Method and vehicle system for the quiescent current management of a motor vehicle and correspondingly equipped motor vehicle

Abstract

The invention relates to a method (15) for quiescent current management of a motor vehicle (1). In this method, a deactivation of the motor vehicle (1) triggered by a user of the motor vehicle (1) is automatically detected in the motor vehicle (1). Immediately thereafter, electrical consumers (4) of the motor vehicle (1) that are not required for access to the motor vehicle (1) and / or its recommissioning are automatically de-energized. The invention also relates to a vehicle system (7) configured for this method and to a correspondingly configured motor vehicle (1).

Description

[0001] The present invention relates to a method and a vehicle system for quiescent current management of a motor vehicle. The invention further relates to a correspondingly configured motor vehicle.

[0002] Today's motor vehicles increasingly incorporate electrically operated devices, such as sensors, electronics, control units, assistance systems, lighting elements, and the like. This can also affect electronic locking mechanisms or access systems, which can then eliminate the need for mechanical locking systems. However, this can be problematic because the additional electrical consumers can cause a battery used to operate or power them to discharge more quickly, especially when the vehicle is parked. This can then lead to a situation where, when the battery is discharged, access to the vehicle or its restart is no longer easily possible.

[0003] If necessary, emergency power supply electronics could be provided that can recharge the battery via external charging points to restore the vehicle's usability. However, this may require additional hardware components and possibly additional software, which in turn can lead to increased complexity, cost, and weight. Furthermore, there is an increased risk of using an unsuitable external power source, which could potentially lead to damage to the vehicle. Therefore, there is a need for improvements here.

[0004] For example, DE 10 2013 208 462 A1 describes a method for controlling the energy consumption of an energy storage device used to supply the on-board electrical system of a motor vehicle during stationary use. Upon the occurrence of a predetermined event, a charge quantity quota is determined, after which the vehicle's energy consumption is reduced. The charge quantity quota is determined depending on a parameter characterizing the aging of the energy storage device.

[0005] DE 10 2011 122 042 A1 describes a circuit arrangement for an electrical system of a vehicle with an electric motor for starting an internal combustion engine and with a vehicle battery from which electrical energy can be supplied to the electric motor. This circuit arrangement allows electrical loads to be decoupled from the vehicle battery by means of a circuit breaker when the vehicle is parked, and particularly when the battery charge level is too low.

[0006] The object of the present invention is to enable a particularly comfortable and reliable use of a motor vehicle in a simple manner

[0007] This object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0008] The method according to the invention is used for the quiescent current management of a motor vehicle. This allows the power or energy consumption of the motor vehicle to be controlled, in particular minimized, when it is at rest, i.e., parked or deactivated. According to the method, a deactivation of the motor vehicle carried out or triggered by a user of the motor vehicle is automatically detected in the motor vehicle. Such a deactivation can therefore, for example, be a switching off or turning off of the motor vehicle, for example after parking, the user getting out, and locking the motor vehicle. Such a deactivation can, for example, be detected by sensors or based on corresponding electrical signals or the like, for example by a vehicle system or control unit or the like configured for the method.

[0009] According to the method according to the invention, immediately upon such a detected deactivation, electrical consumers of the motor vehicle that are not required for access to the motor vehicle and / or reactivation, i.e. restarting the motor vehicle, i.e. corresponding electrical loads in an on-board electrical system of the motor vehicle, are completely de-energized. These electrical consumers can then remain completely de-energized, in particular until a signal or a request for reactivation, i.e. restarting the motor vehicle, is detected. The fact that these electrical consumers are de-energized immediately after deactivation can mean that this occurs immediately, i.e. in particular without first waiting a certain period of time, for example several minutes, hours or days, for the motor vehicle to be reactivated or restarted.Likewise, de-energizing, i.e., disconnecting the electrical consumers from the vehicle's internal electrical power supply, can occur immediately as soon as the consumers have completed a predefined deactivation sequence. This can, for example, mean or include a proper shutdown of computer systems or control units or the like, or a gradual dimming of lighting devices to an off state, or the like.

[0010] Electrical consumers required for accessing and / or restarting the motor vehicle, however, can be, for example, devices for electronically controlled opening of a door and / or a charging flap, i.e., a cover for a charging port for charging a motor vehicle battery. This can, for example, be or include a corresponding interface for detecting a corresponding signal or request to open the door and / or the charging flap, as well as a corresponding control unit.

[0011] Advantageously, the present invention can be implemented and used without the need for complex additional hardware compared to conventional motor vehicles. The present invention can practically enable convenient and reliable access to the motor vehicle by means of electronic access systems, such as the so-called Mobile Device Key. Thus, by immediately switching off the power to unnecessary consumers, the time in which access to or recommissioning of the motor vehicle is possible without further ado and without having to recharge the motor vehicle battery in the meantime can be extended, for example, from approximately 2 months for conventional motor vehicles to approximately 12 months. This can avoid or reduce the risk of uncontrolled and therefore potentially unsuitable external voltage sources being used, i.e. being connected to the motor vehicle ormust be used to gain access to the motor vehicle after a prolonged period of inactivity or to restart the motor vehicle. Furthermore, the present invention can practically eliminate the need for mechanical access or locking systems, such as a conventional lock with a locking cylinder. This can reduce the manufacturing effort and cost of the motor vehicle.

[0012] In one possible embodiment of the present invention, the electrical loads that are not required are de-energized by means of semiconductor switches, i.e. in particular by automatically opening or blocking the semiconductor switches or at least one semiconductor switch in each case. At least one such semiconductor switch can therefore be arranged upstream and / or downstream of each of the electrical loads that are not required. These semiconductor switches can then be controlled, i.e. switched, for example, by the vehicle system or control unit set up for the method according to the invention. In particular, so-called intelligent semiconductor switches can be used here. Such intelligent semiconductor switches can have or implement other functions in addition to interrupting and establishing a current-carrying connection.The semiconductor switches can thus serve to electronically protect the corresponding electrical system or line protection, in particular a low-voltage or low-voltage power system of the motor vehicle, thus assuming the functionality of conventional fuses. Furthermore, the semiconductor switches can, for example, offer, i.e., provide or enable diagnostic options for a wide variety of other functionalities of the motor vehicle. The embodiment of the present invention proposed here enables a simple, effective, and efficient way to completely de-energize unused electrical loads and, at the same time, to effectively and efficiently implement requirements for functional safety in motor vehicles, for example, according to ISO 26262 and VDA 450.

[0013] In a further possible embodiment of the present invention, a control unit is specified or provided as the consumer required for accessing the motor vehicle and / or restarting the motor vehicle, which control unit is configured to operate and / or provide at least one specified interface for detecting a signal from a device external to the vehicle. This control unit is then kept activated, i.e. not deactivated, during and after deactivation of the motor vehicle, i.e. while the motor vehicle is deactivated. An NFC interface, for example, can be used as the corresponding interface. Via this interface, the user of the motor vehicle can gain access to the motor vehicle using the device external to the vehicle, or restart it, or at least open its loading flap.Such an external vehicle device can, in particular, be a mobile electronic device, such as a vehicle key or a mobile phone or the like. This can enable particularly convenient use of the motor vehicle. In particular, after deactivation of the motor vehicle, only this control unit and, as part of it or in addition to it, the interface can be kept activated. This can enable access or recommissioning for a particularly long period of time.

[0014] In a further possible embodiment of the present invention, during and after deactivation, i.e. when the motor vehicle is in the deactivated state, an amount of electrical operating energy available in the motor vehicle, for example a charge level of the battery or batteries of the motor vehicle, is monitored. Furthermore, when the available amount of electrical operating energy reaches or falls below a predetermined first threshold value, a corresponding message is automatically sent to a predetermined receiver, in particular one external to the vehicle. The first threshold value is predetermined such that the remaining available amount of electrical operating energy is greater than a predetermined minimum value, i.e. a predetermined minimum amount of operating energy required for access or re-commissioning. Once the first threshold value is reached, a certain amount of time is then available within which access or re-commissioning can be achieved.the restart is possible without any problems.

[0015] The specified recipient can, for example, be the user or a contact address, mobile phone number, mobile device, or the like, which was specified by the user for this purpose, for example, stored in the motor vehicle, in particular in the vehicle system or control unit mentioned elsewhere, as the recipient, i.e., the notification destination. Likewise, the recipient can, for example, be a server device external to the vehicle, such as a backend, cloud server, data center, or the like. From there, the notice or a corresponding notification can then be forwarded or sent to the user, a mobile electronic device of the user, or a contact address of the user.

[0016] The notification can, for example, inform the recipient or user that the motor vehicle or its battery, in particular a low-voltage battery of the motor vehicle intended to enable access or recommissioning, can only readily enable access or recommissioning for a limited period of time. The user can then react to this notification by, for example, opening the charging flap or charging the battery in a timely manner. The embodiment of the present invention proposed here can therefore be used particularly conveniently and reliably to prevent the motor vehicle from reaching a state in which regular access or recommissioning is not possible.

[0017] In a further possible embodiment of the present invention - as described elsewhere - the amount of electrical operating energy available in the motor vehicle is monitored during and after deactivation, i.e. while the motor vehicle is parked. In this case, the period of time, i.e. for how long, based on the current point in time, the available amount of electrical operating energy is still sufficient or is expected to be sufficient to enable or ensure access or re-operation without further ado, is also automatically detected or determined in the motor vehicle, for example by automatically processing or evaluating corresponding data or signals. If it is detected that, based on the current point in time, the available amount of electrical operating energy is expected to reach or exceed a certain level within a predetermined period of time.the minimum value also specified elsewhere, i.e. a corresponding predetermined minimum operating energy quantity which is required for access or recommissioning, i.e. which is just sufficient, is reached, a corresponding message is automatically sent to a predetermined receiver, in particular one external to the vehicle, which is also described elsewhere.

[0018] For example, the current energy consumption or a current change in the amount of available operating energy over time or a corresponding extrapolation can be used as a basis.

[0019] The embodiment of the present invention proposed here therefore makes it possible to take into account that the actual energy consumption, for example due to different environmental conditions or user settings or the like, does not necessarily always have to be exactly identical. Thus, a dynamic response can be made to correspondingly different situations or circumstances, so that, for example, the resting or idle time of the motor vehicle that can elapse before the notification is sent out can be maximized or optimized in a situation-adapted manner. Furthermore, the embodiment of the present invention proposed here makes it possible to ensure that the user always has a consistently equal amount of time from the time the time is sent to still gain regular, i.e., straightforward, access to the motor vehicle or to restart it.This can enable particularly comfortable and reliable use of the motor vehicle. For example, it can be specified that the warning is always issued when several hours or days—for example, at least 6 hours, at least 12 hours, at least 24 hours, at least 2 days, at least 3 days, or at least a week, or similar—are expected to remain until the specified minimum value is reached.

[0020] In a possible development of the present invention, when the available amount of electrical operating energy reaches the predetermined minimum value or corresponds to the predetermined minimum amount of operating energy, the charging flap, i.e. a cover of a charging port for charging the battery or a battery of the motor vehicle, is automatically unlocked or opened. This can in particular be the battery of the motor vehicle which is intended for the direct or indirect provision or storage of the operating energy. The embodiment of the present invention proposed here makes it possible to achieve a good compromise between maximum protection of the motor vehicle and the simplest and most convenient usability of the motor vehicle. This means that even when the electrical operating energy has been completely used up orIf the available amount of electrical operating energy is no longer sufficient to open the charging flap, the battery can be easily recharged and thus ultimately the motor vehicle can be put back into operation, for example without requiring special measures or risking damage to the motor vehicle. The battery that provides the operating energy for an electronic locking or access system or a corresponding locking or access mechanism, for example, can be directly charged via the charging port. Likewise, another battery or another electrical energy storage device can be directly charged via the charging port, from which the battery that provides the operating energy for the locking or access system or the corresponding mechanism can then be charged or supplied.

[0021] In one possible development of the present invention, a charge state of a low-voltage battery of the motor vehicle is monitored to monitor the available electrical operating energy. Such a low-voltage battery can be a battery which, for example, has a nominal voltage of a maximum of 12 V or a maximum of 24 V or a maximum of 48 V or a maximum of 60 V. Such a low-voltage battery can therefore, in particular, not be intended as a traction battery of the motor vehicle, i.e., it can be different from a possibly present traction battery of the motor vehicle. In other words, it can therefore be provided here that the operating energy for enabling access or recommissioning, i.e., for example, for operating or providing the interface mentioned elsewhere and / or the locking or access system or locking or access mechanism mentioned elsewhere, is provided by the low-voltage battery.This allows any additional high-voltage electrical system or high-voltage battery of the vehicle to be permanently or at least temporarily deactivated while the vehicle is deactivated. This can potentially minimize the quiescent current flowing in the vehicle during this time, i.e., the quiescent current or quiescent energy consumption of the vehicle in the deactivated state. Furthermore, the corresponding locking or access system can then be designed to be particularly simple and cost-effective.

[0022] In a possible development of the present invention, the operating energy for access and / or restarting is provided from a low-voltage battery of the motor vehicle, or from the low-voltage battery mentioned elsewhere. This low-voltage battery, in turn, is fed or supplied by a high-voltage traction battery of the motor vehicle. This can mean, for example, that the low-voltage battery is charged from the high-voltage traction battery if or as soon as a charge level of the low-voltage battery reaches a predetermined threshold value, for example the predetermined minimum value mentioned elsewhere. Likewise, the predetermined threshold value used here can be greater than the minimum value in order to avoid a correspondingly deep discharge of the low-voltage battery. For this purpose, the high-voltage traction battery ora corresponding charging system can be automatically activated at this time, for example by the vehicle system or control unit set up for the method according to the invention. Accordingly, the high-voltage traction battery or a corresponding charging system can be or remain deactivated as long as the low-voltage battery itself has a sufficiently high state of charge to enable access or recommissioning. After the low-voltage battery has been charged, the high-voltage traction battery or the corresponding charging system can be automatically deactivated. The high-voltage traction battery can be a battery that is intended or set up to provide drive energy for an electric drive motor of the motor vehicle. The high-voltage traction battery can, for example, have a nominal voltage of at least 100 V or at least 200 V or at least 400 V or at least 800 V.The development of the present invention proposed here allows the total energy available in the motor vehicle to be utilized particularly fully in order to enable access or recommissioning without any problems for a particularly long period of time.

[0023] The present invention also relates to a vehicle system for a motor vehicle. The vehicle system according to the invention is or comprises at least one control unit and is designed to automatically execute or apply the method according to the invention. For this purpose, the vehicle system or its control unit can have, for example, a corresponding electronic circuit or, for example, a processor device, such as a microprocessor, microchip, or microcontroller, and a computer-readable data memory coupled to the processor device. An operating or computer program that can be executed by means of the circuit or the processor device can be stored or implemented therein, which program encodes or implements the method steps, measures, or sequences, or corresponding control instructions, mentioned in connection with the method according to the invention.The control unit can, in particular, be the vehicle system or control unit mentioned in connection with the method according to the invention. Accordingly, the vehicle system can, for example, have or provide the interface mentioned in connection with the method according to the invention, or be configured for coupling thereto or for its operation. Likewise, the vehicle system can have an electronic locking or access mechanism, for example, for a door and / or the tailgate of the motor vehicle, which can be controlled by the control unit, or can be configured to control or activate such a mechanism.

[0024] The present invention also relates to a motor vehicle equipped with the vehicle system according to the invention and / or configured to automatically execute or apply the method according to the invention. The motor vehicle according to the invention can, in particular, be or correspond to the motor vehicle mentioned in connection with the method according to the invention and / or in connection with the vehicle system according to the invention.

[0025] Further features of the invention can be derived from the following description of the figures and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0026] The drawing shows: Fig. 1 a partial schematic representation of a motor vehicle and a mobile electronic device external to the vehicle to illustrate improved standby current management; and Fig. 2 an exemplary schematic flow chart for a corresponding method.

[0027] Fig. 1 shows a partial schematic representation of a motor vehicle 1 that is configured for optimized standby current management. The motor vehicle 1 has a traction battery 2 for supplying a drive and a low-voltage battery 3 for supplying various electrical consumers 4 of the motor vehicle 1. The low-voltage battery 3 can be charged, for example, by means of an alternator (not shown here) and / or from the traction battery 2. The traction battery 2 or the low-voltage battery 3 can also be charged via a charging port 5. In the normal state, the charging port 5 is covered by a locked charging flap 6 and is therefore not easily accessible. In order to use the charging port 5, for example to connect a charging cable, the charging flap 6 can be electronically unlocked or opened. For illustrative purposes, the charging flap 6 is indicated here by dashed lines in a corresponding open position.

[0028] However, to unlock or open the charging flap 6, a certain minimum amount of operating energy is required. This can typically be provided by the low-voltage battery 3. However, the energy supply of the low-voltage battery 3 and also of the traction battery 2 is limited and continuously decreases due to a non-zero quiescent current or energy demand, even when the motor vehicle 1 is deactivated. This could potentially lead to access to the motor vehicle 1 or the charging port 5 no longer being readily possible beyond a certain point.

[0029] To address this problem, the motor vehicle 1 here has a corresponding vehicle system for idle current management. This vehicle system comprises at least one control unit 7, indicated schematically here. The control unit 7 here has, for example, a processor 8, a data memory 9 coupled to it, and an access interface 10.

[0030] The various electrical consumers 4 of the motor vehicle 1 are connected to the low-voltage battery 3 via intelligent semiconductor switches 11 arranged in corresponding supply lines. These semiconductor switches 11 can be controlled or switched by the control unit 7. For this purpose, the semiconductor switches 11 are connected to the control unit 7 via corresponding control lines 12, as indicated schematically here. The wiring or topology of the aforementioned devices of the motor vehicle 1 shown here is purely schematic and exemplary, and can therefore also be implemented differently in practice.

[0031] If the control unit 7 detects that the motor vehicle 1 has been deactivated, the electrical loads 4 that are no longer required for access to the motor vehicle 1 or for restarting it are automatically and immediately de-energized by the control unit 7. To do this, the control unit 7 opens the corresponding semiconductor switches 11, thereby interrupting the electrical supply to the corresponding loads 4. This means that quiescent currents in these loads 4 can be completely avoided. Only devices necessary for regaining access to or restarting the motor vehicle 1 are not deactivated. This applies to the control unit 7 in this case. Thus, a maximum number of electrical loads in the motor vehicle 1 are switched off in order to avoid quiescent currents for as long as possible while the motor vehicle 1 is deactivated, thanks to the intelligent semiconductor switches 11, which also serve as electronic protection.

[0032] For further illustration, Fig. 2 shows an exemplary schematic flow chart 15 for a corresponding method.

[0033] In this case, in the initially activated state, i.e., during operation of the motor vehicle 1, the control unit 7 can continuously monitor for deactivation or deactivation requests in a method step S1. If such a deactivation or deactivation request is detected, the control unit 7 then switches off the no longer required consumers 4 as quickly as possible in a method step S2, in particular by opening or correspondingly controlling the semiconductor switches 11.

[0034] In a method step S3, continuous or regular monitoring of the charge level of the low-voltage battery 3 can then be started or continued. For example, the charge level of the low-voltage battery 3 can be regularly queried by the control unit 7 from the low-voltage battery 3, or the charge level of the low-voltage battery 3 can be continuously or regularly transmitted to the control unit 7.

[0035] In the control unit 7, for example in its data memory 9, a minimum value for the state of charge or a corresponding minimum amount of operating energy required for electronically unlocking or opening the charging flap 6 can be defined, i.e., predefined or stored. Likewise, a comparatively higher threshold value for the state of charge or the remaining amount of operating energy of the low-voltage battery 3 and / or a predefined warning time can be defined or stored. Within the warning time, sufficient operating energy may still be available for the intended unlocking or opening of the charging flap 6.

[0036] In a method step S4, the control unit 7 can continuously or regularly check whether the amount of operating energy remaining in the low-voltage battery 3 is greater than the predefined threshold value and / or whether the time until the predefined minimum value is expected to be reached is greater than the predefined warning time. As soon as this is no longer the case, the control unit 7 can automatically initiate a Fig.1. This information signal 13 can be used to inform a predetermined recipient about the corresponding status of the motor vehicle 1. For example, the information signal 13 can be sent to a mobile device 14 defined or specified as the corresponding notification destination in the control unit 7. Thus, if there is a risk that the amount of operating energy remaining in the low-voltage battery 3 will no longer be sufficient to unlock or open the charging flap 6 in the foreseeable future, for example after the warning time has elapsed, i.e. if the amount of energy remaining reaches or falls below a correspondingly defined minimum amount of energy required to unlock or open the charging flap 6, this can be communicated to a user of the motor vehicle 1.From this point in time, the user may still have a certain amount of time, for example several hours or days, to gain access to the motor vehicle 1 and / or to charge the low-voltage battery 3 and / or the traction battery 2.

[0037] Optionally, in the event that the user does not respond to the notification signal 13, it can be continuously or regularly monitored or checked in a method step S6 whether the amount of usable operating energy remaining in the low-voltage battery 3 or, if applicable, in total in the low-voltage battery 3 and the high-voltage battery 2 has reached the minimum value. As soon as this is the case, the control unit 7 can also optionally unlock or open the charging flap 6 automatically in a method step S7 to enable easy access or easy recommissioning of the motor vehicle 1.

[0038] By the procedure proposed here, an external emergency supply of operating energy via an appropriate emergency supply electrical system or emergency supply electronics or the like different from the regular charging connection 5 can be avoided and thus corresponding additional hardware can be saved.

[0039] In response to the notification signal 13, the user can, for example, bring the mobile device 14 or an electronic key close to the access interface 10, which can thus be configured, for example, as an NFC interface or the like. This can act as a trigger, upon which the control unit 7 can unlock or open the charging flap 6. The user can then easily charge the low-voltage battery 3 directly or indirectly via the traction battery 2, thus ensuring or maintaining the possibility of continued access to the motor vehicle 1 or its recommissioning.

[0040] Overall, the examples described show how a strategy to improve quiescent current management in vehicles can be implemented, particularly using intelligent semiconductor-based switches. List of reference symbols 1 motor vehicle 2 traction batteries 3 low-voltage battery 4 consumers 5 Charging port 6 tailgate 7 Control unit 8 processor 9 Data storage 10 Access interface 11 semiconductor switches 12 control lines 13 Information signal 14 Mobile device 15 Schedule S1-S7 process steps QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2013 208 462 A1

[0004] DE 10 2011 122 042 A1

[0005]

Claims

[1] Method (15) for managing the quiescent current of a motor vehicle (1), wherein in the motor vehicle (1) automatically - a deactivation of the motor vehicle (1) triggered by a user of the motor vehicle (1) is detected, and - then, immediately, electrical consumers (4) of the motor vehicle (1) that are not required for access to the motor vehicle (1) and / or for restarting the motor vehicle (1) are switched off. [2] Method (15) according to claim 1, characterized by , that the unneeded electrical consumers (4) are switched off by means of semiconductor switches (11). [3] Method (15) according to any one of the preceding claims, characterized by , that a control unit (7) is kept activated as a required consumer, which is set up to operate at least one specified interface (10) for receiving a signal from a vehicle-external device (14). [4] Method (15) according to any one of the preceding claims, characterized by , that during and after deactivation, the amount of electrical operating energy available in the motor vehicle (1) is monitored and then, when the amount of electrical operating energy available reaches or falls below a predetermined first threshold, at which the remaining amount of electrical operating energy available is greater than a predetermined minimum value required for access or recommissioning, a corresponding notification (13) is automatically sent to a predetermined receiver (14). [5] Method (15) according to any one of the preceding claims, characterized by, that during and after deactivation, the amount of electrical operating energy available in the motor vehicle (1) is monitored and then, when it is detected that, starting from the current time, the amount of electrical operating energy available is expected to reach a specified minimum value required for access or recommissioning within a specified time period, a corresponding notification (13) is automatically sent to a specified receiver (14). [6] Method (15) according to claim 4 or 5, characterized by , that when the available electrical operating energy reaches the specified minimum value, a cover (6) of a charging port (5) is automatically unlocked for charging a battery (2, 3) of the motor vehicle (1). [7] Method (15) according to any one of claims 4 to 6, characterized by, that the state of charge of a low-voltage battery (3) of the motor vehicle (1) is monitored in order to monitor the available amount of electrical operating energy. [8] Method (15) according to any one of claims 4 to 7, characterized by , that the operating energy for access and / or restart is provided from a low-voltage battery (3) of the motor vehicle (1) and that this low-voltage battery (3) is supplied by a high-voltage traction battery (2) of the motor vehicle (1). [9] Vehicle system (7) for a motor vehicle (1), wherein the vehicle system (7) comprises a control unit (7) and is configured to automatically execute the method (15) according to any of the preceding claims. [10] Motor vehicle (1) comprising a vehicle system (7) according to claim 9 and / or equipped to automatically execute the method (15) according to any one of claims 1 to 8.

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