JP2012244663A - Charging system for electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging system for an electric automobile that can prolong the lifetime of a secondary battery while suitably securing a cruising range of an electric automobile.SOLUTION: A charging controller 30 starts charging operation while the battery remaining amount (SOC) of a storage battery 23 is lower than a predetermined threshold, and determines whether to execute a standby mode in which continuous charging operation is temporarily stopped and the SOC is held substantially at the threshold at time t1 when the battery remaining amount reaches the threshold or a value close thereto. It is determined whether to execute the standby mode by comparing a first time (t2 to t3) needed for full charging when the charging is carried on as it is with a second time as a time difference between time t1 when the threshold is reached and use start schedule time t4 of an electronic automobile 20. When the second time is longer than the first time, the charging controller 30 executes the standby mode.

Description

  The present invention relates to a charging system that performs a charging operation on a secondary battery provided in an electric vehicle.

  In recent years, electric vehicles have become widespread. However, in order to maintain an electric vehicle, a charging operation for a secondary battery, which is a vehicle battery, is indispensable. Various techniques have been proposed for performing this charging operation safely and reliably. Patent Document 1 discloses a technique for preventing an excessive increase in temperature of a battery, a transformer, or the like due to excessively rapid charging of a vehicle-mounted battery. Patent Document 2 discloses a technique for accurately detecting that an in-vehicle battery is fully charged and preventing further charging operation from being continued after full charging.

  By the way, the cruising distance of an electric vehicle is shorter than that of a gasoline vehicle due to the limitation of the capacity of a vehicle-mounted battery. For this reason, the user often charges the in-vehicle battery immediately in preparation for the next run after running on the electric vehicle. As a result, the on-vehicle battery has an overwhelmingly long period of time when it is kept fully charged. However, a secondary battery such as a lithium ion battery, which is widely used as a vehicle battery, has a characteristic that the battery life is shortened when stored for a long time in a fully charged state. For example, in a general lithium ion battery, a case where the SOC (State of charge) is stored in a high SOC region of about 80% to 100% and a case where it is stored in a middle SOC region of about 50% to 80% are compared. In the case of the former, the increase degree of the battery capacity deterioration degree with respect to the storage period is considerably larger.

Japanese Patent Laid-Open No. 2005-57878 Japanese Patent Laid-Open No. 10-257688

  Patent Documents 1 and 2 are onboard battery protection technologies, but are not protection technologies from the viewpoint of extending battery life. In view of the above problems, an object of the present invention is to provide a charging system for an electric vehicle that can ensure the cruising distance of the electric vehicle properly while extending the life of the secondary battery.

  A charging system for an electric vehicle according to one aspect of the present invention is a charging that controls a charging operation for the secondary battery in a state where a charging setting capable of performing charging for the secondary battery mounted on the electric vehicle is performed. Control means, detection means for detecting a charging state of the secondary battery, input means for receiving an input of a scheduled start time of use of the electric vehicle, and a threshold value for a remaining battery level of the secondary battery, Storage means for storing a threshold value that is lower than the remaining battery level by a predetermined amount, and the charging control unit starts the charging operation in a state where the remaining battery level of the secondary battery is lower than the threshold value. Thereafter, when the remaining battery level detected by the detection means reaches the threshold value, if the charging is continued as it is, the first time required for full charging, the time when the threshold value is reached, and the use start schedule Comparing with a second time, which is a time difference from the time, and executing a standby mode in which the remaining battery level of the secondary battery is not substantially increased or decreased when the second time is longer than the first time. It is characterized (claim 1).

  According to this configuration, when the second time is longer than the first time, the standby mode in which the remaining battery level of the secondary battery is not substantially increased or decreased is executed. It is prevented that the battery is fully charged before the scheduled time. That is, the secondary battery is prevented from being held for a long time in a fully charged state. As a result, the progress of deterioration of the secondary battery is suppressed, and the life of the secondary battery can be extended. On the other hand, since the secondary battery is fully charged at the scheduled start time of use, the cruising distance of the electric vehicle can be fully ensured.

  In the above configuration, it is desirable that the charge control means does not substantially increase or decrease the remaining battery level of the secondary battery by repeatedly applying and interrupting a charge current in the standby mode.

  According to this configuration, the remaining battery level of the secondary battery can be easily maintained in the standby mode.

  In the above-described configuration, it is desirable that the charge control means cuts off a charging current and spontaneously discharges the secondary battery when the charge setting is not canceled at the scheduled start time of use (Claim 3).

  According to this configuration, even when the user cancels the use of the electric vehicle, the secondary battery can be prevented from being held for a long time in a fully charged state.

  Here, when the secondary battery is a lithium ion secondary battery, the charge control means, after the natural discharge, when the remaining battery level detected by the detection means reaches the threshold value or a value in the vicinity thereof In addition, it is desirable to execute the standby mode.

  Lithium ion secondary batteries have the property of deteriorating battery characteristics when overdischarge continues for a long time. According to the above configuration, since the standby mode is executed when the remaining battery level reaches the threshold value or a value in the vicinity thereof, it is possible to prevent the lithium ion secondary battery from reaching an overdischarged state. it can.

  ADVANTAGE OF THE INVENTION According to this invention, while ensuring the cruising distance of an electric vehicle appropriately, the charging system of the electric vehicle which can implement | achieve the life extension of a secondary battery can be provided.

It is a figure showing typically the outline of the charging system of the electric vehicle concerning the embodiment of the present invention. It is a graph which shows the charge condition of the secondary battery of an electric vehicle. It is a block diagram which shows the function structure of a charge control means. It is a graph which shows the aspect (standby mode) of the charge control which a charge control means performs. It is a graph which shows the aspect of the other charge control which a charge control means performs. It is a flowchart which shows operation | movement of a charging system. It is a flowchart which shows operation | movement of a charging system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an outline of a charging system S for an electric vehicle according to an embodiment of the present invention. The charging system S of the present embodiment is a system for charging the electric vehicle 20 using the charging station 11 that receives power supply from the commercial power supply system 10.

  The commercial power supply system 10 is a power transmission system that is operated by a power company and supplies commercial AC power of 50 Hz or 60 Hz. The charging station 11 is provided in the electric vehicle 20, a power receiving facility 12 that receives commercial power from the commercial power supply system 10 through the distribution line 101, a charging outlet 13 that serves as a power receiving port when the electric vehicle 20 is charged. And a charging control device 30 (charging control means) for controlling the charging operation for the secondary battery (storage battery 23).

  The charging station 11 may be a normal charging facility powered by a single-phase AC of 200 V or 100 V provided in a general household or a rapid charging facility powered by a high voltage AC. For example, the electric power company supplies power to the charging station 11 as described above in the daytime power rate time zone (7:00 to 23:00) at a normal power rate, and the nighttime power rate time zone ( From 23:00 to 7:00 the next day, power is supplied at a power rate that is cheaper than the normal power rate.

  The electric vehicle 20 is a vehicle on which a storage battery 23 that can be charged and discharged and a charge controller 24 thereof are mounted, and the electric energy of the storage battery 23 is used as a power source. That is, the storage battery 23 serves as a power source for an electric motor (not shown), a vehicle electrical system, a lamp system, and the like. The body of the electric vehicle 20 is provided with a charging plug. A charging connector 21 attached to the end of the charging cable 22 is connected to the charging plug. When the charging plug of the electric vehicle 20 and the charging outlet 13 are electrically connected via the charging cable 22, a charging setting state in which the charging operation for the storage battery 23 can be performed is formed.

  The storage battery 23 is a secondary battery that can be charged with commercial power via an AC / DC converter (not shown), and various types of secondary batteries can be used. Among them, the lithium ion secondary battery is suitable for the present embodiment because it has a characteristic that the amount of charge power does not decrease even if the operation of charging in a state that does not lead to full discharge is repeated. In addition, a magnesium ion battery having similar characteristics is also applicable.

  The charge controller 24 is a self-supporting charge control unit provided on the electric vehicle 20 side, and performs charge control for the storage battery 23 using DC power supplied from the AC / DC conversion unit.

  The charging control device 30 controls the charging operation for the storage battery 23 on the charging station 11 side in a state where the charging setting is performed for the storage battery 23 of the electric vehicle 20. The charging control device 30 can be incorporated in the charging station 11 as shown in FIG. 1, but may be mounted on the charging connector 21 of the charging cable 22.

  The charging control device 30 generally performs control so that the storage battery 23 is not stored for a long time in a fully charged state. As described above, in a general lithium ion battery, the case where the SOC is stored in the high SOC region where the SOC is about 80% to 100% is compared with the case where the SOC is stored in the middle SOC region where the SOC is about 50% to 80%. In the case of the former, the progress degree of the battery capacity deterioration degree with respect to the storage period is considerably increased. For this reason, it is desirable to reduce the period during which the storage battery 23 is stored in the high SOC region as much as possible. However, in the case of the electric vehicle 20 having a relatively short cruising distance, the user always prepares for the next run. The psychology that wants to be fully charged works.

  FIG. 2 is a graph illustrating an example of a state of charge of a storage battery in an electric vehicle used by a general user. Here, an example is shown in which the use of the electric vehicle is started around 11:00, the driving is finished after 15:00, and charging of the storage battery is started immediately thereafter. In general, the driving distance per day is short even in a gasoline car, and one survey shows that 80% of all cars have a daily driving distance of less than 40 km. When such a travel distance is replaced with an electric vehicle, the discharge depth of the storage battery is about 30% at the maximum. Moreover, the charging time required to reach full charge of such a storage battery is about 2 hours. FIG. 2 shows such a typical example.

  If it is assumed that the user uses the electric vehicle every day as in the example of FIG. 2, the storage battery is fully charged around 17:00, so that the storage battery is fully charged between around 17:00 and around 11:00. It will be held in a charged state. In such a usage mode, the time for which the storage battery is stored in the high SOC region becomes extremely long, and the deterioration of the storage battery is promoted.

  The charging control device 30 according to the present embodiment performs control to solve the above-described problem. The charging control device 30 starts the charging operation in a state where the remaining battery level of the storage battery 23 is lower than a predetermined threshold value, and then performs the continuous charging operation when the remaining battery level reaches the threshold value or a value in the vicinity thereof. It is determined whether or not a standby mode for temporarily stopping is executed. Whether or not the standby mode can be executed is determined by the first time required for full charging when charging is continued as it is and the second time that is the time difference between the time when the threshold is reached and the scheduled start time of use of the electric vehicle 20. It is determined by comparing. When the second time is longer than the first time, the charging control device 30 executes the standby mode.

  FIG. 3 is a block diagram illustrating a functional configuration of the charging control device 30. The charge control device 30 includes an input unit 31 (input means) and a control device 32 (charge control means). The control device 32 includes a CPU (Central Processing Unit), and when a predetermined program is executed, the CPU detects the SOC detection unit 33, the state detection unit 34, the charge control unit 35, the mode setting unit 36, and the threshold storage unit. 37 to function.

  The input unit 31 includes operation buttons, a numeric keypad, and the like provided in the charging station 11 and receives an input of a scheduled use start time of the electric vehicle 20 from the user. In addition, the input unit 31 also accepts various settings relating to the charging operation, input of a threshold value for the remaining battery capacity stored in the threshold value storage unit 37 described later, and the like.

  The SOC detection unit 33 of the control device 32 detects the remaining capacity of the storage battery 23 of the electric vehicle 20. For example, the SOC detection unit 33 performs data communication with the charge controller 24 and acquires information regarding the remaining capacity of the storage battery 23. The charge controller 24 measures, for example, the open voltage of the storage battery 23 and obtains the remaining capacity of the storage battery 23 from the measured open voltage. Instead of this, the SOC detector 33 is provided with an ammeter in the charging circuit for the storage battery 23, or a current transformer for detecting an electromagnetic field generated by the current flowing through the charging cable 22, and the ammeter Alternatively, the discharge capacity may be calculated by integrating the current value measured by the current transformer, and the remaining capacity may be calculated by subtracting this from the rated full charge capacity.

  The state detection unit 34 detects a charging environment for the electric vehicle 20. For example, in the state detection unit 34, the charging plug of the electric vehicle 20 and the charging outlet 13 are connected by the charging cable 22, and the charging of the storage battery 23 by the charging station 11 is physically executable (charging setting state). Detect whether or not.

  The charging control unit 35 controls the charging operation for the storage battery 23. The charging control unit 35 can perform a charging operation on the storage battery 23 in at least two modes of “normal charging mode” and “standby mode”. In the normal charging mode, the charging control unit 35 performs a charging operation by a constant current constant voltage method or a constant current step-down method. On the other hand, in the standby mode, the charge control unit 35 performs charge control for keeping the SOC substantially constant without increasing or decreasing the SOC.

  For example, in the charging control in the standby mode, when the SOC to be maintained at a constant value is set to 75%, the charging current is cut off when the SOC of the storage battery 23 reaches 75% by the charging operation, and the SOC decreases by a predetermined value from 75%. In this control, the charging operation is restarted, a charging current is applied, and then, when the SOC reaches 75%, a cycle in which the charging current is cut off again is repeated. Alternatively, when the SOC is less than 75% due to spontaneous discharge of the storage battery 23, the charging operation is performed. When the SOC recovers to 75%, the charging current is cut off, and then the charging operation is resumed when the SOC decreases from 75% by a predetermined value. In this control, a cycle of applying a charging current is repeated.

  The mode setting unit 36 determines whether the charging control unit 35 performs the charging operation in any one of the normal charging mode and the standby mode. In this determination, the mode setting unit 36 is the timing when the state detection unit 34 detects the charging setting state, and the scheduled start time of use of the electric vehicle 20 set from the input unit 31 and the storage battery detected by the SOC detection unit 33. Reference is made to 23 SOC. Further, reference is also made to the threshold value regarding the remaining battery level stored in the threshold value storage unit 37.

  The threshold value storage unit 37 stores a threshold value for the remaining battery level of the storage battery 23 and lower by a predetermined amount than the fully charged battery level. In a lithium ion secondary battery, if a high SOC region, a medium SOC region, and a low SOC region are distinguished, the SOC is 100% to 80%, the high SOC region, 80% to 50% is the medium SOC region, 50%. The following is the low SOC region. The threshold value is set to a value slightly lower than the SOC (80%) that partitions the high SOC region and the middle SOC region, for example, 75%.

  As described above, the high SOC region is a region where the deterioration of the lithium ion secondary battery proceeds rapidly. Therefore, it should avoid that the storage battery 23 is preserve | saved for a long time in the state of a high SOC area | region. On the other hand, the middle SOC region is a region in which deterioration of the lithium ion secondary battery hardly occurs. In addition, the low SOC region is a region where attention should be paid to the discharge until the lithium ion secondary battery reaches the end-of-discharge voltage, that is, overdischarge, and avoids long-term storage of the storage battery 23 in the state of the low SOC region. Should. From the above, when storing the storage battery 23 for a long time, it is desirable to use the SOC in the middle SOC region. Furthermore, it is more preferable to hold in the upper region (for example, 70% to 80% region) in the middle SOC region because full charge can be reached in a relatively short time. For these reasons, the threshold value of “75%” is one suitable threshold value.

  Next, an example of charge control executed by the charge control device 30 will be described with reference to FIGS. 4 and 5. FIG. 4 is a graph showing an example of the charging operation in the standby mode performed between the charging setting state and the scheduled use start time of the electric vehicle 20. Here, a change curve 41 of the SOC value of the storage battery 23 is shown.

  In the example of FIG. 4, it is assumed that charge setting is performed in a state where the scheduled use start time is set at time t4, the SOC of the storage battery 23 is equal to or lower than the threshold value (75%), and the charging operation is started. Yes. When the SOC of the storage battery 23 reaches the threshold value at the time t1, the mode setting unit 36 determines that the time difference between the time t1 and the time t4 (second time) and the charging control unit 35 continues the charging operation in the normal charging mode. Is compared with the time required for full charge (first time). Here, since the second time is longer than the first time, the mode setting unit 36 changes the charging mode from the normal charging mode to the standby mode. If the second time is equal to or shorter than the first time, the charging operation is continued in the normal charge mode. Further, if the threshold is exceeded at the time of charge setting and the second time is longer than the first time, the standby mode is entered from the time of charge setting.

  In this case, at time t1, the charging current is interrupted and the standby state is entered. Thereafter, the SOC detection unit 33 periodically measures the SOC of the storage battery 23. When the SOC is reduced by a predetermined value (approximately 2 to 3%) from 75% due to natural discharge, the charging control unit 35 resumes the charging operation, applies the charging current, and recovers the SOC. Thereafter, when the SOC reaches 75%, the charging current is cut off again, and the SOC is maintained at about 75%.

  Subsequently, when the time obtained by adding the margin time α to the time (first time) required to change the SOC of the storage battery 23 from 75% to 100% is the time t2 obtained by subtracting from the scheduled start time t4, the mode is set. The unit 36 changes the charging mode from the standby mode to the normal charging mode. Thereby, the continuous charge operation with respect to the storage battery 23 is restarted. Note that the margin time α assumes that the user starts using the electric vehicle 20 slightly earlier than the scheduled start time t4, and the setting of the margin time α may be omitted.

  When the SOC of the storage battery 23 reaches 100% at time t3, the charging operation by the charging control unit 35 is completed. Thereafter, the time corresponding to the margin time α becomes the standby time. And if use of the electric vehicle 20 is started from the scheduled start time t4, the SOC of the storage battery 23 gradually decreases. When the use of the electric vehicle 20 ends at the time t5 and is set to the charge setting state, a routine similar to the above is executed.

  The example of FIG. 4 is an example when the user starts using the electric vehicle 20 as scheduled at the scheduled start time t4. However, the user does not start using the electric vehicle 20 at the scheduled start time t4. The scheduled use start time may be reset to a time later than the time t4. FIG. 5 is a graph showing an example of the charging operation in the standby mode performed after the scheduled use start time t4. Also here, a change curve 42 of the SOC value of the storage battery 23 is shown.

  Until the time t4, it is the same as the example of FIG. When the user does not start using the electric vehicle 20 at time t4, that is, when the state detection unit 34 does not detect the release of the charging setting state, the charging control unit 35 cuts off the charging current and starts the spontaneous discharge of the storage battery 23. Let As a result, the SOC of the storage battery 23 gradually decreases.

  When the natural discharge progresses and the time t6 when the SOC enters the middle SOC region from the high SOC region and decreases to the threshold value (75%), the mode setting unit 36 sets the charging mode to the standby mode. As a result, the SOC of the storage battery 23 is maintained at a value near the threshold, as indicated by the solid line 42A in the figure. When the standby mode is not executed at time t6, as indicated by the dotted line 42B in the figure, the natural discharge further proceeds, the SOC further decreases, and the SOC is largely separated from the full charge. Then, it takes time to return the storage battery 23 to the fully charged state, and there is a concern that the SOC may be lowered to a low SOC region where overdischarge becomes a problem. However, since the SOC is maintained in the standby mode after time t6, such a problem does not occur. Thereafter, when the scheduled use start time is reset, control similar to the charge control described above with reference to FIG. 4 is executed so as to reach full charge in accordance with that time.

  Next, operation | movement of the charging control apparatus 30 is demonstrated based on the flowchart shown in FIG. 6, FIG. The state detection unit 34 of the control device 32 determines whether or not the storage battery 23 of the electric vehicle 20 can be charged, that is, whether or not it is in a charge setting state where the charging cable 22 is connected (step S1). If charging is not possible (NO in step S1), the charging control device 30 stands by as it is.

  When charging is possible (YES in step S1), the SOC detection unit 33 performs data communication with the charge controller 24 and acquires the SOC information of the storage battery 23 (step S2). And the mode setting part 36 reads the threshold value (for example, SOC = 75%) of SOC stored in the threshold value memory | storage part 37, and compares with the acquired SOC of the storage battery 23 (step S3).

  When the SOC of the storage battery 23 is equal to or lower than the threshold (NO in step S3), the mode setting unit 36 sets the charging mode to “normal charging mode”. And the charge control part 35 starts charge operation with respect to the storage battery 23 in normal charge mode (step S4). Thereafter, the SOC detection unit 33 periodically detects the SOC of the storage battery 23, and the mode setting unit 36 determines whether or not the SOC exceeds a threshold value (step S5).

  When the SOC of the storage battery 23 exceeds the threshold at the time of charging setting (YES in step S3), or when the SOC of the storage battery 23 exceeds the threshold during charging in the normal charging mode (YES in step S5) The unit 36 calculates a time obtained by adding a margin time α to the first time T1 required until full charging when the charging is continued as it is (step S6). Then, the mode setting unit 36 compares the second time T2 from the current time when the threshold is reached to the scheduled use start time with the time of the first time T1 + α (step S7).

  When the second time T2 is longer than the first time T1 + α (YES in step S7), the mode setting unit 36 sets the charging mode to “standby mode”. Thereafter, the charging control unit 35 performs the charging operation in the standby mode, and maintains the SOC of the storage battery 23 substantially constant near the threshold (step S8). While the standby mode is executed, the mode setting unit 36 repeats the determination in step S7.

  When the second time T2 is equal to or shorter than the first time T1 + α (NO in step S7), the mode setting unit 36 sets the charging mode to “normal charging mode” (step S9). Thereafter, the charging control unit 35 performs a charging operation on the storage battery 23 in the normal charging mode. This charging operation is continued until the storage battery 23 is fully charged (step S10).

  After the storage battery 23 reaches full charge (YES in step S10), the mode setting unit 36 determines whether or not the scheduled use start time has arrived (step S11). When the scheduled use start time has arrived (YES in step S11), the mode setting unit 36 checks whether or not the state detection unit 34 detects the release of the charging setting (step S12).

  If the charging setting has been cancelled (YES in step S12), the user has started using the electric vehicle 20, so the process is finished as it is. On the other hand, if the charging setting is not released (NO in step S12), mode setting unit 36 causes charging control unit 35 to block the charging current (step S13). Thereby, the natural discharge of the storage battery 23 is started.

  Next, the mode setting unit 36 confirms whether or not the SOC of the storage battery 23 has fallen below the threshold, that is, to the middle SOC region (step S14). If the SOC is not less than or equal to the threshold value (YES in step S14), the mode setting unit 36 checks whether or not the scheduled use start time has been reset from the input unit 31 (step S15). If the scheduled use start time has been reset (YES in step S15), the process returns to step S6, and the same processing is performed based on the new scheduled use start time. On the other hand, when there is no reset of the scheduled use start time (NO in step S15), the process returns to step S12 and the process is repeated.

  On the other hand, if the SOC is equal to or less than the threshold value (YES in step S14), mode setting unit 36 sets the charging mode to “standby mode”. Thereafter, the charging control unit 35 performs the charging operation in the standby mode, and maintains the SOC of the storage battery 23 substantially constant near the threshold (step S16). And while performing this standby mode, confirmation of step S15 is performed periodically.

  According to the charging system of the electric vehicle 20 according to the present embodiment described above, the storage battery 23 is prevented from being fully charged earlier than the scheduled use start time. That is, the storage battery 23 is prevented from being held for a long time in a fully charged state. As a result, the progress of deterioration of the storage battery 23 is suppressed, and the life of the storage battery 23 can be extended. On the other hand, since the storage battery 23 is in a fully charged state at the scheduled use start time, there is an advantage that the cruising distance of the electric vehicle 20 can be ensured fully.

S Charging System for Electric Car 11 Charging Station 12 Power Receiving Equipment 13 Charging Outlet 20 Electric Car 21 Charging Connector 22 Charging Cable 23 Storage Battery (Secondary Battery)
24 charge controller 30 charge control device (charge control means)
31 Input section (input means)
32 Control device (charging control means)
33 SOC detection unit 34 State detection unit 35 Charging control unit 36 Mode setting unit 37 Threshold storage unit 44 Charging control unit

Claims (4)

Charge control means for controlling the charging operation for the secondary battery in a state where the charging setting capable of executing the charging for the secondary battery mounted on the electric vehicle is performed;
Detecting means for detecting a state of charge of the secondary battery;
Input means for receiving an input of the scheduled start time of use of the electric vehicle;
Storage means for storing a threshold value for the remaining battery level of the secondary battery, the threshold being lower than the fully charged battery level by a predetermined amount;
The charge control means includes
The charging operation is started in a state where the remaining battery level of the secondary battery is lower than the threshold value, and then when the remaining battery level detected by the detection means reaches the threshold value,
When the charging is continued as it is, the first time required until full charging is compared with the second time which is the time difference between the time when the threshold is reached and the scheduled use start time, and the second time is the first time. A charging system for an electric vehicle, which executes a standby mode in which the remaining battery level of the secondary battery is not substantially increased or decreased when the time is longer than the time. In the electric vehicle charging system according to claim 1,
In the standby mode, the charging control means does not substantially increase or decrease the remaining battery level of the secondary battery by repeatedly applying and interrupting a charging current. The electric vehicle charging system according to claim 1 or 2,
The electric vehicle charging system according to claim 1, wherein the charging control means cuts off a charging current and spontaneously discharges the secondary battery when the charging setting is not canceled at the scheduled use start time. In the electric vehicle charging system according to claim 3,
The secondary battery is a lithium ion secondary battery;
The charging control means executes the standby mode when the remaining battery level detected by the detection means reaches the threshold value or a value in the vicinity thereof after the natural discharge. system.

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