Method for determining the number of charge-discharge cycles of a battery, method and associated devices

Abstract

Method for determining the number of charge-discharge cycles of a battery, method and associated devices. The present invention relates to a method for determining the number of charge and discharge cycles of an electrochemical cell of a battery at several depths of discharge, the method comprising the following steps: - obtaining the evolution of the state of charge at several instants, - for the first instant, initialization of a reference value for each class, each class being defined by a respective depth of discharge threshold, - for each subsequent instant, counting the number of cycles in each class by: - ​​for each class, increasing the number of cycles by 1 if an increase condition is met, the increase condition being a comparison criterion relating to the evolution of the state of charge, and - decreasing the number of cycles in each class at the instant considered if an increase has occurred.Figure for the abbreviation: figure 2.

Description

Title of the invention: Method for determining the number of charge-discharge cycles of a battery, method and associated devices. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method for determining the number of charge and discharge cycles of at least one electrochemical cell of a battery at a given depth of discharge. The present invention also relates to an estimation method comprising the implementation of the determination method as well as devices, namely a computer, a management system, and a battery. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Typically, a battery comprises one or more current storage cells, also called electrochemical generators, cells, or elements. A battery is an electricity-producing device in which chemical energy is converted into electrical energy. The chemical energy comes from electrochemically active compounds deposited on at least one face of electrodes arranged in the battery. The electrical energy is produced by electrochemical reactions during a discharge of the battery. The electrodes, arranged in a container, are electrically connected to current output terminals that ensure electrical continuity between the electrodes and an electrical load to which the battery is connected.

[0003] To increase the electrical power delivered, several sealed accumulators can be connected together to form a battery. Thus, a battery can be divided into modules, each module being composed of one or more accumulators connected together in series and / or in parallel. For example, a battery may comprise one or more parallel branches of accumulators connected in series and / or one or more parallel branches of modules connected in series.

[0004] A charging circuit is generally provided to which the battery can be connected to recharge the accumulators.

[0005] Furthermore, an electronic management system comprising measurement sensors and an electronic control circuit, more or less sophisticated depending on the application, can be associated with the battery. Such a system makes it possible, in particular, to organize and control the charging and discharging of the battery, in order to balance the charging and discharging of the different cells of the battery with respect to each other.

[0006] The battery health status is useful information for the electronic battery management system to optimize its use and lifespan. The battery health status is often designated by the abbreviation SOH which refers to the English term "State of Health".

[0007] The state of health (SOH) allows us to estimate the aging of the battery between a new state and an end-of-life state, or more generally, between an initial state and a final state.

[0008] One of the factors strongly influencing the state of health SOH is the number of charge and discharge cycles that the battery has undergone at a given depth of discharge.

[0009] The depth of discharge is often referred to by the abbreviation DoD. The term "DoD" refers to the English term "Depth of Discharge," literally meaning "depth of discharge."

[0010] It is therefore desirable to be able to count the charge and discharge cycles accurately.

[0011] A known technique is to use a fixed number of depth thresholds and to count the cycles respecting these depth thresholds.

[0012] However, such a technique has the disadvantage of not being easily adaptable.

[0013] Another known technique is to use a rainflow counting algorithm (more commonly referred to by the corresponding English term "rainflow counting").

[0014] Such a technique avoids overestimation but at the cost of increased complexity. Indeed, this rainflow counting technique involves recording the evolution of the state of charge over a time window representative of battery usage (for example, a day). The memory resources involved are therefore very significant, making the implementation of this technique incompatible with the requirements of embedded applications. Summary of the invention

[0015] There is therefore a need for a method of determining the number of charge and discharge cycles of an electrochemical element of a battery at several given depths of discharge, which makes it possible to obtain the most accurate number of cycles possible while keeping implementation possible with the resources of a computer of a battery management system.

[0016] To this end, the description relates to a method for determining the number of charge and discharge cycles of at least one electrochemical cell of a battery at several given depths of discharge, the method being implemented by a computer and comprising:

[0017] - a phase of obtaining discharge depth thresholds, each defining a respective discharge depth class, and

[0018] - a phase of determining the number of charge and discharge cycles of the minus one electrochemical element at several given discharge depths, the determination phase comprising the following steps:

[0019] - obtaining the evolution of the state of charge of at least one element electrochemical analysis at several measurement points

[0020] - for the first measurement instant of measurement instants, initialization of a reference value of each class to the value of the state of charge of the electrochemical element at the first instant of measurement,

[0021] - for each measurement instant subsequent to the first measurement instant, Counting the number of cycles in each class by implementing two successive sub-steps:

[0022] - a first sub-step during which, for each class, the number of cycles in the class at the time of measurement considered is increased by 1 if an increase condition is met, the increase condition being a criterion for comparing the evolution of the state of charge relative to the reference value of the class and the depth of discharge threshold of said class, and

[0023] - a second sub-step during which, the number of cycles in each class at the measurement time considered is decreased according to at least one decrease rule if an increase occurred during the first sub-step,

[0024] the number of cycles obtained at the end of the counting step for each class being the number of cycles to be determined.

[0025] Such a determination method makes it possible to meet the aforementioned need to obtain the most precise number of cycles possible with possible implementation in embedded systems.

[0026] Furthermore, this process offers a significant operational advantage: the discharge depths are adjustable, both in number and value, according to the user's needs. This flexibility is particularly useful when specific monitoring is required.

[0027] According to other advantageous aspects, the determination method comprises one or more of the following features, taken individually or in all technically possible combinations:

[0028] - each class being identified by a respective class index, the class indices being ordered by increasing discharge depth threshold, the first substep of the counting step is a first loop comprising an iteration of operations, each iteration of the first loop being identified by a first integer iteration variable initialized to a value of 1, and the second substep of the counting step is a second loop comprising an iteration of operations, each iteration of the second loop being identified by a second integer iteration variable initialized to a value of 2.

[0029] - the operations of the first loop include:

[0030] - determination if the current value of the first iteration variable is indeed i less than or equal to the number of classes, the first loop being terminated otherwise,

[0031] - a first test to determine if a condition according to which at least one An electrochemical element is in a phase where the charge is filled.

[0032] the reference value of the class whose index is equal to the value of the iteration variable being modified to the value of the state of charge of at least one electrochemical element at the time of measurement when the value of the state of charge of at least one electrochemical element at the time of measurement is less than the reference value of the class whose index is equal to the value of the iteration variable and the second test operation not being implemented when the condition of the first test is not met,

[0033] - a second test to determine if the increase condition is met and when the increase condition is met, increase by 1 the number of cycles of the class whose index is the first iteration variable and change the reference value to the value of the state of charge of at least one electrochemical element measured at the time of measurement considered for each class whose index is less than or equal to the value of the first iteration variable, and

[0034] - incrementing the first iteration variable by 1.

[0035] - the condition for increasing a class is that the difference between the value of the state of charge of at least one electrochemical element measured at the time of measurement and the reference value of the class whose index is the value of the first iteration variable is greater than or equal to the discharge depth threshold of the class.

[0036] - the second loop includes the following operations:

[0037] - determination if the current value of the second iteration variable is indeed less than or equal to the number of classes, the second loop being terminated otherwise,

[0038] - a test to determine if a condition under which a cycle has been counted in The class whose index is the value of the second iteration variable during the first loop is filled.

[0039] the number of cycles of at least one class being decreased according to at least one decrease rule when the condition of the test operation is met, and

[0040] - incrementing the second iteration variable by 1.

[0041] - a reduction rule is that, for the class whose index is equal to the value of the second iteration variable minus one, the number of cycles is decreased by 1.

[0042] - a reduction rule is that the number of cycles is decreased by 1 for a class whose discharge depth threshold is closest to a difference between two discharge depth thresholds among the discharge depth thresholds less than or equal to the difference, the difference being the difference between the discharge depth threshold of the class whose index is equal to the value of the second iteration variable and the discharge depth threshold of the class whose index is equal to the value of the second iteration variable minus 1.

[0043] - the reduction rule is implemented according to several iterations, each iteration decreasing the number of cycles by 1 for a class whose depth of discharge threshold is closest to a difference while being less than or equal to it, the difference being the difference between the difference of the previous iteration and the depth threshold of the class whose number of cycles was decreased by 1 in the previous iteration, the difference in the first iteration being the difference between the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable and the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable minus 1, the iterations being implemented as long as a decrease for a class takes place.

[0044] - the obtaining phase includes an optimization of the numbers and values ​​of the discharge depth thresholds, with optimization taking into account the computer's capabilities.

[0045] - the obtaining phase includes an optimization of the numbers and values ​​of the discharge depth thresholds, with optimization taking into account the use of at least one electrochemical element.

[0046] The description also relates to a method for estimating a parameter relating to the health status of at least one electrochemical element of a battery, the estimation method comprising the steps of:

[0047] - implementation of a method for determining a number of load cycles and discharging at least one electrochemical element to several given discharge depths, the process being as previously described, and

[0048] - estimation of a parameter relating to the health status of at least one element electrochemical based on the determined number of cycles.

[0049] The description also relates to a calculator designed to determine the number of charge and discharge cycles of at least one electrochemical cell of a battery at several given depths of discharge, the calculator being designed to:

[0050] - obtain discharge depth thresholds, each defining a class of respective discharge depths,

[0051] - determine the number of charge and discharge cycles of at least one element electrochemical at several given discharge depths, the calculator determining the number of cycles in:

[0052] - receiving the evolution of the state of charge of at least one electrochemical element at several moments of measurement,

[0053] - for the first measurement instant of measurement instants, initializing a value of reference of each class to the value of the state of charge of the electrochemical element at the first instant of measurement,

[0054] - for each measurement instant subsequent to the first measurement instant, counting the number of cycles in each class by implementing two successive actions:

[0055] - a first action during which, for each class, the number of cycles in The class at the time of measurement is increased if an increase condition is met, the increase condition being a criterion for comparing the evolution of the state of charge relative to the reference value of the class and the discharge depth threshold of said class, and

[0056] - a second action during which the number of cycles in each class to The measurement time considered is decreased according to at least one decrease rule if an increase occurred during the first sub-step.

[0057] the number of cycles obtained from the implementation of all the actions for each class being the number of cycles to be determined.

[0058] The description also relates to a management system for at least one electrochemical cell of a battery, the at least one electrochemical cell having terminals, the management system comprising:

[0059] - a voltage sensor suitable for measuring the voltage across said at least one electrochemical element, and

[0060] - a calculator as previously described.

[0061] The description also relates to a battery comprising:

[0062] - at least one electrochemical element, and

[0063] - a management system as previously described.

[0064] In this description, the expression "specific to" means interchangeably "suitable for", "adapted to" or "configured for". BRIEF DESCRIPTION OF THE FIGURES

[0065] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0066] - [Fig. 1] [Fig. 1] is a schematic representation of an example of a battery comprising an electrochemical element,

[0067] - [Fig.2] [Fig.2] is a flowchart of an example of the implementation of a method for determining the number of charge and discharge cycles of the electrochemical element of [Fig. 1] at several given discharge depths,

[0068] - [Fig.3] [Fig.3] is a schematic representation of an example of variation state of charge of the electrochemical element of [Fig. 1], and

[0069] - [Fig.4] [Fig.4] is a schematic representation of another example of variation in the state of charge of the electrochemical element of [Fig.1]. DESCRIPTION OF PREFERRED EMBODIMENT MODES System Description

[0070] A battery 10 is shown in [Fig.1].

[0071] In a manner known per se, a battery is generally an arrangement of a plurality of electrochemical elements but in the interest of simplifying the subject, a case with a single electrochemical element is described in what follows, knowing that the transposition to other arrangements is immediate.

[0072] The battery 10 comprises an electrochemical element 12 and a management system 14 for the electrochemical element 12.

[0073] As explained previously, an electrochemical element 12 is an electricity-producing device in which chemical energy is converted into electrical energy.

[0074] The electrochemical element 12 therefore delivers a current and a voltage between two terminals.

[0075] The chemistry of the electrochemical element 12 is irrelevant here, the process described later being able to be used for any type of electrochemical element 12.

[0076] The management system 14 is a system specifically designed to manage the electrochemical element 12.

[0077] The management system 14 includes a voltage sensor 16, a current sensor 18, a temperature sensor 20 and a calculator 22.

[0078] The voltage sensor 16 is suitable for measuring the voltage across the terminals of the electrochemical element 12.

[0079] The current sensor 18 is suitable for measuring the current delivered by the electrochemical element 12.

[0080] The temperature sensor 20 is suitable for measuring the temperature of the electrochemical element 12.

[0081] The calculator 22 is suitable for implementing a determination method described below.

[0082] The calculator 22 is an electronic circuit designed to manipulate and / or transform data represented by electronic or physical quantities in calculator registers and / or memories in other similar data corresponding to physical data in register memories or other types of display devices, transmission devices or storage devices.

[0083] As specific examples, the computer 22 includes a single-core or multi-core processor (such as a central processing unit (CPU), a graphics processing unit (GPU), a microcontroller and a digital signal processor (DSP)), a programmable logic circuit, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic device (PLD) and programmable logic arrays (PLAs), a state machine, a logic gate and discrete hardware components.

[0084] General description of a determination method

[0085] An example of implementation of the determination process is now described with reference to the flowchart of [Fig.2] and to the example of [Fig.3] which illustrates the steps of the process.

[0086] The determination method is a method for determining the number of charge and discharge cycles of the electrochemical element 12 at several given discharge depths.

[0087] The process comprises a production phase PI and a determination phase P2.

[0088] During the PI acquisition phase, the calculator 22 obtains discharge depth thresholds.

[0089] For example, the discharge depth thresholds are equally distributed between 0 and 100% but any distribution of the thresholds is conceivable, including cases where the discharge depth thresholds are not equally distributed.

[0090] In the example given for illustration purposes, there are 3 depth of discharge thresholds, namely a first depth of discharge threshold ADODi at 25%, a second depth of discharge threshold ADOD2 at 50% and a third depth of discharge threshold ADOD3 at 75%.

[0091] The discharge depth thresholds each define a respective discharge depth class.

[0092] By the term "respective" in this context, it is understood that a discharge depth class groups together all charge and discharge cycles at a discharge depth greater than or equal to the discharge depth threshold of the class, while being strictly less than the discharge depth threshold of the nearest higher class.

[0093] Thus, a class of discharge depths groups together all cycles whose discharge depth is continuously between two values, the value

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] lower being the discharge depth threshold of the class and upper being the discharge depth threshold of the higher class. Thus, a discharge depth class designates a range of discharge depth values ​​for which the same discharge depth threshold is associated. By hypothesis, it is possible to disregard cycles whose depth of discharge is between 0% and the depth of discharge threshold of the first class. Each class is identified by a respective class index, with the class indices being ordered by increasing discharge depth threshold. For the rest of this text, a class is thus denoted Q where i is the index. In the three-threshold example, there are three classes, a first class Ci corresponding to the first discharge depth threshold ADODi, a second class C2 corresponding to the second discharge depth threshold ADOD2 and a third class C3 corresponding to the third discharge depth threshold adod3. Calculator 22 obtains the depth of discharge thresholds here by reading from a memory or by receiving values ​​from outside. The P2 determination phase aims to determine the number of cycles of the electrochemical element 12 at several given discharge depths. The determination phase P2 includes a obtaining step E10, an initialization step E20 and a counting step E30. During the E10 acquisition step, the calculator 22 obtains the evolution of the state of charge of the electrochemical element 12 at several measurement times. The state of charge is often referred to by the abbreviation SOC, which stands for "State of Charge". To obtain the state of charge SOC, the calculator 22 can use calculation techniques using continuous measurements of the evolution of voltage, current and temperature (those from sensors 16, 18 and 20). For example, a particular technique can be described as "coulometric" insofar as it utilizes the fact that the state of charge SOC depends on the charge (Ampere-hour count) and the capacity Q of the battery. Indeed, the following formulas are used: SOC = SOC^-^q- Where: SOC0 is the initial value of the charge state SOC at time t=0.

[0109] The calculator 22 can, alternatively, use other techniques to know the value of the state of charge of the electrochemical element 12 at several instants which are referred to hereafter as measurement instants.

[0110] During the initialization step E20, for each class, the calculator 22 initializes a reference value associated with the class to the value of the state of charge of the electrochemical element 12 at the first measurement instant.

[0111] For the index class i, the corresponding reference value is referred to in the following as reference value

[0112] By definition, the reference value Srefj is the minimum value of the class Ci from which the enumeration is performed.

[0113] More specifically, this means that a cycle will be added in class C; if the measured state of charge becomes equal to or exceeds the sum of the reference value Srefj and the depth of charge threshold and that the reference value Srefj will then be updated to this sum (this corresponding substantially to the measured state of charge).

[0114] This reference value Srefj therefore takes into account on the one hand the evolution of the measurement of the state of charge but also the fact that a cycle has been counted.

[0115] At the beginning of the process, the reference values ​​Srefj of each Ci are therefore identical but will be modified as the process is implemented, as will appear later in the description.

[0116] The counting step E30 aims to determine the number of cycles of the electrochemical element 12 in each class Ci.

[0117] For this purpose, the calculator 22 implements, for each measurement instant subsequent to the first measurement instant, two successive loops.

[0118] A flowchart of the first loop B1 is visible on the right (top) part of [Fig.2].

[0119] To better understand this flowchart, the reader can read in parallel the simplified example presented in the "examples" section which illustrates a simple implementation of the loops described.

[0120] The first loop B1 is a loop for increasing the number of cycles in each class at the measurement time considered.

[0121] The first loop B1 thus comprises a set of iterations of operations, each iteration being identified by a first iteration variable VIL

[0122] The first iteration variable Vil is an integer and is initialized to a value of 1.

[0123] In other words, the first loop B1 includes an initialization of the first iteration variable to a value of 1 (see square 40 on [Fig.2]) and then an iteration of operations.

[0124] The operations include a determination operation 01, a first test operation 02, a second test operation 03 and an increment operation 04.

[0125] As will become apparent later, depending on the results of the determination or testing operations, only a portion of the operations are implemented. These results may vary from one iteration to another, so that in one iteration only a portion of the operations are implemented, while in another iteration all the steps are implemented.

[0126] In addition, it was chosen to reserve the term incrementation for iteration variables and the term augmentation for the number of cycles of a class.

[0127] During the determination operation 01, the calculator 22 determines whether the current value of the first iteration variable Vil is less than or equal to the number of classes.

[0128] If the current value of the first iteration variable Vil satisfies such a condition, the first test operation 02 is implemented.

[0129] Otherwise, the first loop B1 is finished and the calculator 22 moves on to the second loop B2.

[0130] This determination operation 01 aims to avoid performing tests for classes that do not exist.

[0131] The calculator 22 implements the first test to determine whether a condition under which the electrochemical element 12 is in a charging phase is met.

[0132] To determine such a condition, it is sufficient to determine that the state of charge at the time of measurement is greater than the state of charge at the previous time.

[0133] If the condition is not met, the reference value of the class whose index is equal to the value of the first iteration variable, i.e., CVn, is modified to the value of the charge state of the electrochemical element at the time of measurement (for the case, of course, where the value of the charge state of the electrochemical element at the time of measurement is less than the reference value). The other reference values ​​are not modified. They may, however, be modified as the first variable Vil is incremented when the measured charge state value is less than the reference value.

[0134] Furthermore, the second test operation 03 is not implemented so that the calculator 22 goes directly to the increment operation 04.

[0135] During the second test operation 03, the calculator 22 determines whether an increase condition for the class is met.

[0136] The condition for increase here is that the difference between the value of the state of charge of the electrochemical element 12 measured at the time of measurement and the reference value of the class whose index is the value of the first iteration variable must be greater than or equal to the discharge depth threshold of the class. This is mathematically expressed as follows:

[0137] SOC (tmj) - Srefj > ADODi

[0138] Where: • SOC( tnij ) denotes the value of the state of charge of the electrochemical element 12 measured at the measurement time tmj, • ^re / .i denotes the reference value of class Ci, and • M)0Di designates the discharge depth threshold of class Ci.

[0139] Two cases are then possible.

[0140] In the first case, the increase condition is not met.

[0141] In this case, the calculator 22 proceeds to the increment operation 04.

[0142] In the second case, the increase condition is met.

[0143] The calculator 22 increases by 1 the number of cycles of the class whose index is the first iteration variable Vil.

[0144] The calculator 22 also changes the reference value to the value of the state of charge of the electrochemical element 12 measured at the measurement time considered for each class whose index is less than or equal to the value of the first iteration variable VIL

[0145] Then, the calculator 22 implements the increment operation 04.

[0146] During this increment operation 04, the first iteration variable Vil is incremented by 1.

[0147] The calculator 22 then starts again at the determination operation 01.

[0148] The calculator 22 repeats these iterations until it exits the first loop B1 at the outcome of the determination operation 01.

[0149] It may be noted here that if the calculator 22 only implements the first loop Bl, an overcounting phenomenon on the classes of low discharge depths takes place because a charge-discharge cycle is counted each time the threshold is exceeded.

[0150] Typically, if the state of charge goes from 0 to 75% and the depth of discharge threshold is at 25%, the implementation of the first loop Bl leads to counting 3 cycles in the class whose threshold is equal to 25%, whereas we would only want to count 1 cycle in the class at 75% and none in the class at 25%.

[0151] The calculator 22 then implements the operations of the second loop B2.

[0152] A flowchart of the second loop B2 is visible on the right (bottom) part of [Fig.2].

[0153] The second loop B2 is a loop for decreasing the number of cycles in each class at the measurement time considered.

[0154] The second loop B2 thus comprises a set of iterations of operations, each iteration being identified by a second integer iteration variable VI2 initialized to a value of 2.

[0155] In other words, the second loop B2 includes an initialization of the second iteration variable to a value of 2 (see square 50 on [Fig.2]) followed by an iteration of operations.

[0156] The operations include a determination operation T1, a test operation T2 and an increment operation T3.

[0157] During the determination operation T1, the calculator 22 determines whether the current value of the second iteration variable VI2 is less than or equal to the number of classes.

[0158] If the current value of the second iteration variable VI2 satisfies such a condition, the test operation is implemented.

[0159] Otherwise, the second loop B2 is finished.

[0160] This Tl determination operation aims to avoid performing tests for classes that do not exist.

[0161] During the test operation T2, the calculator 22 determines whether a condition is met.

[0162] In the example described, the condition to be met is that a cycle has been counted in the class having as its index the value of the second iteration variable VI2 during the first loop Bl.

[0163] When the condition is not met, the calculator 22 proceeds to the increment operation T3.

[0164] If the test operation condition is met, the calculator 22 reduces the number of cycles by at least one class according to at least one reduction rule.

[0165] According to the example described, a first rule of reduction is that, for the class whose index is equal to the value of the second iteration variable minus one, the number of cycles is reduced by 1.

[0166] Formulated mathematically, this means that the cardinality of the CVi21 cycle is decreased by 1.

[0167] A second reduction rule is also applied by calculator 22.

[0168] According to the second rule, the number of cycles is reduced by 1 for a class whose depth of discharge threshold is less than or equal to a difference between two depth of discharge thresholds and the closest to the difference, the difference being the difference between the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable and the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable minus 1.

[0169] This means that we will determine the class whose depth of discharge threshold is closest to kDODc^ - M)ODcVj:2 [ while being less than or equal to it and we will decrease the associated number of cycles by 1.

[0170] In the example described with reference to Figure 3, these two reduction rules are sufficient, in particular because the discharge depth thresholds are equally distributed, so that necessarily, there exists a class satisfying NDODq^ - ADODçv„

[0171] However, in a general case, the second rule is implemented several times until the difference no longer corresponds to a class.

[0172] To express this iterative process mathematically, it is necessary to take into account that the previous mechanism corresponds to a first iteration of the second rule, so that we will denote Ri the difference M)ODcviy - M)ODcv.y ( and Yi the first threshold corresponding to the depth threshold of the selected class.

[0173] In a second iteration, the calculator 22 calculates a second difference R2 as the difference between the first difference Ri and the first threshold Yb, that is to say:

[0174] R2 = RrYi

[0175] The calculator 22 then checks if there is a depth threshold less than or equal to the second difference R2, and if there are several, the calculator 22 selects the largest. This threshold is the second threshold Y2.

[0176] The calculator 22 counts one cycle in the class whose depth threshold is the second threshold Y2.

[0177] In a third iteration, the calculator 22 calculates a third difference R3 as the difference between the second difference R2 and the second threshold Yb, that is to say:

[0178] R3 = R2Y2

[0179] The calculator 22 then checks if there is a depth threshold less than or equal to the third difference R3, and if there are several, the calculator 22 selects the largest. This threshold is the third threshold Y3.

[0180] The calculator 22 counts one cycle in the class whose depth threshold is the third threshold Y3.

[0181] The iterations continue until there is no depth threshold less than or equal to the last calculated difference.

[0182] This happens either because the last calculated difference is zero, or because the last calculated difference is strictly less than the smallest depth threshold value.

[0183] The previous case corresponds to the special case where a single iteration is sufficient.

[0184] However, in general, the number of iterations is greater, especially when a large number of discharge depth thresholds are used.

[0185] To give a numerical example, let us assume the case of a class corresponding to 75%, a class corresponding to 20% and a class corresponding to 10% and that it is appropriate to apply the second rule of reduction.

[0186] At the first iteration, the difference used in the second rule is then 75% - 20% = 55%. Since the depth threshold of 20% is less than 55% and the closest, the number of cycles in the class corresponding to 20% is reduced by 1.

[0187] In the second iteration, the difference used in the second rule is then 55% - 20% = 35%. Since the depth threshold of 20% is closest to 35%, the number of cycles in the class corresponding to 20% is again reduced by 1.

[0188] At the third iteration, the difference used in the second rule is then 35% - 20% = 15%. Since the depth threshold of 10% is the closest to 15% but lower than it, the number of cycles in the class corresponding to 10% is reduced by 1.

[0189] At the fourth iteration, the difference used in the second rule is then 15% - 10% = 5%. No class corresponds to this value. The number of cycles remains unchanged. The iterations of the second rule are complete.

[0190] After application of these rules, the calculator 22 proceeds to the increment operation T3.

[0191] During this increment operation T3, the second iteration variable VI2 is increased by 1.

[0192] The iteration then starts again at the TL determination operation

[0193] The calculator 22 repeats these iterations until it exits the second loop B2 at the end of the TL determination operation

[0194] The two loops B1 and B2 are repeated successively for each measurement instant as will now be described for the case of the example corresponding to the case of [Fig.3].

[0195] The determination process therefore makes it possible to obtain the most precise number of cycles possible.

[0196] This precision is accompanied by a better adaptability of the discharge depth thresholds involved.

[0197] In fact, simply changing the thresholds obtained during the determination phase is sufficient to achieve suitable operation with different thresholds. The determination phase is completely independent of the value and number of the discharge depth thresholds.

[0198] The method thus makes it very easy to modify the configuration of the discharge depth thresholds, that is to say, to modify the number of thresholds and / or the value of the thresholds according to the needs of the application and this without loss of precision.

[0199] This absence of loss of precision has been demonstrated experimentally by the applicant for the example of [Fig.4].

[0200] This allows for consideration of more elaborate embodiments where the obtaining phase includes an optimization of the configuration of the discharge depth thresholds (number and values) according to one or more criteria.

[0201] An example of a criterion is the use of the electrochemical element 12. Typically, an optimal configuration could, for example, be 10 thresholds between 50 and 80% if the use implies that the battery cycles 10 to a depth of discharge between 60% and 70%.

[0202] Another example of a criterion is the capacity (calculating and / or memorization) of calculator 22.

[0203] Thus, if the computing / memory resources of the computer 22 are very large, more thresholds can be added. This is particularly the case for a computer 22 that is not embedded.

[0204] Such a determination method is advantageously used to estimate a parameter relating to the state of health of the electrochemical element 12.

[0205] Such an estimation process then includes a step of implementing the previous determination process and a step of estimating the parameter relating to the state of health of the electrochemical element 12 from the number of cycles determined.

[0206] For example, the estimation step may consist of using an aging law or a table associating a number of cycles with a parameter relating to health status.

[0207] According to another embodiment, in the discharge phase, the first test is simpler, the condition being to determine that the state of charge of the electrochemical element 12 at the time of measurement is greater than the reference value of class i.

[0208] This reduces the computational load of calculator 22. Examples of process implementation Simplified example

[0209] In the case of [Fig.3], these measurement points are noted A, B, C, D and E.

[0210] In this example, the measurement points are spaced 25% apart in state of charge, so the value of the state of charge is 0% at measurement point A, 25% at measurement point B, 50% at measurement point C, 75% at measurement point D and 100% at measurement point E.

[0211] The example described here is simplified insofar as, in reality, the state of charge is monitored in real time, so that between each measurement point A, B, C, D or E, there are multiple measurement points which we do not consider in the following description.

[0212] In the example described, we wish to determine the number of cycles for each of the three discharge depth thresholds ADODi, ADOD2 and ADOD3.

[0213] In other words, the calculator 22 seeks to count the number of cycles of each of the three classes Ci C2 and C3.

[0214] The associated depth thresholds are 25%, 50% and 75%.

[0215] The initialization step 20 initializes the reference values ​​of the three classes Ci C2 and C3.

[0216] In the example described, these reference values ​​are initialized to 0%.

[0217] In practice, the reference values ​​are not initialized at 0% but result from a decrease in the state of charge during a discharge phase leading to a gradual decrease in the value of each of the reference values ​​(each time the measured value is less than the current reference value for the class), until reaching 0%.

[0218] The counting step 30 begins with the implementation of the two loops B1 and B2 for the second measurement instant B.

[0219] At the second measurement instant B, the value of the state of charge of the electrochemical element 12 is 25%.

[0220] At the first iteration of the first loop Bl, the first iteration variable is 1 and therefore the determination operation leads to the implementation of the first test operation.

[0221] The first test operation is positive since the electrochemical element 12 is charged.

[0222] The difference between the value of the state of charge of the measured electrochemical element 12 (25%) and the reference value for the first class Ci (0%) is equal to 25%, so that the depth of discharge is reached for this first class Cp

[0223] We then count one cycle in the first class Ci and we change the reference value for the first class Ci to the value of the charge state of the measured electrochemical element 12 (25%).

[0224] The first iteration variable is incremented to a value of 2.

[0225] At the second iteration of the first loop Bl, the first iteration variable is equal to 2 and therefore the determination operation leads to the implementation of the first test operation.

[0226] The first test operation is positive since the electrochemical element 12 is charged.

[0227] The difference between the value of the charge state of the measured electrochemical element 12 (25%) and the reference value for the second class C2 (0%) is equal to 25%.

[0228] This is strictly less than the discharge depth associated with the second class C2 (50%), so that the calculator 22 goes directly to the increment operation T3.

[0229] The first iteration variable is incremented to a value of 3.

[0230] At the third iteration of the first loop Bl, the first iteration variable is 3 and therefore the determination operation leads to the implementation of the first test operation.

[0231] The first test operation is positive since the electrochemical element 12 is charged.

[0232] The difference between the value of the state of charge of the measured electrochemical element 12 (25%) and the reference value for the third class C3 (0%) is equal to 25%.

[0233] This is strictly less than the discharge depth associated with the third class C3 (75%), so that the calculator 22 goes directly to the increment operation T3.

[0234] The first iteration variable Vil is incremented to a value of 4.

[0235] At the fourth iteration of the first loop B1, the first iteration variable Vil is equal to 4 and therefore the determination operation leads to identifying that the first iteration variable is strictly greater than the total number of classes (3 here).

[0236] The first loop B1 therefore stops and the calculator 22 moves on to the second loop B2.

[0237] At the first iteration of the second loop B2, the second iteration variable is 2 and therefore the determination operation leads to the implementation of the test operation.

[0238] During the test operation, the computer 22 determines that the number of cycles of the second class C2 was not increased during the first BL loop

[0239] The increment operation 04 is then implemented by the computer 22, the second iteration variable VI2 being incremented to 3.

[0240] At the second iteration of the second loop B2, the determination operation leads to identifying that the second iteration variable is equal to the total number of classes (3 here).

[0241] During the test operation, the computer 22 determines that the number of cycles of the third class C3 was not increased during the first BL loop

[0242] The increment operation 04 is then implemented by the computer 22, the second iteration variable VI2 being incremented to 4.

[0243] At the third iteration of the second loop B2, the determination operation leads to the identification that the second iteration variable VI2 is strictly greater than the total number of classes (3 here).

[0244] The second loop B2 therefore stops.

[0245] At the end of the second loop B2, the number of cycles of the first class Ci is equal to 1, the number of cycles of the other classes C2 and C3 being equal to 0.

[0246] The calculator 22 then proceeds to implement the two loops Bl and B2 for the third measurement instant C.

[0247] At the third measurement instant C, the value of the state of charge of the electrochemical element 12 is 50%.

[0248] As before, the first loop B1 comprises four iterations, the fourth iteration ending at the determination operation.

[0249] Moreover, the first test operation systematically leads to the conclusion here that the electrochemical element 12 is in a charging phase.

[0250] It is the second test operations which will therefore vary from one iteration to another.

[0251] During the first iteration of the first loop B1, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (50%) and the reference value for the first class Ci (25%) is equal to 25%, so that the depth of discharge is reached for this first class Ci.

[0252] The calculator 22 then counts one cycle in the first class Cb, the number of cycles in this class going to 2.

[0253] The calculator 22 also changes the reference value for the first class Ci to the value of the state of charge of the measured electrochemical element 12 (50%).

[0254] During the second iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (50%) and the reference value for the second class C2 (0%) is equal to 50%, so that the depth of discharge is reached for this second class C2.

[0255] The calculator 22 then counts one cycle in the second class C2, the number of cycles in this class going to 1.

[0256] The calculator 22 changes the reference value for the second class C2 to the value of the charge state of the measured electrochemical element 12 (50%).

[0257] The calculator 22 also maintains the reference value for the first class Ci at the value of the state of charge of the measured electrochemical element 12 (50%).

[0258] During the third iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the state of charge of the electrochemical element 12 measured (50%) and the reference value for the third class C3 (0%) is equal to 50%.

[0259] This is strictly less than the discharge depth associated with the third class C3 (75%), so that the calculator 22 goes directly to the increment operation.

[0260] As before, the second loop B2 comprises three iterations, the third iteration ending at the determination operation.

[0261] It is the test operations which will therefore vary from one iteration to another.

[0262] During the test operation of the first iteration of the second loop B2, the Calculator 22 determines that the number of cycles of the second class C2 was increased during the first loop Bl.

[0263] Calculator 22 then applies the reduction rules.

[0264] The first rule leads to decreasing the number of cycles of the first class Ci by 1, so that the number of cycles of the first class Ci becomes 1.

[0265] The second rule then applies as follows.

[0266] At the first iteration, the difference used in the second rule is then 50%-25% = 25%. The depth threshold of 25% being the closest, the number of cycles of the first class Ci is 1, so that the number of cycles of the first class Ci becomes 0.

[0267] At the second iteration, the difference used in the second rule is then 25% - 25% = 0%. No class corresponds to this value. The number of cycles remains unchanged. The iterations of the second rule are complete.

[0268] During the test operation of the second iteration of the second loop B2, the computer 22 determines that the number of cycles of the third class C3 was not increased during the first loop BL

[0269] The increment operation is then implemented by the calculator 22.

[0270] At the end of the second loop B2, the number of cycles of the second class C2 is equal to 1, the number of cycles of the other Ciet C3 classes being equal to 0.

[0271] The calculator 22 then proceeds to implement the two loops Bl and B2 for the fourth measurement instant D.

[0272] At the fourth measurement instant D, the value of the state of charge of the electrochemical element 12 is 75%.

[0273] As before, the first loop B1 comprises four iterations, the fourth iteration ending at the determination operation.

[0274] Moreover, the first test operation systematically leads to the conclusion here that the electrochemical element 12 is in a charging phase.

[0275] It is the second test operations which will therefore vary from one iteration to another.

[0276] During the first iteration of the first loop B1, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (75%) and the reference value for the first class Ci (50%) is equal to 25%, so that the depth of discharge is reached for this first class Ci.

[0277] The calculator 22 then counts one cycle in the first class Ch, the number of cycles in this class going to 1.

[0278] The calculator 22 also changes the reference value for the first class Ci to the value of the state of charge of the measured electrochemical element 12 (75%).

[0279] During the second iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the charge state of the measured electrochemical element 12 (75%) and the reference value for the second class C2 (50%) is equal to 25%.

[0280] This is strictly less than the discharge depth associated with the second class C2 (50%), so that the calculator 22 goes directly to the increment operation.

[0281] During the third iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (75%) and the reference value for the third class C3 (0%) is equal to 75%, so that the depth of discharge is reached for this third class C3.

[0282] The calculator 22 then counts one cycle in the third class Ci, the number of cycles in this class going to 1.

[0283] The calculator 22 also changes the reference value for the second class C2 to the value of the state of charge of the measured electrochemical element 12 (75%).

[0284] The calculator 22 also maintains the reference value for the first class Ci at the value of the state of charge of the measured electrochemical element 12 (75%).

[0285] At the end of the first loop Bl, the number of cycles of each class Ci, C2 and C3 is equal to 1, the number of cycles of classes Ci and C3 having been changed to 1 during this first loop Bl and the number of cycles of the second class C2 not having been changed during the implementation of the first loop B1, it remains at 1.

[0286] As before, the second loop B2 comprises three iterations, the third iteration ending at the determination operation.

[0287] It is the test operations which will therefore vary from one iteration to another.

[0288] During the test operation of the first iteration of the second loop B2, the Calculator 22 determines that the number of cycles of the second class C2 was not increased during the first BL loop

[0289] The increment operation is then implemented by the calculator 22.

[0290] During the test operation of the second iteration of the second loop B2, the computer 22 determines that the number of cycles of the third class C3 was increased during the first loop Bl.

[0291] Calculator 22 then applies the reduction rules.

[0292] The first rule leads to decreasing the number of cycles of the second class C2 by 1, so that the number of cycles of the second class C2 goes to 0.

[0293] The second rule then applies as follows.

[0294] At the first iteration, the difference used in the second rule is then 75%-50% = 25%. Since the depth threshold of 25% is the closest, the number of cycles of the first class Ci is decreased by 1, so that the number of cycles of the first class Ci becomes 0.

[0295] At the second iteration, the difference used in the second rule is then 25% - 25% = 0%. No class corresponds to this value. The number of cycles remains unchanged. The iterations of the second rule are complete.

[0296] At the end of the second loop B2, the number of cycles of the third class C3 is equal to 1, the number of cycles of the other classes Ciet C2 being equal to 0.

[0297] The calculator 22 then proceeds to implement the two loops Bl and B2 for the fifth measurement instant E.

[0298] At the fifth measurement instant E, the value of the state of charge of the electrochemical element 12 is 100%.

[0299] As before, the first loop B1 comprises four iterations, the fourth iteration ending at the determination operation.

[0300] Moreover, the first test operation systematically leads to the conclusion here that the electrochemical element 12 is in a charging phase.

[0301] It is the second test operations which will therefore vary from one iteration to another.

[0302] During the first iteration of the first loop B1, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (100%) and the reference value for the first class Ci (75%) is equal to 25%, so that the depth of discharge is reached for this first class Ci.

[0303] The calculator 22 then counts one cycle in the first class Cb, the number of cycles in this class going to 1.

[0304] The calculator 22 also changes the reference value for the first class Ci to the value of the state of charge of the measured electrochemical element 12 (100%).

[0305] During the second iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the state of charge of the electrochemical element 12 measured (100%) and the reference value for the second class C2 (75%) is equal to 25%.

[0306] This is strictly less than the discharge depth associated with the second class C2 (50%), so that the calculator 22 goes directly to the increment operation.

[0307] During the third iteration of the first loop Bl, the calculator 22 determines that the difference between the value of the state of charge of the measured electrochemical element 12 (100%) and the reference value for the third class C3 (75%) is equal to 25%.

[0308] This is strictly less than the discharge depth associated with the third class C3 (75%), so that the calculator 22 goes directly to the increment operation.

[0309] At the end of the first loop Bl, the number of cycles of the first class Ciet of the third class C3 is equal to 1 while the number of cycles of the second class C2, not having been changed during the implementation of the first loop Bl, remains at 0.

[0310] As before, the second loop B2 comprises three iterations, the third iteration ending at the determination operation.

[0311] It is the test operations which will therefore vary from one iteration to another.

[0312] During the test operation of the first iteration of the second loop B2, the Calculator 22 determines that the number of cycles of the second class C2 was not increased during the first loop Bl.

[0313] The increment operation is then implemented by the calculator 22.

[0314] During the test operation of the second iteration of the second loop B2, the computer 22 determines that the number of cycles of the third class C3 was not increased during the first loop BL

[0315] The increment operation is then implemented by the calculator 22.

[0316] At the end of the second loop B2, the number of cycles of the first class Ci is equal to 1, the number of cycles of the second class C2 is equal to 0 and the number of cycles of the third class C3 is equal to 1.

[0317] These numbers of cycles are those obtained at the end of the counting step for each class. These are the numbers of cycles to be determined.

[0318] The determination process thus leads to a number of cycles of the first class Ci equal to 1, a number of cycles of the second class C2 equal to 0 and a number of cycles of the third class C3 equal to 1. Experiences

[0319] In this example, the method was implemented for four different configurations of discharge depth thresholds.

[0320] The first configuration corresponds to 199 discharge depth thresholds equally distributed between 0.5% and 99.5%, the second configuration to 99 discharge depth thresholds equally distributed between 0.5% and 99.5%, the third configuration to 49 discharge depth thresholds equally distributed between 2% and 98% and the fourth configuration to 19 discharge depth thresholds equally distributed between 5% and 95%.

[0321] These four configurations were used for the charge state variation shown in [Fig. 4], namely 5 cycles at a discharge depth of 90%. The number of measurements here corresponds to a 1% sampling (one measurement is obtained for every 1% variation in the charge state of the electrochemical element 12).

[0322] In all four configurations, the implementation of the determination process leads to a correct evaluation, namely 5 cycles at a discharge depth of 90%.

Claims

Demands

1. A method for determining the number of charge and discharge cycles of at least one electrochemical cell (12) of a battery (10) at several given depths of discharge, the method being implemented by a computer (22) and comprising: - a phase of obtaining depth of discharge thresholds, each defining a respective class of depths of discharge, and - a phase of determining the number of charge and discharge cycles of at least one electrochemical cell (12) at several given depths of discharge, the determination phase comprising the following steps: - obtaining the evolution of the state of charge of at least one electrochemical cell (12) at several measurement instants, - for the first measurement instant, initializing a reference value of each class to the value of the state of charge of the electrochemical cell (12) at the first measurement instant,- For each measurement instant subsequent to the first measurement instant, the number of cycles in each class is counted by implementing two successive sub-steps: - a first sub-step during which, for each class, the number of cycles in the class at the measurement instant considered is increased by 1 if an increase condition is met, the increase condition being a criterion for comparing the evolution of the state of charge relative to the reference value of the class and the discharge depth threshold of said class, and - a second sub-step during which the number of cycles in each class at the measurement instant considered is decreased according to at least one decrease rule if an increase occurred during the first sub-step, the number of cycles obtained at the end of the counting step for each class being the number of cycles to be determined.

2. A method of determination according to claim 1, wherein each class is identified by a respective class index, the class indices being ordered by increasing discharge depth threshold, the first substep of the counting step is a first loop comprising an iteration of operations, each iteration of the first loop being identified by a first integer iteration variable initialized to a value of 1 and the second sub-step of the counting step is a second loop comprising an iteration of operations, each iteration of the second loop being identified by a second integer iteration variable initialized to a value of 2.

3. A method for determining according to claim 2, wherein the operations of the first loop comprise: - determining whether the current value of the first iteration variable is indeed less than or equal to the number of classes, the first loop being terminated otherwise, - a first test to determine whether a condition under which at least one electrochemical element (12) is in a charging phase is met, the reference value of the class whose index is equal to the value of the iteration variable being modified to the value of the charge state of at least one electrochemical element (12) at the time of measurement when the value of the charge state of at least one electrochemical element (12) at the time of measurement is less than the reference value of the class whose index is equal to the value of the iteration variable and the second test operation not being carried out when the condition of the first test is not met,- a second test to determine if the increase condition is met and when the increase condition is met, increase by 1 the number of cycles of the class whose index is the first iteration variable and change the reference value to the value of the state of charge of at least one electrochemical element (12) measured at the measurement time considered for each class whose index is less than or equal to the value of the first iteration variable, and - increment by 1 of the first iteration variable.

4. A method for determining according to claim 2 or 3, wherein the second loop comprises the following operations: - determining whether the current value of the second iteration variable is indeed less than or equal to the number of classes, the second loop being terminated otherwise, - a test to determine if a condition under which a cycle has been counted in the class having as its index the value of the second iteration variable during the first loop is met, the number of cycles of at least one class being decreased according to at least one decrease rule when the condition of the test operation is met, and - incrementing the second iteration variable by 1.

5. A method of determination according to any one of claims 1 to 4, wherein the increase condition for a class is that the difference between the value of the state of charge of at least one electrochemical element (12) measured at the time of measurement and the reference value of the class whose index is the value of the first iteration variable is greater than or equal to the depth of discharge threshold of the class.

6. A method of determination according to any one of claims 1 to 5, wherein a reduction rule is that, for the class whose index is equal to the value of the second iteration variable minus one, the number of cycles is reduced by 1.

7. A method of determination according to any one of claims 1 to 6, wherein a reduction rule is that the number of cycles is reduced by 1 for a class whose depth of discharge threshold is closest to a difference between two depth of discharge thresholds among the depth of discharge thresholds less than or equal to the difference, the difference being the difference between the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable and the depth of discharge threshold of the class whose index is equal to the value of the second iteration variable less 1.

8. A method of determination according to claim 7, wherein the reduction rule is implemented in several iterations, each iteration reducing the number of cycles by 1 for a class whose discharge depth threshold is closest to, but less than or equal to, a difference, the difference being the difference between the difference of the previous iteration and the depth threshold of the class whose number of cycles was reduced by 1 in the previous iteration, the difference in the first iteration being the difference between the discharge depth threshold of the class whose index is equal to the value of the second iteration variable and the the discharge depth threshold of the class whose index is equal to the value of the second iteration variable minus 1, with iterations being implemented as long as a decrease for a class occurs.

9. A method for determining according to any one of claims 1 to 8, wherein the obtaining phase includes an optimization of the numbers and values ​​of the discharge depth thresholds, the optimization taking into account the capabilities of the computer (22).

10. A method for determining according to any one of claims 1 to 9, wherein the obtaining phase includes an optimization of the numbers and values ​​of the depth of discharge thresholds, the optimization taking into account the use of at least one electrochemical element (12).

11. Method for estimating a parameter relating to the health status of at least one electrochemical element (12) of a battery (10), the estimation method comprising the steps of: - implementing a method for determining a number of charge and discharge cycles of at least one electrochemical element (12) at several given depths of discharge, the method being according to any one of the preceding claims, and - estimating a parameter relating to the health status of at least one electrochemical element (12) from the number of cycles determined.

12. A calculator (22) suitable for determining the number of charge and discharge cycles of at least one electrochemical cell (12) of a battery (10) at several given depths of discharge, the calculator (22) being suitable for: - obtaining depth of discharge thresholds, each defining a respective depth of discharge class, - determining the number of charge and discharge cycles of at least one electrochemical cell (12) at several given depths of discharge, the calculator (22) determining the number of cycles by: - ​​receiving the evolution of the state of charge of at least one electrochemical cell (12) at several measurement instants, - for the first measurement instant, initializing a reference value of each class to the value of the state of charge of the electrochemical cell (12) at the first measurement instant, - for each measurement instant subsequent to the first measurement instant, counting the number of cycles in each class by implementing two successive actions: - a first action during which, for each class, the number of cycles in the class at the measurement instant considered is increased if an increase condition is met, the increase condition being a criterion for comparison between the evolution of the state of charge relative to the reference value of the class and the depth of discharge threshold of said class, and - a second action during which the number of cycles in each class at the measurement instant considered is decreased according to at least one reduction rule if an increase took place during the first sub-step, the number of cycles obtained from the implementation of all the actions for each class being the number of cycles to be determined.

13. Management system (14) of at least one electrochemical element (12) of a battery (10), the at least one electrochemical element (12) having terminals, the management system (14) comprising: - a voltage sensor (16) adapted to measure the voltage across said at least one electrochemical element (12), and - a computer (22) according to claim 12.

14. Battery (10) comprising: - at least one electrochemical element (12), and - a management system (14) according to claim 13.

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