ELECTRIC VEHICLE

Abstract

An electric vehicle comprises an energy storage device, a drive device, a relay, a voltage sensor that measures the voltage of the energy storage device, a current sensor that measures the charging and discharging current of the energy storage device, and a control unit. With the relay off, the control unit determines an initial open-circuit voltage (OCV). The control unit switches the relay on at least once and then determines a second OCV when the relay is off. Based on a reading from the current sensor, the control unit calculates an integrated current value of the energy storage device for the period from the determination of the first OCV to the determination of the second OCV. The control unit then calculates the full charge capacity of the energy storage device based on the integrated current value, the first OCV, and the second OCV.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present disclosure relates to an electric vehicle. 2. Description of the state of the art

[0002] Conventionally, various methods have been proposed for estimating the full charge capacity of a battery installed in a vehicle. Unexamined Japanese patent application no. 2008-261669 (JP 2008-261669 A) discloses a method for calculating the full charge capacity of a battery from a first open-circuit voltage (hereinafter referred to as the "first OCV") before the start of the plug-in charging process, a second open-circuit voltage (hereinafter referred to as the "second OCV") after the completion of the plug-in charging process, and an integrated current value corresponding to the difference in battery capacity between the first OCV and the second OCV. BRIEF SUMMARY OF THE INVENTION

[0003] If a user initiates plug-in charging immediately after starting the vehicle's journey, the full charging capacity is calculated based on the initial OCV (Open Current Value), which includes the influence of the polarization-induced voltage drop. Consequently, the estimation accuracy of the full charging capacity calculated based on the initial OCV that includes the influence of the polarization voltage drop is lower than the estimation accuracy of the full charging capacity calculated based on the initial OCV that removes the influence of the polarization voltage drop. A method for estimating the initial OCV taking polarization into account immediately after driving is disclosed, for example, in unexamined Japanese patent application no. 2022-150523 (JP 2022-150523 A).However, if the standby time from immediately after driving until the plug-in charging process is short, the estimation accuracy of the first OCV deteriorates when considering polarization, and the full charging capacity cannot be estimated with high accuracy.

[0004] The inventor has now discovered that there are electric vehicles that are parked after journeys, such as trips to other locations, without being plugged in to recharge. The inventor then came up with the idea of ​​calculating the full charging capacity based on the OCV (Overhead Cost), which is determined before and after the journey.

[0005] The present disclosure was made to solve the aforementioned problems, and one objective of it is to provide an electric vehicle that can suppress a deterioration in the accuracy of the full charging capacity estimate by estimating the full charging capacity based on the OCV before and after the vehicle journey.

[0006] An electric vehicle according to a first aspect of the present disclosure comprises an energy storage device installed in the electric vehicle, a drive device that generates a driving force for propulsion using the electrical energy supplied by the energy storage device, a relay arranged between the energy storage device and the drive device, a voltage sensor that measures a voltage of the energy storage device, a current sensor that measures a charging and discharging current of the energy storage device, and a control unit. With the relay switched off, the control unit determines a first open-circuit voltage (OCV). The control unit switches the relay on at least once and then determines a second OCV when the relay is switched off.The control unit calculates an integrated current value of the energy storage device for the period from the determination of the first OCV (Overcurrent Capacity) to the determination of the second OCV, based on a measurement from the current sensor. The control unit then calculates the full charge capacity of the energy storage device based on this integrated current value, the first OCV, and the second OCV.

[0007] The control unit, which according to the first aspect of the present disclosure is included in the electric vehicle, can determine the second OCV after a first period of time has elapsed since the relay was switched off.

[0008] The control unit, which according to the first aspect of the present disclosure is included in the electric vehicle, can determine the first OCV again if a second period of time has elapsed since the determination of the first OCV.

[0009] The control unit, which according to the first aspect of the present disclosure is included in the electric vehicle, can determine the first OCV after the electric vehicle has completed the plug-in charging process.

[0010] The control unit, which according to the first aspect of the present disclosure is included in the electric vehicle, can determine the first OCV after a third period of time has elapsed since the electric vehicle's plug-in charging process was completed.

[0011] A current sensor, arranged in the electric vehicle according to a second aspect of the present disclosure, may be located outside the energy storage device. The energy storage device may comprise an energy storage module. The control unit may store information about an internal current flowing in the energy storage module. The control unit may calculate the full charging capacity of the energy storage device based on the internal current, the integrated current value, the first OCV, and the second OCV. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following describes the features, advantages, and technical and industrial significance of exemplary embodiments of the invention with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and wherein: Fig. 1 a schematic configuration diagram of an electric vehicle according to an embodiment of the present disclosure; Fig. 2 a control flow diagram of the electric vehicle according to the embodiment of the present disclosure; and Fig. Figure 3 shows an example of a method for estimating a full charging capacity, which is carried out by the electric vehicle according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF EXECUTION FORMS

[0013] The following are embodiments of the present disclosure described in detail with reference to the drawings. Identical or corresponding parts are designated with the same reference numerals in the drawings, and their descriptions are not repeated. Overall configuration of the electric vehicle

[0014] Fig. Figure 1 is a schematic configuration diagram of an electric vehicle according to an embodiment of the present disclosure.

[0015] An electric vehicle 1 is, for example, a battery-powered electric vehicle. The electric vehicle 1 comprises a drive device 10, a system main relay (SMR) 14, an electronic control unit (ECU) 20, an energy storage device 40, a voltage sensor 51, a current sensor 52, and a temperature sensor 53. The ECU 20 is configured to communicate with a power control unit (PCU) 13, which is described below, the SMR 14, the voltage sensor 51, the current sensor 52, and the temperature sensor 53.

[0016] The drive device 10 is configured to generate a driving force by using electrical energy supplied by the energy storage device 40. The drive device 10 comprises a motor generator (MG) 11, which is a rotating electric machine, drive wheels 12, and the PCU 13.

[0017] The MG 11, for example, is an internal rotor permanent magnet synchronous motor (IPM motor) and functions as both an electric motor and a generator. The output torque of the MG 11 is transmitted to the drive wheels 12 via a power transmission device comprising a reduction gear, a differential, and the like.

[0018] When the electric vehicle 1 brakes, the MG 11 is driven by the drive wheels 12, and the MG 11 acts as a generator. Thus, the MG 11 also functions as a braking device, converting the kinetic energy of the electric vehicle 1 into electrical energy through regenerative braking. Regenerative electrical energy generated by the regenerative braking force on the MG 11 is stored in the energy storage device 40.

[0019] The PCU 13 is an energy conversion device that converts electrical energy bidirectionally between the MG 11 and the energy storage device 40. The PCU 13 includes, for example, an inverter and a converter, which operate based on control signals from the ECU 20. When the energy storage device 40 discharges, the converter increases the voltage supplied by the energy storage device 40 and delivers the increased voltage to the inverter. The inverter converts the direct current supplied by the converter into alternating current to power the MG 11. It should be noted that the PCU 13 can also be configured without the converter.

[0020] The SMR 14 is located between the energy storage device 40 and the drive device 10. The SMR 14 is electrically connected to a power line that connects the energy storage device 40 and the drive device 10. When the SMR 14 is closed (switched on) in response to a control signal from the ECU 20 (i.e., put into a closed state), electrical energy can be exchanged between the energy storage device 40 and the PCU 13. Conversely, when the SMR 14 is opened (switched off) in response to a control signal from the ECU 20 (i.e., put into an open state), the electrical connection between the energy storage device 40 and the PCU 13 is broken. The SMR 14 is closed (switched on), for example, when the ignition of the electric vehicle 1 is switched on. The SMR 14 acts as a protective device during the operation of the electric vehicle 1.It should be noted that SMR 14 is an example of a “relay” in the present disclosure.

[0021] The control unit 20 comprises a processor 21, a memory 22, and a memory 23. The processor 21 is a computing device such as a central processing unit (CPU), a microprocessor unit (MPU), or similar. The memory 22 is volatile memory (working memory) such as random access memory (RAM) or similar. The memory 23 is rewritable non-volatile memory such as flash memory or similar. The memory 23 stores system programs, including an operating system (OS), and control programs, including computer-readable code required for tax calculations. The processor 21 reads system programs and control programs, which are then loaded into memory 22 and executed to perform various types of processing.The ECU 20 stores voltage information obtained from the voltage sensor 51 and current information obtained from the current sensor 52, which, together with time information, are described below. The control unit 20 can be divided into several control units corresponding to the functions. It should be noted that in this disclosure, the control unit 20 is an example of a "control unit".

[0022] The energy storage device 40 is installed in the electric vehicle 1. The energy storage device 40 comprises a battery pack 41. The battery pack 41 comprises several energy storage modules 42. The energy storage modules 42 are electrically connected in series. Each energy storage module 42 comprises several energy storage cells 43. The energy storage cells 43 are electrically connected in series. The energy storage cells 43 are each a secondary battery, such as a nickel-metal hydride battery, a lithium-ion battery, or the like. A secondary battery is, for example, a battery that has a liquid electrolyte between a cathode and an anode. The energy storage device 40 has a balancing circuit 44 arranged at each of the individual energy storage cells 43 and an integrated monitoring circuit (IC) 45 also arranged at each of the individual energy storage cells 43.The balancing circuit 44 has a discharge resistor. The balancing circuit 44 serves, for example, to balance the storage capacity of each of the energy storage cells 43. The monitoring ICs 45 each comprise the voltage sensor 51 and the temperature sensor 53. The monitoring ICs 45 are each connected in parallel to the respective energy storage cell 43 and are configured to measure the voltage and temperature of each energy storage cell 43 and output the measurement results to the control unit 20.

[0023] The voltage sensor 51 is configured to measure the voltage between the terminals of the battery pack 41 and output the measurement results to the ECU 20. Furthermore, the voltage sensor 51 is configured to measure the voltage of each of the energy storage cells 43 and output the measurement results to the ECU 20.

[0024] The current sensor 52 is located outside the energy storage device 40. The current sensor 52 is configured to measure the charging and discharging current of the battery pack 41 as it is being charged and discharged, and to output the measurement results to the control unit 20. For example, when the battery pack 41 is being discharged, the current sensor 52 can use a positive value measured by the current sensor 52 as the current value. Similarly, when the battery pack 41 is being charged, the current sensor 52 can use a negative value measured by the current sensor 52 as the current value.

[0025] The temperature sensor 53 is configured to measure the temperatures of the energy storage cells 43 and output the measurement results to the ECU 20. Control flow of the electric vehicle

[0026] The following refers to Fig. 2 describes a control flow for calculating the full charging capacity, which is carried out by the electric vehicle 1.

[0027] In step S10, which is in Fig. As shown in Figure 2, ECU 20 checks whether SMR 14 is open (switched off). If SMR 14 is switched off (Yes in step S10), ECU 20 proceeds to step S15. If SMR 14 is not switched off (No in step S10), ECU 20 repeats the processing of step S10.

[0028] In step S15, the ECU 20 determines a first OCV. Specifically, the ECU 20 stores the voltage information determined by the voltage sensor 51 as the first OCV. The processing of the ECU 20 then proceeds to step S20.

[0029] In step S20, ECU 20 checks whether SMR 14 is closed (switched on). If SMR 14 is switched on (Yes in step S20), ECU 20 proceeds to step S25. If SMR 14 is not switched on (No in step S20), ECU 20 continues with step S45.

[0030] In step S25, ECU 20 checks whether SMR 14 is switched off. If SMR 14 is switched off (Yes in step S25), ECU 20 proceeds to step S30. If SMR 14 is not switched off (No in step S25), ECU 20 repeats the processing of step S25.

[0031] In step S30, ECU 20 checks whether a first time interval P1 has elapsed. The first time interval P1 is the period from the moment ECU 20 confirms in step S25 that SMR 14 is switched off. If the first time interval P1 has elapsed after processing step S25 (Yes in step S30), ECU 20 proceeds to step S35. If the first time interval P1 has not elapsed after processing step S25 (No in step S30), ECU 20 performs the processing of step S30 again.

[0032] In step S35, the ECU 20 determines a second OCV. Specifically, the ECU 20 stores the voltage information determined by the voltage sensor 51 as a second OCV. The ECU 20 then proceeds to step S40.

[0033] In step S40, the ECU 20 calculates the full charging capacity. Specifically, the ECU 20 calculates the full charging capacity of the battery pack 41 based on the first OCV, the second OCV, and an integrated current value. The integrated current value is the combined charging and discharging current of the battery pack 41 from the time the first OCV is determined to the time the second OCV is determined. The ECU 20 calculates the integrated current value based on the measured value output by the current sensor 52. The ECU 20 then proceeds to step S20.

[0034] In step S45, ECU 20 checks whether a second time interval P2 has elapsed. This second time interval P2 is the period from the moment ECU 20 determined the first OCV in step S15. For example, the second time interval P2 could be a period of two days to one week. If the second time interval P2 has elapsed since the first OCV was determined in step S45 (Yes in step S45), ECU 20 proceeds to step S50. If the second time interval P2 has not elapsed since the first OCV was determined in step S45 (No in step S45), ECU 20 continues with step S60.

[0035] In step S50, ECU 20 checks whether SMR 14 is switched off. If SMR 14 is switched off (Yes in step S50), ECU 20 proceeds to step S55. If SMR 14 is not switched off (No in step S50), ECU 20 repeats the processing of step S50.

[0036] In step S55, ECU 20 checks whether the first time interval P1 has elapsed. The first time interval P1 is the period from the moment ECU 20 confirms in step S50 that SMR 14 is switched off. If the first time interval P1 has elapsed after processing step S50 (Yes in step S55), ECU 20 proceeds to step S80. If the first time interval P1 has not elapsed after processing step S50 (No in step S55), ECU 20 repeats the processing of step S55.

[0037] In step S60, ECU 20 checks whether electric vehicle 1 has started the plug-in charging process. If electric vehicle 1 has started the plug-in charging process (Yes in step S60), ECU 20 continues processing with step S65. If electric vehicle 1 has not started the plug-in charging process (No in step S60), ECU 20 repeats the processing from step S20.

[0038] In step S65, ECU 20 checks whether electric vehicle 1 has completed the plug-in charging process. If electric vehicle 1 has completed the plug-in charging process (Yes in step S65), ECU 20 continues processing with step S70. If electric vehicle 1 has not completed the plug-in charging process (No in step S65), ECU 20 repeats the processing of step S65.

[0039] In step S70, ECU 20 checks whether a third time interval, P3, has elapsed. This third time interval, P3, is the period from the moment of confirmation in step S65 that the plug-in charging process of electric vehicle 1 has ended. If the third time interval, P3, has elapsed since the confirmation in step S65 that the plug-in charging process of electric vehicle 1 has ended (Yes in step S70), ECU 20 proceeds to step S75. In step S70, if the third time interval, P3, has not elapsed since the confirmation that the plug-in charging process of electric vehicle 1 has ended (No in step S70), ECU 20 repeats the processing of step S70.

[0040] In step S75, ECU 20 checks whether SMR 14 is switched off. If SMR 14 is switched off (Yes in step S75), ECU 20 proceeds to step S80. If SMR 14 is not switched off (No in step S75), ECU 20 repeats the processing of step S75.

[0041] In step S80, the ECU 20 determines the first OCV. Specifically, the ECU 20 stores the voltage information determined by voltage sensor 51 as the first OCV. If the ECU 20 has already stored the first OCV, it overwrites the existing first OCV information with the first OCV information determined in step S80. The ECU 20 then proceeds to step S20.

[0042] According to the in Fig. In the control flow shown in Figure 2, the ECU 20 of the electric vehicle 1, according to the embodiment of the present disclosure, estimates the full charge capacity of the battery pack 41. In particular, in step S15, the ECU 20 determines the first OCV when the SMR 14 is switched off. Subsequently, after the SMR 14 has been switched on and off at least once, i.e., after the ECU 20 has performed the processing of steps S20 and S25, the second OCV is determined. The ECU 20 then estimates the full charge capacity of the battery pack 41 based on the first OCV, the second OCV, and the integrated current value. The use of this estimation method enables the electric vehicle 1 to estimate the full charge capacity of the battery pack 41 based on the OCV determined before and after the vehicle has been driven.

[0043] In this method for estimating the full charging capacity, the ECU 20 determines the second OCV after the SMR 14 is switched off and the first time interval P1 has elapsed (after processing step S30). This allows the ECU 20 to detect the OCV after the polarization caused by the discharge current during driving has been resolved. Consequently, the full charging capacity can be estimated based on the OCV from which the influence of polarization has been eliminated, and thus a deterioration in the accuracy of the full charging capacity estimate can be suppressed.

[0044] Here, the first time interval P1 is, for example, 30 minutes or 1 hour. The ECU 20 can store a map showing a relationship between the temperature of the energy storage cells 43 and the polarization resolution time, and can select the first time interval P1 based on temperature information from the energy storage cells 43 measured by the temperature sensor 53.

[0045] The battery pack 41 consumes electrical energy due to self-discharge and dark current, even in standby mode. As time passes since the initial OCV measurement, the amount of electrical energy consumed by self-discharge and dark current increases. This consumption of electrical energy due to self-discharge and dark current is an energy consumption that cannot be calculated using the voltage sensor 51 and the current sensor 52. Consequently, the accuracy of the full charge capacity estimate deteriorates with increasing time since the initial OCV measurement. Fig. In the control flow shown in Figure 2, the ECU 20 recalculates the first OCV after the second time interval P2 has elapsed since the initial OCV measurement. This prevents the deterioration in estimation accuracy that occurs with every second time interval P2 due to increased electrical energy consumption from self-discharge and dark current. The second time interval P2 could be, for example, a period of two to ten days.

[0046] Traditionally, the full charging capacity was estimated from the OCV and the charging current before and after the plug-in charging process. However, if the plug-in charging process is started immediately after driving, the polarization that occurred during the drive is not yet resolved in the OCV at the start of the plug-in charging process, making it difficult to estimate the full charging capacity with high accuracy. Accordingly, the ECU determines 20 in the Fig. The control flow shown in Figure 2 shows that when the electric vehicle 1 starts the plug-in charging process, after the plug-in charging process is complete, the first OCV (step S80) is executed again, followed by the second OCV (step S35) further down. This prevents a deterioration in the accuracy of the full charge capacity estimate, even if the plug-in charging process starts immediately after driving.

[0047] ECU 20 also determines the first OCV after the plug-in charging process is complete and the third time interval P3 has elapsed (after processing step S70). This allows ECU 20 to capture the OCV after the polarization caused by the charging current during the plug-in charging process has been resolved. Consequently, the full charging capacity can be estimated based on the OCV after the influence of polarization has been removed, thus preventing a deterioration in the accuracy of the full charging capacity estimate.

[0048] Here, the third time interval P3 is, for example, 30 minutes or 1 hour. The control unit 20 can have a map that shows the relationship between the temperature of the energy storage cells 43 and the polarization resolution time, and can select the third time interval P3 based on temperature information from the energy storage cells 43 measured by the temperature sensor 53.

[0049] The estimation of the full charging capacity according to the present disclosure is calculated based on the first OCV, the second OCV, and the integrated current value. However, the present disclosure is not limited to this. The estimation of the full charging capacity can, for example, be calculated based on the first OCV, the second OCV, the integrated current value, and the internal current. The term "internal current" refers to an internal current flowing within the energy storage module 42. In particular, the internal current includes the self-discharge current of the energy storage cells 43, the discharge current flowing through the discharge resistance of the balancing circuits 44 to balance the energy storage cells 43, and the current supplied by each of the energy storage cells 43 to the monitoring ICs 45.The ECU 20 can store information regarding the internal current in advance and calculate the amount of electrical energy consumption based on the internal current between the first and second OCVs. The ECU 20 can suppress deterioration in the estimation accuracy of the full charge capacity by estimating it based on the first OCV, the second OCV, and the total electrical energy consumption, which is the sum of the electrical energy consumption based on the internal current and the integrated current value.

[0050] The information based on the internal current is the electrical energy consumption of the battery pack 41, which is consumed by the internal current. This information on the electrical energy consumption of the battery pack 41, which is consumed by the internal current, includes, for example, information on electrical energy consumption based on a relationship between the state of charge (SOC) and the self-discharge current of each of the energy storage cells 43, information on electrical energy consumption based on a relationship between the state of health (SOH) and the self-discharge current of each of the energy storage cells 43, information on electrical energy consumption based on a relationship between the temperature and the self-discharge current of each of the energy storage cells 43, and so on.Furthermore, the information includes information on the consumption of electrical energy by the monitoring ICs 45 in the energy storage device 40, and information on the consumption of electrical energy based on a relationship between the deviation of the SOC of each of the energy storage cells 43 and the discharge current flowing through the discharge resistor to balance the SOCs of each of the energy storage cells 43. Example for estimating full loading capacity

[0051] Fig. Figure 3 shows the OCV and current value of the energy storage device 40, as well as the open / closed state of the SMR 14 at each time. Based on the in Fig. The example shown in Figure 3 is a concrete example of how to calculate the full charging capacity of the electric vehicle 1.

[0052] At time t1, the electric vehicle 1 completed its plug-in charging process. The ECU 20 determined a first OCVa when the third time interval P3 had elapsed from time t1. At time t2, the electric vehicle 1 switched on the SMR 14 and also began driving. At time t3, the electric vehicle 1 switched off the SMR 14 and also ended its journey. The ECU 20 determined a second OCVa when the first time interval P1 had elapsed from time t3. The ECU 20 then calculated the full charge capacity of the battery pack 41 based on the first OCVa, the second OCVa, and the integrated current value from the time the first OCVa was determined to the time the second OCVa was determined.

[0053] At time t4, electric vehicle 1 switched the SMR 14 back on and also started driving. At time t5, electric vehicle 1 switched the SMR 14 off and also ended its journey. The ECU 20 determines a second OCVb when the first time interval P1 has elapsed from time t5. The ECU 20 then calculates the full charge capacity of the battery pack 41 based on the first OCVa, the second OCVb, and the integrated current value from the time the first OCVa was determined until the second OCVb was determined.

[0054] At time t6, electric vehicle 1 switched the SMR 14 back on and also started driving. At time t8, electric vehicle 1 switched the SMR 14 off and also ended its journey. The ECU 20 determines a second OCVc when the first time interval P1 has elapsed from time t8. The ECU 20 then calculates the full charge capacity of battery pack 41 based on the first OCVa, the second OCVc, and the integrated current value from the time the first OCVa was determined until the second OCVc was determined.

[0055] At time t9, immediately after the calculation of the full charging capacity, the ECU 20 confirmed that the second time interval P2 had elapsed since the time at which the first OCVa was determined. The ECU 20 confirmed that the SMR 14 was switched off and that at time t9 the first time interval P1 had elapsed since time t8, and stored the OCV at the time when the first time interval P1 had elapsed since time t8 as the first OCVb.

[0056] At time t10, electric vehicle 1 switched the SMR 14 back on and also started driving. Afterwards, in conjunction with the end of electric vehicle 1's journey, ECU 20 again determines the second OCV. ECU 20 calculates the full charge capacity of battery pack 41 based on the first OCVb, the second OCV that is determined, and the integrated current value from the time the first OCVb was determined until the time the second OCV is determined.

[0057] The ECU 20, according to the embodiment of the present disclosure, determines the second OCV each time the electric vehicle 1 completes its journey. This increases the difference between the first OCV and the second OCV, which form the basis for calculating the full charging capacity, and thus makes it possible to suppress the influence of polarization and the like on the estimation accuracy. This prevents a deterioration in the accuracy of estimating the full charging capacity.

[0058] The embodiment disclosed herein is to be understood in every respect as exemplary and not limiting. The scope of this disclosure is defined in the claims and not in the above description of the embodiment and is intended to include all modifications within the meaning and scope that correspond to the claims. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] JP 2008-261669

[0002] JP 2008-261669 A

[0002] JP 2022-150523

[0003] JP 2022-150523 A

[0003]

Claims

[1] Electric vehicle that includes: an energy storage device that is installed in the electric vehicle; a propulsion device which generates a driving force for use of the electrical energy supplied by the energy storage device; a relay that is arranged between the energy storage device and the drive device; a voltage sensor that measures the voltage of the energy storage device; a current sensor that measures the charging and discharging current of the energy storage device; and a control unit, wherein the control unit: With the relay switched off, an initial open-circuit voltage (OCV) is determined. the relay switches on at least once and then determines a second OCV when the relay is switched off, an integrated current value of the energy storage device is calculated for a period from the determination of the first OCV to the determination of the second OCV based on a measurement from the current sensor, and a full charging capacity of the energy storage device is calculated based on the integrated current value, the first OCV and the second OCV. [2] Electric vehicle according to claim 1, wherein the control unit determines the second OCV after a first period of time has elapsed since the relay was switched off. [3] Electric vehicle according to claim 1, wherein the control unit determines the first OCV again if a second time period has elapsed since the determination of the first OCV. [4] Electric vehicle according to claim 1, wherein the control unit determines the first OCV after the electric vehicle has completed the plug-in charging process. [5] Electric vehicle according to claim 4, wherein the control unit determines the first OCV after a third period of time has elapsed since the completion of the plug-in charging process of the electric vehicle. [6] Electric vehicle according to claim 1, wherein: the current sensor is located outside the energy storage device; the energy storage device includes an energy storage module; and the control unit: Information about an internal current flowing in the energy storage module is stored, and The full charging capacity of the energy storage device is calculated based on the internal current, the integrated current value, the first OCV and the second OCV.

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