vehicle to indicate him about the battery health condition. Further, the visual alarm can be positioned as tell-tale in an instrument panel display to indicate the same to the user. The alarm or warning or notification to user tells that mal-function or health check-up of the battery is required. Further, the alarm or warning or notification can be provided in advance, i.e., before actual battery failure, thus giving the user sufficient time to get the battery checked and replaced accordingly.
[0089] The present determination of SOH of the battery majorly depends on first voltage drop (VI), the second voltage drop (V2), SOC of the battery, temperature of the battery, and piston position. Further, the cranking profile of the engine depends on the SOH of the battery.
[0090] The cranking load is the most performance intensive load a battery needs to supply. Successful cranking ensures that other loads can also be supplied by the battery. The battery voltage, current and temperature are already monitored in vehicles, thus no additional hardware is required in the present method and system to determine the SOH of the battery. With the present method and system,

continuous monitoring of battery is not required, thus even if the battery is changed the SOH estimation can be done after the next cranking.
[0091] In addition to the existing system, the present system and method incorporates the piston position to prevent any false determination of the SOH of the battery. If the value of initial piston position is not taken into account, case 1 will be OK while case 2 will be NG (not good) even when using the same battery in similar conditions. To prevent these false negative conditions, the initial piston position needs to be used for the estimation of SOH of the battery.
[0092] With the present implementation and use of piston position to determine the health of the battery, the present disclosure provides an accurate system and method to determine SOH of the battery as compared to the existing systems.
[0093] The present system and method are executed using the sensors and processors normally present inside cars to provide economic technical solution for the determination of the state of health of battery of the vehicle.
[0094] The word good/healthy SOH of battery defines that battery is in condition to sufficiently supply power during cranking phase and during other auxiliary electrical devices requirements provided in the vehicle.
[0095] The word bad/un-healthy/low health defines that battery SOH is not in condition to sufficiently supply power during the cranking phase and during other auxiliary electrical devices requirements provided in the vehicle.
[0096] The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art can choose suitable manufacturing and design details.
[0097] It should be understood, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely

convenient labels applied to these quantities. Unless specifically stated otherwise, as apparent from the discussion herein, it is appreciated that throughout the description, discussions utilizing terms such as "receiving," or "setting," or "transmitting," or the like, refer to the action and processes of an electronic control unit, or similar electronic device, that manipulates and transforms data represented as physical (electronic) quantities within the control unit's registers and memories into other data similarly represented as physical quantities within the control unit memories or registers or other such information storage, transmission or display devices.
[0098] Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0099] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
[00100] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants and others.

We claim

1. A method (400) for determining state of health (SOH) of a battery in a vehicle based on real time threshold values, the method comprising:
detecting (402) first voltage drop (VI) during engine cranking phase; determining (404) first voltage drop threshold voltage (Vthl) from a lookup table based on the first voltage drop (VI) of the battery;
detecting (406) second voltage drop (V2) during the engine cranking phase;
determining (408) voltage difference (AV) between the first voltage drop (VI) and the second voltage drop (V2);
calculating (410) state of charge (SOC) and measuring temperature (T) of the battery before the engine cranking phase;
determining (412) SOC threshold voltage (Vthsoc) from a lookup table based on the SOC of the battery;
determining (412) temperature threshold voltage (Vthtemp) from a lookup table based on the temperature (T) of the battery;
determining (414) piston position (P) during the engine cranking phase;
determining (416) piston position threshold voltage (Vthp) from a lookup table based on the piston position (P) of the engine;
calculating (418) total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp); and
determining (420) an unhealthy state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal).

2. The method (400) as claimed in claim 1, wherein the piston position (P) are detected by camshaft position (CKP) sensor and crankshaft position (CMP) sensors.
3. The method (400) as claimed in claim 1, wherein determining (420) the healthy state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
4. The method (400) as claimed in claim 1, wherein the method further comprises generating an alarm upon determining un-healthy state of health of the battery.
5. An electronic Control Unit (ECU) (100) to determine state of health (SOH) of a battery in a vehicle based on real time threshold values, the ECU (100) comprising:
one or more processors (102) coupled to a memory (106) and a battery state of health (SOH) determination unit (110), the battery SOH determination unit (110) is to:
determine first voltage drop threshold voltage (Vthl) from a lookup table based on a first voltage drop (VI) of the battery during an engine cranking phase;
determine second voltage drop (V2) during the engine cranking phase; determine voltage difference (AV) between the first voltage drop (VI) and the second voltage drop (V2);
determine state of charge (SOC) threshold voltage (Vthsoc) from a lookup table based on a SOC of the battery before the engine cranking phase;
determine temperature threshold voltage (Vthtemp) from a lookup table based on temperature (T) of the battery before the engine cranking phase;
detect, by camshaft position (CKP) sensor and crankshaft position (CMP) sensors, piston position (P) before the engine cranking phase;

determine piston position threshold voltage (Vthp) from a lookup table based on the piston position (P) of the engine;
calculate total threshold voltage (Vtotal) by adding the first voltage drop threshold voltage (Vthl), the SOC threshold voltage (Vthsoc), the temperature threshold voltage (Vthtemp), and the piston position threshold voltage (Vthp); and
determine an unhealthy state of health (SOH) of the battery when the voltage difference (AV) is less than the total threshold voltage (Vtotal).
6. The ECU (100) as claimed in claim 5, wherein the battery SOH determination unit (110) determines a healthy state of health (SOH) of the battery when the voltage difference (AV) is more than the total threshold voltage (Vtotal).
7. The ECU (100) as claimed in claim 5, wherein the battery SOH determination unit (110) generates an alarm corresponding to determined un-healthy state of health (SOH) of the battery.