PROCEDURE USING A BATTERY STATUS CARD

Description

[0001] The present invention claims priority from French application No. 2012038 filed on 24.11.2020.

[0002] The invention relates to a method for motor vehicles having safety functions powered by an electric battery, and more particularly vehicles with purely electric drive.

[0003] A safety function, or safety device, is defined as a function or device that compromises the safety of the driver or passengers if it malfunctions. In this case, the malfunction is caused by the battery's inability to maintain sufficient voltage for the safety function or safety device following a significant current draw, for example, on the order of 100 A. Examples of functions or devices involving a significant current draw include electric power steering or electric braking systems (such as service brakes, emergency brakes, braking assistance systems, or traction control).

[0004] Throughout this document, "powering on the vehicle" will be understood to mean an action by the driver, for example via an ignition key in a position generally marked by the symbol +APC, powering on computers for the purpose of starting the vehicle but leaving the drive controls inoperative, the vehicle remaining stationary.

[0005] Throughout this document, "starting the vehicle" refers to an additional action by the driver that allows the vehicle to move using its engine. This action occurs after the vehicle's power is switched on, at which point the drive controls become operational. For example, an accelerator pedal becomes operational when the ignition key is turned to a starting position, usually indicated by symbols such as +DEM, START, or READY, which is one or more clicks past the ignition position.

[0006] Throughout this document, stopping the vehicle will be understood as an action opposite to the additional action, this opposite action prohibiting the movement of the vehicle, for example signifying the driver's intention to leave the vehicle by the reverse action of the ignition key returning to the power-on position or a power-off position.

[0007] Vehicle operation will be understood to mean all actions occurring between the moment the vehicle starts and stops.

[0008] We know from patent document EP-A1-1207083 a method for detecting a battery capacity below a threshold, this threshold being sized, for example, to meet the minimum requirements of an electric power steering or electric braking system. If this capacity is below this threshold, this method limits the vehicle's maximum speed, for example.

[0009] Unfortunately, this process assumes that the battery capacity information is reliable, without taking into account any uncertainty, and does not prioritize measures. Therefore, the driver's intentions are directly thwarted by these measures, which may be disproportionate or, conversely, insufficient, thus presenting a safety risk.

[0010] Furthermore, a method according to the preamble of claim 1 is known from US patent document 2017 / 0059661 A1.

[0011] The aim of the invention is to remedy this deficiency by proposing a reliable process.

[0012] To this end, the invention relates to a method for controlling a vehicle battery comprising the battery and a control unit implementing the method, this method performing a first step: causing an electrical load on the battery resulting in a current draw, then determining a pair of values ​​comprising a voltage and an internal resistance of the battery, from the current draw, then the process executes a third step which, starting from a predetermined mapping of voltages as a function of internal resistances comprising at least: a first zone corresponding to a low voltage and / or a high internal resistance, a third zone corresponding to a high voltage and / or a low internal resistance, a second zone, intermediate to the first and third zones, determines, depending on the zone in which the pair of values ​​is located, that: the battery is capable of responding to a predetermined electrical demand if the pair of values ​​is in the third zone, or that the battery is not capable of responding to this predetermined electrical demand if the pair of values ​​is in the first zone, or that an uncertainty remains in responding to this predetermined electrical demand if the pair of values ​​is in the second zone.

[0013] This process is remarkable in that: In the first step, the process determines the current inrush intensity at the time of voltage determination, and the predetermined mapping is further a function of the current inrush intensity, the three zones extending to three volumes, and in the third step, the process determines, based on the three volumes in which the pair of representative values ​​associated with the current inrush intensity is located, that: the battery is capable of responding to the predetermined electrical demand if the pair of values ​​associated with the current inrush intensity is located in the third volume from the third zone, or that the battery is not capable of responding to this predetermined electrical demand if the pair of values ​​associated with the current inrush intensity is located in the first volume from the first zone,or that uncertainty remains in responding to this predetermined electrical demand if the pair of values ​​associated with the current inrush intensity is found in the second volume originating from the second zone.

[0014] Thus the invention allows a more precise gradation of the battery's capacity to respond to the predetermined electrical demand, in particular for a vehicle safety device or function.

[0015] Note that these curves are, for example, increasing and not strictly increasing. Thus, throughout this document, the definition of an increasing curve will include a curve with a constant value on the x-axis or y-axis; that is, a curve that is not strictly decreasing.

[0016] According to one embodiment of the invention, following the third step, the method performs a fifth step consisting of incrementing a first counter by a value of 1 if the battery is not able to respond to this predetermined electrical demand, or incrementing a second counter by a value of 1 if the uncertainty remains in responding to this predetermined electrical demand.

[0017] According to one embodiment, the fifth step resets the first and second counters to zero if the battery is able to meet the predetermined electrical demand.

[0018] According to one embodiment of the invention, following the fifth step, the process executes a sixth step emitting a maximum alert if the first counter is greater than or equal to a first predetermined threshold, or the second counter is greater than or equal to a second predetermined threshold.

[0019] According to one embodiment of the invention, this sixth step issues an intermediate alert if the second counter is greater than or equal to a third predetermined threshold, and is strictly less than the second predetermined threshold, and the first counter is strictly less than the first predetermined threshold.

[0020] According to one embodiment of the invention, if the maximum alert is issued, the process: activates a stop information for the driver, and / or activates a steady battery warning light to encourage the driver to have the battery checked, and / or activates a power cut-off for a predefined electrical consumer that is not a priority over other consumers, including a comfort function over a safety function.

[0021] According to one embodiment of the invention, if the intermediate alert is issued, the method activates a service information for the driver to encourage him at a minimum to recharge the battery.

[0022] Other features and advantages will become apparent upon reading the following description of a particular, non-limiting embodiment of the invention, made with reference to the figures in which: [ Fig 1 ] : is a schematic representation of an electrically powered vehicle, according to the invention; [ Fig 2 ] : is a simplified flowchart representing the process according to one embodiment of the invention. [ Fig 3 ] : represents an example of mapping used by the process according to the invention.

[0023] It should be borne in mind that the figures are given by way of example and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. Furthermore, in what follows, reference is made to all the figures taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the identification of the designated numerals. The numerals of unchanged elements or elements having the same function are common to all figures and variant embodiments.

[0024] La figure 1 schematically represents a motor vehicle conforming to the invention and to which a process according to the invention is applied.

[0025] The motor vehicle 2 is of the electrically powered type, such as a pure electric vehicle or a hybrid vehicle. The motor vehicle 2 includes a low-voltage battery 4, such as a lead-acid battery, but not necessarily; this battery could also be a lithium-ion battery. This low-voltage battery 4 powers the vehicle's onboard systems, including the dashboard, lighting and signaling devices, engine control, etc.

[0026] Low voltage is defined as a voltage of 48 volts or less, although 12 volts is currently the most common standard. The motor vehicle 2 also includes a high-voltage battery 6 intended to power one or more electric traction motors of the vehicle. The voltage across this battery can vary between 100 and 600 volts. A DC-DC converter (DC stands for Direct Current) 8 is electrically connected to the high-voltage battery 6 and the low-voltage battery 4 and is configured to recharge the low-voltage battery 4 from the high-voltage battery 6. It converts the high voltage of the high-voltage battery 6 into a low voltage suitable for recharging the low-voltage battery 4.

[0027] This converter 8 also allows the entire 12V on-board network to be powered, in addition to recharging the low-voltage battery 4.

[0028] In the illustrated example, this converter 8 is unidirectional and voltage-controlled, but alternatively, particularly for hybrid vehicles, this converter 8 can be bidirectional and voltage- or current-controlled. Under normal operating conditions, the low-voltage battery 4 only intervenes when the converter 8 is insufficient to power the vehicle's electrical system on its own, or to provide the power required when safety functions or devices are activated, due to insufficient converter 8 dynamics.

[0029] Still referring to the figure 1 The motor vehicle 2 also includes a low-voltage battery control unit 10. The low-voltage battery 4 plays a crucial role in the vehicle by powering the entire on-board electrical system, including safety features such as the anti-lock braking system (ABS), electric power steering, etc., when, as previously described, the converter 8's dynamics are insufficient to meet the demands of these safety functions. Therefore, it is essential to verify the proper functioning of the low-voltage battery 4 before allowing the vehicle to exceed a certain speed, such as 30 mph.

[0030] For this purpose, several prior electrical stresses on the battery 4, causing several successive current draws, is a way to test a real capacity of said battery 4 to provide power necessary for the safety function, i.e. maintain a predetermined minimum voltage for a given current draw, by evaluating parameters such as the internal resistance Rint, as well as the minimum voltage of the storage Umin, reached during each of these current draws.

[0031] In this example of the figure 2 The control unit 10 is a means of implementing the method according to the invention, and this control unit 10 controls, for example, the DC-DC converter 8 to perform these successive electrical activations, but other means of performing these successive electrical activations are conceivable. These means of electrical activation are controlled by the control unit 10, and may include, for example, a passive resistor connected, by connection means also controlled by the control unit 10, to the terminals of the battery 4.

[0032] It should be noted that, as an alternative, only an electrical stimulus may be implemented.

[0033] La figure 2 is a flowchart illustrating the operating principle of a control method according to the invention, for example by means of the control unit 10.

[0034] This control unit 10 includes, for example, a battery charge status indicator (BECB) or battery management system (BMS) and / or other control units, or may itself be arranged as a dedicated control unit (or control unit) including optional dedicated software, for example. Therefore, a control unit 10, according to the invention, can be implemented in the form of software modules, electronic circuits, or hardware, or a combination of electronic circuits and software modules.

[0035] The battery 4 control process begins with a first step E0 of low voltage battery 4 diagnostics.

[0036] This first step E0 includes, after the vehicle has been powered on, an optional initial substep to check for a low-voltage battery diagnostic requirement. Such a requirement may be present after the vehicle has been powered on, and before starting the vehicle or beginning to drive, or as long as the vehicle speed does not exceed a speed limit beyond which the safety of the occupant(s) can no longer be ensured without a positive low-voltage battery diagnostic.

[0037] If the initial sub-step of interrogation is successful, and after the vehicle has started, the first step E0 includes a first sub-step consisting of controlling the means of electrical requests in diagnostic mode of the low voltage battery 4. For example, controlling the converter 8 in diagnostic mode of the low voltage battery 4.

[0038] It should be noted that, advantageously, the diagnostic need information is such that it allows the execution of the first sub-step at each vehicle start, in particular only once at each vehicle start.

[0039] The process then performs a second sub-step consisting of carrying out the diagnosis of the low voltage battery 4.

[0040] This second sub-step: causes several electrical demands on battery 4 in succession, each causing a current draw, and monitoring for the occurrence of an internal fault in the control unit 10, then determines a pair of values ​​comprising a voltage Umin and an internal resistance Rint of battery 4, from each current draw.

[0041] The first step E0 executes, consecutively to the second sub-step, a third sub-step determining a STATUS for each pair of values, this status taking a state: unreliable STNF if the current inrush caused by the electrical stress was too low compared to a predetermined threshold within a given time, or if an internal fault in the control unit 10 was present during this given time, reliable STF if the current inrush caused by the electrical stress was greater than or equal to the predetermined threshold within this given time, and if there was no internal fault in the control unit 10 during this given time.

[0042] The electrical signal(s) are obtained, for example, in the following way: The control unit 10 sends a voltage command from the battery 4, i.e., a diagnostic voltage command, applied to an input 8.1 of the converter 8 ( figure 1 This setting imposes a voltage value lower than the initial voltage across the battery terminals. It is advantageous to adjust this setting to a value that provides the best accuracy for diagnosing the subsequent steps. Ideally, this setting is a voltage lower than the initial voltage (i.e., before converter 8 enters diagnostic mode) between the terminals of battery 4. For example, for a low-voltage 12V battery 4 which, when charged and unloaded, has a voltage closer to 13V than 12V, this setting is, for example, between 10V and 12V, specifically 10.6V.

[0043] Alternatively, and depending on the technology of the converter 8 present, this converter 8 can be controlled by a current setpoint (a flow current with respect to the battery 4) instead of the diagnostic voltage setpoint.

[0044] Alternatively, this second sub-step causes a single electrical stimulus.

[0045] Alternatively, this status takes on a state: Not reliable STNF if the current inrush caused by the electrical stress was too low compared to the predetermined threshold within the allotted time, or reliable STF if the current inrush caused by the electrical stress was greater than or equal to the predetermined threshold within that allotted time.

[0046] The phrase "the current draw caused by the electrical load was too low compared to a predetermined threshold" throughout this document refers to a comparison of the difference between the maximum current draw within the allotted time and the current at the start of the draw, with the predetermined threshold. It is understood that these are absolute current values. Furthermore, these currents and voltages are values ​​measured at the terminals of battery 4.

[0047] This allotted time is, for example, 0.05 seconds, but ideally it can be between 0.04 and 0.1 seconds. The predetermined current threshold is, for example, 60A, but ideally it can be between 50A and 130A. This corresponds to a minimum electrical load that requires an increase in the current delivered by battery 4 of at least 60A in less than 0.05 seconds.

[0048] It should be noted that the electrical demand causes a voltage drop in the low voltage battery 4 simultaneously with the current draw; the voltage Umin is then the lowest voltage measured during the electrical demand causing this voltage drop.

[0049] The internal resistance Rint is the value of this voltage drop due to the current draw, divided by the value of the change in current due to the current draw, assuming that the electromotive force of the battery 4 is substantially constant.

[0050] Optionally, this process counts the number of successive STNF states, for example, over one or more trips. Thus, as soon as this number exceeds a threshold, for example 6 consecutive STNF states, a service alert is issued to the driver.

[0051] Following the first step E0, the process executes a second step E1, analyzing the previously determined SATUT, Umin, and Rint information and providing verified information on the internal resistance Rint and the minimum voltage Umin reached during the current surge used to calculate the internal resistance Rint. This second step E1 consists of retaining only the pairs of Umin and Rint values ​​associated with the STATUT status in the reliable STF state, and determining a single pair of representative values ​​Ur and Rr from the retained pairs of Umin and Rint values.

[0052] For example, the unique pair of representative values ​​Ur, Rr is equal to the last pair of values ​​Umin, Rint that is retained.

[0053] For example, the unique pair of representative values ​​Ur, Rr is the average of the pairs of values ​​Umin, Rint that are conserved.

[0054] It should be noted that the internal fault in the control unit, if detected within the allotted time, forces the status of the pair of values ​​associated with it to unreliable STNF and this pair of values ​​is not retained, or ignored.

[0055] Advantageously, when the status changes from a reliable STF state to an unreliable STNF state because of the presence of this internal fault in the control unit 10, the process will ignore all pairs of values ​​following the occurrence of this fault until the next vehicle start.

[0056] For the variant with only a single electrical stimulus, the single pair of representative values ​​Ur, Rr is equal to the single pair of values ​​Umin, Rint. Alternatively, the single pair of representative values ​​Ur, Rr is unavailable if the single pair of values ​​Umin, Rint resulting from the single electrical stimulus is associated with the unreliable status STNF or if it is ignored.

[0057] Following the second step E1, the process executes a third step E2 which, based on a predetermined mapping of the voltages Umin as a function of the internal resistances Rint comprising at least: a first zone Z1 corresponding to a low voltage Umin and / or a high internal resistance Rint, a third zone Z3 corresponding to a high voltage Umin and / or a low internal resistance Rint, a second zone Z2, intermediate to the first and third zones Z1, Z3, determines, depending on the zone Z1, Z2, Z3 in which the unique pair of representative values ​​Ur, Rr is located, that: the battery is capable of responding to a predetermined electrical demand if the unique pair of representative values ​​is located in the third zone Z3, or that the battery is not capable of responding to this predetermined electrical demand if the unique pair of representative values ​​is located in the first zone Z1, or that an uncertainty remains in responding to this predetermined electrical demand if the unique pair of representative values ​​is located in the second zone Z2.

[0058] Thus this mapping makes it possible to be representative of the capacity of battery 4 to respond to a current demand from one or more simultaneous safety functions or devices, as previously defined.

[0059] There figure 3 illustrates a simplified example of such a mapping. The x-axis represents the voltage Umin, of which several singular values ​​U1 to U5 are plotted; the y-axis represents the internal resistance Rint, of which several singular values ​​R1 to R4 are plotted.

[0060] The third zone Z3 is the area between a first curve C3 and the x-axis, this first curve intersecting the x-axis at the voltage point U2 shown. This first curve C3 is therefore a curve of the internal resistance Rint as a function of the voltage Umin. This curve C3 is increasing and begins at the torque value U2, R1 and ends at the torque value U5, R4, with U5 > U2 and R4 > R1. This first curve C3 also passes through two other singular pairs U3, R2 and U4, R3 and is a succession of three segments, but it can take more complex forms. In general, R1 <R2<R3<R4 et U1<U2<U3<U4<U5.

[0061] The first zone Z1 is the area between a second curve C4 and the y-axis. This second curve C4 intersects the x-axis at the voltage point U1 shown. This curve C4 is also increasing, starting at the torque value U1, R1 and ending at the torque value U5, R4, but this is only a simplified example; this second curve C4 does not necessarily end at the same point as the first curve C3. This second curve C4 is in the form of a step function, so the first zone Z1 corresponds to a voltage Umin less than or equal to U1 and / or an internal resistance Rint greater than or equal to R4. But of course, this second curve C4 can take other, more complex forms.

[0062] The second zone Z2 is then delimited by this first curve C3 on one side, and this second curve C4 on the other.

[0063] This mapping is predetermined, for example, by an experimental design determining the values ​​of singular Umin, Rint pairs for the construction of the C4, C3 curves.

[0064] For example, for a 12V lead-acid battery, U1 will have a value of 10V and U5 a value of 16V, and R1 a value of 3 mΩ and R4 a value of 14 mΩ.

[0065] Note that the origin point of the axes does not have a zero value, but corresponds to a pair with a value of 0V, R1, R1 being non-zero (3 mΩ in our example).

[0066] It should be noted that current surges are, for example, within a range of 0 to 130 A, specifically between 50 and 130 A. For a low-voltage battery in a car, these currents are relatively low compared to the 300 to 500 A currents encountered when starting an internal combustion engine, for example. Thus, for these current surges, the minimum voltage Umin of the battery depends on the battery's condition, and not on the current surge intensity. This is why this mapping can have only two dimensions: the minimum voltage Umin and the internal resistance Rint.

[0067] For higher current demands, in the order of 300 to 400 A, this mapping would be advantageously three-dimensional, adding the current to the minimum voltage Umin and the internal resistance Rint to be more accurate.

[0068] As an alternative: In the first step E0, the process determines the intensity of the induced current draw at the time of determining the voltage Umin, and the predetermined mapping is further a function of the intensity of the induced current draw, the three zones Z1, Z2, Z3 extending to three volumes, and in the third step E2, the process determines, as a function of the three volumes, in which the pair of representative values ​​Umin, Rint associated with the intensity of the induced current draw is located: the battery is capable of responding to the predetermined electrical demand if the pair of values ​​associated with the intensity of the induced current draw is located in the third volume resulting from the third zone Z3, or that the battery is not capable of responding to this predetermined electrical demand if the pair of values ​​associated with the intensity of the induced current draw is located in the first volume resulting from the first zone Z1,or that uncertainty remains in responding to this predetermined electrical demand if the pair of values ​​associated with the intensity of the induced current draw is located in the second volume resulting from the second zone Z2.

[0069] The process of figure 2 According to the invention, advantageously performs a fourth step E3 from the moment the vehicle starts, consisting of: start a first timer, at the start of the vehicle, of a first predetermined configurable duration and emit an AUT-OK authorization signal at the end of this first timer, this AUT-OK authorization signal being maintained only for a second predetermined configurable duration.

[0070] Thus this AUT-OK authorization allows, for example, the exploitation of the single pair of representative values ​​Ur, Rr only when it is relevant, that is to say when it is certain that the succession of electrical excitations and measurements of voltage Umin and internal resistance Rint of the battery 4 for each excitation is completed, and that the single pair of representative values ​​Ur, Rr is completely determined.

[0071] The first preset duration can be set, for example, between 4 and 8 seconds, specifically 5 seconds or even 7 seconds. This first preset duration is longer than the time required to complete the series of electrical activations.

[0072] For example, the time required to complete an electrical activation, from the start of the current surge to the return of the current to its pre-activation value, is between 0.3 and 2 seconds, specifically 0.4 seconds. Thus, for a predetermined, configurable duration of 5 seconds, the process can perform a series of 3 to 6 electrical activations, for example.

[0073] The second predetermined duration allows the update of the single pair of representative values ​​Ur, Rr to be dated: if it is too old, then AUT-OK = false and the process will not take into account the same values ​​of the single pair of representative values ​​Ur, Rr twice in a row.

[0074] However, this fourth step E3 is not mandatory. Furthermore, the same result can be achieved in a different way, for example with autonomous management of electrical demands by converter 8.

[0075] Following the third step E2, the process executes a fifth step E4 consisting of incrementing a first counter C1 by a value of 1 if: The AUT-OK authorization signal performs a transition from false to true E41 and the battery is not able to respond to this predetermined electrical demand Z1, i.e. that the pair of values ​​is in the first zone Z1, or to increment a second counter C2 by a value of 1 if: the AUT-OK authorization signal makes a transition from false to true E42 and the uncertainty remains to respond to this predetermined electrical stimulus Z2, that is, whether the pair of values ​​is in the second zone Z2.

[0076] Thus, at this fifth stage E4, the process records the number of times battery 4 is detected as being unable to respond to the electrical demand predetermined by the first counter C1, or as being uncertain to respond to the electrical demand predetermined by counter C2. These counters are updated once at the beginning of each drive. Therefore, by relying on the single pair of representative values ​​Ur and Rr over several successive vehicle drives, this process makes it possible to distinguish several alert levels corresponding to different states of battery 4.

[0077] It should be noted that the values ​​taken by these counters are kept in memory from one ride to the next in order to be able to make the diagnosis of the battery reliable over several successive rides.

[0078] Furthermore, following the fifth step E4, the process according to the invention advantageously resets the first and second counters C1, C2 to a zero value if: the AUT-OK authorization signal makes a transition from false to true E43 and the battery is able to respond to a predetermined electrical demand Z3, i.e. the torque values ​​are in the third zone Z3.

[0079] Thus the process takes into account the fact that, between two successive drives, the driver was able to recharge the battery 4.

[0080] It should be noted that the prior detection of the transition of the AUT-OK authorization signal from false to true E41, E42, E43 at any increment or zeroing of the first counter C1 and the second counter C2 makes it possible to be certain that, thanks to the first time delay, the single pair of representative values ​​Ur, Rr determined is relevant, that is to say for example: the only pair of representative values ​​Ur, Rr retained is the pair of values ​​of the last stress train, the STATUS status having remained in the reliable state STF for each stress without the appearance of the internal fault of the control unit 10 or the only pair of representative values ​​Ur, Rr retained is the average of the values ​​of each of the stresses of the stress train, the STATUS status having remained in the reliable state STF for each stress without the appearance of the internal fault of the control unit 10 or the only pair of representative values ​​Ur, Rr retained is the pair of values ​​of the last stress train with the status STF, this status having changed for the next stress.

[0081] Following the fifth step E4, the process executes a sixth step E5, issuing a maximum alert AL-MAX if: the start of this sixth step E5 is within a time window DURATION between the start of the execution of the second sub-step and the stopping of the vehicle, and if the authorization signal AUT-OK is true, and if the first counter C1 is greater than or equal to a first predetermined threshold THRESHOLD 1, or the second counter C2 is greater than or equal to a second predetermined threshold THRESHOLD 22.

[0082] In addition, or independently, this sixth step E5 issues an AL-MED intermediate alert if: the start of this sixth step E5 is in a time window DURATION between the start of the execution of the second sub-step and the stopping of the vehicle, and if the authorization signal AUT-OK is true, and if the second counter C2 is greater than or equal to a third predetermined threshold THRESHOLD 2, and is strictly less than the second predetermined threshold THRESHOLD 22, and the first counter C1 is strictly less than the first predetermined threshold THRESHOLD 1.

[0083] It should be noted that, advantageously, the intermediate AL-MED alert and the maximum AL-MAX alert are maintained until the vehicle is switched off, or even until the vehicle's computers go to sleep (switching off the computers).

[0084] Examples of thresholds include: the first predetermined threshold THRESHOLD 1 is at a value of 1, the second predetermined threshold THRESHOLD 22 is at a value of 2, the third predetermined threshold THRESHOLD 2 is at a value of 1.

[0085] The process allows for the distinction of several alert levels corresponding to different levels of severity. The maximum alert, AL-MAX, will be issued when battery 4 is identified as presenting a high risk to the safety of the driver and passengers. The intermediate alert, AL-MED, will be issued when battery 4 is identified as presenting a medium risk to the safety of the driver and passengers.

[0086] Depending on the alert issued, the process will perform different actions. For example:

[0087] If the AL-MAX maximum alert is issued, the procedure is: activates a stop information for the driver, and / or activates a steady battery warning light to encourage the driver to have the battery checked 4, and / or activates a power cut-off of a predefined electrical consumer that is not a priority over other consumers, including a comfort function over a safety function.

[0088] The process can also limit the speed of the vehicle, or even immobilize the vehicle if, after a specified period, the maximum alert is still true (issued).

[0089] This comfort function includes, for example, the electric heating of a seat or the vehicle's interior once it exceeds a defrosting temperature.

[0090] If the AL-MED intermediate alert is issued, the process activates a service information for the driver to encourage them at a minimum to recharge the battery 4.

[0091] The information includes, for example, warning lights on the dashboard, audible alarms, or messages displayed on an on-board computer screen.

[0092] This invention makes it possible to advantageously provide on electric vehicles an improvement in the safety of the driver and passengers, by testing at start-up the capacity of the battery 4 to ensure the safety functions allocated to it.

[0093] This invention is all the more advantageous because on an electric vehicle, the start-up phase of the internal combustion engine, which generally allows for a strong electrical load to be placed on the battery 4 and thus tested, no longer exists.

[0094] This process allows, firstly, for the determination of a battery's actual capacity to provide the power necessary for the proper functioning of safety features, such as power steering, by systematically performing a representative test at the start of driving. The result of this test ensures robustness to the various variables to which the battery may be subjected, such as its state of charge, temperature, level of aging, damage, or even connection to the vehicle's electrical system. Secondly, this process allows for clear and unobtrusive communication with the customer without disrupting vehicle operation.

[0095] Furthermore, this process confirms, if necessary, the actual capacity of a battery to provide the power necessary for the proper functioning of safety functions over several successive journeys, so as to provide the user with reliable warning information about the danger to which he is exposed.

[0096] Furthermore, this process acts preventively, by reducing the electrical energy consumed by the battery, in order to prioritize the power available in the battery for safety functions.

[0097] Another advantage of this method is that, through this test and the analysis of the result, the battery's actual capacity to power the safety function will be determined. Indeed, it is possible, for example, to have a fully charged battery, at 90% for instance, and still be diagnosed as risky using this method. This is simply because the battery is very old or damaged, and its state of charge is then misleading. In contrast, the method of the invention induces a representative stress (simulation) on the battery, and the analysis of the result using this method, as described, will provide the best possible picture of what the battery is actually capable of doing.

Claims

1. Method for controlling a battery (4) of a vehicle comprising the battery (4) and a control unit (10) implementing the method, this method executing a first step (E0): - causing an electrical stress on the battery (4) causing a current draw, - then determining a pair of values comprising a voltage (Umin) and an internal resistance (Rint) of the battery (4), from the current draw, then the method executes a third step (E2) which, from a predetermined mapping of the voltages (Umin) as a function of the internal resistances (Rint) comprising at least: - a first zone (Z1) corresponding to a low voltage (Umin) and / or a high internal resistance (Rint), - a third zone (Z3) corresponding to a high voltage (Umin) and / or a low internal resistance (Rint), - a second zone (Z2), intermediate to the first and third zones (Z1, Z3), determines as a function of the zone (Z1, Z2, Z3) in which the pair of values (Umin, Rint) is located that: - the battery (4) is capable of responding to a predetermined electrical demand if the pair of values is located in the third zone (Z3), or that - the battery (4) is not capable of responding to this predetermined electrical demand if the pair of values is located in the first zone (Z1), or that - an uncertainty remains in responding to this predetermined electrical demand if the pair of values is located in the second zone (Z2), this method further comprising: - during the first step (E0), the method determines the intensity of the current draw at the time of determining the voltage (Umin), and the method being characterized in that - the predetermined mapping is furthermore a function of the intensity of the current draw, the three zones (Z1, Z2, Z3) extending to three volumes, and - during the third step (E2), the method determines depending on the three volumes in which the pair of representative values (Umin, Rint) associated with the current draw intensity is located that: - the battery (4) is capable of responding to the predetermined electrical demand if the pair of values associated with the current draw intensity is located in the third volume from the third zone (Z3), or that - the battery (4) is not capable of responding to this predetermined electrical demand if the pair of values associated with the current draw intensity is located in the first volume from the first zone (Z1), or that - an uncertainty remains in responding to this predetermined electrical demand if the pair of values associated with the current draw intensity is located in the second volume from the second zone (Z2).

2. Method according to claim 1, characterized in that following the third step (E2), the method executes a fifth step (E4) consisting of incrementing a first counter (C1) by a value of 1 if the battery (4) is not capable of responding to this predetermined electrical demand (Z1), or of incrementing a second counter (C2) by a value of 1 if the uncertainty remains in responding to this predetermined electrical demand (Z2).

3. Method according to claim 2, characterized in that the fifth step (E4) resets the first and second counters (C1, C2) to a zero value if the battery (4) is capable of responding to the predetermined electrical demand (Z3).

4. Method according to claim 3, characterized in that following the fifth step (E4), the method executes a sixth step (E5) issuing a maximum alert (AL-MAX) if the first counter (C1) is greater than or equal to a first predetermined threshold (THRESHOLD 1), or the second counter (C2) is greater than or equal to a second predetermined threshold (THRESHOLD 22).

5. Method according to claim 4, characterized in that this sixth step (E5) issues an intermediate alert (AL-MED) if the second counter (C2) is greater than or equal to a third predetermined threshold (THRESHOLD 2), and is strictly less than the second predetermined threshold (THRESHOLD 22), and the first counter (C1) is strictly less than the first predetermined threshold (THRESHOLD 1).

6. Method according to claim 4 or 5, characterized in that if the maximum alert (AL-MAX) is issued, the method: - activates a stop signal for the driver, and / or - activates a fixed indicator light relating to the battery (4) to encourage the driver to have this battery (4) examined, and / or - activates a power cut to an electrical consumer predefined as not having priority over other consumers, in particular a comfort function with respect to a safety function.

7. Method according to claim 5, characterized in that if the intermediate alert (AL-MED) is issued, the method activates a service signal for the driver to encourage him to at least recharge the battery (4).