Improved method for estimating the state of charge of a battery

Abstract

A method is performed by electronic processing resources (6; 40) for estimating the state of charge of a battery (5) during at least one of charging and discharging of the battery. During a charging phase of the battery the method comprises: receiving battery data indicative of voltage (Vb) and current (Ib) of the battery during the charging phase; determining, based on the battery data, a capacity (QEOC(j)) of the battery; and determining a state of charge (SOC(j)) of the battery based on said capacity. During a discharging phase of the battery, the method comprises: receiving a capacity (Qadj) of the battery (5) estimated at the end of a charging phase occurred before the discharging phase; and determining a state of charge (SOCdis) of the battery (5) based on said capacity.

Description

[0001] “IMPROVED METHOD FOR ESTIMATING THE STATE OF CHARGE OF A BATTERY”

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No.

[0004] 102025000000888 filed on January 20, 2025, the entire disclosure of which is incorporated herein by reference.

[0005] Technical Field

[0006] The present invention relates to an improved method for estimating the state of charge of a battery.

[0007] The present invention finds its preferred, although not exclusive, application to the estimation of the state of charge of a battery of a vehicle, such as for example a vehicle for transportation of goods and / or people, and in particular of a hybrid or electric vehicle.

[0008] Background of the Invention

[0009] As known, the state of charge (SOC) of a battery is a critical parameter that indicates the remaining charge of the battery.

[0010] A precise SOC calculation is crucial both in terms of safety and optimal battery management.

[0011] However, during charging of the battery, SOC estimation may be difficult; in particular an accurate SOC estimation becomes increasingly difficult towards the end of the charging cycle, due to nonlinear behavior of the battery.

[0012] As shown in Figure 1, known methods for estimating the SOC provide a behavior of the SOC over time that exhibits a "stable area" towards the end of the charging process, even if the battery has not reached full charge (100%).

[0013] This stable area can be misleading, as it might suggest to both a battery management system and a user that the battery reached end of charge, when it is not.

[0014] Such false stability can cause the user to believe that the charging process is complete and prematurely disconnect the battery from the charger, even though the battery still requires additional charging to reach its end of charge condition.

[0015] Therefore, such behavior of the SOC can mask the true state of the battery.

[0016] Other known methods for estimating the SOC of a battery provide a sudden jump of the SOC to 100% at the end of the charging process, as shown in Figure 2.

[0017] The Applicant has verified that the sudden jump is caused by an incorrect capacityestimation deriving from a charging strategy that does not account for the fact that the full battery capacity, from an electrochemical point of view, depends on the temperature of the battery.

[0018] In fact, if the charging strategy does not correctly account for temperature, the battery management system (BMS) might underestimate or overestimate the actual capacity of the battery.

[0019] So, at the end of charging, the Battery Management System recalculates the capacity incorrectly, thereby causing an abrupt jump in the estimated SOC.

[0020] Additionally, known charging strategies provide for a charging cutoff voltage that is dependent on temperature.

[0021] In detail, when the temperature is high, the cutoff voltage is lowered, but the charging current is maintained at the same level. This implies that the battery can never reach its full charge, as the reduced cutoff voltage prevents the battery from being fully charged to its nominal capacity.

[0022] As a result, the battery is always left undercharged, and the SOC estimation could show an abrupt jump near the end of the charge cycle when the system recalculates the available capacity based on the lower cutoff voltage.

[0023] For example, the Applicant has verified that a known battery charging process in slow charge mode at 25°C may allow to reach only 90 Ah at the end of charging process, while nominal battery capacity is 100 Ah. So, by using the Coulomb counting formula for estimating the SOC, the resulting SOC at the end of the charging process is

[0024] SOC = 100% × Σ(I / Q) × Δt = 100% × 90Ah / 100Ah

[0025] SOC = 100% × Σ(I / Q) × Δt = 100% × 90Ah / 100Ah ≅ 90%.

[0026]

[0027] 100Ah

[0028] A value of SOC at end of charge lower than 100% does not reflect the user requirement that the SOC should reach 100% at the end of charging.

[0029] Thus, in this case, for fulfilling said user requirement, the known SOC estimation method would create a jump in the estimated SOC, even though the actual charge added to the battery during the charging process did not reach full value (Figure 2).

[0030] In addition to the above, an inaccurate SOC estimation also has other disadvantages. For example, with reference to the battery of a vehicle, an accurate SOC estimation is crucial for completing the Worldwide Harmonized Light Vehicles Test Cycle (WLTC), which is a standard procedure for measuring the performance and efficiency of vehicles.An accurate SOC estimation is crucial for completing the WLTC, as it determines the energy available for the test cycle.

[0031] Overestimation of the SOC means that the battery is assumed to have more charge than it actually does. This can cause the vehicle to run out of energy before the test cycle is completed, leading to an incomplete test and unreliable performance data. Such inaccuracies not only compromise the validity of the test results but also affect the vehicle's compliance with regulatory standards.

[0032] Moreover, as depicted in Figure 3, an incorrect SOC estimation could lead to an undervoltage condition of the battery.

[0033] In detail, with reference to the example of Figure 3, when the voltage of the battery reaches the minimum threshold Vmin, the estimated SOC is approximately 36%, wherein instead the SOC should be 0%. Therefore, the estimated SOC indicates a higher percentage of charge than was truly available.

[0034] In response, the battery management system does not perform a current derating; thus, the battery is continued to be used in an undervoltage condition possibly leading the vehicle to instability and early shutdown.

[0035] Therefore, this misrepresentation of the SOC causes the vehicle to underperform, disrupting the test cycle and skewing the performance metrics.

[0036] The issue of inaccurate SOC estimation is not only limited to the WLTC, but can occur in other driving cycles as well, such as the Urban Dynamometer Driving Schedule (UDDS) or the New European Driving Cycle (NEDC), where precise SOC estimation is also critical.

[0037] In general, overestimation of SOC in any driving cycle can lead to similar problems, including undervoltage, early power loss, and incomplete testing. These errors could have broader implications, including misleading performance evaluations and failure to meet regulatory requirements across various testing standards.

[0038] Moreover, the problem of inaccurate SOC estimation is not limited to controlled testing environments and can also affect use of the vehicle by the final user, for example a use on the road during regular use by everyday drivers.

[0039] In this case, inaccurate SOC estimation while driving could cause a vehicle to unexpectedly run out of power, stranding the user and potentially causing safety concerns.

[0040] On the road, overestimation of SOC may prevent the vehicle from applyingnecessary current derating towards the end of the charge, leading to sudden power loss, system shutdown, or insufficient range to reach a charging station.

[0041] Such incidents can severely affect user confidence and the reliability of electric vehicles in real-world driving conditions.

[0042] Therefore, the need is felt to increase the SOC estimation.

[0043] An aim of the present invention is to satisfy at least in part the above-mentioned needs and overcome at least in part the above-mentioned disadvantages in an optimized and cost-effective way.

[0044] Summary of the Invention

[0045] The aforementioned aim is obtained by a method for estimating the state of charge of a battery, a computer program and a system, as claimed in the appended set of claims that are integral part of the present description.

[0046] Brief Description of Drawings

[0047] For a better understanding of the present invention, preferred embodiments are described in the following, by way of non-limiting examples, with reference to the attached drawings wherein:

[0048] • Figures 1-3 show exemplificative plots of the state of charge of a battery that has been estimated by known methods;

[0049] • Figure 4 shows the block diagram of a system according to the invention;

[0050] • Figure 5 shows the flow chart of a method for estimating the state of charge of a battery, according to an embodiment;

[0051] • Figure 6 shows the flow chart of a method for estimating the state of charge of a battery during charging of the battery, according to an embodiment;

[0052] • Figure 7 shows an exemplificative plot of the behavior of the SOC estimated during charging of the battery according to the method of Figure 6;

[0053] • Figure 8 shows the flow chart of steps performed at the end of a charging phase of the battery; and

[0054] • Figure 9 shows the flow chart of a method for estimating the state of charge of the battery during discharge of the battery, according to an embodiment.

[0055] Detailed Description of the Invention

[0056] Figure 4 shows the block diagram of a system 1 comprising a vehicle 3, for examplea vehicle for transportation of goods and / or people.

[0057] Preferably, the vehicle 3 is a road vehicle; however, the vehicle 3 may be a different kind of vehicle.

[0058] Preferably, the vehicle 3 is an electrically propelled vehicle, for example a hybrid vehicle or fully electric vehicle.

[0059] In detail, the vehicle 3 comprises a battery 5, in particular a rechargeable battery, which may be for example a single-cell battery or a battery pack comprising a plurality of battery cells.

[0060] The battery 5 is configured to provide energy for the propulsion of the vehicle 5 and / or for the functioning of other elements of the vehicle 3.

[0061] Preferably, the battery 5 comprises one or more Lithium-ion (Li-ion) battery cells, such as for example Lithium Iron Phosphate (LiFePO4). However, the battery 5 may be based on different technology; for example, the battery 5 may comprise one or more Nickel-Metal Hybride (NiMH) battery cells or other electrochemical battery cells. In addition or in alternative, the battery 5 may comprise one or more solid-state battery cells.

[0062] The vehicle 3 further comprises a Battery Management System (BMS) 6, a detection system 7, a load system 8 and a charger system 9, which may be mutually coupled with each other and with the battery 5 for allowing functioning of the vehicle 3.

[0063] In detail, the load system 8 comprises one or more components of the vehicle 3 that are powered by energy received from the battery 5.

[0064] In particular, the load system 8 comprises one or more components for propulsion of the vehicle 3 and / or one or more components configured for performing specific functions such as for example a HVAC system of the vehicle 3.

[0065] The charging system 9 is configured to recharge the battery 5.

[0066] For example, the charging system 9 may be configured to recharge the battery 5 upon coupling with an energy recharging source that is external to the vehicle 3 and / or by means of energy recovery procedures performed during use of the vehicle 3 (e.g. during braking of the vehicle 3).

[0067] Preferably, the charging system 9 is configured to perform a constant current (CC) charging of the battery 5.

[0068] The detection system 7 comprises one or more sensors that are configured to detect quantities indicative of the functioning of any one or more of battery 5, load system 8 andcharging system 9.

[0069] According to an embodiment, the detection system 7 is configured to detect quantities that are indicative of any one or more of current lb, voltage Vb and temperature Tb of the battery 5.

[0070] In detail, the current lb may be a cell current of the battery 5; the voltage Vb may be one or more cell voltages, such as minimum and maximum cell voltages of the battery 5; and / or the temperature Tb may be a cell temperature of the battery 5.

[0071] The BMS 6 is configured to control functioning of any one of battery 5, detection system 7, charging system 9 and load system 8.

[0072] The BMS 6 may comprise one or more memories, for example volatile and nonvolatile; one or more processors; one or more microcontrollers; any other known electronic processing and / or control resources, depending on the specific application and implementation.

[0073] The BMS 6 is configured to perform a method for estimating the state of charge (SOC) of the battery 5, as discussed in detail hereinafter.

[0074] According to an embodiment, as shown in Figure 5, the BMS 6 receives, step S15, battery data that are indicative of the actual functioning of the battery 5.

[0075] The battery data are indicative of the quantities lb, Vb, Tb detected by the detection system 7.

[0076] In detail, the battery data may comprise current data indicative of the current (e.g., cell current) lb of the battery 5; voltage data indicative of one or more voltages Vb of the battery 5, such as minimum and maximum cell voltages; and temperature data indicative of a cell temperature Tb of the battery 5.

[0077] The battery data may be received in real time from the detection system 7 or retrieved in a memory of the BMS 6.

[0078] Current, voltage and temperature of the battery 5 may be measured at different frequencies one from the other, depending on the specific application.

[0079] For example, the BMS 6 may collect the current data at a high frequency, for example ranging between every few milliseconds and every few seconds; voltage data may be collected at a lower frequency than the current data; and temperature data may be collected at a lower frequency than the voltage data.

[0080] This implies that the data points of the current data, voltage data and temperaturedata may not be synchronized with each other.

[0081] In other words, current data, voltage data and temperature data comprise data points that are not temporally aligned one with the other.

[0082] Then, step S16, the BMS 6 initializes the state of charge SOC of the battery 5. In detail, the BMS 6 determines an initial state of charge SOC(O) of the battery 5 at an initial time t=0.

[0083] The BMS 6 may be configured to perform a first initialization step wherein the BMS 6 retrieves a stored value SOCprev of SOC that has been previously stored in a memory, for example a non-volatile memory of the BMS 6.

[0084] Said stored value SOCprev may be an SOC value stored before last shutdown of the vehicle 3. In particular, the BMS 6 may be configured, during a shutdown sequence of the vehicle 3 (e.g., in response to a received “key-off’ command), to store the current SOC value of the battery 5.

[0085] In addition, the BMS 6 may be configured to perform a second initialization step wherein the BMS 6 calculates a candidate initial SOC value SOCo based on an SOC-OCV function, wherein the OCV is the Open Circuit Voltage of the battery 5.

[0086] In detail, the BMS 6 may determine the OCV value OCVo at t=0 based on the actual battery data (e.g., at t=0) and, in response, determine the candidate estimated value SOCo based on the determined OCV, for example based on an OCV-SOC curve of the battery 5 that has been determined during calibration of the battery 5 and stored in the BMS 6.

[0087] Preferably, the first initialization step and the second initialization step may be performed in parallel.

[0088] Preferably, at the initialization step SI 6, the BMS 6 may compare the stored value SOCprev with the candidate estimated value SOCo and determine the initial SOC value SOC(O) as a function of said comparison. This may enhance the accuracy and reliability of the initialization of the SOC.

[0089] In detail, the BMS 6 may set the initial SOC value SOC(O) to the stored value SOCprev, if a difference between the stored value SOCprev and the candidate measured value SOCo is lower than a threshold. On the contrary, the BMS 6 may set the initial SOC value SOC(O) to the candidate measured value SOCo, if a difference between the stored value SOCprev and the candidate measured value SOCo is higher than a threshold. This may further increase the accuracy and reliability of the initialization of the SOC.In fact, a difference between SOCprev and SOCo may indicate an error during the previous shutdown procedure or the occurrence of a forced shutdown procedure.

[0090] Then, based on the initialization value SOC(O), the BMS 6 estimates the state of charge SOC of the battery 5 according to different procedures, depending if the battery 5 is being charged (step S17) or is being discharged (step S18).

[0091] During an actual charging phase of the battery 5, step S17, the BMS 6 estimates a first capacity of the battery 5 based on battery data acquired during the charging phase, and determines the state of charge of the battery 5 based on the estimated first capacity.

[0092] During a discharging phase of the battery 5, step S18, the BMS 6 determines the state of charge of the battery 5 based on a second capacity that has been estimated during the previous charging cycle, in particular at the end of the charging cycle immediately preceding the actual discharging phase.

[0093] In particular, according to an embodiment, the second capacity may be obtained, at the end of a charging cycle, by correcting the first capacity estimated during charging based on one or more correction factors depending on a capacity of the battery 5 at low SOC level, a capacity of the battery 5 at high SOC level, and an ideal capacity of the battery 5.

[0094] A detailed embodiment of step S17 for estimating the SOC during charging of the battery 5 is described hereinafter with reference to Figure 6. The charging may occur for example while the charging system 9 is coupled to an external energy resource.

[0095] The embodiment of Figure 6 refers to a constant current charging phase of the battery 5.

[0096] During constant current charging, the charging system 9 is configured to provide a constant current to the battery 5.

[0097] In detail, constant current charging phase may comprise a plurality of charging steps. Each charging step, indicated hereinafter by CSk, may have a fixed time duration or a variable time duration depending on the specific charging algorithm.

[0098] For example, a charging step CSk may be terminated in response to the voltage Vb of the battery 5 reaching a stop charging voltage Vstop,k, as later discussed in detail.

[0099] Each charging step CSk has a nominal charging current Ik that is provided to the battery 5, for example by the charging system 9.

[0100] The nominal charging current Ik is a constant charging current.Each charging step CSk, may have its own respective charging current Ik; for example, the charging current may decrease at increasing steps, e.g. Ik> Ik+i.

[0101] For illustration purpose only, it is provided hereinbelow a table showing an example of the charging current Ii of the first charging step CSi and the respective stop charging voltage Vstop,i at different values of the temperature Tb of the battery 5:

[0102] Tb, °C 20 25 35 45

[0103] Ii 0.6C 0.6C 0.6C 0.6C

[0104] Vstop,l 4.2 4.2 4.1 4.05

[0105]

[0106] When the battery data indicates that the maximum cell voltage of the battery 5 has reached the stop charging voltage Vstop,i, then the charging current is reduced to a low value, for example 10 A, for a short period, for example for 5 s, and then the second charging step CS2 is performed.

[0107] For illustration purpose only, it is provided hereinbelow a table showing an example of the charge current b of the second charging step CS2 and the respective stop charging voltage Vstop,2 at different values of the temperature Tb of the battery 5:

[0108] Tb, °C 20 25 35 45

[0109] I2 0.2C 0.4C 0.4C 0.4C Vstop,2 4.2 4.2 4.1 4.05

[0110]

[0111] When the battery data indicates that the maximum cell voltage of the battery 5 has reached the stop charging voltage Vstop,2, then a third charging step CS3 may start, and so on.

[0112] For illustration purposes, the following steps are described with reference to a generic charging step CSk.

[0113] At a step S20, during a charging step CSk, the BMS 6 calculates one or more values of the internal resistance Rest of the battery 5 based on the battery data.

[0114] The internal resistance Rest may correspond to the Direct Current Internal Resistance, DCIR, of the battery 5.

[0115] In detail, the BMS 6 performs a plurality of iterations, each indicated by j, and foreach iteration j calculates a respective internal resistance Rest(j).

[0116] The number of iterations j may depend on the ratio between the update frequency of the current data and / or the voltage data with respect to the duration of the charging step CSk.

[0117] In detail, at step S20, the BMS 6 calculates an actual value of the OCV of the battery 5, indicated by OCVin, based on the actual value of the SOC, i.e. the latest available value of the SOC indicated by SOC(j).

[0118] For example, at the beginning of the first charging step CSi, the actual value of the SOC corresponds to the initialization value SOC(O) calculated at step S16.

[0119] The actual OCV value OCVin may be calculated from the actual value of the SOC by using an SOC-OCV relationship, for example by means of a look-up table stored in the BMS 6.

[0120] Preferably, the actual OCV value OCVin may be a function of the actual SOC and the temperature Tb; e.g., OCVin = OCV(Tb, SOC(j)).

[0121] Then, at each iteration j, the BMS 6 calculates a difference Av(j) between the actual battery cell voltage Vb(j) indicated by the voltage data and the actual OCV value OCVin; e.g.:

[0122] Δv(j) = Vb(j) - OCVin.

[0123] Then, the internal resistance Rest(j ) is calculated as:

[0124]

[0125] wherein Ib(j ) is the actual current as indicated by the current data. In other words, Ib(j) is the actual current provided to the battery 5.

[0126] In fact, the actual current Ib(j) may differ from the nominal charging current Ik supplied to the battery during the charging step CSk.

[0127] Then, step S21, at each iteration j, a voltage drop ΔV(j) on the battery 5 is calculated based on the internal resistance Rest(j)that has been previously calculated.

[0128] In detail, the voltage drop ΔV(j) may be calculated as:

[0129] ΔV = Ib(j) × Rest(j),

[0130] wherein lb is the actual current provided to the battery 5.

[0131] Then, step S22, the BMS 6 estimates the OCV value of the battery 5, indicated by OCVEOCC / ), based on the voltage drop ΔV(j). Preferably, the OCV value OCVEOC(j) isalso a function of the temperature Tb(j) as indicated by the temperature data.

[0132] In detail, the OCV value OCVEOC(J) may be calculated as:

[0133] O

[0134]

[0135] Cl'roc(j') = Kc““(j) - AK(j'),

[0136] wherein is the cutoff voltage of the battery 5 associated to charging step CSk; said 5 cutoff voltage

[0137]

[0138] maY retrieved by a memory and depends on the specific type, model, etc., of the battery 5. For example, the cutoff voltage may be determined from a lookup table that associates the cutoff voltage with the temperature Tb of the battery 5 and the k-th charging step.

[0139] Said lookup table may be provided for example by a manufacturer of the battery 5.

[0140] 0 For illustrative purpose only, hereinbelow is provided an example of values of the cutoff voltage for different values of the temperature Tb of the battery.

[0141] Tb, °C 25 26 27 28 29 30 31 32 33 34 35 yEOC.k y

[0142] vcutoff ’v4.2 4.19 4.18 4.17 4.16 4.15 4.14 4.13 4.12 4.11 4.10

[0143]

[0144] Therefore, at iteration j, the cutoff voltage

[0145]

[0146] may be a function of the specific number k of charging step and the actual temperature Tb of the battery as indicated by the 5 temperature data.

[0147] Then, step S23, the BMS 6 calculates a preliminary SOC value SOCocv(j) based on the OCV value OCVEOCestimated at step S22; in particular:

[0148] SOCocv(j) = OCV-1(OCVEOC(j)),

[0149] wherein OCV-1represents a function providing an SOC value from an OCV value.

[0150] 0 In other words, OCV-1may be the inverse function to calculate SOC based on an SOC- OCV curve.

[0151] Then, step S24, the BMS 6 calculates a capacity QEOC(J) of the battery 5 at the end of charging step CSk, based on the preliminary SOC value SOCocv(j) calculated at step S23.

[0152] 5 In detail, the capacity QEOC(J) of the battery 5 at the end of charge step CSk may be calculated as:

[0153] sococv(j)

[0154] QEOC(j) — 100XQBOL '

[0155] wherein QBOL is the capacity of the battery 5 at the beginning of life, for example anominal capacity of the battery 5 as provided by the manufacturer of the battery 5.

[0156] Finally, step S25, the state of charge SOC(j) is estimated based on the capacity QEOC(J) determined at step S24.

[0157] According to an embodiment, the state of charge SOC(j) may be calculated by using a Coulomb counting method, wherein the value QEOc(j)is used for the Coulomb counting.

[0158] In detail, the state of charge SOC(j) during charging step CSk may be estimated as:

[0159] SOCfj) = f(I, QEOCUX W = SOC (J - 1) + 100% x x At,

[0160]

[0161] QEOCU) wherein SOC(j-1) is the state of charge calculated at the end of the previous iteration j-1 (for example, at the first iteration j=1 of the first charging step CS1, SOC(j-1) may be the initialization value SOC(0)), Ib j) is the battery current lb indicated by the current data at iteration j and At is the time distance between two consecutive iterations j, j+1.

[0162] Then, the method of Figure 6 may return to step S20 for performing a new iteration (j=j+l).

[0163] The steps S20 to S25 may be performed for every charging step CSk.

[0164] In this case, with reference to what discussed for step S20, the actual value of the state of charge used at step S20 at the beginning of the subsequent charging step CSk+i is the last state of charge value SOC(j) calculated at the end of charging step CSk.

[0165] The method of Figure 6 may be repeated until the charging procedure does not come to an end, for example because the charging procedure has been completed or because a user stops charging.

[0166] The method according to the invention may further comprise to provide a signal indicative of the estimated SOC value of the battery 5, for example by showing the estimated SOC on a user interface 29 of the vehicle 3 such as a graphical user interface or any other known interfacing means, wherein the signal indicates the SOC(j) values determined during the charging steps while the battery 5 is in charge mode, and a value of 100% if charging has finished. This would allow to satisfy the user requirements of having a 100% SOC at the end of charging.

[0167] It would be clear that the method of the invention for estimating the SOC during charging provides a behavior of the SOC that does not have any jump at the end of the charging procedure, as indicated for example by a solid line in Figure 7 as opposed to the dashed line which indicates the estimated SOC provided by known methods duringcharging.

[0168] At the end of the charging phase, for example after interruption of the charging phase by a user or after the battery has reached full charge, the BMS 6 estimates an adjusted battery capacity to be used during the subsequent discharging phase for estimating the state of charge.

[0169] Figure 8 shows a detailed embodiment of the steps performed at the end of the charging phase for calculating the adjusted battery capacity Qadj.

[0170] In particular, the adjusted battery capacity Qadj may be estimated in response to the detection of an event indicating the end of the charging phase (step S30), before the beginning of the subsequent discharging phase. For example, by considering an exemplificative case wherein the battery is the battery of a vehicle that is being charged while being in an off state, the adjusted battery capacity Qadj may be estimated in response to the event indicating the end of a charging phase (e.g., unplugging of the charging system from the external source), before the subsequent turning on of the vehicle, which would initiate the discharging phase.

[0171] In response to the detection of the end-of-charge event, the adjusted battery capacity Qadj is estimated based on battery charging data indicative of the status of the battery 5 at the end of the charging phase (also indicated hereinafter as charging cycle).

[0172] In detail, the battery charging data may be indicative of:

[0173] - the SOC of the battery 5 at the beginning of the charging phase, SOCBOC;

[0174] - the SOC of the battery 5 at the end of the charging phase, SOCEOC;

[0175] - one or more of the voltages Vb at the end of the charging phase, VEOC;

[0176] - the current lb at the end of the charging phase, IEOC;

[0177] - the temperature Tb at the end of the charging phase, TEOC.

[0178] The values SOCBOC, SOCEOC, VEOC, IEOC, TEOC are recorded, for example stored in a memory of the BMS 6, at the end of the charging phase or, in other words, may correspond to the values stored in a memory of the BMS 6 in response to the detection of the event indicating the end of charge.

[0179] Then, step S31, the BMS 6 estimates the OCV value OCVend of the battery 5 at the end of the charging cycle, as:

[0180] OCVend= VEOC— IEOC• Rest,

[0181] wherein Rest is a value of the internal resistance that has been estimated during thecharging cycle; in particular, it may be the last value of the internal resistance estimated before the end of the charging cycle.

[0182] Then, step S32, an ideal state of charge SOCocv is estimated from the OCV value OCVend at the end of the charging cycle; e.g.:

[0183] SOCocv= OCV-1(OCVend).

[0184] Then, step S33, the BMS 6 estimates the adjusted capacity Qadj of the battery 5. According to an embodiment, the adjusted capacity Qadj is estimated based on: an ideal capacity Qideai, a low capacity Qiow, a high capacity Qhigh, and a total capacity Qtotai of the battery 5.

[0185] In detail, the total capacity Qtotai is the total charge added in the battery 5 during the just-ended charging cycle.

[0186] The ideal capacity Qideai is the capacity of the battery 5 if charge is subject to a constant voltage (CV) condition and the OCV of the battery 5 reaches the value OCVend as soon as the battery 5 stops charging (e.g., as soon as it disconnects from a charging source). In particular:

[0187] „ > sococv-socBOC n

[0188] ideal — VBOL •

[0189] The low capacity Qiowis the capacity of the battery 5 for low values of the state of charge, for example comprised between 0% and 25%. In detail, the low capacity Qiowmay be estimated as:

[0190] zi _ SOCBOC ■SOCmin zi

[0191] v

[0192]

[0193] low—r00 '

[0194] wherein SOCmin is the minimum nominal value of the state of charge, e.g., 0%, which may depend on the specific application of the battery 5; and wherein a is a correction factor that is a function of a ratio between the ideal capacity Qideai and the total capacity Qtotai, for example:

[0195] a> Qtotai

[0196] Qideai

[0197] The high capacity Qhigh is the capacity of the battery 5 for high values of the state of charge, for example comprised between 75% and 100%. In detail, the high capacity Qhigh may be estimated as:

[0198] _ SOCmax SO^EQC

[0199] high—

[0200]

[0201] rOO '

[0202] wherein SOCmax is the maximum nominal value of the state of charge, e.g., 100%,which may depend on the specific application of the battery 5.

[0203] The adjusted capacity Qadj may be determined as a function of, for example a linear combination of the low capacity Qiow, the high capacity Qhigh, and the total capacity Qtotai of the battery 5; in particular:

[0204] Qadj = Ql ow T Qtotai T Qhigh •

[0205] Figure 9 shows the flow chart of a method for estimating the state of charge SOCdis during the discharging phase, based on the adjusted capacity Qadj determined at the end of the previous charging phase.

[0206] In detail, at a step S34, the BMS 6 may detect an event indicating the beginning of a discharging phase. For example, in case of a vehicle, the event may be the detection of a key-on event.

[0207] In response to the detection of said event, step S35, the BMS 6 receives the adjusted battery capacity Qadj, for example by retrieving it from a memory wherein it has been previously stored.

[0208] Then, the BMS 6 estimates, step S36, the state of charge SOCdis during the discharging phase.

[0209] According to an embodiment, the state of charge SOCdis may be calculated by using a Coulomb counting method, wherein the value Qadj is used as capacity value for the Coulomb counting.

[0210] In detail, during discharge, the BMS 6 may perform a plurality of iterations j, wherein for each iteration j the state of charge SOC(j)dis may be estimated as:

[0211] SOC(j)dis= f(l, Qadj, M) = SOC(j - 1) - 100% x x At,

[0212]

[0213] Qadj wherein SOC(j - 1 ) is the state of charge calculated at the previous iteration j-1 (at the first iteration j=l during discharge, SOC(j=0) may be the state of charge estimated at the end of the previous charging cycle), Ib(j ) is the battery current lb indicated by the current data and measured during discharge of the battery 5, and At is the time distance between two consecutive current measurements.

[0214] It would be clear to the person skilled in the art that the state of charge during discharge SOCdis may be updated in real time during discharge.

[0215] Moreover, the fact that the SOC during discharge is estimated based on the amount of charge Qtotai added in the battery 5 during the previous charging cycle, allows anaccurate monitoring of the SOC during discharging. This allows to avoid undesired working conditions of the battery 5, such as an undervoltage condition.

[0216] From the above description it follows that the present method allows an accurate estimation of the state of charge of the battery 5 both during charging and discharging.

[0217] According to an embodiment, the steps performed at the end of the charging phase (Figure 8), may further comprise to compare the state of charge SOCBOC at the beginning of the charging cycle with the state of charge SOCEOC at the end of the charging cycle and, in response, estimate the adjusted capacity Qadj if a difference between SOCBOC and SOCEOC is equal to or higher than a threshold Pthr, for example equal to or higher than 70%.

[0218] If said difference is lower than the threshold Pthr, then steps S31 to S33 may not be performed and, during discharge, the BMS 6 may receive at step S35 (Figure 9) a battery capacity value stored in a memory of the BMS 6 in a previous extrapolation cycle.

[0219] This may further increase the SOC accuracy estimation; in fact, if the charge introduced during the charging cycle is too low, the adjusted capacity Qadj may not be estimated with sufficient accuracy due to the non-linear behaviour of the battery 5.

[0220] It is clear that what described above can be subject to modifications, without departing from the scope of the invention as defined by the appended claims.

[0221] For example, one or more of the sensors of the detection system 7 may be incorporated within battery 5, load system 8 and / or charging system 9, or may form separate entities, depending on the specific implementation, vehicle type, etc.

[0222] For example, the BMS 6 may be configured to estimate other parameters of the battery 5, such as the state of health and the like.

[0223] For example, the initialization step S16 of Figure 5 may be optional or the state of charge may be initialized by following a different initialization procedure with respect to what has been described with reference to step SI 6.

[0224] For example, any one or more of the steps described with reference to figures 5, 6, 8 and 9 can be performed by processing resources that are external to the vehicle 3, such a computing system 40 (indicated by a dashed line in Figure 4) that is coupled to the BMS 6 for mutual exchange of data. The computing system 40 may for example comprise centralized or distributed computing resources.

[0225] For example, any one or more of the steps of the method according to the inventionmay be performed in cloud.

[0226] For example, what described above can be applied to a battery configured to supply energy to a device or apparatus different from a vehicle.

[0227] One or more of the above-described embodiments can be combined to provide further solutions falling within the scope of the appended claims.

[0228] The disclosure may be summarized by the following examples.

[0229] Example 1: A method, performed by electronic processing resources (6; 40), for estimating the state of charge of a battery (5) during at least one of charging and discharging of the battery, wherein the method comprises at least one of:

[0230] during a charging phase (CSk):

[0231] receiving first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) during the charging phase of the battery;

[0232] determining, based on the first battery data, a first capacity (QEOC(J)) of the battery (5); and

[0233] determining a first state of charge (SOC(j)) of the battery based on the first capacity, and

[0234] during a discharging phase of the battery:

[0235] receiving a second capacity (Qadj) of the battery (5) estimated at the end of a charging phase occurred before the discharging phase; and

[0236] determining a second state of charge (SOCdis) of the battery (5) based on the second capacity.

[0237] Therefore, according to Example 1, the method may be a method for estimating the state of charge of a battery during charging of the battery and comprise, during a charging phase (CSk):

[0238] receiving first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) during the charging phase of the battery;

[0239] determining, based on the first battery data, a first capacity (QEOC(J)) of the battery (5); and

[0240] determining a first state of charge (SOC(j)) of the battery based on the first capacity, In addition or in alternative, the method according to Example 1 may be a method for estimating the state of charge of a battery during discharging of the battery and comprise, during a discharging phase of the battery:receiving a second capacity (Qadj) of the battery (5) estimated at the end of a charging phase occurred before the discharging phase; and

[0241] determining a second state of charge (SOCdis) of the battery (5) based on the second capacity.

[0242] Example 2: The method according to Example 1, wherein at least one of determining the first state of charge based on the first capacity during the charging phase and determining the second state of charge based on the second capacity during the discharging phase comprise determining the state of charge based on Coulomb counting.

[0243] Example 3: The method according to Example 1 or 2, wherein determining the first capacity (QEOC(J)) comprises:

[0244] determining an internal resistance (Rest(j)) of the battery (5) based on the first battery data;

[0245] determining a voltage drop (AV(j)) of the battery as a function of the internal resistance and the actual current (lb) of the battery indicated by the first battery data; determining a first open circuit voltage value (OCVEOC(J)) of the battery as a function of the voltage drop;

[0246] determining a preliminary state of charge value (SOCocv(j)) as a function of the first open circuit voltage value; and

[0247] determining the first capacity (QEOC(J)) as a function of the preliminary state of charge and a nominal capacity (QBOL) of the battery.

[0248] Example 4: The method according to Example 3, wherein determining an internal resistance comprises:

[0249] determining an actual open circuit voltage value (OCVin) based on an actual state of charge (SOC(j)) of the battery;

[0250] determining a voltage parameter (Av( / )) indicative of a difference between the actual open circuit voltage value and the actual voltage (Vb(j)) of the battery.

[0251] Example 5: The method according to Example 4, wherein the first open circuit voltage value (OCVEOC(J)) is determined as a function of a difference between the voltage drop (AV(j)) and a cutoff voltage associated with an actual charging step (CSk) of the charging phase.Example 6: The method according to Example 5, wherein the first battery data is also indicative of a temperature (Tb) of the battery (5) during the charging phase, the cutoff voltage being a function of the temperature of the battery.

[0252] Example 7: The method according to any of Examples 1-6, further comprising: detecting (S30), during the charging phase of the battery, a first event indicative of an end of the charging phase of the battery; and

[0253] in response to the detection of the first event, determining (S31, S32, S33) the second capacity of the battery based on charging data indicative of one or more parameters of the battery associated to the charging phase.

[0254] Example 8: The method according to Example 7, wherein determining the second capacity (Qadj) comprises, based on the charging data:

[0255] determining a low capacity (Qlow) of the battery indicative of the capacity of the battery corresponding to the state of charge (SOCBOC) of the battery at the beginning of the charging phase;

[0256] determining a high capacity (Qhigh) of the battery indicative of the capacity of the battery corresponding to a state of charge (SOCEOC) of the battery at the end of the charging phase; and

[0257] determining a total capacity (Qtotal) of the battery indicative of the amount of charge provided to the battery during the charging phase,

[0258] the second capacity being a function of the low capacity, the high capacity and the total capacity.

[0259] Example 9: The method according to Example 8, wherein determining the second capacity further comprises:

[0260] determining an ideal capacity (Qideal) of the battery indicative of the capacity of the battery if, during the charging phase, the battery has been subject to a constant voltage condition; and

[0261] determining a correction factor (a) that is a function of a ratio between the total capacity (Qtotal) and the ideal capacity (Qideal),

[0262] the low capacity (Qlow) and the high capacity (Qhigh) being a function of the correction factor.

[0263] Example 10: The method according to Example 9, wherein determining an ideal capacity (Qideal) comprises:determining an open circuit voltage (OCVend) at the end of the charging phase, based on the charging data;

[0264] determining an ideal state of charge (SOCocv) of the battery as a function of the open circuit voltage (OCVend) at the end of the charging phase,

[0265] the ideal capacity being a function of the ideal state of charge (SOCocv) and the state of charge (SOCBOC) of the battery at the beginning of the charging phase.

[0266] Example 11: The method according to any of Examples 7-10, wherein the charging data is indicative of:

[0267] a state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase; a state of charge (SOCEOC) of the battery (5) at the end of the charging phase; a voltage (VEOC) of the battery at the end of the charging phase;

[0268] a current (IEOC) of the battery at the end of the charging phase; and

[0269] an internal resistance (Rest) of the battery at the end of the charging phase.

[0270] Example 12: The method according to any of Examples 7-11, wherein determining a second capacity (Qadj) of the battery (5) comprises:

[0271] comparing, based on the charging data, the state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase with the state of charge (SOCEOC) of the battery (5) at the end of the charging phase; and

[0272] estimating the second capacity based on the charging data or retrieving the second capacity estimated during a previous charging phase, based on the comparison between the state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase and the state of charge (SOCEOC) of the battery (5) at the end of the charging phase.

[0273] Example 13: The method according to any of Examples 1-12, further comprising initializing (S16) the state of charge of the battery to an initial state of charge (SOC(O)), wherein the state of charge during the discharging phase and / or during the charging phase is determined also based on the initial state of charge,

[0274] wherein initializing the state of charge comprises:

[0275] receiving a first candidate value (SOCprev) indicative of the state of charge of the battery before a latest shutdown event of a system incorporating the battery;

[0276] determining a second candidate value (SOCo) indicative of an actual state of charge of the battery, the second candidate value being determined as a function of an actual open circuit voltage (OCVo) of the battery; andsetting the initial state of charge based on a comparison between the first candidate value and the second candidate value.

[0277] Example 14: The method according to any of Examples 1-13, wherein the charging phase comprises at least one charging step (CSk) being a constant-current charging step.

[0278] Example 15: The method according to any of Examples 1-14, wherein the battery (5) is a battery of a vehicle (3).

[0279] Example 16: The method according to any of Examples 1-15, further comprising providing, to a user interface (29), a signal that is indicative of the estimated state of charge of the battery (5), wherein the signal is configured to indicate the first state of charge while the battery is under charge and to indicate that the battery is fully charged upon completion of the charging phase.

[0280] Example 17: The method according to any of Examples 1-16, further comprising, during the discharging phase, receiving second battery data indicative of at least a current (lb) of the battery (5) during the discharging phase, the second state of charge (SOCdis) of the battery (5) being determined as a function of the second capacity and the second battery data.

[0281] Example 18: A computer program comprising instructions that, when executed by electronic processing resources (6; 40), cause the electronic processing resources to perform a method for estimating the state of charge of a battery (5) during at least one of charging and discharging of the battery according to any of Examples 1-17.

[0282] Example 19: A system (1) comprising:

[0283] a vehicle (3) including a battery (5);

[0284] a detection system (7) that is configured to detect one or more quantities indicative of a functioning of the battery; and

[0285] electronic processing resources (6; 40) configured to estimate the state of charge of the battery (5) during at least one of charging and discharging of the battery, wherein the electronic processing resources are configured to at least one of: during a charging phase of the battery:

[0286] receive first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) detected by the detection system (7) during the charging phase of the battery;

[0287] determine, based on the first battery data, a first capacity (QEOC(J)) of the battery (5); anddetermine a first state of charge (SOCk) of the battery based on the first capacity, and

[0288] during a discharging phase of the battery:

[0289] receive a second capacity (Qadj) of the battery (5) estimated at the end of a charging phase performed before the discharging phase; and

[0290] determine a second state of charge (SOCdis) of the battery (5) based on the second capacity.

[0291] Example 20: The system according to Example 19, wherein at least one of the detection system and the electronic processing resources is included in the vehicle.

Claims

CLAIMS1.- A method, performed by electronic processing resources (6; 40), for estimating the state of charge of a battery (5) during discharging of the battery, wherein the method comprises, during a discharging phase of the battery:receiving a first capacity (Qadj) of the battery (5) estimated at the end of a charging phase occurred before the discharging phase; anddetermining a first state of charge (SOCdis) of the battery (5) based on the first capacity.2.- The method according to the preceding claim, further comprising: detecting (S30), during the charging phase of the battery, a first event indicative of an end of the charging phase of the battery; andin response to the detection of the first event, determining (S31, S32, S33) the first capacity of the battery based on charging data indicative of one or more parameters of the battery associated to the charging phase.3.- The method according to the preceding claim, wherein determining the first capacity (Qadj) comprises, based on the charging data:determining a low capacity (Qlow) of the battery indicative of the capacity of the battery corresponding to the state of charge (SOCBOC) of the battery at the beginning of the charging phase;determining a high capacity (Qhigh) of the battery indicative of the capacity of the battery corresponding to a state of charge (SOCEOC) of the battery at the end of the charging phase; anddetermining a total capacity (Qtotal) of the battery indicative of the amount of charge provided to the battery during the charging phase,the first capacity being a function of the low capacity, the high capacity and the total capacity.4.- The method according to the preceding claim, wherein determining the first capacity further comprises:determining an ideal capacity (Qideal) of the battery indicative of the capacity of the battery if, during the charging phase, the battery has been subject to a constant voltage condition; anddetermining a correction factor (a) that is a function of a ratio between the total capacity (Qtotal) and the ideal capacity (Qideal),the low capacity (Qlow) and the high capacity (Qhigh) being a function of the correction factor.5.- The method according to the preceding claim, wherein determining an ideal capacity (Qideal) comprises:determining an open circuit voltage (OCVend) at the end of the charging phase, based on the charging data;determining an ideal state of charge (SOCocv) of the battery as a function of the open circuit voltage (OCVend) at the end of the charging phase,the ideal capacity being a function of the ideal state of charge (SOCocv) and the state of charge (SOCBOC) of the battery at the beginning of the charging phase.6.- The method according to any of claims 2-5, wherein the charging data is indicative of:a state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase; a state of charge (SOCEOC) of the battery (5) at the end of the charging phase; a voltage (VEOC) of the battery at the end of the charging phase;a current (IEOC) of the battery at the end of the charging phase; andan internal resistance (Rest) of the battery at the end of the charging phase.7.- The method according to any of claims 2-6, wherein determining a first capacity (Qadj) of the battery (5) comprises:comparing, based on the charging data, the state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase with the state of charge (SOCEOC) of the battery (5) at the end of the charging phase; andestimating the first capacity based on the charging data or retrieving the first capacity estimated during a previous charging phase, based on the comparison between the state of charge (SOCBOC) of the battery (5) at the beginning of the charging phase and the state of charge (SOCEOC) of the battery (5) at the end of the charging phase.

8. The method according to any of the preceding claims, the method being further for estimating the state of charge of the battery (5) during charging of the battery, wherein the method comprises, during a charging phase (CSk):receiving first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) during the charging phase of the battery;determining, based on the first battery data, a second capacity (QEOC(J)) of the battery (5); anddetermining a second state of charge (SOC(j)) of the battery based on the second capacity.9.- The method according to the preceding claim, wherein at least one of determining the second state of charge based on the second capacity during the charging phase and determining the first state of charge based on the first capacity during the discharging phase comprise determining the state of charge based on Coulomb counting.10.- The method according to claim 8 or 9, wherein determining the second capacity (QEOC(J)) comprises:determining an internal resistance (Rest(j)) of the battery (5) based on the first battery data;determining a voltage drop (AV(j)) of the battery as a function of the internal resistance and the actual current (lb) of the battery indicated by the first battery data; determining a first open circuit voltage value (OCVEOC(J)) of the battery as a function of the voltage drop;determining a preliminary state of charge value (SOCocv(j)) as a function of the first open circuit voltage value; anddetermining the second capacity (QEOC(J)) as a function of the preliminary state of charge and a nominal capacity (QBOL) of the battery.11.- The method according to the preceding claim, wherein determining an internal resistance comprises:determining an actual open circuit voltage value (OCVin) based on an actual state of charge (SOC(j)) of the battery;determining a voltage parameter (Av(j)) indicative of a difference between the actual open circuit voltage value and the actual voltage (Vb(j )) of the battery.12.- The method according to the preceding claim, wherein the first open circuit voltage value (OCVEOC(J)) is determined as a function of a difference between the voltage drop (AV(j)) and a cutoff voltage associated with an actual charging step (CSk) of the charging phase.13.- The method according to the preceding claim, wherein the first battery data is also indicative of a temperature (Tb) of the battery (5) during the charging phase, the cutoff voltage being a function of the temperature of the battery.14.- The method according to any of claims 8-13, further comprising providing, to a user interface (29), a signal that is indicative of the estimated state of charge of the battery (5), wherein the signal is configured to indicate the second state of charge while the battery is under charge and to indicate that the battery is fully charged upon completion of the charging phase.15.- The method according to any of the preceding claims, further comprising initializing (S16) the state of charge of the battery to an initial state of charge (SOC(O)), wherein the state of charge during the discharging phase and / or during the charging phase is determined also based on the initial state of charge,wherein initializing the state of charge comprises:receiving a first candidate value (SOCprev) indicative of the state of charge of the battery before a latest shutdown event of a system incorporating the battery;determining a second candidate value (SOCo) indicative of an actual state of charge of the battery, the second candidate value being determined as a function of an actual open circuit voltage (OCVo) of the battery; andsetting the initial state of charge based on a comparison between the first candidate value and the second candidate value.16.- The method according to any of the preceding claims, wherein the charging phase comprises at least one charging step (CSk) being a constant-current charging step.17.- The method according to any of the preceding claims, wherein the battery (5) is a battery of a vehicle (3).18.- The method according to any of the preceding claims, further comprising, during the discharging phase, receiving second battery data indicative of at least a current (lb) of the battery (5) during the discharging phase, the first state of charge (SOCdis) of the battery (5) being determined as a function of the first capacity and the second battery data.19.- A method, performed by electronic processing resources (6; 40), for estimating the state of charge of a battery (5) during charging of the battery, wherein the method comprises, during a charging phase (CSk):receiving first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) during the charging phase of the battery;determining, based on the first battery data, a first capacity (QEOC(J)) of the battery (5); anddetermining a first state of charge (SOC(j)) of the battery based on the first capacity.20.- The method according to the preceding claim, wherein determining the first state of charge based on the first capacity during the charging phase comprises determining the state of charge based on Coulomb counting.21.- The method according to claim 19 or 20, wherein determining the first capacity (QEOC(J)) comprises:determining an internal resistance (Rest(j)) of the battery (5) based on the first battery data;determining a voltage drop (AV(j)) of the battery as a function of the internal resistance and the actual current (lb) of the battery indicated by the first battery data; determining a first open circuit voltage value (OCVEOC(J)) of the battery as a function of the voltage drop;determining a preliminary state of charge value (SOCocv(j)) as a function of the first open circuit voltage value; anddetermining the first capacity (QEOC(J)) as a function of the preliminary state of charge and a nominal capacity (QBOL) of the battery.22.- The method according to the preceding claim, wherein determining an internal resistance comprises:determining an actual open circuit voltage value (OCVin) based on an actual state of charge (SOC(j)) of the battery;determining a voltage parameter (Av(j)) indicative of a difference between the actual open circuit voltage value and the actual voltage (Vb(j)) of the battery.23.- The method according to the preceding claim, wherein the first open circuit voltage value (OCVEOC(J)) is determined as a function of a difference between the voltage drop (AV(j)) and a cutoff voltage associated with an actual charging step (CSk) of the charging phase.24.- The method according to the preceding claim, wherein the first battery data is also indicative of a temperature (Tb) of the battery (5) during the charging phase, the cutoff voltage being a function of the temperature of the battery.25.- The method according to any claims 19-24, further comprising initializing (S16) the state of charge of the battery to an initial state of charge (SOC(O)), wherein the state of charge during the charging phase is determined also based on the initial state of charge,wherein initializing the state of charge comprises:receiving a first candidate value (SOCprev) indicative of the state of charge of the battery before a latest shutdown event of a system incorporating the battery;determining a second candidate value (SOCo) indicative of an actual state of charge of the battery, the second candidate value being determined as a function of an actual open circuit voltage (OCVo) of the battery; andsetting the initial state of charge based on a comparison between the first candidate value and the second candidate value.26.- The method according to any claims 19-25, wherein the charging phase comprises at least one charging step (CSk) being a constant-current charging step.27.- The method according to any claims 19-26, wherein the battery (5) is a battery of a vehicle (3).28.- The method according to any of claims 19-27, further comprising providing, to a user interface (29), a signal that is indicative of the estimated state of charge of the battery (5), wherein the signal is configured to indicate the first state of charge while the battery is under charge and to indicate that the battery is fully charged upon completion of the charging phase.29.- A computer program comprising instructions that, when executed by electronic processing resources (6; 40), cause the electronic processing resources to perform a method for estimating the state of charge of a battery (5) according to any of the preceding claims.30.- A system (1) comprising:a vehicle (3) including a battery (5);a detection system (7) that is configured to detect one or more quantities indicative of a functioning of the battery; andelectronic processing resources (6; 40) configured to estimate the state of charge of the battery (5) during discharging of the battery,wherein the electronic processing resources are configured toduring a discharging phase of the battery:receive a first capacity (Qadj) of the battery (5) estimated at the end of a charging phase performed before the discharging phase; anddetermine a first state of charge (SOCdis) of the battery (5) based on the first capacity.31.- A system (1) comprising:a vehicle (3) including a battery (5);a detection system (7) that is configured to detect one or more quantities indicative of a functioning of the battery; andelectronic processing resources (6; 40) configured to estimate the state of charge of the battery (5) during charging of the battery,wherein the electronic processing resources are configured to, during a charging phase of the battery:receive first battery data indicative of at least a voltage (Vb) and a current (lb) of the battery (5) detected by the detection system (7) during the charging phase of the battery;determine, based on the first battery data, a first capacity (QEOC(J)) of the battery (5); anddetermine a first state of charge (SOCk) of the battery based on the first capacity.32.- The system according to claim 30 or 31, wherein at least one of the detection system and the electronic processing resources is included in the vehicle.

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