Patent Publication Number: US-2022227229-A1

Title: Battery state display device, battery state display method, and program

Description:
TECHNICAL FIELD 
     The present invention relates to a battery state display device, a battery state display method, and a program. 
     BACKGROUND ART 
     Conventionally, there is technology for displaying a battery state of a secondary battery in an electric vehicle (see, for example, Patent Literature 1). When the battery state of the secondary battery is displayed, for example, a ratio of a full charge capacity at a present time point to a full charge capacity of the secondary battery at an initial time point is displayed using an icon or the like. 
     CITATION LIST 
     Patent Literature 
     
         
         [Patent Literature 1] 
       
    
     PCT International Publication No. WO 2016/194082 
     SUMMARY OF INVENTION 
     Technical Problem 
     Because a secondary battery mounted in an electric vehicle deteriorates due to use, the display is assumed to be made in a state in which the deterioration has progressed from the time of purchase in the case where the electric vehicle is resold or the like. For this reason, a purchaser may feel that he/she has lost money and feel uncomfortable. 
     The present invention has been made in consideration of such circumstances and provides a battery state display device, a battery state display method, and a program capable of reducing a feeling of discomfort given to a user. 
     Solution to Problem 
     A battery state display device, a battery state display method, and a program according to the present invention adopt the following configurations. 
     (1): According to an aspect of the present invention, there is provided a battery state display device including: an acquirer configured to acquire a full charge capacity of a secondary battery mounted in a vehicle; a display configured to display an image; and a display controller configured to control the display so that a display process before a prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point before the prescribed time point to a full charge capacity of the secondary battery at an initial time point and a display process after the prescribed time point is performed to display an image based on a ratio of a full charge capacity at a time point after the prescribed time point to a full charge capacity at the prescribed time point. 
     (2): In the above-described aspect (1), the prescribed time point is a time point when the vehicle has been resold. 
     (3): In the above-described aspect (1), the display controller controls the display so that a display process after an operation on an execution switch is performed is performed on the basis of a ratio of a full charge capacity at a time point after the operation to a full charge capacity at a time point when the operation on the execution switch has been performed. 
     (4): In the above-described aspect (1), the execution switch is provided in the vehicle. 
     (5): In the above-described aspect (1), the display controller causes the display to display information indicating that the display process based on the ratio of the full charge capacity to the full charge capacity at the prescribed time point is being performed on the basis of the prescribed time point. 
     (6): In the above-described aspect (5), the display controller causes the display to display the information indicating that the display process based on the ratio of the full charge capacity to the full charge capacity at the prescribed time point is being performed on the basis of the prescribed time point in a form in which it is difficult for a general user to understand the information. 
     (7): According to an aspect of the present invention, there is provided a battery state display method including: acquiring, by a computer, a full charge capacity of a secondary battery mounted in a vehicle; controlling, by the computer, displaying of an image so that a display process before a prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point before the prescribed time point to a full charge capacity of the secondary battery at an initial time point and a display process after the prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point after the prescribed time point to a full charge capacity at the prescribed time point; and displaying, by the computer, the image. 
     (8): According to an aspect of the present invention, there is provided a program for causing a computer to: acquire a full charge capacity of a secondary battery mounted in a vehicle; control displaying of an image so that a display process before a prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point before the prescribed time point to a full charge capacity of the secondary battery at an initial time point and a display process after the prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point after the prescribed time point to a full charge capacity at the prescribed time point; and display the image. 
     Advantageous Effects of Invention 
     According to (1) to (8), it is possible to reduce a feeling of discomfort given to a user. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing an example of a configuration of a vehicle  10  including a battery state display device  100  according to an embodiment. 
         FIG. 2  is a diagram showing an example of a configuration of a cabin of the vehicle  10 . 
         FIG. 3  is a diagram showing an example of a full charge capacity map  151 . 
         FIG. 4  is a flowchart showing an example of a process executed by the battery state display device  100 . 
         FIG. 5  is a diagram showing an example of a change in the display of a battery state. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of a battery state display device, a battery state display method, and a program of the present invention will be described with reference to the drawings. The following embodiments do not limit the present invention covered by claims. Also, not all combinations of features described in the embodiments are necessary for solutions of the present invention. Although a vehicle  10  is assumed to be an electric vehicle, the vehicle  10  may be a hybrid vehicle or a fuel cell vehicle as long as it is a vehicle equipped with a secondary battery that supplies electric power for traveling of the vehicle  10 . 
       FIG. 1  is a diagram showing an example of a configuration of the vehicle  10  including a battery state display device  100  according to the embodiment. As shown in  FIG. 1 , the battery state display device  100  is provided in a plurality of vehicles  10 . The battery state display device  100  displays a battery state of a battery (which is hereinafter assumed to be synonymous with a secondary battery) mounted in the vehicle  10 . 
     [Vehicle  10 ] 
     As shown in  FIG. 1 , the vehicle  10  includes, for example, a motor  12 , drive wheels  14 , a brake device  16 , a vehicle sensor  20 , a power control unit (PCU)  30 , a battery  40 , battery sensors  42  such as a voltage sensor, a current sensor, and a temperature sensor, a charging port  70 , a converter  72 , a steering switch  90 , and a battery state display device  100 . [ 0019 ] 
     The motor  12  is, for example, a three-phase alternating current (AC) electric motor. A rotor of the motor  12  is connected to the drive wheels  14 . The motor  12  outputs motive power to the drive wheels  14  using electric power that is supplied. Also, the motor  12  generates electric power using kinetic energy of the vehicle when the vehicle is decelerated. [ 0020 ] 
     The brake device  16  includes, for example, a brake caliper, a cylinder that transfers hydraulic pressure to the brake caliper, and an electric motor that generates hydraulic pressure in the cylinder. The brake device  16  may include a mechanism that transfers hydraulic pressure generated by the operation of the brake pedal to the cylinder via a master cylinder as a backup. Also, the brake device  16  is not limited to the above-described configuration and may be an electronically controlled hydraulic brake device that transfers the hydraulic pressure of the master cylinder to the cylinder. [ 0021 ] 
     The vehicle sensor  20  includes an accelerator opening degree sensor, a vehicle speed sensor, and a brake depression amount sensor. The accelerator opening degree sensor is attached to an accelerator pedal, which is an example of an operation element for receiving an acceleration instruction from a driver, detects an amount of operation of the accelerator pedal, and outputs the detected amount of operation as an accelerator opening degree to a control unit  36 . The vehicle speed sensor includes, for example, a wheel speed sensor and a speed calculator attached to each wheel and combines wheel speeds detected by wheel speed sensors to derive the speed of the vehicle (a vehicle speed) and outputs the derived speed to the control unit  36  and a display device  60  The brake depression amount sensor is attached to the brake pedal, detects the amount of operation of the brake pedal, and outputs the detected amount of operation as an amount of brake depression to the control unit  36 . 
     The PCU  30  includes, for example, a converter  32 , a voltage control unit (VCU)  34 , and the control unit  36 . Also, a group of the above components is configured as the PCU  34  as only an example and these components may be arranged in a distributed form. 
     The converter  32  is, for example, an AC-direct current (DC) converter. A DC side terminal of the converter  32  is connected to a DC link DL. The battery  40  is connected to the DC link DL via the VCU  34 . The converter  32  converts an AC generated by the motor  12  into a DC and outputs the DC to the DC link DL. 
     The VCU  34  is, for example, a DC-DC converter. The VCU  34  boosts electric power supplied by the battery  40  and outputs the boosted electric power to the DC link DL. 
     The control unit  36  includes, for example, a motor control unit, a brake control unit, and a battery/VCU control unit. The motor control unit, the brake control unit, and the battery/VCU control unit may be replaced with separate control devices such as a motor ECU, a brake ECU, and a battery ECU. 
     The motor control unit controls the motor  12  on the basis of an output of the vehicle sensor  20 . The brake control unit controls the brake device  16  on the basis of an output of the vehicle sensor  20 . The battery/VCU control unit calculates a state of charge (SOC) (hereinafter also referred to as a “battery charge rate”) of the battery  40  on the basis of an output of the battery sensor  42  attached to the battery  40 . In battery/VCU control, the calculated SOC is output to the VCU  34 . The VCU  34  causes a voltage of the DC link DL to be raised in accordance with an instruction from the battery/VCU control unit. 
     The battery  40  is, for example, a secondary battery such as a lithium-ion battery. The battery  40  stores electric power introduced from a charger  200  outside the vehicle  10  and is discharged with the electric power for traveling of the vehicle  10 . The battery sensors  42  include, for example, a current sensor, a voltage sensor, and a temperature sensor. The battery sensors  42  detect, for example, a current value, a voltage value, and a temperature of the battery  40 . The battery sensors  42  output the detected current value, voltage value, and temperature and the like to the control unit  36 . 
     The charging port  70  is provided oriented toward outside of the vehicle body of the vehicle  10 . The charging port  70  is connected to the charger  200  via a charging cable  220 . The charging cable  220  includes a first plug  222  and a second plug  224 . The first plug  222  is connected to the charger  200  and the second plug  224  is connected to the charging port  70 . The electricity supplied from the charger  200  is supplied to the charging port  70  via the charging cable  220 . 
     Also, the charging cable  220  includes a signal cable attached to a power cable. The signal cable mediates communication between the vehicle  10  and the charger  200 . Therefore, each of the first plug  222  and the second plug  224  is provided with a power connector and a signal connector. 
     The converter  72  is provided between the charging port  70  and the battery  40 . The converter  72  converts a current introduced from the charger  200  via the charging port  70 , for example, an AC, into a DC. The converter  72  outputs the DC obtained in the conversion to the battery  40 . 
     The steering switch  90  includes an execution switch  90 A and a changeover switch  90 B. The execution switch  90 A outputs calibration information to the battery state display device  100  in accordance with a pressing operation by the driver&#39;s finger. The changeover switch  90 B outputs a signal for switching the display of the battery state display device  100  to the battery state display device  100  in accordance with a pressing operation by the driver&#39;s finger. 
       FIG. 2  is a diagram showing an example of a configuration of a cabin of the vehicle  10 . As shown in  FIG. 2 , the vehicle  10  includes, for example, the display device  60 , the steering switch  90 , the steering wheel  91  that controls the steering of the vehicle  10 , a front windshield  92  that separates the outside and the inside of the vehicle, an instrument panel  93 , a first display device  94 , a second display device  95 , and an in-wheel area display  97 . 
     The display device  60  is arranged, for example, in a meter panel unit including an instrument such as a vehicle speedometer provided on the instrument panel  93  in front of the driver&#39;s seat. The steering switch  90  is arranged on the steering wheel  91 . The steering switch  90  is an input device arranged at a position where an operation by the driver&#39;s finger holding the steering wheel  91  is possible. The execution switch  90 A and the changeover switch  90 B of the steering switch  90  are arranged at the right end of the steering switch  90  and the execution switch  90 A is arranged above the changeover switch  90 B. 
     The front windshield  92  is a member allowing light transmission. The first display device  94  and the second display device  95  are provided near the left front of the driver&#39;s seat  96  on the instrument panel  93  within the cabin. 
     The first display device  94  is, for example, a liquid crystal display arranged on a central portion of the instrument panel  93 . The first display device  94  is, for example, a touch panel that receives an input operation by the contact of an operator&#39;s finger. For example, the first display device  94  displays an image corresponding to a navigation process executed by a navigation device (not shown) mounted in the vehicle  10  or displays a video of the other party and the like on a videophone. 
     The second display device  95  is a liquid crystal display arranged above the first display device  94  on the instrument panel  93 . The second display device  95  is, for example, a touch panel that receives an input operation by the contact of the operator&#39;s finger. The second display device  95  is arranged at a position where visual recognition of the driver of the vehicle  10  is easy as compared with the first display device  94 . Compared with the first display device  94 , the second display device  95  is arranged at a position allowing visual recognition by the driver who is driving the vehicle  10  with a smaller movement of a line of sight. The second display device  95  is arranged, for example, at a position closer to the front windshield  92  than the first display device  94 , a position closer to a gaze range in front of the driver in an appropriate driving posture than the first display device  94 , or the like. The second display device  95  displays a television program, performs DVD reproduction, and displays content such as a downloaded movie. 
     For example, the in-wheel area display  97  is arranged above the steering wheel  91 . For example, the vehicle speed of the vehicle  10  or the like is displayed on the in-wheel area display  97 . The display device  60  may be arranged at another position such as a position where the in-wheel area display  97  is arranged. Display content of display devices such as the display device  60 , the first display device  94 , the second display device  95 , and the in-wheel area display  97  may be switched appropriately. 
     [Battery State Display Device  100 ] 
     The battery state display device  100  includes an acquirer  110 , a display controller  120 , a display  130 , and a storage  150 . The acquirer  110  and the display controller  120  are implemented by, for example, a hardware processor such as a central processing unit (CPU) executing a program (software). Some or all of these components may be implemented by hardware (including a circuit unit; circuitry) such as a large-scale integration (LSI) circuit, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a graphics processing unit (GPU) or may be implemented by software and hardware in cooperation. The program may be prestored in a storage device (a non-transitory storage medium) such as a hard disk drive (HDD) or a flash memory or may be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or CD-ROM and installed when the storage medium is mounted in a drive device. The storage  150  is implemented by the storage device described above. The storage  150  stores various types of information. 
     The acquirer  110  measures a period (the number of years) that has elapsed from a time point when the battery  40  was mounted in the vehicle  10  (hereinafter referred to as an “initial time point”) and a period (the number of years) that has elapsed from a time point when calibration information was output by the execution switch  90 A. The acquirer  110  reads a full charge capacity map  151  stored in the storage  150 . The acquirer  110  acquires a full charge capacity at a present time point and a full charge capacity of the battery  40  at the initial time point on the basis of the measured period (the measured number of years). 
     When the calibration information has been output by the execution switch  90 A, the acquirer  110  acquires the full charge capacity of the battery  40  at that time point (a time point when the calibration information has been output by the execution switch  90 A, hereinafter referred to as a “calibration start time point”). The acquirer  110  outputs the full charge capacities at the present time point, the initial time point, and the calibration start time point to the display controller  120 . The calibration start time point is a prescribed time point. When the execution switch  90 A is operated a plurality of times and the calibration information is output a plurality of times, the calibration start time point is set each time and a time point at which the calibration information was last output becomes a calibration start time point. 
     The display controller  120  causes the display to display a battery state indicating a deterioration rate of the battery  40  using the full charge capacities at the present time point, the initial time point, and the calibration start time point output by the acquirer  110 . The battery state of the battery  40  differs between before and after the calibration start time point. Before the calibration start time point, the display controller  120  causes the display  130  to display a ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point as the battery state of the battery. After the calibration start time point, the display controller  120  causes the display  130  to display a ratio of the full charge capacity at the present time point to the full charge capacity at the calibration start time point as the battery state of the battery. 
     After the calibration start time point, the display controller  120  causes the display  130  to display calibration execution information when a calibration execution information flag is turned on. The display controller  120  causes the display  130  to display the calibration execution information in a form in which it is difficult for the driver who is a general user to understand the information. The display controller  120  executes control for switching the display of the display device  60  according to a signal output by the changeover switch  90 B. 
     The display  130  includes, for example, the display device  60  shown in  FIG. 2 . The display  130  is, for example, a multi-information display (MID), and displays information based on control of the display controller  120 , for example, the battery state of the battery  40  and/or the calibration execution information. 
     The storage  150  stores the full charge capacity map  151  as one of various types of information.  FIG. 3  is a diagram showing an example of the full charge capacity map. As shown in  FIG. 3 , the full charge capacity map  151  is represented by a graph showing a ratio to the full charge capacity at the initial time point on the vertical axis and showing the number of years elapsed from the initial time point on the horizontal axis. The full charge capacity map  151  sets the full charge capacity of the battery  40  at the initial time point to 100% and shows a ratio of a full charge capacity in the number of years elapsed from the initial time point to the full charge capacity at the initial time point. 
     In the example shown in  FIG. 3 , the full charge capacity map  151  in which the full charge capacity of the battery  40  at the initial time point is 100%, a full charge capacity after 3 years is 80% of the full charge capacity at the initial time point, and a full charge capacity after 8 years is 60% of the full charge capacity at the initial time point is shown. Also, for example, a design value when the battery  40  is manufactured is included as the full charge capacity at the initial time point in advance. 
     Next, a process of the battery state display device  100  will be described.  FIG. 4  is a flowchart showing an example of the process executed by the battery state display device  100 . The flowchart shown in  FIG. 4  is iteratively executed at certain time intervals. The acquirer  110  provided in the battery state display device  100  first reads the full charge capacity map  151  from the storage  150  (step S 101 ). 
     Subsequently, the acquirer  110  acquires a period (the number of years) that has elapsed from an initial time point during measurement (step S 103 ). Subsequently, the acquirer  110  refers to the acquired elapsed time period in the full charge capacity map  151 , acquires a ratio of a full charge capacity at the present time point to the full charge capacity at the initial time point, and acquires the full charge capacity at the present time point by multiplying the acquired ratio by the full charge capacity at the initial time point (step S 105 ). 
     Subsequently, the acquirer  110  outputs the acquired full charge capacity at the initial time point and the acquired full charge capacity at the present time point to the display controller  120  (step S 107 ). Subsequently, the acquirer  110  determines whether or not the execution switch  90 A has been operated and the present time point is before a calibration start time point (whether or not calibration has been performed) (step S 109 ). 
     When it is determined that the execution switch  90 A has not been operated and the present time point is before the calibration start time point (that calibration has not been performed), the display controller  120  calculates the battery state of the battery  40  as a ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point according to the following Eq. (1) (step S 111 ). 
       Battery state=Full charge capacity at present time point/Full charge capacity at initial time point  (1)
 
     When it is determined that the execution switch  90 A has been operated and the present time point is not before the calibration start time point (that the time point is after the calibration start time point and the calibration is being performed) in step S 109 , the acquirer  110  refers to the calibration start time point in the full charge capacity map  151 , acquires a ratio of a full charge capacity at the calibration start time point to the full charge capacity at the initial time point, and acquires the full charge capacity at the calibration start time point by multiplying the acquired ratio by the full charge capacity at the initial time point (step S 113 ). Also, after the full charge capacity at the calibration start time point is calculated once, a calculated value may be stored in the storage  150  and the stored full charge capacity at the calibration start time point may be read and acquired. 
     Subsequently, the acquirer  110  outputs the acquired full charge capacity at the calibration start time point to the display controller  120  (step S 115 ). The display controller  120  calculates the battery state of the battery  40  as a ratio of the full charge capacity at the present time point to the full charge capacity at the calibration start time point by the following Eq. (2) (step S 117 ). 
       Battery state=Full charge capacity at present time point/Full charge capacity at calibration start time point  (2)
 
     Subsequently, the display controller  120  turns on the calibration execution information flag (step S 119 ). 
     Subsequently, the display controller  120  controls a display process of the display  130  so that a display process based on the battery state calculated in step S 113  or step S 117  is performed (step S 121 ). Further, the display controller  120  performs display control for causing the display  130  to display calibration execution information when the calibration execution information flag is turned on (step S 121 ). In this way, the battery state display device  100  ends the flow shown in  FIG. 4 . 
     Next, an example of a display process based on the battery state of the battery  40  will be described.  FIG. 5  is a diagram showing an example of a change in a display process based on the battery state of the battery  40 . In  FIG. 5 , an example of an image based on battery states before the calibration start time point and after the calibration start time point is shown with respect to each of the batteries  40  after the elapse of 3 years and 8 years from an initial time point. 
     The image based on the battery state of the battery  40  is an image in which segments SG 1  to SG 6  displayed inside a display frame F are brightly or darkly displayed. In the image based on the battery state of the battery  40 , when the number of segments SG (SG 1  to SG 6 ), which are displayed darkly, is more, this indicates that the deterioration of the battery  40  has progressed. 
     For example, when the battery  40  is in the initial state and the deterioration of the battery  40  has not started, all of the  6  segments SG are brightly displayed. As the period elapses from the initial time point and the battery state of the battery  40  advances, the number of brightly displayed segments SG decreases and the number of darkly displayed segments SG increases. 
     For example, when 3 years have elapsed from the initial time point, for example, the battery  40  deteriorates to the extent that the full charge capacity decreases from 100% to 80%. When the calibration is not executed when 3 years have elapsed from the initial time point and the time point is before the calibration start time point, for example, as shown on the upper left side of  FIG. 5 , all of the first to fourth segments SG 1  to SG 4  among the 6 segments SG and a part of the fifth segment SG 5  are displayed brightly and the sixth segment SG 6  is displayed darkly. The above display process corresponds to the case where the full charge capacity at the present time point corresponds to about 80% of the full charge capacity at the initial time point. Thus, the user is allowed to recognize that the deterioration of the battery  40  has started. 
     Further, if 8 years have elapsed from the initial time point and the time point is before the calibration start time point, the first to third segments SG 1  to SG 3  and a part of the fourth segment SG 4  are brightly displayed and the fifth segment SG 5  and the sixth segment SG 6  are darkly displayed. The above display process corresponds to the case where the full charge capacity at the present time point corresponds to about  60 % of the full charge capacity at the initial time point. By performing the above display process, the user is allowed to recognize that the deterioration of the battery  40  has progressed. 
     On the other hand, it is assumed that the calibration is executed at a time point when 3 years have elapsed from the initial time point and the time point when 3 years have elapsed from the initial time point is a calibration start time point. After the calibration start time point, as shown on the right side of  FIG. 5 , the first to sixth segments SG 1  to SG 6  remain brightly displayed. The above display process corresponds to the case where the full charge capacity at the present time point corresponds to about 100% of the full charge capacity at the calibration start time point. Thus, the user is allowed to recognize that the deterioration of the battery  40  has not progressed from the calibration start time point. 
     Calibration is executed at the time point when 3 years have elapsed from the initial time point. At a time point when 8 years have elapsed from the initial time point, the first to fourth segments SG 1  to SG 4  and a part of the fifth segment SG 5  are brightly displayed and the sixth segment SG 6  is darkly displayed. The above display process corresponds to the case where the full charge capacity at the present time point corresponds to about 75% of the full charge capacity at the calibration start time point. Thus, a rate at which the battery  40  has deteriorated from the calibration start time point is shown. 
     Also, when the calibration is started, a calibration execution lamp CL is turned on as shown on the right side of  FIG. 5 . The calibration execution lamp CL is a lamp indicating information about the battery state of the battery  40  shown as a ratio of the full charge capacity at the present time point to the full charge capacity at the calibration start time point. The calibration execution lamp CL may be provided at a position other than the display  130 , may be provided, for example, in a corner of the instrument panel  93 , or may be provided at a position invisible from the driver&#39;s seat, for example, at a position where the battery  40  is mounted, in a trunk room, or the like. The calibration execution lamp CL is displayed in a small size at the lower right of the display frame F, and is displayed in a form in which it is difficult for a general user to understand the calibration execution lamp CL. Thus, the general user may not notice the ON state of the calibration execution lamp CL. 
     In this way, the display based on the battery state of the battery  40  is different between before the calibration start time point and after the calibration start time point. Also, the calibration execution lamp CL indicating that the calibration has been executed is displayed in a form in which it is difficult for a general user to understand the calibration execution lamp CL. 
     The battery state display device  100  of the embodiment displays the battery state of the battery  40  before the calibration start time point on the display  130  on the basis of a ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point and displays the battery state of the battery  40  after the calibration start time point on the display  130  on the basis of a ratio of the full charge capacity at the present time point to the full charge capacity at the calibration start time point. Thus, because the battery state of the battery  40  is displayed on the basis of the calibration start time point, it is possible to reduce a feeling of discomfort of display of the battery state of the battery  40  given to the user. 
     In particular, for example, when the vehicle  10  equipped with the battery  40  is resold, it is difficult for a user who has acquired the vehicle  10  in resale to recognize the deterioration of the battery  40  due to his/her own use because the battery state of the battery  40  before resale will be inherited if the calibration is not performed. In this regard, for example, by executing calibration at a time point when the vehicle  10  equipped with the battery  40  is resold, a process in which the full charge capacity of the battery  40  at the resale time point is displayed as 100% is performed and a deterioration rate of the battery  40  can be displayed on the basis of the above value. Therefore, the user who has acquired the vehicle  10  in resale can easily recognize the deterioration of the battery  40  due to his/her own use. In this case, the resale time point becomes a prescribed time point. Also, by providing the execution switch  90 A for executing the calibration, for example, the battery state of the battery  40  from a time point desired by the user can be displayed, so that the display process can be performed according to the user&#39;s request. 
     Further, the battery state display device  100  of the embodiment causes the display  130  to display the calibration execution lamp CL when the time point is after the calibration start time point. Thus, it is possible to recognize whether the display based on the battery state of the battery  40  displayed on the display  130  is before the calibration start time point or after the calibration start time point. The calibration execution lamp CL is displayed in a form in which it is difficult for a general user to understand the calibration execution lamp CL. Thus, for example, even if the user tries to sell the vehicle  10  to the used vehicle business operator and the like while falsely hiding a fact that the present time point is after the calibration start time point, not before the calibration start time point, the used vehicle business operator can detect the false fact. 
     In the above embodiment, the full charge capacity map  151  is used to acquire the full charge capacities at the initial time point, the calibration start time point, and the full charge capacity at the present time point, but these full charge capacities may be acquired by other means. For example, the control unit  36  may cause the battery state display device  100  to output an SOC of the battery  40  and obtain the full charge capacity of the battery  40  on the basis of a change in the SOC of the battery  40  or the like or may correct the full charge capacity acquired by the full charge capacity map  151  on the basis of the change in the SOC of the battery  40 . 
     Alternatively, relationships between states of use of batteries and battery states of the batteries in a plurality of vehicles may be obtained, these relationships may be learned, and a learning result may be used to obtain the battery state of the battery. In this case, for example, a state of use of the vehicle  10  and a battery state of the battery may be transmitted to an external server and a learning result provided by the external server and the like may be used. 
     Although the display controller  120  does not cause the display  130  to display a ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point as the battery state of the battery after the calibration is started in the above embodiment, a process of causing the display  130  to display a ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point as the battery state of the battery even after the calibration is started may also be able to be performed. In this case, for example, a return switch for causing the display  130  to display the ratio of the full charge capacity at the present time point to the full charge capacity at the initial time point as the battery state of the battery even after the calibration is started or the like may be provided. When the return switch has been operated, for example, the calibration execution information flag may be turned off so that the calibration execution lamp CL is not displayed. 
     Although a display process based on the ratio of the full charge capacity at the present time point to the full charge capacity of the battery  40  at the initial time point and a display process based on the ratio of the full charge capacity at the present time point to the full charge capacity of the battery  40  at the calibration start time point are performed in the above embodiments, a display process may be configured to be performed with respect to a full charge capacity other than the full charge capacity at the present time point. For example, a display process based on a ratio of an estimated value of the full charge capacity after several years to the full charge capacity of the battery  40  at the initial time point or a display process based on the ratio of an estimated value of the full charge capacity after several years to the full charge capacity at the calibration start time point may be configured to be performed. 
     The present invention has been described above using the above embodiments, but the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Those skilled in the art can make various changes or improvements to the above embodiments. It is obvious from the description of the claims that the changes or improvements may be included in the technical scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, a battery state display device includes an acquirer configured to acquire a full charge capacity of a secondary battery mounted in a vehicle; a display configured to display an image; and a display controller configured to control the display so that a display process before a prescribed time point is performed on the basis of a ratio of a full charge capacity at a time point before the prescribed time point to a full charge capacity of the secondary battery at an initial time point and a display process after the prescribed time point is performed to display an image based on a ratio of a full charge capacity at a time point after the prescribed time point to a full charge capacity at the prescribed time point. 
     The battery state display device of the present invention is particularly useful for the cases where the impression of deterioration in a secondary battery given to a user can be reduced. 
     REFERENCE SIGNS LIST 
       10  Vehicle 
       12  Motor 
       14  Drive wheels 
       16  Brake device 
       20  Vehicle sensor 
       40  Battery 
       42  Battery sensors 
       60  Display device 
       70  Charging port 
       72  Converter 
       90  Steering switch 
       90 A Execution switch 
       90 B Changeover switch 
       91  Steering wheel 
       92  Front windshield 
       93  Instrument panel 
       94  First display device 
       95  Second display device 
       96  Driver&#39;s seat 
       97  In-wheel area display 
       100  Battery state display device 
       110  Acquirer 
       120  Display controller 
       130  Display 
       150  Storage 
       151  Full charge capacity map