JP7793438B2 - Battery replacement determination system and battery replacement determination method - Google Patents

Description

The technology disclosed in this application relates to a battery replacement determination system and a battery replacement determination method.

The battery state determination device described in Patent Document 1 determines whether a battery needs to be replaced based on the difference between the lowest battery voltage at the most recent engine start and the lowest battery voltage at engine start when a new, fully charged battery is used.

JP 2011-056976 A

However, in vehicles with high-voltage systems, such as hybrid vehicles, the load on the battery (e.g., a lead battery) does not reach its maximum when the engine is started, so the voltage drop during normal load discharge may be greater, making it impossible to accurately obtain the minimum voltage. If the minimum voltage cannot be accurately obtained, as with the battery state determination device described in Patent Document 1, it may not be possible to properly determine whether the battery needs to be replaced.

The objective of the technology disclosed in this application is to provide a battery replacement determination system that can appropriately determine whether or not a battery replacement is necessary.

According to a first feature, the battery replacement determination system includes a voltage detection unit and a controller. The voltage detection unit detects the voltage of the vehicle's battery. The controller selects a representative voltage value from multiple detected voltage values detected by the voltage detection unit at multiple different times during the vehicle operation period, from start-up to shutdown of the vehicle's system. The controller determines whether or not the battery needs to be replaced based on the temporal relationship between the multiple representative voltage values selected during each of the multiple vehicle operation periods.

The battery replacement determination system according to the first aspect uses the temporal relationship between multiple representative voltage values to accurately grasp changes in the battery state over multiple vehicle operation periods. This allows for an appropriate determination of whether or not the battery needs to be replaced.

According to a second feature, in the battery replacement determination system according to the first feature, the controller selects the lowest voltage value among the multiple detected voltage values as the representative voltage value.

The battery replacement determination system according to the second feature selects the lowest voltage value during the vehicle operation period as the representative voltage value, thereby more appropriately determining whether the battery needs to be replaced.

According to a third feature, the battery replacement determination system according to the first or second feature further includes a charge level detection unit that detects the battery charge level as a detected charge level. When the detected charge level is equal to or greater than a charge level threshold, the controller selects the lowest voltage value from among the multiple detected voltage values as a representative voltage value. When the detected charge level is lower than the charge level threshold, the controller does not select a representative voltage value.

The battery replacement determination system according to the third feature determines whether or not to select a representative voltage value based on the detected charge level, so that voltage values detected when the battery charge level is at a level that is inappropriate for determining battery replacement can be excluded from the candidates for the representative voltage value. This improves the accuracy of the representative voltage value, enabling a more appropriate determination of whether or not the battery needs to be replaced.

According to a fourth feature, in the battery replacement determination system according to the third feature, when the controller determines whether the detected charge level is equal to or greater than the charge level threshold, it uses the detected charge level detected by the charge level detection unit within a predetermined time before performing the charge level determination.

The battery replacement determination system according to the fourth feature can further improve the accuracy of the representative voltage value, enabling a more accurate determination of whether or not the battery needs to be replaced.

According to a fifth feature, in the battery replacement determination system according to any one of the first to fourth features, the controller selects a representative voltage value from a plurality of detected voltage values including the latest detected voltage value when the latest detected voltage value output from the voltage detection unit is equal to or lower than the voltage threshold value. If the latest detected voltage value is higher than the voltage threshold value, the controller does not select a representative voltage value from a plurality of detected voltage values including the latest detected voltage value.

The battery replacement determination system according to the fifth feature can exclude relatively high detected voltage values from the candidates for the representative voltage value. This improves the accuracy of the representative voltage value, enabling a more accurate determination of whether the battery needs to be replaced.

According to a sixth feature, the battery replacement determination system according to any one of the first to fifth features further includes a temperature sensor that detects the battery temperature as the detected temperature. The controller corrects the detected voltage value based on the detected temperature.

The battery replacement determination system according to the sixth feature can reduce the effect of battery temperature on the detected voltage value, thereby improving the accuracy of the detected voltage value.

According to a seventh feature, in the battery replacement determination system according to any one of the first to sixth features, the controller creates a voltage ranking in which the representative voltage values are arranged in ascending order.

The battery replacement determination system according to the seventh feature makes it easier to manage multiple representative voltage values selected during multiple vehicle operation periods using voltage rankings.

According to an eighth feature, in the battery replacement determination system according to the seventh feature, the controller selects at least two representative voltage values ranked in a predetermined order in the voltage ranking from among the plurality of representative voltage values. The controller determines whether or not the battery needs to be replaced based on at least two elapsed times from a reference time to the time when the at least two representative voltage values are detected, respectively.

The battery replacement determination system according to the eighth feature is able to determine how much time has passed since a reference time until at least two representative voltage values ranked in a predetermined order are detected, allowing for a more appropriate determination of whether or not the battery needs to be replaced.

According to a ninth feature, in the battery replacement determination system according to the eighth feature, the controller calculates the standard deviation of at least two elapsed times and determines whether or not the battery needs to be replaced based on the standard deviation.

In the battery replacement determination system according to the ninth feature, by using the standard deviation of at least two elapsed times, it is possible to determine the frequency with which representative voltage values ranked in a predetermined order are detected, thereby more appropriately determining whether or not the battery needs to be replaced.

According to a tenth feature, in the battery replacement determination system according to the ninth feature, the multiple vehicle operation periods include a first vehicle operation period and a second vehicle operation period that follows the first vehicle operation period. The controller determines whether or not the battery needs to be replaced based on a first standard deviation calculated as the standard deviation during the first vehicle operation period and a second standard deviation calculated as the standard deviation during the second vehicle operation period.

In the battery replacement determination system according to the tenth feature, by using the first and second standard deviations, it is possible to accurately determine the frequency with which representative voltage values ranked in a predetermined order are detected, thereby more appropriately determining whether or not the battery needs to be replaced.

According to an eleventh feature, in the battery replacement determination system according to the tenth feature, the controller issues a replacement determination result indicating that the battery needs to be replaced when the ratio of the second standard deviation to the first standard deviation is smaller than the standard deviation threshold value.

The battery replacement determination system according to the eleventh feature can determine the relationship between the first standard deviation and the second standard deviation based on a fixed criterion, enabling a more appropriate determination of whether or not the battery needs to be replaced.

According to a twelfth feature, in the battery replacement determination system according to the eleventh feature, the controller calculates the average of at least two elapsed times as the average elapsed time.

In the battery replacement determination system according to the twelfth feature, by using the average elapsed time, it is possible to grasp the frequency with which representative voltage values ranked in a predetermined order are detected, thereby more appropriately determining whether or not the battery needs to be replaced.

According to a thirteenth feature, in the battery replacement determination system according to the twelfth feature, the controller determines whether or not the battery needs to be replaced based on a first average elapsed time calculated by the controller as the average elapsed time during a first vehicle operation period, and a second average elapsed time calculated by the controller as the average elapsed time during a second vehicle operation period.

In the battery replacement determination system according to the thirteenth feature, by using the first average elapsed time and the second average elapsed time, it is possible to grasp the frequency with which representative voltage values ranked in a predetermined order are detected, thereby more appropriately determining whether or not the battery needs to be replaced.

According to a fourteenth feature, in the battery replacement determination system according to the thirteenth feature, the controller calculates, as a first difference, the difference between a first elapsed time from a reference time to the time when the representative voltage value is detected by the controller during the first vehicle operation period and a first average elapsed time. The controller calculates, as a second difference, the difference between a second elapsed time from the reference time to the time when the representative voltage value is detected by the controller during the second vehicle operation period and a second average elapsed time. If the ratio of the second difference to the first difference is smaller than a time threshold, the controller issues a replacement determination result indicating that the battery needs to be replaced.

In the battery replacement determination system according to the fourteenth feature, by using the first and second differences, it is possible to accurately determine the frequency with which representative voltage values ranked in a predetermined order are detected, thereby more appropriately determining whether or not the battery needs to be replaced.

According to a fifteenth feature, the battery replacement determination system according to any one of the first to fourteenth features further includes a notification unit that notifies the user of the determination result of the controller.

The battery replacement determination system according to the fifteenth feature can notify the user that a battery replacement is necessary.

According to a sixteenth feature, the battery replacement determination system according to any one of the first to fifteenth features further includes at least one of a server and a terminal.

The battery replacement determination system according to the sixteenth feature can utilize a replacement determination result indicating that a battery replacement is required in at least one of the server and the terminal.

According to a seventeenth feature, the battery replacement determination method includes detecting the voltage supplied from the vehicle battery using a voltage detection unit, selecting a representative voltage value using a controller from multiple detected voltage values detected by the voltage detection unit at multiple different times during the vehicle operation period from startup to shutdown of the vehicle system, and determining the battery state using the controller based on the temporal relationship between the multiple representative voltage values selected by the controller during the multiple vehicle operation periods.

The battery replacement determination method according to the seventeenth feature uses the temporal relationship between multiple representative voltage values to accurately grasp changes in the battery state over multiple vehicle operation periods. This allows for an appropriate determination of whether or not the battery needs to be replaced.

The technology disclosed in this application provides a battery replacement determination system that can appropriately determine whether or not a battery replacement is necessary.

FIG. 1 is a schematic block diagram of a vehicle including a battery replacement determination system according to an embodiment. FIG. 2 is a schematic diagram showing an outline of the battery replacement determination process of the battery replacement determination system shown in FIG. FIG. 3 is a graph showing detected voltage values and elapsed time of the battery replacement determination system shown in FIG. FIG. 4 is a graph showing detected voltage values and elapsed time of the battery replacement determination system shown in FIG. FIG. 5 shows an example of a flowchart of a battery replacement determination method of the battery replacement determination system shown in FIG. FIG. 6 shows an example of a flowchart of a battery replacement determination method of the battery replacement determination system shown in FIG. FIG. 7 shows an example of a flowchart of a battery replacement determination method of the battery replacement determination system shown in FIG. FIG. 8 is a schematic block diagram showing information exchange in a battery replacement determination system according to a modified example. FIG. 9 is a schematic block diagram of a battery replacement determination system according to a modified example.

Embodiments will be described below with reference to the drawings. The same reference numerals in the drawings indicate corresponding or identical components.

As shown in FIG. 1, vehicle 2 includes battery 4, load 6, power supply circuit 8, and battery replacement determination system 10. Examples of vehicle 2 include automobiles. Examples of automobiles include automobiles equipped with an engine (internal combustion engine) as a power source, hybrid vehicles equipped with an engine and a vehicle drive motor as a power source, and electric vehicles or fuel cell vehicles equipped with a vehicle drive motor as a power source. Therefore, for example, vehicle 2 may include a vehicle drive battery in addition to battery 4. Vehicle 2 is not limited to the above vehicles. Furthermore, battery replacement determination system 10 may be configured as a single device or multiple units as long as its functions are located within vehicle 2.

The battery 4 is electrically connected to the load 6 via the power supply circuit 8. The battery 4 supplies power (electricity) to the load 6 via the power supply circuit 8.

The loads 6 operate using electricity supplied from the battery 4. Examples of the loads 6 include an electronic control unit (ECU), lights, a heater, audio equipment, sensors, and a camera. The battery 4 may be connected to multiple loads 6. The loads 6 may also be referred to as on-board equipment 6.

The power supply circuit 8 controls the power supply from the battery 4 to the load 6. The power supply circuit 8 supplies the output voltage of the battery 4 (e.g., 12 V) directly to the load 6. The power supply circuit 8 also converts the output voltage of the battery 4 to a predetermined control voltage (e.g., 3 V or 5 V) as needed and supplies it to the load 6. The power supply circuit 8 is electrically connected to the start-up operation unit 2A of the vehicle 2. The start-up operation unit 2A is configured to receive a start-up operation by the user to start the vehicle 2. The start-up operation unit 2A is configured to receive a stop-down operation by the user to stop the system of the vehicle 2.

The startup operation unit 2A includes, for example, at least one of an engine start key and a start button. Examples of a user startup operation include a user turning the engine start key on the startup operation unit 2A to the start side (e.g., turning the engine ignition ON) and a user pressing the start button on the startup operation unit 2A. Examples of a user stop operation include a user turning the engine start key on the startup operation unit 2A to the stop side (e.g., turning the engine ignition OFF) and a user pressing the start button on the startup operation unit 2A again. When the startup operation unit 2A receives a user startup operation, it outputs a startup signal. When the startup operation unit 2A receives a user stop operation, it outputs a stop signal. When the power supply circuit 8 receives the startup signal from the startup operation unit 2A, it starts supplying power to the load 6 and the battery replacement determination system 10. When the power supply circuit 8 receives the stop signal from the startup operation unit 2A, it stops supplying power to the load 6 and the battery replacement determination system 10.

The battery replacement determination system 10 includes a voltage detection unit 12 and a controller 14. The voltage detection unit 12 detects the voltage of the battery 4 of the vehicle 2. The voltage detection unit 12 is electrically connected to the battery 4 and detects the voltage between the positive and negative terminals of the battery 4 as a detected voltage value VD. The controller 14 is electrically connected to the voltage detection unit 12. The detected voltage value VD output from the voltage detection unit 12 is input to the controller 14. The controller 14 is electrically connected to the power supply circuit 8. Power (electricity) is supplied to the controller 14 from the battery 4 via the power supply circuit 8.

The controller 14 determines whether the battery 4 needs to be replaced based on the detected voltage value VD. The controller 14 selects a representative voltage value VR from multiple detected voltage values VD detected by the voltage detection unit 12 at multiple different times during the vehicle operation period PV from the start-up to the shutdown of the vehicle 2 system. In this embodiment, examples of starting the vehicle 2 system include a user's start-up operation (e.g., turning the engine ignition ON) and the start of power supply from the power supply circuit 8 to the controller 14. Examples of stopping the vehicle 2 system include a user's stop operation (e.g., turning the engine ignition OFF) and the stop of power supply from the power supply circuit 8 to the controller 14. Examples of the vehicle operation period PV from the start-up to the shutdown of the vehicle 2 system include the period from the user's start-up operation to the shutdown operation and the period from the start to the shutdown of power supply from the power supply circuit 8 to the controller 14.

The controller 14 includes, for example, a processor 14P, memory 14M, a circuit board 14C, and a bus 14B. The processor 14P includes, for example, a CPU (Central Processing Unit) and/or an MPU (Micro Processing Unit). The memory 14M includes, for example, volatile and/or non-volatile memory. Examples of volatile memory include RAM (Random Access Memory). Examples of non-volatile memory include ROM (Read Only Memory) and EEPROM (Electrically Erasable Programmable ROM). The processor 14P and memory 14M are electrically mounted on the circuit board 14C. The processor 14P and memory 14M are electrically connected to each other via the circuit board 14C and the bus 14B.

The memory 14M of the battery replacement determination system 10 stores information such as control programs and firmware for implementing the control algorithm of the battery replacement determination system 10. The processor 14P implements the control algorithm of the battery replacement determination system 10 by reading and executing the control programs stored in the memory 14M. The configuration of the battery replacement determination system 10 is not limited to the processor 14P and memory 14M. The configuration of the battery replacement determination system 10 can be implemented using hardware only, software only, or a combination of hardware and software.

As shown in FIG. 2, when power supply from the power supply circuit 8 begins, the controller 14 acquires the detected voltage value VD at a predetermined interval and stores the detected voltage value VD in memory 14M. The controller 14 associates detection time information indicating when the detected voltage value VD is detected by the voltage detection unit 12 (e.g., when the controller 14 acquires the detected voltage value VD) with the detected voltage value VD and stores it in memory 14M. Examples of detection time information include the date and time when the detected voltage value VD is detected and the elapsed time from reference time T0 to the time when the detected voltage value VD is detected. In this embodiment, the controller 14 associates the elapsed time TE from reference time T0 to the time when the detected voltage value VD is detected with the detected voltage value VD and stores it in memory 14M.

The controller 14 stores period identification information indicating the vehicle operation period PV in memory 14M. For example, the controller 14 assigns a period identification number NP to each vehicle operation period PV. The controller 14 associates the detected voltage value VD, detection time information (e.g., elapsed time TE) corresponding to the detected voltage value VD, and period identification information (e.g., period identification number NP) of the vehicle operation period PV corresponding to the detected voltage value VD with each other and stores these in memory 14M.

As shown in FIG. 1, the battery replacement determination system 10 further includes a temperature sensor 16. The temperature sensor 16 detects the temperature of the battery 4 as a detected temperature TD. The controller 14 corrects the detected voltage value VD based on the detected temperature TD. The controller 14 corrects the detected voltage value VD based on the detected temperature TD, for example, using the Nernst equation. The controller 14 associates the corrected detected voltage value VD, detection time information (e.g., elapsed time TE) corresponding to the detected voltage value VD, and period identification information (e.g., period identification number NP) of the vehicle operation period PV corresponding to the detected voltage value VD, and stores them in memory 14M. Note that the temperature correction of the detected voltage value VD can be omitted from the battery replacement determination process.

As shown in FIG. 2 , the controller 14 selects a representative voltage value VR from multiple detected voltage values VD during the vehicle operation period PV. In this embodiment, the controller 14 selects the lowest voltage value among the multiple detected voltage values VD as the representative voltage value VR. For example, the controller 14 stores the first detected voltage value VD obtained from the voltage detection unit 12 as the representative voltage value VR in memory 14M. Thereafter, the controller 14 compares the most recent detected voltage value VD obtained from the voltage detection unit 12 with the representative voltage value VR stored in memory 14M. If the most recent detected voltage value VD is lower than the representative voltage value VR, the controller 14 stores the most recent detected voltage value VD as the representative voltage value VR in memory 14M. If the representative voltage value VR is lower than the most recent detected voltage value VD, the controller 14 retains the representative voltage value VR stored in memory 14M. Note that the controller 14 may be configured to select the representative voltage value VR based on other criteria.

Relatively high detected voltage values VD may be excluded from the selection process for the representative voltage value VR. For example, if the latest detected voltage value VD output from the voltage detection unit 12 is equal to or lower than the voltage threshold VD0, the controller 14 selects a representative voltage value VR from multiple detected voltage values VD including the latest detected voltage value VD. On the other hand, if the latest detected voltage value VD is higher than the voltage threshold VD0, the controller 14 does not select a representative voltage value VR from multiple detected voltage values VD including the latest detected voltage value VD. The controller 14 stores the voltage threshold VD0 in memory 14M. Note that the process of comparing the latest detected voltage value VD with the voltage threshold VD0 can be omitted from the battery replacement determination process.

As shown in FIG. 1, the battery replacement determination system 10 further includes a charge level detection unit 18. The charge level detection unit 18 detects the charge level of the battery 4 as a detected charge level LD. The charge level detection unit 18 is electrically connected to the battery 4. The controller 14 is electrically connected to the charge level detection unit 18. The charge level includes the SOC (State of Charge). The SOC is an index indicating the charge rate or charge state of the battery 4. For example, the charge level detection unit 18 outputs 100% as the detected charge level LD when the battery 4 is fully charged and 0% as the detected charge level LD when the battery 4 is fully discharged. The charge level detection unit 18 calculates the detected charge level LD based on the OCV (Open Circuit Voltage), the SOC-OCV characteristics, and other factors. The controller 14 acquires the detected charge level LD output from the charge level detection unit 18 at a predetermined interval. The controller 14 associates the detected voltage value VD, detection time information (e.g., elapsed time TE) corresponding to the detected voltage value VD, the detected charge level LD corresponding to the detected voltage value VD, and period identification information (e.g., period identification number NP) of the vehicle operation period PV corresponding to the detected voltage value VD, and stores these in memory 14M.

When the detected charge level LD is equal to or greater than the charge level threshold LD0, the controller 14 selects the lowest voltage value among the multiple detected voltage values VD as the representative voltage value VR. When the detected charge level LD is lower than the charge level threshold LD0, the controller 14 does not select the representative voltage value VR. When the controller 14 performs a charge level determination to determine whether the detected charge level LD is equal to or greater than the charge level threshold LD0, it uses the detected charge level LD detected by the charge level detection unit 18 within a predetermined time before performing the charge level determination. For example, the predetermined time is 100 ms, and the charge level threshold LD0 is 60%. When the detected charge level LD is equal to or greater than the charge level threshold LD0, it becomes easier to ensure the reliability of the detected voltage value VD. However, the above processing based on the detected charge level LD can be omitted from the battery replacement determination process.

As shown in FIG. 2, the controller 14 determines whether or not the battery 4 needs to be replaced based on the temporal relationship of multiple representative voltage values VR selected during multiple vehicle operation periods PV. Specifically, the controller 14 creates a voltage ranking RK in which the multiple representative voltage values VR are arranged in ascending order. In the voltage ranking RK, the lower the representative voltage value VR, the higher the ranking. If there are two or more representative voltage values VR with the same value among the multiple representative voltage values VR included in the voltage ranking RK, the controller 14 ranks the two or more equal representative voltage values VR as the same. The controller 14 stores the voltage ranking RK in memory 14M.

Each time a representative voltage value VR is selected, the controller 14 compares the newly selected representative voltage value VR with the multiple representative voltage values VR included in the voltage ranking RK. The controller 14 determines the ranking of the newly selected representative voltage value VR in the voltage ranking RK. After determining the ranking of the newly selected representative voltage value VR, the controller 14 updates the voltage ranking RK using the newly selected representative voltage value VR.

The controller 14 selects at least two representative voltage values VR ranked in a predetermined order in the voltage ranking RK from the plurality of representative voltage values VR. The controller 14 determines whether or not the battery 4 needs to be replaced based on at least two elapsed times TE from the reference time T0 to the time when at least two representative voltage values VR are detected. The controller 14 calculates the standard deviation SD of the at least two elapsed times TE, and determines whether or not the battery 4 needs to be replaced based on the standard deviation SD.

In this embodiment, the controller 14 selects at least two representative voltage values VR ranked 1st to Nth (N is an integer equal to or greater than 2) in the voltage ranking RK as at least two top voltage values VL (e.g., N top voltage values VL). That is, at least two representative voltage values VR ranked in a predetermined order in the voltage ranking RK can be referred to as at least two top voltage values VL. If there are two or more representative voltage values VR ranked in the same order in the voltage ranking RK, the number of top voltage values VL selected by the controller 14 will be greater than N. The predetermined order is not limited to 1st to Nth. The controller 14 selects at least two elapsed times TE (e.g., N elapsed times TE) corresponding to the at least two top voltage values VL. The controller 14 stores the at least two top voltage values VL and the at least two elapsed times TE in memory 14M.

For example, the controller 14 selects a plurality of representative voltage values VR (e.g., 10 representative voltage values VR) ranked from 1st to 10th in the voltage ranking RK as at least two top voltage values VL. The controller 14 selects at least two elapsed times TE (e.g., 10 elapsed times TE) corresponding to the at least two top voltage values VL. For example, the controller 14 stores the 10 top voltage values VL and the 10 elapsed times TE in the memory 14M.

The controller 14 calculates the standard deviation SD of at least two elapsed times TE. The controller 14 stores the standard deviation SD in the memory 14M as a second standard deviation SD2. The controller 14 determines whether or not the battery 4 needs to be replaced based on the second standard deviation SD2. Note that the integer N is not limited to 10.

The multiple vehicle operation periods PV include a first vehicle operation period PV1 and a second vehicle operation period PV2 that follows the first vehicle operation period PV1. In this embodiment, the second vehicle operation period PV2 is the vehicle operation period PV that is executed next after the first vehicle operation period PV1. Therefore, the first vehicle operation period PV1 may also be referred to as the previous vehicle operation period PV1. The second vehicle operation period PV2 may also be referred to as the current vehicle operation period PV2. However, the temporal relationship between the first vehicle operation period PV1 and the second vehicle operation period PV2 is not limited to the above relationship.

The controller 14 determines whether the battery 4 needs to be replaced based on the first standard deviation SD1 calculated as the standard deviation SD during the first vehicle operation period PV1 and the second standard deviation SD2 calculated as the standard deviation SD during the second vehicle operation period PV2. Specifically, the controller 14 issues a replacement determination result indicating that the battery 4 needs to be replaced when the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is smaller than the standard deviation threshold RS0. The first standard deviation SD1 may also be referred to as the previous standard deviation SD. The second standard deviation SD2 may also be referred to as the current standard deviation SD.

After the start of the second vehicle operation period PV2, but before calculating a new second standard deviation SD2, the controller 14 stores the second standard deviation SD2 stored in memory 14M as the first standard deviation SD1 in memory 14M. The controller 14 calculates the standard deviation SD of at least two higher voltage values VL selected during the second vehicle operation period PV2 as the second standard deviation SD2. The controller 14 stores the newly calculated second standard deviation SD2 in memory 14M. That is, the controller 14 stores the first standard deviation SD1 calculated during the first vehicle operation period PV1 and the second standard deviation SD2 calculated during the second vehicle operation period PV2 in memory 14M.

The standard deviation threshold RS0 is, for example, 1. When the standard deviation threshold RS0 is 1, the relationship in which the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is smaller than the standard deviation threshold RS0 indicates that the second standard deviation SD2 is smaller than the first standard deviation SD1. Therefore, when the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is smaller than the standard deviation threshold RS0, the variation in the at least two upper voltage values VL during the current vehicle operation period PV is smaller than the variation in the at least two upper voltage values VL during the previous vehicle operation period PV. The standard deviation threshold RS0 is not limited to 1 and may be any positive number. The standard deviation threshold RS0 may also be a positive number less than 1. The controller 14 may determine whether or not the battery 4 needs to be replaced by comparing the second standard deviation SD2 with a predetermined threshold without using the first standard deviation SD1.

The controller 14 calculates the average value of at least two elapsed times TE as the average elapsed time TA. The controller 14 determines whether or not the battery 4 needs to be replaced based on at least two upper voltage values VL and at least two elapsed times TE from the reference time T0 to the time when each of the at least two upper voltage values VL is detected. When calculating the standard deviation SD, the controller 14 calculates the average elapsed time TA corresponding to the at least two upper voltage values VL.

The controller 14 determines whether the battery 4 needs to be replaced based on a first average elapsed time TA1 calculated by the controller 14 as the average of at least two elapsed times TE during the first vehicle operation period PV1, and a second average elapsed time TA2 calculated by the controller 14 as the average of at least two elapsed times TE during the second vehicle operation period PV2. Before calculating the second standard deviation SD2 and the second average elapsed time TA2, the controller 14 stores the second standard deviation SD2 and the second average elapsed time TA2 stored in memory 14M as the first standard deviation SD1 and the first average elapsed time TA1 in memory 14M. The controller 14 stores the newly calculated standard deviation SD and average elapsed time TA as the second standard deviation SD2 and the second average elapsed time TA2 in memory 14M. That is, the controller 14 stores in the memory 14M the first standard deviation SD1 and first average elapsed time TA1 calculated during the first vehicle operation period PV1, and the second standard deviation SD2 and second average elapsed time TA2 calculated during the second vehicle operation period PV2. The first average elapsed time TA1 may also be referred to as the previous average elapsed time TA. The second average elapsed time TA2 may also be referred to as the current average elapsed time TA.

The controller 14 calculates the first difference ΔT1 as the difference between a first elapsed time TE1 from the reference time T0 to the time when the representative voltage value VR is detected by the controller 14 during the first vehicle operation period PV1 and a first average elapsed time TA1. The controller 14 calculates the second difference ΔT2 as the difference between a second elapsed time TE2 from the reference time T0 to the time when the representative voltage value VR is detected by the controller 14 and a second average elapsed time TA2 during the second vehicle operation period PV2. After the start of the second vehicle operation period PV2, and before newly calculating the second difference ΔT2, the controller 14 newly stores the second difference ΔT2 stored in memory 14M as the first difference ΔT1 in memory 14M. The controller 14 associates the newly calculated second difference ΔT2 with the second standard deviation SD2 and stores it in memory 14M. That is, the controller 14 stores the first difference ΔT1 calculated during the first vehicle operation period PV1 and the second difference ΔT2 calculated during the second vehicle operation period PV2 in the memory 14M.

The controller 14 issues a replacement determination result indicating that the battery 4 needs to be replaced when the ratio RT of the second difference ΔT2 to the first difference ΔT1 is smaller than the time threshold value RT0. In this embodiment, the controller 14 issues a replacement determination result indicating that the battery 4 needs to be replaced when the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is smaller than the standard deviation threshold value RS0 and the ratio RT of the second difference ΔT2 to the first difference ΔT1 is smaller than the time threshold value RT0.

The time threshold RT0 is, for example, 1. When the time threshold RT0 is 1, the relationship in which the ratio RT of the second difference ΔT2 to the first difference ΔT1 is smaller than the time threshold RT0 indicates that the second difference ΔT2 is smaller than the first difference ΔT1. Therefore, when the ratio RT of the second difference ΔT2 to the first difference ΔT1 is smaller than the time threshold RT0, the lowest voltage value of the battery 4 tends to be detected frequently. However, the time threshold RT0 is not limited to 1 and may be any positive number. The time threshold RT0 may also be a positive number less than 1. The controller 14 may determine whether or not the battery 4 needs to be replaced by comparing the second difference ΔT2 or the second average elapsed time TA2 with a predetermined threshold, without using the first difference ΔT1.

As shown in FIG. 1, the battery replacement determination system 10 further includes a notification unit 20. The notification unit 20 notifies the user of the determination result of the controller 14. Examples of the notification unit 20 include a display, a lamp, and a speaker. The notification unit 20 notifies the user of information visually or audibly. When the controller 14 determines that the battery 4 needs to be replaced, it transmits the replacement determination result to the notification unit 20. When the notification unit 20 receives the replacement determination result, it displays the replacement determination result, for example, to notify the user of the replacement determination result. When the controller 14 determines that the battery 4 needs to be replaced, it terminates the battery replacement determination process.

As shown in Figure 3, the representative voltage values VR finally selected for each of the vehicle operation periods PV are distributed within a range below the voltage threshold VD0. It is assumed that at least two top voltage values VL ranked from 1st to Nth (e.g., 10th) among the representative voltage values VR are distributed as shown in Figure 3.

As shown in FIG. 4, if a representative voltage value VR (e.g., VR1) newly selected from multiple detected voltage values VD during a second vehicle operation period PV2 (e.g., the current vehicle operation period PV2) is ranked 1st to Nth (e.g., 10th), the newly selected representative voltage value VR replaces the highest voltage value VL (e.g., VL10) among the at least two top voltage values VL shown in FIG. 3 and is selected as the new top voltage value VL. When the voltage ranking RK changes from 1st to Nth, the standard deviation SD of the multiple elapsed times TE corresponding to the multiple top voltage values VL may change. Similarly, when the voltage ranking RK changes from 1st to Nth, the average elapsed time TA of the multiple elapsed times TE may change. The battery replacement determination system 10 performs battery replacement determination processing based on these changes.

The battery replacement determination method executed by the battery replacement determination system 10 will be described with reference to Figures 5 to 7.

As shown in Figures 5 to 7, the battery replacement determination method includes detecting the voltage supplied from the battery of the vehicle 2 using the voltage detection unit 12, selecting a representative voltage value VR using the controller 14 from multiple detected voltage values VD detected by the voltage detection unit 12 at multiple different times during the vehicle operation period PV from the start-up to the shutdown of the vehicle 2 system, and determining the state of the battery 4 using the controller 14 based on the temporal relationship of the multiple representative voltage values VR selected by the controller 14 during the multiple vehicle operation periods PV.

As shown in FIG. 5, after the vehicle 2 is started, power supply to the battery replacement determination system 10 is initiated (steps S1 and S2). After power supply to the battery replacement determination system 10 is initiated, the controller 14 increments the period identification number NPNT for the vehicle operation period PV (step S3). The second standard deviation SD2 and second difference ΔT2 stored in memory 14M are newly stored in memory 14M by the controller 14 as the first standard deviation SD1 and first difference ΔT1 (step S4). The voltage detection unit 12, temperature sensor 16, and charge level detection unit 18 begin detecting the voltage value, temperature, and charge level of the battery 4 (step S5). The controller 14 acquires the detected voltage value VD, detected temperature TD, and detected charge level LD from the voltage detection unit 12, temperature sensor 16, and charge level detection unit 18 at a predetermined interval. The controller 14 corrects the detected voltage value VD based on the detected temperature TD (step S6).

In steps S7 and S8, the controller 14 determines whether the detected voltage value VD detected first during the vehicle operation period PV is selected as the representative voltage value VR. Specifically, the controller 14 determines whether the detected charge level LD is equal to or greater than the charge level threshold LD0 (step S7). If the detected charge level LD is lower than the charge level threshold LD0, the controller 14 repeatedly determines the detected charge level LD until the detected charge level LD is equal to or greater than the charge level threshold LD0 (step S7). On the other hand, if the detected charge level LD is equal to or greater than the charge level threshold LD0, the controller 14 determines whether the detected voltage value VD input from the voltage detection unit 12 to the controller 14 is equal to or less than the voltage threshold VD0 (steps S7 and S8). If the detected voltage value VD is higher than the voltage threshold VD0, the process returns to step S7 (step S8). On the other hand, if the detected voltage value VD is equal to or less than the voltage threshold value VD0, the detected voltage value VD becomes the first detected voltage value VD during the vehicle operation period PV that satisfies the conditions of the charge level threshold value LD0 and the voltage threshold value VD0. Therefore, the detected voltage value VD is selected by the controller 14 as the representative voltage value VR, and the representative voltage value VR is stored in the memory 14M (steps S8 and S9).

The selected representative voltage value VR, detection time information corresponding to the representative voltage value VR (e.g., elapsed time TE), and period identification information (e.g., period identification number NP) of the vehicle operation period PV corresponding to the representative voltage value VR are associated with each other by the controller 14 and stored in memory 14M (step S10). The controller 14 updates the voltage ranking RK using the selected representative voltage value VR (step S11). Specifically, the controller 14 compares the newly selected representative voltage value VR with multiple representative voltage values VR included in the voltage ranking RK. The controller 14 determines the ranking of the newly selected representative voltage value VR in the voltage ranking RK. After determining the ranking of the newly selected representative voltage value VR, the controller 14 updates the voltage ranking RK using the newly selected representative voltage value VR.

As shown in FIG. 6 , in steps S12 to S14, after the representative voltage value VR is initially selected during the vehicle operation period PV, the controller 14 determines whether the detected voltage value VD is selected as the representative voltage value VR. Specifically, the controller 14 determines whether the detected charge level LD is equal to or greater than the charge level threshold LD0 (step S12). If the detected charge level LD is lower than the charge level threshold LD0, the controller 14 repeatedly determines the detected charge level LD until the detected charge level LD is equal to or greater than the charge level threshold LD0 (step S12). On the other hand, if the detected charge level LD is equal to or greater than the charge level threshold LD0, the controller 14 determines whether the detected voltage value VD input from the voltage detection unit 12 to the controller 14 is equal to or less than the voltage threshold VD0 (steps S12 and S13). If the detected voltage value VD is higher than the voltage threshold VD0, the process returns to step S12 (step S13). On the other hand, if the detected voltage value VD is equal to or less than the voltage threshold value VD0, the controller 14 determines whether the detected voltage value VD is lower than the representative voltage value VR (steps S13 and S14). If the detected voltage value VD is equal to or greater than the representative voltage value VR, the representative voltage value VR stored in memory 14M is the lowest voltage value, and processing proceeds to step S19. On the other hand, if the detected voltage value VD is lower than the representative voltage value VR, the controller 14 newly selects the detected voltage value VD as the representative voltage value VR and stores it in memory 14M (step S15).

Similar to steps S10 and S11, the selected representative voltage value VR, detection time information corresponding to the representative voltage value VR (e.g., elapsed time TE), and period identification information (e.g., period identification number NP) of the vehicle operation period PV corresponding to the representative voltage value VR are associated with each other by the controller 14 and stored in memory 14M (step S16). The controller 14 updates the voltage ranking RK using the selected representative voltage value VR (step S17).

After determining the representative voltage value VR, the controller 14 determines whether the total number NT of vehicle operation periods PV is equal to or greater than the threshold value NT0 (step S18). If the total number NT of vehicle operation periods PV is less than the threshold value NT0, the total number of representative voltage values VR in the voltage ranking RK is small, and processing returns to step S12 (step S18). On the other hand, if the total number NT of vehicle operation periods PV is equal to or greater than the threshold value NT0, at least two representative voltage values VR from 1st to Nth (N is an integer equal to or greater than 2) in the voltage ranking RK are selected by the controller 14 as at least two top voltage values VL and stored in memory 14M (steps S18 and S19).

As shown in FIG. 7, the controller 14 calculates the standard deviation SD of at least two elapsed times TE corresponding to at least two upper voltage values VL selected in step S19 (step S20). The controller 14 then calculates the average value of the at least two elapsed times TE corresponding to the at least two upper voltage values VL selected in step S19 as the average elapsed time TA (step S21). The standard deviation SD and average elapsed time TA newly calculated by the controller 14 are stored in the memory 14M of the controller 14 as the second standard deviation SD2 and second average elapsed time TA2.

The controller 14 calculates the second difference ΔT2 as the difference between the elapsed time TE from the reference time TO to the time when the representative voltage value VR selected in step S15 is detected and the second average elapsed time TA2 (step S22). The calculated second difference ΔT2 is stored in memory 14M by the controller 14. The controller 14 calculates the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 (step S23). The controller 14 calculates the ratio RT of the second difference ΔT2 to the first difference ΔT1 (step S24).

The controller 14 compares the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 with a standard deviation threshold RS0 (step S25). If the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is equal to or greater than the standard deviation threshold RS0, the process returns to step S12. If the ratio RS of the second standard deviation SD2 to the first standard deviation SD1 is less than the standard deviation threshold RS0, the controller 14 compares the ratio RT of the second difference ΔT2 to the first difference ΔT1 with a time threshold RT0 (steps S25 and S26). If the ratio RT of the second difference ΔT2 to the first difference ΔT1 is equal to or greater than the time threshold RT0, the process returns to step S12. On the other hand, if the ratio RT of the second difference ΔT2 to the first difference ΔT1 is less than the time threshold RT0, the controller 14 outputs a replacement determination result indicating that the battery 4 needs to be replaced (steps S26 and S27). Based on the replacement determination result, the notification unit 20 notifies the user that a battery replacement is necessary (step S28), and the battery replacement determination process ends.

In the above-described embodiment, the battery replacement determination system 10 is mounted on the vehicle 2, but the battery replacement determination system 10 may further include at least one of a server and a terminal. For example, the battery replacement determination system 210 shown in FIG. 8 includes a main unit 211, a server 230, and a terminal 240. The configuration of the main unit 211 is substantially the same as the configuration of the above-described battery replacement determination system 10. The main unit 211 is configured to communicate with at least one of the server 230 and the terminal 240. The main unit 211 is configured to communicate with the server 230. The server 230 is configured to communicate with the terminal 240. The main unit 211 is configured to transmit a replacement determination result BR to the server 230, indicating that the battery 4 needs to be replaced. The server 230 is configured to transmit the replacement determination result BR to the terminal 240.

As shown in FIG. 8, the server 230 is connectable to the Internet. The main device 211 and the terminal 240 are connectable to the server 230 via the Internet. The main device 211 is configured to communicate with the server 230 via the Internet. The terminal 240 is configured to communicate with the server 230 via the Internet. Examples of the terminal 240 include a smartphone, a tablet computer, and a personal computer. Note that the main device 211 may also be configured to communicate with the terminal 240 via the Internet.

As shown in FIG. 8 , the main device 211 further includes an interface 220 electrically connected to the controller 14. That is, the battery replacement determination system 210 further includes an interface 220 electrically connected to the controller 14. The interface 220 is configured to transmit the replacement determination result BR to at least one of the server 230 and the terminal 240.

As shown in FIG. 9, the interface 220 is electrically connected to the processor 14P and memory 14M via the circuit board 14C and the bus 14B. The interface 220 operates using electricity supplied from the controller 14. The interface 220 includes a communication unit 224.

The communication unit 224 is electrically connected to the controller 14. The communication unit 224 is electrically connected to the processor 14P and memory 14M via the circuit board 14C and the bus 14B. The communication unit 224 is configured to transmit the exchange determination result BR (see FIG. 8) to at least one of the server 230 and the terminal 240.

The communication unit 224 includes a wireless communication circuit. The wireless communication circuit is electrically connected to the controller 14 and can be connected wirelessly to the Internet, for example. The wireless communication circuit is configured to transmit the replacement determination result BR (see FIG. 8) to the server 230 via the Internet. When the battery 4 is installed in a vehicle, the communication unit 224 includes, for example, a wireless communication circuit and a gateway ECU.

The wireless communication circuit includes, for example, an antenna, a wireless transmission circuit, and a wireless reception circuit. The antenna is electrically connected to the wireless transmission circuit and the wireless reception circuit. The wireless transmission circuit is configured to transmit signals wirelessly via the antenna. The wireless reception circuit is configured to receive signals wirelessly via the antenna. The wireless transmission circuit is configured to encrypt signals using a predetermined protocol. The wireless reception circuit is configured to decrypt wireless signals using the predetermined protocol.

As shown in FIG. 9, server 230 may, for example, constitute part of a data center or cloud and be connected to the Internet. Server 230 includes a controller 232, an interface 233, and a display 234. Interface 233 and display 234 are electrically connected to controller 232. Display 234 is electrically connected to controller 232 and configured to display information. Controller 232 is configured to control display 234 to display information.

The controller 232 includes, for example, a processor 232P, memory 232M, a circuit board 232C, and a bus 232B. The processor 232P includes, for example, a CPU and/or an MPU. The memory 232M includes, for example, volatile and/or non-volatile memory. Examples of volatile memory include RAM. Examples of non-volatile memory include ROM and EEPROM. The processor 232P and memory 232M are electrically mounted on the circuit board 232C. The processor 232P and memory 232M are electrically connected to each other via the circuit board 232C and the bus 232B.

Memory 232M of server 230 stores information such as control programs and firmware for implementing server 230's control algorithms. Processor 232P implements server 230's control algorithms by reading and executing control programs stored in memory 232M. The configuration of server 230 is not limited to processor 232P and memory 232M. Server 230 can be implemented using only hardware, only software, or a combination of hardware and software.

The interface 233 is electrically connected to the processor 232P and memory 232M via the circuit board 232C and the bus 232B. The interface 233 includes a user interface 235 and a communication unit 236.

The user interface 235 is electrically connected to the controller 232. The user interface 235 is electrically connected to the processor 232P and the memory 232M via the circuit board 232C and the bus 232B. The user interface 235 is used by the user to operate the server 230. Examples of the user interface 235 include a keyboard, a mouse, and a touch panel.

The communication unit 236 is electrically connected to the controller 232. The communication unit 236 is electrically connected to the processor 232P and memory 232M via the circuit board 232C and the bus 232B. The communication unit 236 is configured to communicate with the main device 211 and the terminal 240.

The communication unit 236 includes, for example, a wired communication circuit. The wired communication circuit is electrically connected to the controller 232 and can be connected, for example, to the Internet via a wired connection (e.g., a cable such as a LAN cable, or a router). The wired communication circuit is configured to communicate with the main device 211 and the terminal 240 via the Internet. The communication unit 236 may also include a wireless communication circuit.

The communication unit 236 is configured to receive the replacement determination result BR (see FIG. 8) from the main device 211. The communication unit 236 is configured to transmit the replacement determination result BR (see FIG. 8) received from the main device 211 to the terminal 240. The communication unit 236 is configured to receive input information from the terminal 240. The communication unit 236 is configured to transmit the input information received from the terminal 240 to the main device 211.

As shown in FIG. 8, the terminal 240 is configured to communicate with the server 230. The terminal 240 is a device used by a user of the battery replacement determination system 210. The terminal 240 is configured to display the replacement determination result BR (see FIG. 8) transmitted from the server 230. The terminal 240 is also configured to receive input of information necessary for battery status determination from the user of the battery replacement determination system 210, and to transmit the input information to the server 230. Examples of the terminal 240 include a smartphone, a tablet computer, and a personal computer. The terminal 240 may also be configured to communicate with the main device 211 via the Internet.

The terminal 240 includes a controller 242, an interface 243, and a display 244. The interface 243 and the display 244 are electrically connected to the controller 242. The display 244 is electrically connected to the controller 242 and configured to display information. The controller 242 is configured to control the display 244 to display information.

The controller 242 includes, for example, a processor 242P, memory 242M, a circuit board 242C, and a bus 242B. The processor 242P includes, for example, a CPU and/or an MPU. The memory 242M includes, for example, volatile and/or non-volatile memory. Examples of volatile memory include RAM. Examples of non-volatile memory include ROM and EEPROM. The processor 242P and memory 242M are electrically mounted on the circuit board 242C. The processor 242P and memory 242M are electrically connected to each other via the circuit board 242C and the bus 242B.

Memory 242M of server 230 stores information such as control programs and firmware for implementing the control algorithm of server 230. Processor 242P implements the control algorithm of server 230 by reading and executing the control program stored in memory 242M. The configuration of server 230 is not limited to processor 242P and memory 242M. Server 230 can be implemented using only hardware, only software, or a combination of hardware and software.

The interface 243 is electrically connected to the processor 242P and memory 42M via the circuit board 242C and the bus 242B. The interface 243 includes a user interface 245 and a communication unit 246.

The user interface 245 is electrically connected to the controller 242. The user interface 245 is electrically connected to the processor 242P and the memory 242M via the circuit board 242C and the bus 242B. The user interface 245 is configured to receive input information from the user. The controller 242 stores the input information input from the user interface 245 in the memory 242M. Examples of the user interface 245 include a keyboard, a mouse, and a touch panel.

The communication unit 246 is electrically connected to the controller 242. The communication unit 246 is electrically connected to the processor 242P and the memory 242M via the circuit board 242C and the bus 242B. The communication unit 246 is configured to communicate with the server 230. The communication unit 246 includes a wireless communication circuit. The wireless communication circuit is electrically connected to the controller 242 and configured to communicate wirelessly with the server 230 via the Internet. The communication unit 246 may also include a wired communication circuit.

Similar to the communication unit 224, the wireless communication circuit of the communication unit 246 includes, for example, an antenna, a wireless transmission circuit, and a wireless reception circuit. The antenna is electrically connected to the wireless transmission circuit and the wireless reception circuit. The wireless transmission circuit is configured to transmit signals wirelessly via the antenna. The wireless reception circuit is configured to receive signals wirelessly via the antenna. The wireless transmission circuit is configured to encrypt signals using a predetermined protocol. The wireless reception circuit is configured to decrypt wireless signals using a predetermined protocol.

The communication unit 246 is configured to transmit input information to the server 230 via the Internet. The communication unit 246 is configured to receive, via the Internet, the replacement determination result BR (see FIG. 8) transmitted from the server 230. The controller 242 controls the display 244 to display the replacement determination result BR (see FIG. 8). This allows the user to recognize that the battery 4 needs to be replaced. In this way, the replacement determination result BR indicating that the battery 4 needs to be replaced can be used in at least one of the server 230 and the terminal 240.

In the battery replacement determination system 210 shown in FIGS. 8 and 9, the main device 211 performs control based on the flowcharts shown in FIGS. 5 to 7. However, at least one step included in the flowcharts shown in FIGS. 5 to 7 may be executed by at least one of the main device 211, the server 230, and the terminal 240. For example, at least one of steps S6 to S27 shown in FIGS. 5 to 7 may be executed by at least one of the server 230 and the terminal 240. For example, one of the controllers 232 and 242 may be configured to select a representative voltage value from multiple detected voltage values detected by the voltage detection unit at multiple different times during the vehicle operation period from system startup to shutdown of the vehicle 2. Furthermore, one of the controllers 232 and 242 may be configured to determine whether or not the battery 4 needs to be replaced based on the temporal relationship between multiple representative voltage values selected during multiple vehicle operation periods. In such a modification, the necessary information is transmitted and received between the main device 211, the server 230, and the terminal 240.

Furthermore, the battery replacement determination systems 10 and 210 and battery replacement determination methods according to the above-described embodiments and variations can be applied to, for example, privately owned vehicles, vehicles used for rental cars, and vehicles used for car sharing. When at least one of the battery replacement determination systems 10 and 210 is applied to a privately owned vehicle, the terminal 240 is used, for example, by the vehicle owner or driver to monitor the insufficient charge of the battery 4 installed in the vehicle. When at least one of the battery replacement determination systems 10 and 210 is applied to a vehicle used for rental cars, the terminal 240 is used, for example, by the rental car company and its staff to monitor the insufficient charge of the battery 4 installed in the rented vehicle. When at least one of the battery replacement determination systems 10 and 210 is applied to a vehicle used for car sharing, the terminal 240 is used, for example, by the car sharing company and its staff to monitor the insufficient charge of the battery 4 installed in the shared vehicle.

Furthermore, the battery replacement determination systems 10 and 210 and battery state determination methods according to the above-described embodiments and variations can also be applied to devices other than vehicles. For example, they can also be used to monitor batteries 4 that store electricity generated by solar power generation systems, etc.

In this application, the terms "comprise" and their derivatives are open-ended terms that describe the presence of elements and do not exclude the presence of other elements not listed. This also applies to the terms "have," "include," and their derivatives.

In this application, ordinal numbers such as "first" and "second" are merely terms for identifying components and do not have any other meaning (such as a particular order). For example, the presence of a "first element" does not imply the presence of a "second element," and the presence of a "second element" does not imply the presence of a "first element."

Words expressing degrees such as "substantially," "about," and "approximately" can mean a reasonable deviation that does not significantly change the final result. All numerical values described in this application can be interpreted to include words such as "substantially," "about," and "approximately."

In addition, the expression "at least one of A and B" in this disclosure includes, for example, (1) A only, (2) B only, and (3) both A and B. The expression "at least one of A, B, and C" includes, for example, (1) A only, (2) B only, (3) C only, (4) A and B, (5) B and C, (6) A and C, and (7) all of A, B, and C. In this disclosure, the expression "at least one of A and B" is not to be interpreted as "at least one of A and at least one of B."

In light of the above disclosure, it is apparent that various modifications and variations of the present invention are possible. Therefore, the present invention may be practiced in a manner different from the specific disclosure of this application without departing from the spirit of the present invention.

2: vehicle 2A: start operation unit 4: battery 6: load 8: power supply circuit 10, 210: battery replacement determination system 12: voltage detection unit 14: controller 16: temperature sensor 18: charge level detection unit 20: notification unit LD: detected charge level LD0: charge level threshold PV: vehicle operation period PV1: first vehicle operation period PV2: second vehicle operation period RK: voltage ranking RS0: standard deviation threshold RT0: time threshold SD: standard deviation SD1: first standard deviation SD2: second standard deviation T0: reference time TA: average elapsed time TA1: first average elapsed time TA2: second average elapsed time TD: detected temperature TE: elapsed time TE1: first elapsed time TE2: second elapsed time VD: detected voltage value VD0: voltage threshold VL: upper voltage value VR : Representative voltage value ΔT1 : First difference ΔT2 : Second difference

Claims (16)

a voltage detection unit that detects the voltage of the vehicle battery;
a controller that selects a representative voltage value from a plurality of detected voltage values detected by the voltage detection unit at a plurality of different timings during a vehicle operation period from start-up to stop-up of a system of the vehicle;
the controller determines whether or not the battery needs to be replaced based on a temporal relationship between a plurality of representative voltage values selected during a plurality of vehicle operation periods ;
the controller creates a voltage ranking in which the plurality of representative voltage values are arranged in ascending order .
Battery replacement determination system. the controller selects the lowest voltage value from the plurality of detected voltage values as the representative voltage value;
The battery replacement determination system according to claim 1 . a charge level detection unit that detects the charge level of the battery as a detected charge level;
the controller selects the lowest voltage value among the plurality of detected voltage values as the representative voltage value when the detected charge level is equal to or greater than a charge level threshold;
the controller does not select the representative voltage value when the detected charge level is lower than the charge level threshold.
The battery replacement determination system according to claim 1 or 2. When the controller determines whether the detected charge level is equal to or greater than the charge level threshold, the controller uses the detected charge level detected by the charge level detection unit within a predetermined time before the controller determines whether the detected charge level is equal to or greater than the charge level threshold.
The battery replacement determination system according to claim 3 . the controller, when a latest detected voltage value output from the voltage detection unit is equal to or lower than a voltage threshold, selects the representative voltage value from the plurality of detected voltage values including the latest detected voltage value;
when the latest detected voltage value is higher than the voltage threshold, the controller does not select the representative voltage value from the plurality of detected voltage values including the latest detected voltage value;
The battery replacement determination system according to any one of claims 1 to 4. a temperature sensor for detecting the temperature of the battery as a detected temperature;
The controller corrects the detected voltage value based on the detected temperature.
The battery replacement determination system according to any one of claims 1 to 5. the controller selects at least two representative voltage values ranked in a predetermined order in the voltage ranking from the plurality of representative voltage values;
the controller determines whether or not the battery needs to be replaced based on at least two elapsed times from a reference time to the time when the at least two representative voltage values are detected, respectively;
The battery replacement determination system according to any one of claims 1 to 6 . the controller calculates a standard deviation of the at least two elapsed times and determines whether or not the battery needs to be replaced based on the standard deviation.
The battery replacement determination system according to claim 7 . the plurality of vehicle operation periods include a first vehicle operation period and a second vehicle operation period that is subsequent to the first vehicle operation period;
the controller determines whether or not the battery needs to be replaced based on a first standard deviation calculated as the standard deviation during the first vehicle operation period and a second standard deviation calculated as the standard deviation during the second vehicle operation period.
The battery replacement determination system according to claim 8 . the controller issues a replacement determination result indicating that the battery needs to be replaced when a ratio of the second standard deviation to the first standard deviation is smaller than a standard deviation threshold value;
The battery replacement determination system according to claim 9 . The controller calculates an average value of the at least two elapsed times as an average elapsed time.
The battery replacement determination system according to claim 10 . the controller determines whether or not the battery needs to be replaced based on a first average elapsed time calculated as the average elapsed time by the controller during the first vehicle operation period and a second average elapsed time calculated as the average elapsed time by the controller during the second vehicle operation period.
The battery replacement determination system according to claim 11 . the controller calculates, as a first difference, a difference between a first elapsed time from the reference time to a time when the representative voltage value is detected by the controller during the first vehicle operation period and the first average elapsed time;
the controller calculates, as a second difference, a difference between a second elapsed time from the reference time to a time when the representative voltage value is detected by the controller during the second vehicle operation period and the second average elapsed time;
the controller issues a replacement determination result indicating that the battery needs to be replaced when a ratio of the second difference to the first difference is smaller than a time threshold value;
The battery replacement determination system according to claim 12 . further comprising a notification unit that notifies a user of a determination result of the controller.
The battery replacement determination system according to any one of claims 1 to 13 . further comprising at least one of a server and a terminal;
The battery replacement determination system according to any one of claims 1 to 14 . detecting a voltage supplied from a vehicle battery by a voltage detection unit;
selecting a representative voltage value from a plurality of detected voltage values detected by the voltage detection unit at a plurality of different timings during a vehicle operation period from start-up to stop-up of the vehicle system ;
the controller determines the state of the battery based on a temporal relationship of a plurality of representative voltage values respectively selected by the controller during a plurality of periods of vehicle operation; and
creating a voltage ranking in which the plurality of representative voltage values are arranged in ascending order by the controller;
A battery replacement determination method comprising: