SE541183C2

SE541183C2 - Motor Vehicle and Method for Charging a Motor Vehicle Battery

Info

Publication number: SE541183C2
Application number: SE1650643A
Authority: SE
Inventors: André Claesson; Robert Sjödin
Original assignee: Scania Cv Ab
Priority date: 2016-05-13
Filing date: 2016-05-13
Publication date: 2019-04-23
Also published as: DE102017004069A1; SE1650643A1

Abstract

To increase a state-of-charge (SOC), a chargeable battery (120) in a motor vehicle (100) is connected to an external power source (110) via an electric power interface (130). A control unit (140) supervises the charging process and predicts an estimated duration (D) for the charging process. The estimated duration (D) is based on a battery type, an initial state-of-charge (SOC) of the chargeable battery (120), and a desired final state-of-charge (SOC) when the charging process can be terminated. The control unit (140) also determines a typical duration (D) for the charging process based on the battery type, the initial state-of-charge (SOC) and the desired state-of-charge (SOC). If the estimated duration (D) deviates from the typical duration (D) by more than a threshold value (D) , the control unit (140) generates at least one alarm indicator (ALM, ALM).

Description

Motor Vehicle and Method for Charging a Motor Vehicle Battery THE BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates generally to solutions for charging batteries in motor vehicles. More particularly, the invention relates to a motor vehicle according to the preamble of claim 1 and a corresponding method. The invention also relates to a computer program product and a non-transitory computer readable medium.

The demand for electric-powered motor vehicles is very high today. This has placed a strong focus on battery charging and issues related thereto. For instance, it is important that the batteries in a vehicle can be charged as quickly and safely as possible. Below follows examples of various solutions in this area.

US 2013/0245970 shows methods and an apparatus for detecting abnormality of a battery pack. The battery pack includes multiple battery cells coupled in series via at least one connecting wire. A first voltage drop between a positive electrode and a negative electrode of the battery pack is detected. A first set of voltage drops between a positive electrode and a negative electrode of each battery cell in the battery pack is also detected. A total voltage drop across the at least one connecting wire in the battery pack is calculated based on an absolute difference between the first voltage drop and a sum of the first set of voltage drops. Whether the battery pack is abnormal is determined by assessing the total voltage drop across the at least one connecting wire with respect to a predetermined threshold.

US 2014/0354295 reveals a method for characterizing an electrical connection between an energy storage device of an electrical or hybrid vehicle and an external power supply. The method may include, in the vehicle, receiving an alternating waveform from the power supply, determining a fundamental frequency of the waveform, determining if the waveform is distorted, and, if it is determined that the waveform is distorted, determining if the distortion is an indication of a loose connection between the vehide and the power supply. There is further provided a charging system for characterizing an electrical connection between an energy storage device of an electrical or hybrid vehicle and an external power supply.

US 2013/0169261 describes a device for classifying electrical contacting between a first connecting element of a battery and a second connecting element, which is directly or indirectly connected to an electrical load. A temperature sensor is provided for detecting the temperature of the first connecting element and/or of the second connecting element and a control device, which is coupled to the temperature sensor and which is configured, on the basis of a detecting signal of the temperature sensor, to classify the electrical contacting between the first connecting element and the second connecting element. A corresponding method and to a battery system, as well as a battery receiving system including such a device for classifying electrical contacting. Moreover, there is provided an electrical power supply system with such a battery system and such a battery receiving system.

US 2011/0298472 discloses a solution for detecting battery connection failures, which solution relies upon measuring battery cell body temperature and battery connector temperature at a measured current. The difference between these two temperatures is calculated using a software driven comparator. The comparator compares the difference as measured against a predetermined safe difference for the measured current. If the measured value exceeds the predetermined safe value an alarm is given. In one embodiment of the invention the difference between the two temperatures is compared to a predetermined safe difference independent of current measurements.

US 2011/0204849 describes a charging cable for an electric vehicle, which cable includes a power plug adapted to be detachably connected to a power socket of a commercial power source; a temperature detecting unit for detecting a temperature of the power plug; a cable connector adapted to be detachably connected to an electric vehicle for supplying a charging current to a battery of the electric vehicle; and a switching unit for opening and closing a current path between the power plug and the cable connector. The charging cable further includes a leakage detecting unit for detecting an electric leakage based on a current flowing through the current path; and a power cutoff unit for opening the switching unit when the detected temperature of the temperature detection means exceeds a threshold value or when the leakage detection means detects the electric leakage.

US 2008/0125932 shows a solution for detecting an abnormality of a current sensor or a voltage sensor. An abnormality detecting section reads out a charging/discharging current I of a secondary battery detected by the current sensor and a battery voltage V of the secondary battery, calculates an estimated battery voltage Vs on the basis of an electromotive force E and an internal resistance r of the secondary battery, and judges the current sensor to be abnormal if the difference between the battery voltage V and the estimated battery voltage Vs is greater than a predetermined threshold and the charging/discharging current I exceeds a predetermined allowable range, and judges the voltage sensor to be abnormal if the difference is greater than the predetermined threshold and the charging/discharging current I is within the predetermined allowable range.

PROBLEMS ASSOCIATED WITH THE PRIOR ART Consequently, although many solutions exist for detecting various battery-related problems there is yet no satisfying solution for handling charging times, which, for some reason, become longer than normal. Unexpectedly long charging times are prob lematic, especially if the vehicle has no alternative source of power and the available charging time is limited. Namely, as a result, a commercial driver risks missing a deadline (due to the longer downtime) and/or risks not reaching the intended destination at all (due to insufficient charging). Also when the vehicle has another source of energy, e.g. in the form of a combustion engine, an unusually long charging time is problematic, since it typically deteriorates the overall fuel economy.

Additionally, an exceptionally long estimated charging time is often caused by electrical problems, which if they remain unattended, might result in overheating, and eventually fire.

SUMMARY OF THE INVENTION The object of the present invention is therefore to solve the above problems, and thus offer an efficient means of handling unexpectedly long charging times.

According to one aspect of the invention, the object is achieved by the initially described motor vehicle, wherein the control unit is configured to predict an estimated duration for the charging process. The estimated duration is based on a battery type, an initial state-of-charge of the chargeable battery when the charging process is started, and a desired final state-of-charge when the charging process can be terminated. The control unit is further configured to determine a typical duration for the charging process based on the battery type, the initial state-of-charge and the desired state-of-charge. If the estimated duration deviates from the typical duration by more than a threshold value, the control unit is configured to cause at least one of the at least alarm indicator to be generated.

This motor vehicle is advantageous because it provides its user with an earliest possible warning about any unexpected prolongation of the charging process. Thus, the user can take appropriate measures while there is still time for resolving the problem and meet any external timing requirements. Sometimes, it is sufficient to merely push the connector plug fully into the socket and/or to remove oxide from the contact pins, and thus avoid a temporary loose contact between the power source and the battery.

According to one preferred embodiment of this aspect of the invention the motor vehicle further includes an alarm module configured to generate a local alarm indicator in response to a first alarm control signal from the control unit. The first alarm control signal is generated by the control unit if the estimated duration deviates from the typical duration by more than the threshold value. Hence, an alarm can be produced in the motor vehicle in the form of an acoustic signal and/or a light signal. For example, the local alarm indicator is preferably represented by activation of an external light source on the motor vehicle, activation an internal light source in the motor vehicle and/or activation of at least one loudspeaker to produce an acoustic signal.

According to another preferred embodiment of this aspect of the invention the motor vehicle further includes a remote signal interface configured to transmit a wireless signal forming a basis for a remote alarm indicator in response to a second alarm control signal from the control unit. Analogous to the above, the second alarm control signal is generated by the control unit if the estimated duration deviates from the typical duration by more than the threshold value. The remote alarm indicator is preferably represented by sending a message to a workshop, sending a message to a command central and/or sending a message to an application in a mobile device. Thereby, either the driver, a command central or both can be conveniently and efficiently informed about the fact that the charging process is estimated to take unexpectedly long time, and troubleshooting steps can be initiated at an early stage.

According to yet another preferred embodiment of this aspect of the invention the electric power interface includes at least one temperature sensor configured to register a connector temperature of at least one connection line through which the electric energy is fed from the external power source into the motor vehicle. The at least one temperature sensor is also configured to forward the registered connector temperature to the control unit. The control unit, in turn, is configured to cause the at least one of the at least alarm indicator to be generated if at least one registered connector temperature exceeds a threshold temperature level. Namely, increased temperature is a common result for loose contact in the connector pins (e.g. due to oxide), and therefore temperature monitoring is appropriate to identify potential contact problems.

According to still another preferred embodiment of this aspect of the invention the electric power interface includes at least two temperature sensors, which are configured to register a respective connector temperature of at least two connection lines through which the electric energy is fed from the external power source into the motor vehicle. The control unit is further configured to cause at least one alarm indicator to be generated if a temperature difference between a registered connector temperature of a first connector associated with a first connection line and a registered connector temperature of a second connector associated with a second connection line exceeds a threshold temperature difference. Such temperature differences may namely occur if there is oxide on one of the connector plug’s connector pins, however not the other, and is hence a suitable loose-contact indicator.

According to another aspect of the invention, the object is achieved by the method described initially, wherein an estimated duration for the charging process is predicted. The estimated duration is based on a battery type, an initial state-of-charge of the chargeable battery when the charging process is started, and a desired final state-of-charge when the charging process can be terminated. A typical duration for the charging process is also determined based on the battery type, the initial state-of-charge and the desired state-of-charge. If the estimated duration deviates from the typical duration by more than a threshold value, at least one of the at least alarm indicator is caused to be generated. The advantages of this method, as well as the preferred embodiments thereof, are apparent from the discussion above with reference to the proposed motor vehicle.

According to a further aspect of the invention the object is achieved by a computer program product, which is loadable into the memory of a computer, and includes software for performing the above proposed method when executed on a computer.

According to another aspect of the invention the object is achieved by a non-transitory computer readable medium, having a program recorded thereon, where the program is make a computer perform the method proposed above when the program is loaded into the computer.

Further advantages, beneficial features and applications of the present invention will be apparent from the following description and the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is now to be explained more closely by means of preferred embodiments, which are disclosed as examples, and with reference to the attached drawings, where: Figure 1 schematically shows a motor vehicle according to one embodiment of the invention; Figure 2 shows a graph illustrating an example of how the state of charge may vary as a function of time when a vehicle battery is charged according to one embodiment of the invention; and Figure 3 illustrates, by means of a flow diagram, a method according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE IN-VENTION Initially, we refer to Figure 1 showing a motor vehicle 100 according to one embodiment of the invention. The motor vehicle 100 contains a chargeable battery 120, an electric power interface 130 and a control unit 140.

The electric power interface 130 is configured to be connected to a power source 110 external to the motor vehicle 100, and when thus connected, feed electric energy from the external power source 110 to the chargeable battery 120 so as to increase a state-of-charge SOC of the chargeable battery 120.

The control unit 140 is configured to supervise a charging process through which the state-of-charge SOC of the chargeable battery 120 is increased. If at least one alarm condition is fulfilled, the control unit 140 is configured to cause at least one alarm indicator ALMLand/or ALMRto be generated. In particular, the control unit 140 is configured to predict an estimated duration Destfor the charging process.

The estimated duration Destis based on a first set of parameters including a battery type of the chargeable battery 120, an initial state-of-charge SOCIof the chargeable battery 120 when the charging process is started, and a desired final state-of-charge SOCEof the chargeable battery 120 when the charging process can be terminated. In addition to said first set of parameters, the control unit 140 calculates the estimated duration Destbased on measured battery parameters, such as a charging voltage, a charging current and/or an impedance of the chargeable battery 120. According to the invention, the first set of parameters may also include additional information, such as a data reflecting an environmental temperature.

The control unit 140 is also configured to determine a typical duration Dtypfor the charging process based on a second set of parameters including the battery type, the initial state-of-charge SOCIand the desired state-of-charge SOCE. Of course, the second set of parameters may also include additional information, such as a data reflecting the environmental temperature. In any case, if the estimated duration Destdeviates from the typical duration Dtypby more than a threshold value Dth, the control unit is configured to cause at least one of the at least alarm indicator ALMLand/or ALMRto be generated.

Figure 2 shows a graph illustrating an example of how the state of charge SOC of the chargeable battery 120 in the motor vehicle 100 may vary as a function of time t when said battery 120 is charged according to one embodiment of the invention.

Here, a bold graph reflects the progress of a typical charging process for the battery type in question from the initial state-ofcharge SOCIto the desired final state-of-charge SOCE, for example at a typical environmental temperature level.

At a first point in time ti after starting the charging process, it is expected that the desired final state-of-charge SOCEwould be reached for a non-faulty battery with good electrical connection to the external power source 110. Consequently, the typical duration Dtypis defined to end at ti. In other words, the typical duration Dtypextends from an initial point in time to (when the charging process is started) to ti. Based on the battery type, the initial state-of-charge SOCIand the desired final state-of-charge SOCE, the control unit 140 predicts that for the chargeable battery 120, the charging process is estimated to end at a point in time t3l.e. the estimated duration Destends at t3, or in in other words, the estimated duration Destextends from to to t3.

As can be seen, in the example illustrated in Figure 2, the point in time t3is substantially later than ti. In fact, the point in time t3is also later than a point in time t2defining a threshold value Dthfrom the typical duration Dtyp. The threshold value Dthrepresents an interval within which it is considered acceptable that the point in time t3lies. However, if the estimated duration Destdeviates from the typical duration Dtypby more than the threshold value Dth, the control unit 140 is configured to cause the at least one alarm indicator ALMLand/or ALMRto be generated. Preferably, the threshold value Dthat least defines a duration exceeding the typical duration Dtyp. However, an estimated duration Destbeing shorter than the typical duration Dtypby an amount equal to the threshold value Dth, or more, should normally also be regarded as a sign of anomaly, and may thus form a basis for the at least one alarm indicator ALMLand/or ALMR.

To effect the at least one alarm indicator ALMLand/or ALMR, the motor vehicle 100 preferably contains an alarm module 150 configured to generate a local alarm indicator ALMLin response to a first alarm control signal from the control unit 140. The control unit 140 is configured to generate the first alarm control signal if the estimated duration Destdeviates from the typical duration Dtypby more than the threshold value Dth. The local alarm indicator ALMLmay be represented by activating one or more external light sources on the motor vehicle 100 activating one or more internal light sources in the motor vehicle 100 and/or activating at least one loudspeaker in the motor vehicle 100, such that the at least one loudspeaker produces an acoustic signal.

In addition to, or as an alternative to the alarm module 150, the motor vehicle 100 may contain a remote signal interface 160, which in response to a second alarm control signal from the control unit 140, is configured to transmit a wireless signal forming a basis for a remote alarm indicator ALMR. The control unit 140 is configured to generate the second alarm if the estimated duration Destdeviates from the typical duration Dtypby more than the threshold value Dth. The remote alarm indicator ALMRmay be represented by sending a message to a workshop, sending a message to a command central and/or sending a message to an application in a mobile device, e.g. the driver’s cell phone. Consequently, at an early stage, relevant instances and/or operators can be efficiently and conveniently informed of the fact that the charging process is expected to take unusually long time, and appropriate measures can be taken in due time.

Additionally, to further enhance the monitoring of the charging, the electric power interface 130 may also include at least one temperature sensor 135. Said sensor(s) is/are configured to register at least one connector temperature of at least one connection line through which the electric energy is fed from the external power source 110 into the motor vehicle 100. The registered connector temperature(s) is/are forwarded to the control unit 140, which, in turn, is configured to cause the at least one of the at least alarm indicator ALMLand/or ALMRto be generated also if at least one registered connector temperature exceeds a threshold temperature level.

It is advantageous if the electric power interface 130 includes at least two temperature sensors 135, which are configured to register a respective connector temperature of at least two different connection lines through which the electric energy is fed from the external power source 110 into the motor vehicle 100. The control unit 140 is further configured to cause the at least one of the at least alarm indicator ALMLand/or ALMRto be generated if a temperature difference between a registered connector temperature of a first connector associated with a first connection line and a registered connector temperature of a second connector associated with a second connection line exceeds a threshold temperature difference. Namely, although a high temperature per se may be problematic, it is often the case that only a single connector is oxidized, and as a result, this connector becomes considerably warmer than the other connector(s). Such a scenario is efficiently detected by the above-described multiple temperature sensors design.

Preferably, the control unit 140 contains, or is in communicative connection with a memory unit storing a computer program product, which includes software for making at least one processor in the control unit 140 execute the above-described actions when the computer program product is run on the at least one processor.

To sum up, we will now we will describe the general method according to the invention with reference to the flow diagram in Figure 3. The method described by the flow diagram in Figure 3 is preferably executed by the control unit 140.

In a first step 310, it is checked if the electric power interface of the motor vehicle has been electrically connected to an external power source, such that charging of a chargeable battery in the motor vehicle can be initiated. If so, a step 320 follows; and otherwise, the procedure loops back and stays in step 310.

In step 320, an initial state-of-charge of the chargeable battery is determined, and subsequently a step 330 follows. In step 330, it is checked if stop data reflecting a desired final state-of-charge has been received from a user of the motor vehicle, i.e. a stateof-charge which the user wishes that the chargeable battery has when the charging process is terminated. If no stop data has been received, the procedure loops back and stays in step 330; and otherwise, steps 340 and 350 follow, preferably (however not necessarily) in parallel. If no stop data has been received within a response interval, preferably a default value is set for the desired final state-of-charge, say 90 % of a maximum value.

In step 340, an estimated duration Destfor the charging process is predicted. The estimated duration Destis based at least on a battery type of the chargeable battery, the initial state-of-charge of the chargeable battery and the desired final state-of-charge. Flowever, of course, the estimated duration Destis also based on various measured electrical parameters, e.g. a charging current, a charging voltage and/or an impedance of the chargeable battery.

In step 350, a typical duration Dtypfor the charging process is determined based on the battery type of the chargeable battery, the initial state-of-charge of the chargeable battery and the desired state-of-charge.

After steps 340 and 350, which preferably are executed in parallel, however, which may also be executed in series in arbitrary order, a step 360 follows. In step 360, it is checked if the estimated duration Destdeviates from the typical duration (Dtyp) by more than a threshold value Dth. If so, the procedure continues to a step 370; and otherwise, the procedure ends.

In step 370, at least alarm indicator is caused to be generated in order to notify an operator/user that the charging is not expected to be completed within a typical time frame for this process. As mentioned above, this is primarily believed to be the effect of an electrical problem, either with the chargeable battery as such, on the connection lines between the power source and the chargeable battery, or both.

Subsequent to completing step 370 the procedure ends.

All of the process steps, as well as any sub-sequence of steps, described with reference to Figure 3 above may be controlled by means of a programmed computer apparatus. Moreover, although the embodiments of the invention described above with reference to the drawings comprise a computer apparatus and processes performed in a computer apparatus, the invention thus also extends to computer programs, particularly computer programs on or in a carrier, adapted for putting the invention into practice. The program may be in the form of source code, object code, a code intermediate source and object code such as in partially compiled form, or in any other form suitable for use in the implementation of the process according to the invention. The program may either be a part of an operating system, or be a separate application. The carrier may be any non-transitory entity or device capable of carrying the program. For example, the carrier may comprise a storage medium, such as a Flash memory, a ROM (Read Only Memory), for example a DVD (Digital Video/Versatile Disk), a CD (Compact Disc) or a semiconductor ROM, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a magnetic recording medium, for example a floppy disc or hard disc. Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted for performing, or for use in the performance of, the relevant processes.

The term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components. However, the term does not preclude the presence or addition of one or more additional features, integers, steps or components or groups thereof.

The invention is not restricted to the described embodiments in the figures, but may be varied freely within the scope of the claims.

Claims

1. A motor vehicle (100), comprising: a chargeable battery (120), an electric power interface (130) configured to: be connected to a power source (110) external to the motor vehicle (100), and feed electric energy from the external power source (110) to the chargeable battery (120) so as to increase a state-of-charge (SOC) of the chargeable battery (120), a control unit (140) configured to: supervise a charging process through which the state-of-charge (SOC) of the chargeable battery (120) is increased, and if at least one alarm condition is fulfilled, cause at least one alarm indicator (ALML, ALMR) to be generated, characterized in that the control unit (140) is configured to: predict an estimated duration (Dest) for the charging process, the estimated duration (Dest) being based on a first set of parameters including a battery type, an initial state-of-charge (SOCI) of the chargeable battery (120) when the charging process is started, and a desired final state-of-charge (SOCE) when the charging process can be terminated, and in addition to said first set of parameters, measured battery parameters, such as a charging voltage, a charging current and/or impedance of the chargeable battery (120), determine a typical duration (Dtyp) for the charging process based on the battery type, the initial state-of-charge (SOCI) and the desired state-of-charge (SOCE), and if the estimated duration (Dest) deviates from the typical duration (Dtyp) by more than a threshold value (Dth) cause at least one of the at least alarm indicator (ALML, ALMR) to be generated.

2. The motor vehicle (100) according to claim 1, further comprising an alarm module (150) configured to generate a local alarm indicator (ALML) in response to a first alarm control signal from the control unit (140), the first alarm control signal being generated by the control unit (140) if the estimated duration (Dest) deviates from the typical duration (Dtyp) by more than the threshold value (Dth).

3. The motor vehicle (100) according to claim 2, wherein the local alarm indicator (ALML) is represented by at least one of activation of at least one external light source on the motor vehicle (100), activation of at least one internal light source in the motor vehicle (100) and activation of at least one loudspeaker in the motor vehicle (100) such that the at least one loudspeaker produces an acoustic signal.

4. The motor vehicle (100) according to any one of the preceding claims, further comprising a remote signal interface (160) configured to transmit a wireless signal forming a basis for a remote alarm indicator (ALMR) in response to a second alarm control signal from the control unit (140), the second alarm control signal being generated by the control unit (140) if the estimated duration (Dest) deviates from the typical duration (DtyP) by more than the threshold value (Dth).

5. The motor vehicle (100) according to claim 4, wherein the remote alarm indicator (ALMR) is represented by at least one of sending of a message to a workshop, sending a message to a command central and sending a message to an application in a mobile device.

6. The motor vehicle (100) according to any one of the preceding claims, wherein the electric power interface (130) comprises at least one temperature sensor (135) configured to register a connector temperature of at least one connection line through which the electric energy is fed from the external power source (110) into the motor vehicle (100), and forward the registered connector temperature to the control unit (140); and the control unit (140) is configured to cause the at least one of the at least alarm indicator (ALML, ALMR) to be generated if at least one registered connector temperature exceeds a threshold temperature level.

7. The motor vehicle (100) according to claim 6, wherein the electric power interface (130) comprises at least two temperature sensors (135) configured to register a respective connector temperature of at least two connection lines through which the electric energy is fed from the external power source (110) into the motor vehicle (100), and the control unit (140) is configured to cause the at least one of the at least alarm indicator (ALML, ALMR) to be generated if a temperature difference between a registered connector temperature of a first connector associated with a first connection line and a registered connector temperature of a second connector associated with a second connection line exceeds a threshold temperature difference.

8. A method performed in a motor vehicle (100) comprising a chargeable battery (120) and an electric power interface (130) configured to: be connected to a power source (110) external to the motor vehicle (100), and feed electric energy from the external power source (110) to the chargeable battery (120) so as to increase a state-of-charge (SOC) of the chargeable battery (120), the method comprising: supervising a charging process through which the state-ofcharge (SOC) of the chargeable battery (120) is increased, and if at least one alarm condition is fulfilled, causing at least one alarm indicator (ALML, ALMR) to be generated, characterized by: predicting an estimated duration (Dest) for the charging process, the estimated duration (Dest) being based on a first set of parameters including a battery type, an initial state-of-charge (SOCI) of the chargeable battery (120) when the charging process is started, and a desired final state-of-charge (SOCE) when the charging process can be terminated, and in addition to said first set of parameters, battery parameters including charging voltage, charging currant and/or impedance of the chargeable battery (120), determining a typical duration (Dtyp) for the charging process based on the battery type, the initial state-of-charge (SOCI) and the desired state-of-charge (SOCE), and if the estimated duration (Dest) deviates from the typical duration (Dtyp) by more than a threshold value (Dth) causing at least one of the at least alarm indicator (ALML, ALMR) to be generated.

9. The method according to claim 8, wherein motor vehicle (100) further comprises an alarm module (150) configured to generate a local alarm indicator (ALML) in response to a first alarm control signal, and the method comprises: generating the first alarm control signal if the estimated duration (Dest) deviates from the typical duration (Dtyp) by more than the threshold value (Dth).

10. The method according to claim 9, wherein the local alarm indicator (ALML) is represented by at least one of activation of at least one external light source on the motor vehicle, activation of at least one internal light source in the motor vehicle and activation of at least one loudspeaker to produce an acoustic signal.

11. The according to any one of the claims 8 to 10, wherein motor vehicle (100) further comprises a remote signal interface (160) configured to transmit a wireless signal forming a basis for a remote alarm indicator (ALMR) in response to a second alarm control signal from the control unit (140), and the method comprises: generating the second alarm control signal if the estimated duration (Dest) deviates from the typical duration (Dtyp) by more than the threshold value (Dth).

12. The method according to claim 11, wherein the remote alarm indicator (ALMR) is represented by at least one of sending of a message to a workshop, sending a message to a command central and sending a message to an application in a mobile device.

13. The method according to any one of the claims 8 to 12, wherein the electric power interface (130) comprises at least one temperature sensor (135) configured to register a connector temperature of at least one connection line through which the electric energy is fed from the external power source (110) into the motor vehicle (100), and the method comprises: causing the at least one of the at least alarm indicator (ALML, ALMR) to be generated if at least one registered connector temperature exceeds a threshold temperature level.

14. The method according to claim 13, wherein the electric power interface (130) comprises at least two temperature sensors (135) configured to register a respective connector temperature of at least two connection lines through which the electric energy is fed from the external power source (110) into the motor vehicle (100), and the method comprises: causing the at least one of the at least alarm indicator (ALML, ALMR) to be generated if a temperature difference between a registered connector temperature of a first connector associated with a first connection line and a registered connector temperature of a second connector associated with a second connection line exceeds a threshold temperature difference.

15. A computer program product loadable into a memory of at least one computer, comprising software for performing the method according to any of the claims 8 to 14 when executed on the at least one computer.

16. A non-transitory computer readable medium having a program recorded thereon, where the program is to make at least one computer perform the method of any of the claims 8 to 14 when executed on the at least one computer.