Method and device for displaying capacity

Abstract

To promote a user to exchange a secondary battery when a time to exchange a secondary battery is coming.SOLUTION: A capacity display device 1 for displaying the capacity of a secondary battery B in a display unit DSP acquires the current capacity of the secondary battery B and the current capacity maintenance rate of the secondary battery, displays the current capacity in the display unit DSP when the current capacity maintenance rate is at least a capacity maintenance rate threshold value Sth11, reduces the current capacity according to the current capacity maintenance rate when the current capacity maintenance rate is smaller than the capacity maintenance rate threshold value Sth11, and displays the capacity after the reduction in the display unit DSP.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for displaying the capacity of a secondary battery on a display unit.

Background Art

[0002] As a capacity display method, there is one in which the indicator itself indicating the capacity of the secondary battery is made smaller as the deterioration of the secondary battery progresses. As a related technique, there is Patent Document 1.

[0003] However, although the above capacity display method can allow the user to recognize the degree of progress of the deterioration of the secondary battery due to the change in the size of the indicator itself, there is a concern that the user cannot be prompted to replace the secondary battery when the replacement time of the secondary battery approaches.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object according to one aspect of the present invention is to provide a capacity display method and a capacity display device capable of prompting a user to replace a secondary battery when the replacement time of the secondary battery approaches.

Means for Solving the Problems

[0006] One form of the capacity display method according to the present invention is a capacity display method performed by a capacity display device that causes a display unit to display the capacity of a secondary battery whose capacity retention rate decreases as deterioration progresses. The capacity display device acquires the current capacity of the secondary battery and the current capacity retention rate of the secondary battery. When the current capacity retention rate is equal to or higher than a capacity retention rate threshold, the current capacity is displayed on the display unit. When the current capacity retention rate is lower than the capacity retention rate threshold, the current capacity is decreased according to the current capacity retention rate, and the decreased capacity is displayed on the display unit.

[0007] Another form of the capacity display method according to the present invention is a capacity display method performed by a capacity display device that causes a display unit to display the capacity of a secondary battery whose deterioration rate increases as deterioration progresses. The capacity display device acquires the current capacity of the secondary battery and the current deterioration rate of the secondary battery. When the current deterioration rate is equal to or lower than a deterioration rate threshold, the current capacity is displayed on the display unit. When the current deterioration rate is higher than the deterioration rate threshold, the current capacity is decreased according to the current deterioration rate, and the decreased capacity is displayed on the display unit.

[0008] By setting the capacity retention rate of the secondary battery when the replacement time of the secondary battery approaches to the capacity retention rate threshold, or by setting the deterioration rate of the secondary battery when the replacement time of the secondary battery approaches to the deterioration rate threshold, it is possible to cause the display unit to display a capacity decreased according to the capacity retention rate or the deterioration rate when the replacement time of the secondary battery approaches. Therefore, even though the secondary battery is charged until it is fully charged, the capacity displayed on the display unit does not reach the maximum, or the rate of decrease in the capacity displayed on the display unit during use of the secondary battery becomes faster than before, so that the user can be made to feel that the life of the secondary battery is shortened, and the user can be made to think that it is necessary to replace the secondary battery. That is, when the replacement time of the secondary battery approaches, the user can be prompted to replace the secondary battery.

[0009] Also, when the segment bar corresponding to the capacity after the decrease is displayed on the display unit, the color of the segment bar may be configured to be different from the color of the segment bar when the segment bar corresponding to the current capacity is displayed on the display unit.

[0010] Thereby, it is possible to easily make the user think that the replacement time of the secondary battery is approaching.

[0011] Also, when the number corresponding to the capacity after the decrease is displayed on the display unit, the color of the number may be configured to be different from the color of the number when the number corresponding to the current capacity is displayed on the display unit.

[0012] Thereby, it is possible to easily make the user think that the replacement time of the secondary battery is approaching.

[0013] Also, the current deterioration rate may be obtained based on the internal resistance value of the secondary battery.

[0014] Also, the capacity maintenance rate threshold or the deterioration rate threshold may be determined in advance.

[0015] Thereby, it is possible to prevent the user from changing the capacity maintenance rate threshold or the deterioration rate threshold.

[0016] Also, when the current capacity maintenance rate is less than the capacity maintenance rate threshold, the capacity display device refers to information in which the capacity maintenance rate of the secondary battery and an adjustment value are associated, obtains an adjustment value corresponding to the current capacity maintenance rate, and uses the multiplication result of the obtained adjustment value and the current capacity as the remaining capacity after the decrease. In the information, the decrease width of the adjustment value per unit capacity maintenance rate in the range from the first capacity maintenance rate, which is the capacity maintenance rate threshold, to the second capacity maintenance rate, which is less than the first capacity maintenance rate, is smaller than the decrease width of the adjustment value per unit capacity maintenance rate in the range from the second capacity maintenance rate to the third capacity maintenance rate, which is less than the second capacity maintenance rate. It may be configured as such.

[0017] Further, when the current degradation rate is greater than the degradation rate threshold, the capacity display device refers to information in which the degradation rate of the secondary battery and an adjustment value are associated, obtains an adjustment value corresponding to the current degradation rate, and uses the multiplication result of the obtained adjustment value and the current capacity as the remaining capacity after the decrease. In the information, the decrease width of the adjustment value per unit degradation rate in the range from a first degradation rate, which is the degradation rate threshold, to a second degradation rate greater than the first degradation rate may be configured to be smaller than the decrease width of the adjustment value per unit degradation rate in the range from the second degradation rate to a third degradation rate greater than the second degradation rate.

[0018] Thereby, as the degradation of the secondary battery progresses, the decrease width of the capacity displayed on the display unit can be gradually increased, so that the user can be gently made to feel that the replacement time of the secondary battery is approaching.

[0019] A capacity display device according to one embodiment of the present invention includes an acquisition unit that acquires the current capacity of a secondary battery and the current capacity maintenance rate of the secondary battery, and when the current capacity maintenance rate is equal to or higher than a capacity maintenance rate threshold, causes the current capacity to be displayed on a display unit, and when the current capacity maintenance rate is smaller than the capacity maintenance rate threshold, decreases the current capacity according to the current capacity maintenance rate, and causes the decreased capacity to be displayed on the display unit.

[0020] Further, a capacity display device according to one embodiment of the present invention includes an acquisition unit that acquires the current capacity of a secondary battery and the current degradation rate of the secondary battery, and when the current degradation rate is equal to or lower than a degradation rate threshold, causes the current capacity to be displayed on a display unit, and when the current degradation rate is greater than the degradation rate threshold, decreases the current capacity according to the current degradation rate, and causes the decreased capacity to be displayed on the display unit.

[0021] By setting the capacity retention rate of the secondary battery when the replacement time of the secondary battery approaches to the capacity retention rate threshold, or by setting the deterioration rate of the secondary battery when the replacement time of the secondary battery approaches to the deterioration rate threshold, it is possible to cause the display unit to display the reduced capacity according to the capacity retention rate or the deterioration rate when the replacement time of the secondary battery approaches. Therefore, even though the secondary battery is charged until it is fully charged, the capacity displayed on the display unit may not reach the maximum, or the rate of decrease in the capacity displayed on the display unit during use of the secondary battery may become faster than before, making the user feel that the battery life has become shorter and making the user think that it is necessary to replace the secondary battery. That is, when the replacement time of the secondary battery approaches, it is possible to prompt the user to replace the secondary battery.

Advantages of the Invention

[0022] According to the present invention, when the replacement time of the secondary battery approaches, it is possible to prompt the user to replace the secondary battery.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Best Mode for Carrying Out the Invention

[0024] The embodiments will be described in detail below with reference to the drawings.

[0025] FIG. 1 is a diagram showing an example of a vehicle equipped with the capacity display device of the embodiment.

[0026] The vehicle Ve shown in FIG. 1 is, for example, an industrial vehicle such as a forklift or a vehicle such as a hybrid vehicle or an electric vehicle, and includes a power storage device BP, a load Lo, a display unit DSP, and a capacity display device 1. Note that the load Lo is, for example, an inverter circuit that drives a traveling motor, electrical equipment, or the like. The display unit DSP is composed of, for example, an LED (Light Emitting Diode) display or a liquid crystal display, and displays the capacity of the secondary battery B described later, and functions as an indicator showing the capacity of the secondary battery B.

[0027] The power storage device BP includes a secondary battery B, an ammeter 2, a voltmeter 3, switches SW1, SW2, SW3, and a control unit (battery ECU (Electronic Control Unit)) 4.

[0028] The secondary battery B is composed of, for example, one or more lithium ion batteries. The plus terminal of the secondary battery B is connected to the plus input terminal of the load Lo and the plus output terminal of a charger Ch provided outside the vehicle Ve. The minus terminal of the secondary battery B is connected to the minus input terminal of the load Lo via the ammeter 2, the switch SW1, and the switch SW3, and is also connected to the minus output terminal of the charger Ch via the ammeter 2, the switch SW1, and the switch SW2.

[0029] The ammeter 2 is composed of a shunt resistor or the like, detects the current flowing through the secondary battery B, and sends the detected current to the control unit 4.

[0030] The voltmeter 3 is composed of a voltage-dividing resistor or the like, detects the voltage of the secondary battery B, and sends the detected voltage to the control unit 4.

[0031] The switches SW1, SW2, and SW3 are each composed of a semiconductor relay (for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor)) or an electromagnetic relay.

[0032] When the switches SW1 and SW3 are conducting and the switch SW2 is open, it becomes possible to supply power from the secondary battery B to the load Lo, and at the same time, it becomes possible to supply regenerative power or the like from the load Lo to the secondary battery B. Also, when the switches SW1 and SW2 are conducting and the switch SW3 is open, it becomes possible to supply power from the charger Ch to the secondary battery B.

[0033] When power is supplied from the secondary battery B to the load Lo, the secondary battery B is discharged and the capacity of the secondary battery B decreases. When power is supplied to the secondary battery B from the load Lo or the charger Ch, the secondary battery B is charged and the capacity of the secondary battery B increases.

[0034] When AC power is supplied from the charger Ch to the vehicle Ve, in the vehicle Ve, the AC power supplied from the charger Ch is converted into DC power, and the secondary battery B is charged by supplying the DC power to the secondary battery B.

[0035] The control unit 4 is composed of, for example, a CPU (Central Processing Unit), a multi-core CPU, a programmable device (such as an FPGA (Field Programmable Gate Array) or a PLD (Programmable Logic Device)), sends a current command value to the charger Ch, and performs charging control of the secondary battery B.

[0036] Further, when the control unit 4 receives from the capacity display device 1 that the ignition switch has been turned on, the control unit 4 conducts switches SW1 and SW3 and cuts off switch SW2, thereby enabling power to be supplied from the secondary battery B to the load Lo and enabling regenerative power or the like to be supplied from the load Lo to the secondary battery B. When the control unit 4 receives from the capacity display device 1 that the ignition switch has been turned off, the control unit 4 cuts off switches SW1 to SW3.

[0037] Further, when the control unit 4 receives a charge start instruction from the capacity display device 1, the control unit 4 conducts switches SW1 and SW2 and cuts off switch SW3, thereby enabling power to be supplied from the charger Ch to the secondary battery B. Thereafter, the control unit 4 starts the charge control process for the secondary battery B. When it is determined that the secondary battery B is in a fully charged state, the control unit 4 ends the charge control process for the secondary battery B and cuts off switches SW1 to SW3. For example, when starting the constant current constant voltage charge control process, the control unit 4 sends a current command value to the charger Ch so that the voltage of the secondary battery B gradually rises while the current flowing through the secondary battery B is maintained at a constant current. Next, when the voltage of the secondary battery B reaches a predetermined voltage, the control unit 4 sends a current command value to the charger Ch so that the current flowing through the secondary battery B gradually decreases while the voltage of the secondary battery B is maintained at the predetermined voltage. Then, when the current flowing through the secondary battery B becomes equal to or less than the end current, the control unit 4 determines that the secondary battery B is in a fully charged state, sets the current command value to zero, and ends the constant current constant voltage charge control process.

[0038] Further, the control unit 4 periodically obtains the current capacity of the secondary battery B and the current capacity maintenance rate or the current deterioration rate of the secondary battery B and sends them to the capacity display device 1.

[0039] For example, the control unit 4 refers to OCV-SOC correspondence information in which the open circuit voltage OCV of the secondary battery B and the state of charge SOC of the secondary battery B (the ratio [%] of the remaining capacity [Ah] of the secondary battery B to the full charge capacity [Ah] of the secondary battery B) are associated with each other, and sets the state of charge SOC corresponding to the current open circuit voltage OCV of the secondary battery B as the current capacity. Alternatively, the control unit 4 sets the calculation result of the state of charge SOC [%] before charging or discharging+(integrated value of the current flowing through the secondary battery B during charging or discharging [Ah] / current full charge capacity of the secondary battery B [Ah])×100 as the current capacity. Alternatively, the control unit 4 sets the current open circuit voltage [V] of the secondary battery B or the current closed circuit voltage [V] of the secondary battery B as the current capacity. Alternatively, the control unit 4 sets the integrated value of the current flowing through the secondary battery B from the start of charging to the end of charging when the secondary battery B in a fully discharged state is charged or the integrated value of the current flowing out of the secondary battery B from the start of discharging to the end of discharging when the secondary battery B in a fully charged state is discharged as the current capacity of the secondary battery B. Further, for example, the control unit 4 divides the integrated value of the current flowing through the secondary battery B when the secondary battery B in a fully discharged state is charged until it becomes a fully charged state by the current state of charge [%] and multiplies the result by 100 to obtain the current full charge capacity of the secondary battery B.

[0040] The capacity display device 1 includes a memory 11 and a processor 12.

[0041] The memory 11 is constituted by, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), etc. In addition to the above OCV-SOC correspondence information, it stores a capacity maintenance rate threshold value, capacity maintenance rate-adjustment value correspondence information, deterioration rate threshold value, deterioration rate-adjustment value correspondence information, etc. to be described later. Further, it is assumed that the capacity maintenance rate threshold value, capacity maintenance rate-adjustment value correspondence information, deterioration rate threshold value, and deterioration rate-adjustment value correspondence information stored in the memory 11 are determined in advance by experiments, simulations, etc. Thereby, it is possible to prevent the capacity maintenance rate threshold value, capacity maintenance rate-adjustment value correspondence information, deterioration rate threshold value, and deterioration rate-adjustment value correspondence information from being changed by a user such as a driver of the vehicle Ve.

[0042] The processor 12 includes a travel control unit 121, an acquisition unit 122, and a display control unit 123. Note that the travel control unit 121, the acquisition unit 122, and the display control unit 123 are realized by the processor 12 executing a program stored in the memory 11.

[0043] The travel control unit 121 controls the operation of the load Lo to control the travel of the vehicle Ve.

[0044] The acquisition unit 122 acquires the current capacity of the secondary battery B and the current capacity maintenance rate or current deterioration rate of the secondary battery B sent from the control unit 4 of the power storage device BP.

[0045] Based on the current capacity maintenance rate or current deterioration rate of the secondary battery B, the display control unit 123 determines whether to decrease the display capacity to be displayed on the display unit DSP. If it is determined not to decrease, the current capacity is displayed on the display unit DSP as the display capacity. On the other hand, if the display control unit 123 determines to decrease, the current capacity is decreased according to the current capacity maintenance rate or current deterioration rate, and the decreased capacity is displayed on the display unit DSP as the display capacity.

[0046] <Example 1> In Example 1, a capacity maintenance rate that decreases as the deterioration of the secondary battery B progresses is adopted as a parameter for obtaining the display capacity. For example, the control unit 4 obtains, as the current capacity maintenance rate, the result of multiplying 100 by the quotient obtained by dividing the current full charge capacity of the secondary battery B by the full charge capacity of the secondary battery B at the start of use. Note that the full charge capacity of the secondary battery B at the start of use is stored in the memory 11, for example. Also, the parameter for obtaining the capacity maintenance rate is not limited to the full charge capacity of the secondary battery B.

[0047] FIG. 2 is a flowchart showing the operation of the capacity display device 1 in Example 1. It is assumed that the operation of the flowchart shown in FIG. 2 is executed at every predetermined cycle.

[0048] First, the acquisition unit 122 of the capacity display device 1 acquires the current capacity of the secondary battery B and the current capacity maintenance rate of the secondary battery B (step S11).

[0049] Next, when the current capacity maintenance rate is equal to or higher than the capacity maintenance rate threshold Sth11 (step S12: No), the display control unit 123 of the capacity display device 1 causes the display unit DSP to display the current capacity as the capacity for display (step S13). The capacity maintenance rate threshold Sth11 is the capacity maintenance rate of the secondary battery B when the replacement time of the secondary battery B approaches due to the life of the secondary battery B guaranteed by the manufacturer of the secondary battery B, and is, for example, 60 to 80 [%]. Further, the capacity maintenance rate threshold Sth11 is obtained, for example, by calculating "the capacity maintenance rate of the secondary battery B at the replacement time of the secondary battery B" + "the change width of the capacity maintenance rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance". The "change width of the capacity maintenance rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance" may be obtained, for example, by statistical analysis from the operation data of the secondary battery B in the past, or may be obtained by using simulation from the assumed operation data of the secondary battery B.

[0050] On the other hand, when the current capacity maintenance rate is smaller than the capacity maintenance rate threshold Sth11 (step S12: Yes), the display control unit 123 obtains an adjustment value α corresponding to the current capacity maintenance rate (step S14), decreases the current capacity using the adjustment value α (step S15), and causes the display unit DSP to display the decreased capacity as the capacity for display (step S16).

[0051] FIG. 3A is a diagram showing an example of capacity retention rate - adjustment value correspondence information D11. In FIG. 3A, the horizontal axis of the two-dimensional coordinates indicates the capacity retention rate (capacity retention rate SOH11 to capacity retention rate SOH12), and the vertical axis indicates the adjustment value α (0 to 1). Also, let the capacity retention rate SOH12 = the capacity retention rate threshold value Sth11, and the capacity retention rate SOH11 < the capacity retention rate SOH12. The capacity retention rate SOH11 is the capacity retention rate of the secondary battery B at the time of replacement of the secondary battery B according to the life of the secondary battery B guaranteed by the manufacturer of the secondary battery B. Further, the solid line shown in FIG. 3A indicates the capacity retention rate - adjustment value correspondence information D11. In the capacity retention rate - adjustment value correspondence information D11 shown in FIG. 3A, in the range from the capacity retention rate SOH11 to the capacity retention rate SOH12, it is assumed that the adjustment value α becomes smaller as the current capacity retention rate decreases.

[0052] 4A to 4D are diagrams showing an example of the display screen of the display unit DSP. On the display screens of the display unit DSP shown in FIGS. 4A and 4B, ten segment bars SB1 to SB10 are respectively displayed. For example, when the display capacity is within the range of 0 to 10 [%], the display control unit 123 hatches the segment bar SB1 among the segment bars SB1 to SB10 and leaves the other segment bars SB2 to SB10 blank. When the display capacity is within the range of 11 to 20 [%], the display control unit 123 hatches the segment bars SB1 and SB2 among the segment bars SB1 to SB10 and leaves the other segment bars SB3 to SB10 blank. When the display capacity is within the range of 21 to 30 [%], the display control unit 123 hatches the segment bars SB1 to SB3 among the segment bars SB1 to SB10 and leaves the other segment bars SB4 to SB10 blank. When the display capacity is within the range of 31 to 40 [%], the display control unit 123 hatches the segment bars SB1 to SB4 among the segment bars SB1 to SB10 and leaves the other segment bars SB5 to SB10 blank. When the display capacity is within the range of 41 to 50 [%], the display control unit 123 hatches the segment bars SB1 to SB5 among the segment bars SB1 to SB10 and leaves the other segment bars SB6 to SB10 blank. When the display capacity is within the range of 51 to 60 [%], the display control unit 123 hatches the segment bars SB1 to SB6 among the segment bars SB1 to SB10 and leaves the other segment bars SB7 to SB10 blank. When the display capacity is within the range of 61 to 70 [%], the display control unit 123 hatches the segment bars SB1 to SB7 among the segment bars SB1 to SB10 and leaves the other segment bars SB8 to SB10 blank. When the display capacity is within the range of 71 to 80 [%], the display control unit 123 hatches the segment bars SB1 to SB8 among the segment bars SB1 to SB10 and leaves the other segment bars SB9 and SB10 blank.When the capacity for display is within the range of 81 to 90 [%], the display control unit 123 hatches segment bars SB1 to SB9 among the segment bars SB1 to SB10 and leaves the other segment bar SB10 blank. When the capacity for display is within the range of 91 to 100 [%], the display control unit 123 hatches the segment bars SB1 to SB10.

[0053] Here, for example, assume that the current capacity is 56 [%] and the current capacity maintenance rate is equal to or higher than the capacity maintenance rate threshold Sth11.

[0054] In this case, when the display control unit 123 determines that the current capacity maintenance rate is equal to or higher than the capacity maintenance rate threshold Sth11, in order to cause the display unit DSP to display the current capacity as the capacity for display, as shown in FIG. 4A, among the segment bars SB1 to SB10 shown on the display screen of the display unit DSP, the segment bars SB1 to SB6 are hatched and the other segment bars SB7 to SB10 are left blank. Note that when the display control unit 123 determines that the current capacity maintenance rate is equal to or higher than the capacity maintenance rate threshold Sth11, in order to cause the display unit DSP to display the current capacity as the capacity for display, as shown in FIG. 4C, it may be configured to display the current capacity (56 [%]) in numbers (percentages).

[0055] Also, for example, assume that the current capacity is 56 [%], the current capacity maintenance rate is less than the capacity maintenance rate threshold Sth11, and in the capacity maintenance rate - adjustment value correspondence information D11, the adjustment value α corresponding to the current capacity maintenance rate is 0.5.

[0056] In this case, when the display control unit 123 determines that the current capacity retention rate is less than the capacity retention rate threshold Sth11, it refers to the capacity retention rate - adjustment value correspondence information D11 and obtains 0.5 as the adjustment value α corresponding to the current capacity retention rate. Then, the display control unit 123 calculates 56[%] × 0.5 to obtain 28[%] as the capacity after reduction. In order to display the capacity after reduction on the display unit DSP as the display capacity, as shown in FIG. 4B, among the segment bars SB1 to SB10 shown on the display screen of the display unit DSP, the segment bars SB1 to SB3 are hatched and the other segment bars SB4 to SB10 are left blank. Note that when the display control unit 123 determines that the current capacity retention rate is less than the capacity retention rate threshold Sth11, in order to display the capacity after reduction on the display unit DSP as the display capacity, as shown in FIG. 4D, it may be configured to display the capacity after reduction (28[%]) in numbers (percentage).

[0057] Note that the color of the segment bar when the segment bar corresponding to the capacity after reduction is displayed on the display unit DSP may be configured to be different from the color of the segment bar when the segment bar corresponding to the current capacity is displayed on the display unit DSP. For example, the color of the segment bar when the segment bar corresponding to the current capacity is displayed on the display unit DSP may be set to a bright color such as red or yellow, and the color of the segment bar when the segment bar corresponding to the capacity after reduction is displayed on the display unit DSP may be set to a dark color such as black or gray. Thereby, it can be made easier for the user to recognize that the replacement time of the secondary battery B is approaching.

[0058] Also, the color of the number when the number (percentage) corresponding to the capacity after reduction is displayed on the display unit DSP may be configured to be different from the color of the number when the number (percentage) corresponding to the current capacity is displayed on the display unit DSP. For example, the color of the number when the number corresponding to the current capacity is displayed on the display unit DSP may be set to a bright color such as red or yellow, and the color of the number when the number corresponding to the capacity after reduction is displayed on the display unit DSP may be set to a dark color such as black or gray. Thereby, it can be made easier for the user to recognize that the replacement time of the secondary battery is approaching.

[0059] Also, when causing the display unit DSP to display a segment bar or a number (percentage) corresponding to the capacity after reduction, as the adjustment value α required when obtaining the capacity after reduction approaches zero, the blinking interval of the segment bar or the number displayed on the display unit DSP may be shortened. Thereby, it is possible to make it easier for the user to recognize that the replacement time of the secondary battery B is approaching.

[0060] Also, based on the result of statistical analysis using the operation data of the secondary battery B in the past or the result of simulation using the assumed operation data of the secondary battery B, etc., when the "change width of the capacity maintenance rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance" becomes relatively large, that is, when the load on the secondary battery B is relatively light and the life of the secondary battery B can be extended to delay the replacement time of the secondary battery B, the timing to prompt the user to replace the secondary battery B can be delayed. Therefore, a capacity maintenance rate threshold Sth11' smaller than the capacity maintenance rate threshold Sth11 may be used, and the capacity maintenance rate - adjustment value correspondence information D12 shown in FIG. 3B may be used instead of the capacity maintenance rate - adjustment value correspondence information D11 shown in FIG. 3A. Note that the horizontal axis of the two - dimensional coordinates shown in FIG. 3B indicates the capacity maintenance rate (capacity maintenance rate SOH11 to capacity maintenance rate SOH12), and the vertical axis indicates α (0 to 1). Also, let the capacity maintenance rate SOH12' = the capacity maintenance rate threshold Sth11', and the capacity maintenance rate SOH11 < the capacity maintenance rate SOH12' < the capacity maintenance rate SOH12. Also, the solid line shown in FIG. 3B indicates the capacity maintenance rate - adjustment value correspondence information D12. In the capacity maintenance rate - adjustment value correspondence information D12 shown in FIG. 3B, in the range from the capacity maintenance rate SOH11 to the capacity maintenance rate SOH12', as the current capacity maintenance rate decreases, the adjustment value α becomes smaller. Also, since the capacity maintenance rate SOH12' is smaller than the capacity maintenance rate SOH12, the decrease width of the adjustment value α per unit capacity maintenance rate in the capacity maintenance rate - adjustment value correspondence information D12 shown in FIG. 3B is made larger than the decrease width of the adjustment value α per unit capacity maintenance rate in the capacity maintenance rate - adjustment value correspondence information D11 shown in FIG. 3A.

[0061] Alternatively, when the "change range of the capacity retention rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance" becomes relatively large based on the results of statistical analysis using the operation data of the past secondary battery B or the results of simulation using the assumed operation data of the secondary battery B, that is, when the load on the secondary battery B is relatively light and the life of the secondary battery B can be extended to delay the replacement time of the secondary battery B, it is possible to gradually (step by step) prompt the user that the replacement time of the secondary battery B is approaching. Therefore, instead of the capacity retention rate-adjustment value correspondence information D11 shown in FIG. 3A, the capacity retention rate-adjustment value correspondence information D13 shown in FIG. 3C may be used. Note that the horizontal axis of the two-dimensional coordinates shown in FIG. 3C represents the capacity retention rate (capacity retention rate SOH11 to capacity retention rate SOH12), and the vertical axis represents α (0 to 1). Also, let the capacity retention rate SOH12 = the capacity retention rate threshold Sth11, and the capacity retention rate SOH11 < the capacity retention rate SOH12´´ < the capacity retention rate SOH12. Further, the solid line shown in FIG. 3C represents the capacity retention rate-adjustment value correspondence information D13. In the capacity retention rate-adjustment value correspondence information D13 shown in FIG. 3C, in the range from the capacity retention rate SOH11 to the capacity retention rate SOH12, the adjustment value α becomes smaller as the current capacity retention rate decreases. Also, in the capacity retention rate-adjustment value correspondence information D13 shown in FIG. 3C, the decrease width (slope) of the adjustment value α per unit capacity retention rate in the range from the capacity retention rate SOH12 (the first capacity retention rate) to the capacity retention rate SOH12´´ (the second capacity retention rate) is smaller than the decrease width (slope) of the adjustment value α per unit capacity retention rate in the range from the capacity retention rate SOH12´´ to the capacity retention rate SOH11 (the third capacity retention rate).

[0062] As described above, when the current capacity retention rate of the secondary battery B is equal to or higher than the capacity retention rate threshold Sth11, the capacity display device 1 of the first embodiment causes the display unit DSP to display the current capacity of the secondary battery B. When the current capacity retention rate is smaller than the capacity retention rate threshold Sth11, the current capacity is decreased according to the current capacity retention rate, and the decreased capacity is caused to be displayed on the display unit DSP.

[0063] By setting the capacity retention rate of the secondary battery B when the replacement time of the secondary battery B approaches to the capacity retention rate threshold Sth11, it is possible to cause the display unit DSP to display the capacity that has decreased according to the capacity retention rate when the replacement time of the secondary battery B approaches. Therefore, even though the secondary battery B is charged until it is fully charged, the capacity displayed on the display unit DSP may not reach the maximum, or the rate of decrease in the capacity displayed on the display unit DSP during use of the secondary battery B may become faster than before, which may intentionally cause inconvenience to the user or make the user feel that the life of the secondary battery B has become shorter, and it is possible to make the user think that it is necessary to replace the secondary battery B. That is, it is possible to prompt the user to replace the secondary battery B when the replacement time of the secondary battery B approaches.

[0064] In addition, since an indicator indicating the capacity of the secondary battery B is diverted as an indicator for prompting the replacement of the secondary battery B, it is not necessary to separately provide a dedicated indicator for prompting the replacement of the secondary battery B, and an increase in the manufacturing cost of the entire vehicle Ve can be suppressed.

[0065] <Example 2> In the above Example 1, as a parameter for obtaining the display capacity, a capacity retention rate that decreases as the deterioration of the secondary battery B progresses is adopted. However, a deterioration rate that increases as the deterioration of the secondary battery B progresses may also be adopted.

[0066] For example, as a parameter for obtaining the deterioration rate, the internal resistance value (ohmic resistance value) of the secondary battery B may be adopted. In this case, the display control unit 123 sets the current deterioration rate to 100 multiplied by the result of dividing the current internal resistance value of the secondary battery B by the internal resistance value of the secondary battery B at the start of use. The internal resistance value of the secondary battery B at the start of use is assumed to be stored in the memory 11, for example.

[0067] Alternatively, as a parameter for obtaining the degradation rate, the cumulative usage time from the start of use of the secondary battery B to the present may be adopted. In this case, the display control unit 123 periodically obtains the cumulative usage time from the start of use of the secondary battery B to the present, and sets the cumulative usage time as the current degradation rate.

[0068] Alternatively, as a parameter for obtaining the degradation rate, the cumulative number of charge and discharge cycles of the secondary battery B from the start of use of the secondary battery B to the present may be adopted. In this case, the display control unit 123 obtains the cumulative number of charge and discharge cycles of the secondary battery B from the start of use of the secondary battery B to the present each time charging ends or each time discharging ends, and sets the cumulative number of cycles as the current degradation rate.

[0069] Alternatively, as a parameter for obtaining the degradation rate, the integrated value of the current flowing through the secondary battery B from the start of use of the secondary battery B to the present may be adopted. In this case, the display control unit 123 obtains the integrated value of the current flowing through the secondary battery B from the start of use of the secondary battery B to the present each time charging ends or each time discharging ends, and sets the integrated current value as the current degradation rate.

[0070] Note that the parameter for obtaining the degradation rate is not limited to the internal resistance value, cumulative usage time, cumulative number of charge and discharge cycles, or integrated current value of the secondary battery B.

[0071] FIG. 5 is a flowchart showing the operation of the capacity display device 1 in the second embodiment. It is assumed that the operation of the flowchart shown in FIG. 5 is executed at each predetermined cycle.

[0072] First, the acquisition unit 122 of the capacity display device 1 acquires the current capacity of the secondary battery B and the current degradation rate of the secondary battery B (step S21).

[0073] Next, when the display control unit 123 of the capacity display device 1 determines that the current degradation rate is equal to or less than the degradation rate threshold Sth21 (step S22: No), it causes the display unit DSP to display the current capacity as the display capacity (step S23). Note that the degradation rate threshold Sth21 is the degradation rate of the secondary battery B when the replacement time of the secondary battery B approaches due to the life of the secondary battery B guaranteed by the manufacturer of the secondary battery B.

[0074] On the other hand, when the display control unit 123 determines that the current degradation rate is greater than the degradation rate threshold Sth21 (step S22: Yes), it obtains an adjustment value α corresponding to the current degradation rate (step S24), reduces the current capacity using the adjustment value α (step S25), and causes the display unit DSP to display the reduced capacity as the display capacity (step S26).

[0075] FIG. 6A is a diagram showing an example of the degradation rate - adjustment value correspondence information D21. In the two - dimensional coordinates shown in FIG. 6A, the horizontal axis represents the degradation rate (degradation rate SOH21 to degradation rate SOH22), and the vertical axis represents α (0 to 1). Also, the degradation rate SOH21 = the degradation rate threshold Sth21, and the degradation rate SOH21 < the degradation rate SOH22. The degradation rate SOH22 is the degradation rate of the secondary battery B at the replacement time of the secondary battery B due to the life of the secondary battery B guaranteed by the manufacturer of the secondary battery B. Further, the solid line shown in FIG. 6A represents the degradation rate - adjustment value correspondence information D21. In the degradation rate - adjustment value correspondence information D21 shown in FIG. 6A, between the degradation rate SOH21 and the degradation rate SOH22, it is assumed that the adjustment value α decreases as the current degradation rate increases.

[0076] Here, for example, assume that the current capacity is 56[%] and the current degradation rate is equal to or less than the degradation rate threshold Sth21.

[0077] In this case, when the display control unit 123 determines that the current degradation rate is equal to or less than the degradation rate threshold Sth21, in order to cause the display unit DSP to display the current capacity as the display capacity, as shown in FIG. 4A, among the segment bars SB1 to SB10 shown on the display screen of the display unit DSP, the segment bars SB1 to SB6 are hatched, and the other segment bars SB7 to SB10 are left blank. Note that when the display control unit 123 determines that the current degradation rate is equal to or less than the degradation rate threshold Sth21, in order to cause the display unit DSP to display the current capacity as the display capacity, as shown in FIG. 4C, it may be configured to display the current capacity (56 [%]) in numbers (percentage).

[0078] Also, for example, assume that the current capacity is 56 [%], the current degradation rate is greater than the degradation rate threshold Sth21, and in the degradation rate - adjustment value correspondence information D21, the adjustment value α corresponding to the current degradation rate is 0.5.

[0079] In this case, when the display control unit 123 determines that the current degradation rate is greater than the degradation rate threshold Sth21, it refers to the degradation rate - adjustment value correspondence information D21 to obtain 0.5 as the adjustment value α corresponding to the current degradation rate. Then, the display control unit 123 calculates 56 [%] × 0.5 to obtain 28 [%] as the capacity after reduction, and in order to cause the display unit DSP to display the capacity after reduction as the display capacity, as shown in FIG. 4B, among the segment bars SB1 to SB10 shown on the display screen of the display unit DSP, the segment bars SB1 to SB3 are hatched, and the other segment bars SB4 to SB10 are left blank. Note that when the display control unit 123 determines that the current degradation rate is greater than the degradation rate threshold Sth21, in order to cause the display unit DSP to display the capacity after reduction as the display capacity, as shown in FIG. 4D, it may be configured to display the capacity after reduction (28 [%]) in numbers (percentage).

[0080] In addition, based on the results of statistical analysis using the operation data of the past secondary battery B and the results of simulation using the assumed operation data of the secondary battery B, when the "change range of the deterioration rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance" is relatively large, that is, when the load on the secondary battery B is relatively light and the life of the secondary battery B is extended, so that the replacement timing of the secondary battery B can be postponed, the deterioration rate threshold Sth21' larger than the deterioration rate threshold Sth21 can be used, and the deterioration rate-adjustment value correspondence information D22 shown in FIG. 6B can be used instead of the deterioration rate-adjustment value correspondence information D21 shown in FIG. 6A. Note that the horizontal axis of the two-dimensional coordinates shown in FIG. 6B represents the deterioration rate (deterioration rate SOH21 to deterioration rate SOH22), and the vertical axis represents α (0 to 1). Also, let the deterioration rate SOH21' = the deterioration rate threshold Sth21', and the deterioration rate SOH21 < the deterioration rate SOH21' < the deterioration rate SOH22. Further, the solid line shown in FIG. 6B represents the deterioration rate-adjustment value correspondence information D22. In the deterioration rate-adjustment value correspondence information D22 shown in FIG. 6B, in the range from the deterioration rate SOH21' to the deterioration rate SOH22, it is assumed that the adjustment value α decreases as the current deterioration rate increases. Also, since the deterioration rate SOH21' is larger than the deterioration rate SOH21, the decrease width of the adjustment value α per unit deterioration rate in the deterioration rate-adjustment value correspondence information D22 shown in FIG. 6B is larger than the decrease width of the adjustment value α per unit deterioration rate in the deterioration rate-adjustment value correspondence information D21 shown in FIG. 6A.

[0081] Alternatively, when the "change range of the deterioration rate of the secondary battery B that decreases during the period from the previous regular maintenance to the current regular maintenance" is relatively large based on the results of statistical analysis using the operation data of the past secondary battery B or the results of simulation using the assumed operation data of the secondary battery B, that is, when the load on the secondary battery B is relatively light and the life of the secondary battery B is extended, making it possible to extend the replacement time of the secondary battery B, it is possible to gradually (step by step) prompt the user that the replacement time of the secondary battery B is approaching. Therefore, instead of the deterioration rate-adjustment value correspondence information D21 shown in FIG. 6A, the deterioration rate-adjustment value correspondence information D23 shown in FIG. 6C may be used. Note that the horizontal axis of the two-dimensional coordinates shown in FIG. 6C indicates the deterioration rate (deterioration rate SOH21 to deterioration rate SOH22), and the vertical axis indicates α (0 to 1). Also, let the deterioration rate SOH21 = the deterioration rate threshold value Sth21, and the deterioration rate SOH21 < the deterioration rate SOH21´´ < the deterioration rate SOH22. Further, the solid line shown in FIG. 6C indicates the deterioration rate-adjustment value correspondence information D23. In the deterioration rate-adjustment value correspondence information D23 shown in FIG. 6C, in the range from the deterioration rate SOH21 to the deterioration rate SOH22, as the current deterioration rate increases, the adjustment value α decreases. Also, in the deterioration rate-adjustment value correspondence information D23 shown in FIG. 6C, the decrease width (slope) of the adjustment value α per unit deterioration rate in the range from the deterioration rate SOH21 (the first deterioration rate) to the deterioration rate SOH21´´ (the second deterioration rate) is smaller than the decrease width (slope) of the adjustment value α per unit deterioration rate in the range from the deterioration rate SOH21´´ to the deterioration rate SOH22 (the third deterioration rate).

[0082] As described above, when the current deterioration rate of the secondary battery B is less than or equal to the deterioration rate threshold value Sth21, the capacity display device 1 of the second embodiment causes the display unit DSP to display the current capacity of the secondary battery B. When the current deterioration rate is greater than the deterioration rate threshold value Sth21, the current capacity is decreased according to the current deterioration rate, and the decreased capacity is caused to be displayed on the display unit DSP.

[0083] By setting the deterioration rate of the secondary battery B when the replacement time of the secondary battery B approaches to the deterioration rate threshold value Sth21, it is possible to cause the display unit DSP to display the reduced capacity according to the deterioration rate when the replacement time of the secondary battery B approaches. Therefore, even though the secondary battery B is charged until it is fully charged, the capacity displayed on the display unit DSP may not reach the maximum, or the rate of decrease in the capacity displayed on the display unit DSP during use of the secondary battery B may become faster than before, which may intentionally cause inconvenience to the user or make the user feel that the life of the secondary battery B is shortened, and the user can be made to think that it is necessary to replace the secondary battery B. That is, when the replacement time of the secondary battery B approaches, the user can be prompted to replace the secondary battery B.

[0084] In addition, since an indicator indicating the capacity of the secondary battery B is diverted as an indicator for prompting the replacement of the secondary battery B, it is not necessary to separately provide a dedicated indicator for prompting the replacement of the secondary battery B, and an increase in the manufacturing cost of the entire vehicle Ve can be suppressed.

[0085] The present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the gist of the present invention.

[0086] <Modification Example 1> Instead of the capacity maintenance rate-adjustment value correspondence information D11 shown in FIG. 3A, the capacity maintenance rate-adjustment value correspondence information D14 shown in FIG. 7A may be adopted. Note that the horizontal axis of the two-dimensional coordinates shown in FIG. 7A indicates the capacity maintenance rate (capacity maintenance rate SOH11 to 100 [%]), and the vertical axis indicates α (0 to 1). Also, let the capacity maintenance rate SOH11 < the capacity maintenance rate SOH12 < 100 [%]. The solid line shown in FIG. 7A indicates the capacity maintenance rate-adjustment value correspondence information D14. In the capacity maintenance rate-adjustment value correspondence information D14 shown in FIG. 7A, when the current capacity maintenance rate is equal to or higher than the capacity maintenance rate SOH12 and equal to or lower than 100 [%], the adjustment value α becomes 1, and when the current capacity maintenance rate is smaller than the capacity maintenance rate SOH12 and equal to or higher than the capacity maintenance rate SOH11, the adjustment value α becomes smaller as the current capacity maintenance rate decreases.

[0087] When obtaining the display capacity using the capacity retention rate - adjustment value correspondence information D14 shown in FIG. 7A, first, the acquisition unit 122 of the capacity display device 1 acquires the current capacity of the secondary battery B and the current capacity retention rate of the secondary battery B.

[0088] Next, the display control unit 123 of the capacity display device 1 refers to the capacity retention rate - adjustment value correspondence information D14 to obtain the adjustment value α corresponding to the current capacity retention rate. At this time, when the current capacity retention rate is equal to or higher than the capacity retention rate SOH12 and equal to or lower than 100 [%], 1 is obtained as the adjustment value α. When the current capacity retention rate is less than the capacity retention rate SOH12 and equal to or higher than the capacity retention rate SOH11, the adjustment value α corresponding to the current capacity retention rate is obtained.

[0089] Then, the display control unit 123 obtains the multiplication result of the obtained adjustment value α and the current capacity as the display capacity and causes the display unit DSP to display it.

[0090] Even with such a configuration, when the replacement time of the secondary battery B approaches, the user can be prompted to replace the secondary battery B.

[0091] <Modification Example 2> Instead of the degradation rate - adjustment value correspondence information D21 shown in FIG. 6A, the degradation rate - adjustment value correspondence information D24 shown in FIG. 7B may be adopted. Note that the horizontal axis of the two - dimensional coordinates shown in FIG. 7B indicates the degradation rate (100 [%] - degradation rate SOH22), and the vertical axis indicates α (0 - 1). Also, 100 [%] < degradation rate SOH21 < degradation rate SOH22. The solid line shown in FIG. 7B indicates the degradation rate - adjustment value correspondence information D24. In the degradation rate - adjustment value correspondence information D24 shown in FIG. 7B, when it is 100 [%] or more and the current degradation rate is equal to or less than the degradation rate SOH21, the adjustment value α becomes 1. When the current degradation rate is greater than the degradation rate SOH21 and equal to or less than the degradation rate SOH22, the adjustment value α becomes smaller as the current degradation rate increases.

[0092] When obtaining the display capacity using the degradation rate - adjustment value correspondence information D24 shown in FIG. 7B, first, the acquisition unit 122 of the capacity display device 1 acquires the current capacity of the secondary battery B and the current degradation rate of the secondary battery B.

[0093] Next, the display control unit 123 of the capacity display device 1 refers to the degradation rate - adjustment value correspondence information D24 to obtain the adjustment value α corresponding to the current degradation rate. At this time, when the current degradation rate is 100 [%] or more and the degradation rate SOH21 or less, 1 is obtained as the adjustment value α. When the current degradation rate is greater than the degradation rate SOH21 and the degradation rate SOH22 or less, the adjustment value α corresponding to the current degradation rate is obtained.

[0094] Then, the display control unit 123 obtains the multiplication result of the obtained adjustment value α and the current capacity as the display capacity and causes the display unit DSP to display it.

[0095] Even with such a configuration, when the replacement time of the secondary battery B approaches, the user can be prompted to replace the secondary battery B.

Explanation of Reference Numerals

[0096] 1 Capacity display device 2 Ammeter 3 Voltmeter 4 Control unit 11 Memory 12 Processor 121 Travel control unit 122 Acquisition unit 123 Display control unit Ve Vehicle BP Power storage device Ch Charger SW1, SW2, SW3 Switches Lo Load DSP Display unit

Claims

1. A capacity display method performed by a capacity display device that causes a display unit to display the capacity of a secondary battery whose capacity retention rate decreases as deterioration progresses, wherein the capacity display device acquires the current capacity of the secondary battery and the current capacity retention rate of the secondary battery, when the current capacity retention rate is equal to or higher than a capacity retention rate threshold, causes the display unit to display the current capacity, when the current capacity retention rate is less than the capacity retention rate threshold, decreases the current capacity according to the current capacity retention rate, and causes the display unit to display the capacity after the decrease Capacity display method.

2. A capacity display method performed by a capacity display device that causes a display unit to display the capacity of a secondary battery whose deterioration rate increases as deterioration progresses, wherein the capacity display device acquires the current capacity of the secondary battery and the current deterioration rate of the secondary battery, when the current deterioration rate is equal to or less than a deterioration rate threshold, causes the display unit to display the current capacity, when the current deterioration rate is greater than the deterioration rate threshold, decreases the current capacity according to the current deterioration rate, and causes the display unit to display the capacity after the decrease Capacity display method.

3. The capacity display method according to claim 1 or claim 2, wherein the color of the segment bar when the segment bar corresponding to the capacity after the decrease is displayed on the display unit is different from the color of the segment bar when the segment bar corresponding to the current capacity is displayed on the display unit Capacity display method.

4. The capacity display method according to claim 1 or claim 2, wherein the color of the number when the number corresponding to the capacity after the decrease is displayed on the display unit is different from the color of the number when the number corresponding to the current capacity is displayed on the display unit Capacity display method.

5. The capacity display method according to claim 2, wherein the current deterioration rate is obtained based on the internal resistance value of the secondary battery Capacity display method.

6. The capacity display method according to claim 1, wherein the capacity retention rate threshold is determined in advance Capacity display method.

7. The capacity display method according to claim 2, wherein the deterioration rate threshold is determined in advance Capacity display method.

8. The capacity display method according to claim 1, When the current capacity retention rate is less than the capacity retention rate threshold, the capacity display device refers to information in which the capacity retention rate of the secondary battery is associated with an adjustment value, obtains an adjustment value corresponding to the current capacity retention rate, and uses the multiplication result of the obtained adjustment value and the current capacity as the remaining capacity after the decrease. In the information, the decrease width of the adjustment value per unit capacity retention rate in the range from the first capacity retention rate, which is the capacity retention rate threshold, to the second capacity retention rate, which is less than the first capacity retention rate, is smaller than the decrease width of the adjustment value per unit capacity retention rate in the range from the second capacity retention rate to the third capacity retention rate, which is less than the second capacity retention rate. Capacity display method.

9. The capacity display method according to claim 2, When the current degradation rate is greater than the degradation rate threshold, the capacity display device refers to information in which the degradation rate of the secondary battery is associated with an adjustment value, obtains an adjustment value corresponding to the current degradation rate, and uses the multiplication result of the obtained adjustment value and the current capacity as the remaining capacity after the decrease. In the information, the decrease width of the adjustment value per unit degradation rate in the range from the first degradation rate, which is the degradation rate threshold, to the second degradation rate, which is greater than the first degradation rate, is smaller than the decrease width of the adjustment value per unit degradation rate in the range from the second degradation rate to the third degradation rate, which is greater than the second degradation rate. Capacity display method.

10. An acquisition unit that acquires the current capacity of the secondary battery and the current capacity retention rate of the secondary battery; A display control unit that causes the display unit to display the current capacity when the current capacity retention rate is equal to or greater than the capacity retention rate threshold, and when the current capacity retention rate is less than the capacity retention rate threshold, decreases the current capacity according to the current capacity retention rate, and causes the display unit to display the capacity after the decrease. A capacity display device comprising the above.

11. An acquisition unit that acquires the current capacity of the secondary battery and the current degradation rate of the secondary battery; A display control unit that causes the display unit to display the current capacity when the current degradation rate is equal to or less than the degradation rate threshold, and when the current degradation rate is greater than the degradation rate threshold, decreases the current capacity according to the current degradation rate, and causes the display unit to display the capacity after the decrease. A capacity display device comprising the above.

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