TECHNICAL FIELD

[0001] The present disclosure relates to electric ve- hide charging, and more particularly to a charging mon itoring device and method.

BACKGROUND

[0002] When the number of electric vehicle (EV) charg- ing stations grows, their effect on electrical grids becomes larger. At the same time, the security of charg ing station hardware may require improvements. If an attacker or a malicious user could take over a big net work of charging stations and control the charging of a large number of EVs, the attack could have a significant adverse effect on the electrical grid. For example, the attacker could switch on and off the charging of a large number of charging stations in a synchronized manner. Such fast variation in the electrical load of the grid could have serious adverse effects on many components in the electrical grid.

SUMMARY

[0003] This summary is provided to introduce a selec- tion of concepts in a simplified form that are further described below in the detailed description. This sum mary is not intended to identify key features or essen tial features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0004] It is an object to provide an electric vehicle charging monitoring device and an electric vehicle charging monitoring method. The foregoing and other ob jects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

[0005] According to a first aspect, a device for mon- itoring electric vehicle charging comprises: an elec trical input; an electrical output; a current measure ment device, configured to measure an electrical current flowing from the electrical input to the electrical output; and a computing device electrically coupled to the current measurement device, configured to: monitor a number of charging sessions based on the electrical current flow from the electrical input to the electri cal output; compare the number of charging sessions to a first preconfigured value; and detect abnormal current flow based on the charging session comparison. With such configurations, the device can, for example, detect ma licious use of a charging station connected to the de vice .

[0006] In an implementation form of the first aspect, the first preconfigured value comprises a number of charging sessions per a time interval. With such con figurations, the device can, for example, detect mali cious use where a charging session is started and stopped repeatedly. [0007] In a further implementation form of the first aspect, the computing device is further configured to: monitor an amplitude of the electrical current flow from the electrical input to the electrical output; compare the amplitude to a second preconfigured value; and de tect abnormal current flow based on the amplitude com parison. With such configurations, the device can, for example, detect malicious use causing abnormally high current flow through the device.

[0008] In a further implementation form of the first aspect, the device further comprises a switch electri cally arranged between the electrical input and the electrical output, wherein the computing device is elec trically coupled to the switch, and wherein the compu- ting device is further configured to: in response to detecting abnormal current flow, open the switch. With such configurations, the device can, for example, detect and prevent malicious use of a charging station con nected to the device.

[0009] In a further implementation form of the first aspect, the first preconfigured value comprises an alert limit, and wherein the computing device is further con figured to: in response to the number of charging ses sions being greater than the alert limit, transmit an alert to a backend device; and in response to the number of charging sessions being greater than an emergency limit, open the switch. [001 0] In a further implementation form of the first aspect, the emergency limit is greater than the alert limit .

[001 1] In a further implementation form of the first aspect, the computing device is further configured to close the switch after a preconfigured time interval has passed from the detection. With such configurations, the device can, for example, detect malicious use of a charging station connected to the device, and then en- able normal operation of the charging station after the preconfigured time interval.

[001 2] In a further implementation form of the first aspect, the computing device is further configured to, in response to detecting abnormal current flow, transmit an alert to a backend device via a data connection. With such configurations, the device can, for example, detect malicious use of a charging station connected to the device and report the malicious use to the backend de vice .

[001 3] In a further implementation form of the first aspect, the alert comprises at least one of: an identi fication of the device; a time of the detection; the number of charging sessions; the amplitude of the elec trical current flow; the first preconfigured value; or the second preconfigured value. With such configura tions, the device can, for example, detect malicious use of a charging station connected to the device and pro vide additional information to the backend device so that the backend device can, for example, identify the device and/or analyse other information provided by the device .

[0014] In a further implementation form of the first aspect, the computing device is further configured to: receive the first preconfigured value, the second pre configured value, and/or the emergency limit from a backend device via a data connection. With such config urations, the device can, for example, receive config urations remotely so that the device can be configured remotely.

[0015] In a further implementation form of the first aspect, the computing device is further configured to: calculate the first preconfigured value and/or the sec ond preconfigured value based on the monitored electri- cal current flow. With such configurations, the device can, for example, calculate the first preconfigured value based on normal use of a charging station con nected to the device. Thus, the device can adapt to the normal use of the charging station and detect abnormal use based on a deviation from the normal use.

[0016] In a further implementation form of the first aspect, the computing device is further configured to calculate the first preconfigured value and/or the sec ond preconfigured value using at least one of: linear regression; decision forest; boosted decision tree; fast forest quantile; neural network; or Poisson regression. With such configurations, the device can, for example, calculate the first preconfigured value so that it re flect well the normal use of the charging station. [001 7] According to a second aspect, a method com prises: measuring an electrical current flowing from an electrical input to an electrical output; monitoring a number of charging sessions based on the electrical cur- rent flow from the electrical input to the electrical output; comparing the number of charging sessions to a first preconfigured value; and detecting abnormal cur rent flow based on the charging session comparison.

[001 8] According to a third aspect, a computer program product is provided, comprising program code configured to perform a method according to the second aspect when the computer program is executed on a computer.

[001 9] It is to be understood that the implementation forms of the second aspect described above may be used in combination with each other. Several of the imple mentation forms may be combined together to form a fur ther implementation form.

[0020] Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description consid ered in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0021] In the following, example embodiments are de- scribed in more detail with reference to the attached figures and drawings, in which:

[0022] Fig. 1 illustrates a schematic representation of a system comprising a device configured for charging monitoring according to an embodiment; [0023] Fig. 2 illustrates a schematic representation of a computing device configured for current flow mon itoring according to an embodiment;

[0024] Fig. 3 illustrates a schematic representation of current flow as a function of time according to an embodiment ;

[0025] Fig. 4 illustrates a schematic representation of current flow as a function of time according to an embodiment; and

[0026] Fig. 5 illustrates a flow chart representation of a method for charging monitoring according to an embodiment .

[0027] In the following, identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION

[0028] In the following description, reference is made to the accompanying drawings, which form part of the disclosure, and in which are shown, by way of illustra tion, specific aspects in which the present disclosure may be placed. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, there fore, is not to be taken in a limiting sense, as the scope of the present disclosure is defined be the ap pended claims. [0029] For instance, it is understood that a disclo sure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding de vice may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. On the other hand, for ex ample, if a specific apparatus is described based on functional units, a corresponding method may include a step performing the described functionality, even if such step is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various example aspects described herein may be combined with each other, unless specifically noted oth erwise .

[0030] Fig. 1 illustrates a schematic representation of a device 100 for monitoring electric vehicle charging according to an embodiment. The device 100 may also be used in monitoring charging in other applications, such as building battery pack charging monitoring.

[0031] According to an embodiment, a device 100 for monitoring electric vehicle charging comprises an elec trical input 101 and an electrical output 102. The de- vice 100 may further comprise a current measurement de vice 103. The current measurement device 103 may be configured to measure an electrical current flowing from the electrical input 101 to the electrical output 102. The device may further comprise a computing device 200. The computing device 200 may be electrically coupled to the current measurement device 103. The computing device 200 may be configured to monitor a number of charging sessions based on the electrical current flow from the electrical input 101 to the electrical output 102. The computing device 200 may be further configured to com pare the number of charging sessions to a first precon figured value. The computing device 200 may be further configured to detect abnormal current flow based on the charging session comparison.

[0032] The electrical input 101 may comprise a con nector for connecting the device 100 to a power source. Thus, the electrical input 101 may be electrically cou pled to a power source. The power source may be, for example, an electrical grid.

[0033] The electrical output 102 may comprise a con nector for connecting the device 100 to one or more charging stations 107. Thus, the electrical output 102 may be electrically coupled to one or more charging stations 107. The charging stations 107 may be config ured to charge, for example, electric vehicles. Due to the connectors, a user may connect the device 100 into a pre-existing charging system, such as a private or a public charging system.

[0034] The current measurement device 103 may com prise, for example, any device that is configured to sense electrical current. The current measurement device 103 may for example comprise a sensor that is configured to sense an electrical current based on Faraday's law. The current measurement device 103 may comprise, for example, a current transformer or a Rogowski coil. Al ternatively or additionally, the current measurement device 103 may sense the electrical current based on a magnetic field generated by the current. The current measurement device 103 may comprise, for example, a Hall effect sensor, a flux gate sensor, or a magneto-resis tive current sensor. The operating principle of the cur rent measurement device 103 may depend on whether the current to be sensed is an alternating current (AC) or a direct current (DC) . The current measurement device 103 may also be referred to as a current sensor or similar .

[0035] The current measurement device 103 may convert the electrical current into an electrical voltage. The current measurement device 103 may further comprise an analog-to-digital converter (ADC) that may be configured to convert the analog voltage/current generated by the current measurement device 103 into a digital signal. Alternatively, the ADC may be a separate device from the current measurement device 103. The digital signal may be detected by the computing device 200.

[0036] All electricity to the charging stations 107 may flow through the device 100. Thus, the device 100 can monitor the current flow independently of the charg ing stations 107. If the device 100 notices any abnor mality in the usage of the charging stations 107 via the current flow through the device 100, the device 100 may, for example, send a warning to the backend device 106 and/or shut down the all the charging stations 107 by opening the switch 104. Thus, the device 100 does not need to rely on remote monitoring and administration. If, for example, an attacker prevented or faked traffic from the device 100 to a backend system, such as the backend device 106, the device 100 would still be able to function properly.

[0037] The device 100 may be a stand-alone device or it may be integrated into, for example, a charging de- vice. The device 100 may monitor the current flow and detect abnormal charging independently.

[0038] The backend device 106 may be connected to the device 100 and/or the computing device 200 via the data connection 105. The backend device 106 can set different parameters to the device 100. These parameters may com prise, for example, alert or emergency stop limits.

[0039] The computing device 200 may communicated with the backend device 106 via a data connection 105. The data connection 105 may be any connection that enables the device 100 to communicate with the backend device 106. The data connection 105 may comprise, for example, internet, Ethernet, 3G, 4G, long-term evolution (LTE) , new radio (NR) , Wi-Fi, or any other wired or wireless connections or some combination of these. For example, the data connection 105 may comprise a wireless connec tion, such as Wi-Fi, an internet connection, and an Ethernet connection. [0040] The computing device 200 can perform different actions based on the current flow from the electrical input 101 to the electrical output 102.

[0041] The computing device 200 can keep a connection open to backend device 106, so that the backend device 106 can monitor if the device 100 is online and working.

[0042] The backend device 106 may be configured to receive alerts from the device 100. The backend device 106 may also fetch statistics data, such as energy us- age, from the device 100.

[0043] The backend device 106 may also monitor if it has an open connection to the device 100. If the con nection is lost the backend device 106 can send an alert to an administrator. Alternatively or additionally, in response to losing connection to the backend device 106, the computing device 200 can store some information into the memory 202. Such information may comprise, for ex ample, number of charging sessions and time they hap pened. When the computing device 200 is again connected to the backend device 106, the computing device 200 can transmit the information to backend device 106.

[0044] The backend device 106 may comprise any compu ting apparatus. The backend device 106 may comprise, for example, a server or a plurality of servers.

[0045] The backend device 106 may comprise at least one processor. The at least one processor may comprise, for example, one or more of various processing devices, such as a co-processor, a microprocessor, a controller, a digital signal processor (DSP) , a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated cir cuit (ASIC) , a field programmable gate array (FPGA) , a microcontroller unit (MCU) , a hardware accelerator, a special-purpose computer chip, or the like.

[0046] The backend device 106 may further comprise a memory. The memory may be configured to store, for ex ample, computer programs and the like. The memory may comprise one or more volatile memory devices, one or more non-volatile memory devices, and/or a combination of one or more volatile memory devices and non-volatile memory devices. For example, the memory may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, and semiconductor memories (such as mask ROM, PROM (programmable ROM) , EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.) .

[0047] As a person skilled in the art can appreciate, when the backend device 106 is configured to implement some functionality, some component and/or components of the backend device 106, such as the at least one pro cessor and/or the memory, may be configured to implement this functionality. Furthermore, when the at least one processor is configured to implement some functionality, this functionality may be implemented using program code comprised, for example, in the memory.

[0048] According to an embodiment, the first precon figured value comprises a number of charging sessions per a time interval. The first preconfigured value may comprise, for example, an alert limit and/or an emer gency limit. For example, the first preconfigured value may comprise a maximum number of charging sessions per a time interval. The time interval may be, for example, a minute, an hour, or a day. The computing device 200 may, for example, compare if the number of charging sessions is greater than the maximum number of charging sessions per time interval. The computing device 200 may deduce that the current flow is abnormal, if the number of charging sessions is greater than the maximum number of charging sessions per time interval. Since typical users of the charging stations 107 may be unlikely to cause large numbers of charging sessions per time in- terval, the computing device 200 may be able to detect, for example, malicious use of the charging stations 107 based on the aforementioned comparison.

[0049] According to an embodiment, the computing de vice 200 may be further configured to monitor an ampli- tude of the electrical current flow from the electrical input 101 to the electrical output 102. The computing device 200 may be further configured to compare the amplitude to a second preconfigured value and detect abnormal current flow based on the amplitude comparison. For example, the second preconfigured value may com prise a maximum current amplitude. The computing device 200 may, for example, compare if the amplitude of the electrical current flow is greater than the maximum cur rent amplitude. The computing device 200 may deduce that the current flow is abnormal, if the amplitude of the electrical current flow is greater than the maximum cur rent amplitude. Herein, the term "amplitude" may refer to, for example, the absolute value of a DC current, the amplitude of an AC current, the RMS current of an AC current, or similar.

[0050] According to an embodiment, the device 100 may further comprise a switch 104 electrically arranged be tween the electrical input 101 and the electrical output 102. The computing device 200 may be electrically cou- pled to the switch 104. The computing device 200 may be further configured to in response to detecting abnormal current flow, open the switch 104. When the switch 104 is in an open position, substantially no current can flow through the switch 104. When the switch 104 is in an open position, the electrical output 102 can be sub stantially electrically disconnected from the electri cal input 101. Thus, the device 100 may stop current flow from the electrical input 101 to the electrical output 102 when abnormal current flow is detected. The device 100 may perform this independent of the backend device 106 or any other device.

[0051] The switch 104 may comprise, for example, one or more transistors or one or more relays. The computing device 104 may control the switch 104 using, for exam- pie, a voltage and/or a current applied to the switch 104.

[0052] According to a further embodiment, the compu ting device 200 is further configured to close the switch 104 after a preconfigured time interval has passed from the detection. When the switch 104 is in a closed position, current can flow through the switch. When the switch 104 is in closed position, the electri cal output 102 can be electrically connected to the electrical input 101. Thus, after the preconfigured time interval, the charging stations 107 may continue normal operation .

[0053] According to an embodiment, the computing de vice 200 is further configured to, in response to de- tecting abnormal current flow, transmit an alert to the backend device 106 via the data connection 105. For example, the alert may comprise at least one of: an identification of the device, a time of the detection, the number of charging sessions, the amplitude of the electrical current flow, the first preconfigured value; or the second preconfigured value. The alert may also comprise any other information. Based on the alert, the backend device 106 may, for example, identify the device 100 and monitor operation of the device 100. For exam- pie, if a single device 100 transmits multiple alerts in a short period of time, the backend device 106 may notify an administrator so that the device 100 can be, for example, examined physically. Alternatively or ad ditionally, the backend device 106 may analyse the in- formation in the alert and deduce a cause for the alerts. For example, the device 100 may be malfunctioning or a malicious user may be performing an attack on the device 100. [0054] The device 100 may be configured to open the switch 104 and transmit the alert to the backend device 106 according to different preconfigured values. For example, the device 100 may be configured to open the switch 104 when the number of charging sessions per time interval is greater than an emergency stop limit. The device 100 may also be configured to transmit the alert when the number of charging sessions per time interval is greater than an alert limit. The first and/or the second preconfigured value may correspond to the emer gency stop limit and/or the alert limit. In some embod iments, the emergency stop limit and the alert limit may be equal .

[0055] According to an embodiment, the first precon- figured value comprises an alert limit. The computing device 200 may be further configured to, in response to the number of charging sessions being greater than the alert limit, transmit an alert to a backend device 106. The computing device 200 may further be configured to, in response to the number of charging sessions being greater than an emergency limit, open the switch 104.

[0056] According to an embodiment, the emergency limit is greater than the alert limit. For example, the alert limit may be two charging sessions per hour and the emergency limit may be 100 charging sessions per hour. The device 100 may determine/obtain the alert limit and/or the emergency limit using any procedure disclosed herein for the first preconfigure value and/or for the second preconfigured value. [0057] According to an embodiment, the computing de vice 200 is further configured to receive the first preconfigured value, the second preconfigured value, and/or the emergency limit from a backend device 106 via a data connection 105. The backend device 106 may use, for example, similar procedures as described herein for the computing device 200 for calculating the first and/or the second preconfigured value. Alternatively or additionally, the backend device 106 may collect infor- matron from a plurality of devices 100 and configure the first and/or the second preconfigured value for each device 100 based on the information.

[0058] According to another embodiment, the computing device 200 is further configured to calculate the first preconfigured value and/or the second preconfigured value based on the monitored electrical current flow. For example, the computing device 200 may calculate one or more statistical properties of the electrical current flow over time. The computing device 200 may then com- pare the number of charging sessions per time interval to the statistical properties and deduce if the current flow is abnormal. For example, the computing device 200 may be configured to calculate an average/mean number of charging sessions per time interval based on the monitoring. The computing device 200 may then calculate the first preconfigured value based on the average num ber of charging sessions per time interval. For example, the first preconfigured value may be equal to a precon figured scaling factor times the average number of charging sessions per time interval.

[0059] Alternatively or additionally, the computing device 200 may calculate a mean and a variance of the number of charging sessions per time interval. The com puting device 200 may then calculate the first precon figured value based on the mean and the variance and, for example, a preconfigured percentile limit.

[0060] The computing device 200 may be configured to calculate the first preconfigured value and/or the sec ond preconfigured value using at least one of: linear regression, decision forest, boosted decision tree, fast forest quantile, neural network, or Poisson regression. The computing device 200 may, for example, calculate one or more statistical values, such as those disclosed herein, and using the one or more statistical values, calculate the first or the second preconfigured value using at least one of the procedures disclosed above. Linear regression may work well on, for example, high dimensional, sparse data sets lacking complexity. Deci sion trees can be efficient in both computation and memory usage during training and prediction.

[0061] Fig. 2 illustrates a schematic representation of the computing device 200 according to an embodiment.

[0062] The computing device 200 may comprise at least one processor 201. The at least one processor 201 may comprise, for example, one or more of various processing devices, such as a co-processor, a microprocessor, a controller, a digital signal processor (DSP) , a pro cessing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , a microcontroller unit (MCU) , a hardware accelerator, a special-purpose computer chip, or the like .

[0063] The computing device 200 may further comprise a memory 202. The memory 202 may be configured to store, for example, computer programs and the like. The memory 202 may comprise one or more volatile memory devices, one or more non-volatile memory devices, and/or a com bination of one or more volatile memory devices and non- volatile memory devices. For example, the memory 202 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), opti cal magnetic storage devices, and semiconductor memories (such as mask ROM, PROM (programmable ROM) , EPROM (eras- able PROM) , flash ROM, RAM (random access memory) , etc . ) .

[0064] When the computing device 200 is configured to implement some functionality, some component and/or com ponents of the computing device 200, such as the at least one processor 201 and/or the memory 202, may be configured to implement this functionality. Further more, when the at least one processor 201 is configured to implement some functionality, this functionality may be implemented using program code comprised, for exam ple, in the memory 202.

[0065] Fig. 3 illustrates a schematic representation of a current flow 301 as a function of time 302 according to an embodiment. The embodiment of Fig. 3 comprises various charging sessions 303.

[0066] During a charging session 303, the current flow 301 may be non-zero. Outside a charging session 303, the current flow 301 may be substantially zero. The compu- ting device 102 may be configured to detect the charging sessions 303 based on the current flow 301. Alterna tively, or additionally, during a charging sessions 303, amplitude of the current flow 301 may be greater than a preconfigured minimum current value. The preconfigured minimum current value may be, for example, 1 microam pere, 10 microamperes, 100 microamperes, 1 milliampere, 10 milliamperes , or 100 milliamperes . The computing de vice 102 may be configured to detect the charging ses sions 303 by comparing the current flow 301 to the pre- configured minimum value. The current flow 301 may cor respond to electrical current flowing from the electri cal input 101 to the electrical output 102.

[0067] A charging session 303 may correspond to any period of time when at least one electric vehicle is being charged in the charging stations 107. A charging session 303 may refer to the time period when a single electric vehicle is being charged. Thus, if a plurality electric vehicles are charged simultaneously, there may be a plurality of charging sessions simultaneously, one for each vehicle, for example. For example, during the last charging session 303 presented in the embodiment of Fig. 3, two vehicles may be charged. While a first vehicle may be charging in a first charging station, a second vehicle may start charging in a second starting station. This can be observed as an increase in the current flow 301 during the last charging session 303. This may be regarded as a single charging session or two separate charging sessions that happen to overlap in time.

[0068] As can be seen from the embodiment of Fig. 3, the current flow 301 may vary during a charging session 303. For example, as the charge level of a battery of an electric vehicle being charged increases, the charg- ing rate, and therefore the current flow 301, may de crease. The current flow 301 may also vary due to various other factors during a charging session 303.

[0069] The current flow 301 may also vary between dif ferent charging sessions 303 as can be seen from the embodiment of Fig. 3. The length in time of a charging session 303 may also vary between charging sessions 303.

[0070] Fig. 4 illustrates a schematic representation of a current flow 301 as a function of time 302 according to another embodiment. The time scale of the embodiment of Fig. 4 may not be the same as the same scale of the embodiment of Fig. 3.

[0071] The current flow 301 presented in the embodi ment of Fig. 4 may be considered abnormal. The device 100 may detect the abnormal current flow 301 based on, for example, the large number of charging sessions 303 per time interval. Alternatively or additionally, the device 100 may detect the abnormal current flow 301 based on, for example, the short duration of the charg- ing sessions 303 and/or short duration of the time in terval between the charging sessions 303.

[0072] The abnormal current flow 301 may be due to, for example, a malicious user of the charging station.

[0073] According to an embodiment, the first precon- figured value comprises a number of charging sessions per a time interval. The number of charging sessions per time interval may comprise, for example, 10 charging sessions per minute, 10 charging sessions per hour, 20 charging sessions per hour, 100 charging sessions per hour, or 1000 charging sessions per hour.

[0074] Even though the current flow 301 in the embod iments of Fig. 3 and Fig. 4 may be illustrated as sub stantially constant, the current flow 301 may not be a direct current (DC) . The current flow 301 may be DC or an alternating current (AC) . The current flow 301 pre sented in the embodiments may refer, for example, to a root mean square (RMS) value of an AC current flow.

[0075] The current flows presented in the embodiments of Fig. 3 and Fig. 4 are only exemplary and the actual current flow in the device 100 may differ from these. For example, due to physical limitations, such capaci tance, the rate of change of the current flow 301 may be limited. [0076] Fig. 5 illustrates a flow chart representation of a method 500 according to an embodiment.

[0077] According to an embodiment, the method 500 com prises measuring 501 an electrical current flowing from an electrical input to an electrical output. The meas uring 501 may be performed, for example, by the current measuring device 103.

[0078] The method 500 may further comprise monitoring

502 a number of charging sessions based on the electri- cal current flow from the electrical input to the elec trical output. The monitoring 502 may be performed, for example, by the computing device 200.

[0079] The method 500 may further comprise comparing

503 the number of charging sessions to a first precon- figured value. The comparing 503 may be performed, for example, by the computing device 200.

[0080] The method 500 may further comprise detecting

504 abnormal current flow based on the charging session comparison. The detecting 504 may be performed, for ex- ample, by the computing device 200.

[0081] Any range or device value given herein may be extended or altered without losing the effect sought. Also any embodiment may be combined with another embod iment unless explicitly disallowed.

[0082] Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equiv alent features and acts are intended to be within the scope of the claims.

[0083] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be un derstood that reference to 'an' item may refer to one or more of those items.

[0084] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter de scribed herein. Aspects of any of the embodiments de scribed above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought.

[0085] The term 'comprising' is used herein to mean including the method, blocks or elements identified, but that such blocks or elements do not comprise an exclu- sive list and a method or apparatus may contain addi tional blocks or elements.

[0086] It will be understood that the above descrip tion is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exem plary embodiments. Although various embodiments have been described above with a certain degree of particu- larity, or with reference to one or more individual embodiments, those skilled in the art could make numer ous alterations to the disclosed embodiments without departing from the spirit or scope of this specifica tion.