Battery capacity calculation device and battery capacity calculation method

Abstract

To provide a battery capacity calculation device and a battery capacity calculation method that calculate a full charge capacity at a high frequency.SOLUTION: A battery capacity calculation device includes a controller. The controller acquires the first voltage value and charge current value of a battery during charging of the battery; acquires the second voltage value of the battery while charging of the battery is discontinued; calculates the impedance value of the battery by using the first voltage value, the second voltage value, and the charge current value; acquires a cycle count of the battery; acquires a time during which the battery temperature is included in a prescribed temperature range and the output voltage value of the battery is included in a prescribed voltage range; and calculates the full charge capacity of the battery by using the cycle count, the impedance value, and the time.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery capacity calculation device and a battery capacity calculation method. [Background technology]

[0002] The development of products that users can use for a long time leads to a reduction in carbon emissions. If users replace the batteries of electronic devices such as notebook PCs (Personal Computers) at the appropriate time, e-waste (E-waste) will be reduced and environmental problems will be improved. Therefore, a function that prompts users to replace the batteries at the appropriate time is desired.

[0003] As a function for notifying the user of the degree of battery deterioration, there is a function that estimates the battery state based on the capacity retention rate and the number of cycles, and displays the state. The capacity retention rate is obtained by dividing the full charge capacity (FCC: Full Charge Capacity) by the design capacity. In addition, there is a known prior art that calculates the full charge capacity based on the current value until the battery changes from a fully charged state to a completely discharged state.

[0004] The device disclosed in Patent Document 1 selects a method for estimating the full charge capacity according to the state of the battery, and estimates the full charge capacity using the selected method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-125320 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional techniques for estimating the full charge capacity require the battery to be completely discharged, so the full charge capacity is calculated infrequently.

[0007] An object of the present invention is to provide a battery capacity calculation device and a battery capacity calculation method that are capable of calculating a full charge capacity with high frequency. [Means for solving the problem]

[0008] One aspect of the present invention is a battery capacity calculation device that includes a controller that acquires a first voltage value and a charging current value of the battery while the battery is being charged, acquires a second voltage value of the battery while charging of the battery is paused, calculates an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculates an impedance increase which is a ratio of the impedance value to an initial impedance value pre-recorded in a memory, acquires the number of cycles of the battery, acquires the time during which the temperature of the battery is within a predetermined temperature range and the output voltage value of the battery is within a predetermined voltage range, and calculates a full charge capacity of the battery by using the number of cycles, the impedance increase, and the time.

[0009] In one embodiment of the invention, the controller may calculate the full charge capacity according to the formula FCC=1.0+a*CYC+b*HTVT+c*IMP, where FCC is the full charge capacity, CYC is the number of cycles, HTVT is the time, IMP is the impedance increase, and a, b, and c are predetermined coefficients.

[0010] In one aspect of the present invention, the controller may correct the impedance value in accordance with the temperature during charging of the battery.

[0011] In one aspect of the present invention, the controller may record in a memory the calculated full charge capacity and time information at which the full charge capacity was calculated, and use the full charge capacity and the time information recorded in the memory to calculate the time until the full charge capacity of the battery will become equal to or less than a predetermined capacity.

[0012] One aspect of the present invention is a battery capacity calculation device that includes a controller that acquires a first voltage value and a charging current value of the battery while the battery is being charged, acquires a second voltage value of the battery while charging of the battery is paused, calculates an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculates an impedance increase that is a ratio of the impedance value to an initial impedance value pre-recorded in a memory, acquires a number of cycles of the battery, and calculates a full charge capacity of the battery by using the number of cycles and the impedance increase.

[0013] One aspect of the present invention is a battery capacity calculation method comprising the steps of acquiring a first voltage value and a charging current value of the battery while the battery is being charged, acquiring a second voltage value of the battery while charging of the battery is paused, calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculating an impedance increase which is a ratio of the impedance value to an initial impedance value pre-recorded in a memory, acquiring the number of cycles of the battery, acquiring the time during which the temperature of the battery is within a predetermined temperature range and the output voltage value of the battery is within a predetermined voltage range, and calculating a full charge capacity of the battery by using the number of cycles, the impedance increase, and the time.

[0014] One aspect of the present invention is a battery capacity calculation method comprising the steps of acquiring a first voltage value and a charging current value of the battery while the battery is being charged, acquiring a second voltage value of the battery while charging of the battery is paused, calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculating an impedance increase which is the ratio of the impedance value to an initial impedance value pre-recorded in a memory, acquiring a number of cycles of the battery, and calculating a full charge capacity of the battery by using the number of cycles and the impedance increase. Effect of the Invention

[0015] According to the present invention, the battery capacity calculation device and the battery capacity calculation method can calculate the full charge capacity with high frequency. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing an example of the hardware configuration of an electronic device according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of the configuration of a battery according to a first embodiment of the present invention. [Diagram 3] 5 is a flowchart showing an example of an impedance value calculation process according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing an example of a change in voltage of a battery according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram showing an example of a change in voltage of a battery according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing an example of impedance of a battery according to the first embodiment of the present invention. [Figure 7] FIG. 4 is a diagram showing an example of a correction coefficient according to the first embodiment of the present invention. [Figure 8]5 is a flowchart showing an example of a capacity calculation process according to the first embodiment of the present invention. [Figure 9] 4 shows an example of the relationship between the number of cycles and the capacity retention rate and the relationship between the number of cycles and the increase in impedance according to the first embodiment of the present invention. [Figure 10] 3 is a diagram showing an example of the relationship between impedance increase and capacity maintenance rate of the battery according to the first embodiment of the present invention. FIG. [Figure 11] 3 is a diagram showing an example of the relationship between impedance increase and capacity maintenance rate of the battery according to the first embodiment of the present invention. FIG. [Figure 12] FIG. 5 is a block diagram showing an example of the configuration of a battery according to a second embodiment of the present invention. [Figure 13] 10 is a flowchart showing an example of a capacity calculation process according to a second embodiment of the present invention. [Figure 14] FIG. 11 is a diagram showing an example of a change over time in full charge capacity according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (First embodiment) A first embodiment of the present invention will be described below. Fig. 1 is a block diagram showing an example of a hardware configuration of an electronic device 10 according to this embodiment.

[0019] The electronic device 10 includes a CPU 11, a main memory 12, a video subsystem 13, a display unit 14, a chipset 21, a BIOS memory 22, a storage medium 23, an audio system 24, a WLAN card 25, a USB connector 26, an embedded controller 31, an input unit 32, a power supply circuit 33, and a battery 40.

[0020] The CPU 11 executes various arithmetic processing under program control, and controls the entire electronic device 10. For example, the CPU 11 executes processing based on programs of an OS (Operating System) and a BIOS (Basic Input Output System). The CPU 11 is an example of a processor.

[0021] The main memory 12 is a writable memory used as a read area for the execution program of the CPU 11 or as a work area for writing processing data for the execution program. The main memory 12 is composed of, for example, a plurality of DRAM (Dynamic Random Access Memory) chips. The execution program includes the OS and various drivers for operating peripheral devices, various services / utilities, application programs, etc.

[0022] Video subsystem 13 is a subsystem for implementing functions related to image display, and includes a video controller. The video controller processes drawing commands from CPU 11, writes the processed drawing information to a video memory, and also reads the drawing information from the video memory and outputs it to display unit 14 as drawing data (display data).

[0023] The display unit 14 is, for example, a liquid crystal display or an organic EL display, and displays a display screen based on drawing data (display data) output from the video subsystem 13.

[0024] The chipset 21 includes controllers for a Universal Serial Bus (USB), a serial AT Attachment (Serial ATA), a Serial Peripheral Interface (SPI) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express bus, and a Low Pin Count (LPC) bus, and is connected to a plurality of devices. For example, the plurality of devices include a BIOS memory 22 (described later), a storage medium 23, an audio system 24, a WLAN card 25, a USB connector 26, and an embedded controller 31.

[0025] The BIOS memory 22 is configured with an electrically rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash ROM. The BIOS memory 22 stores a BIOS program and system firmware for controlling the embedded controller 31, etc. The BIOS memory 22 is an example of a sub-memory.

[0026] The storage medium 23 includes a hard disk drive (HDD) or a solid state drive (SSD), etc. For example, the storage medium 23 stores an OS, various drivers, various services / utilities, application programs, and various data.

[0027] The audio system 24 is connected to a microphone and a speaker (not shown) and records, plays, and outputs audio data. The microphone and the speaker are built into the electronic device 10, for example.

[0028] The WLAN (Wireless Local Area Network) card 25 connects to a network via a wireless LAN to perform data communication. For example, when the WLAN card 25 receives data from the network, it generates an event trigger indicating that the data has been received. The USB connector 26 is a connector for connecting peripheral devices that use USB.

[0029] The input unit 32 collectively indicates input devices (input equipment) provided in the electronic device 10. The input devices included in the input unit 32 output, to the embedded controller 31, input information input by a user's operation.

[0030] The power supply circuit 33 includes, for example, a DC / DC converter, a charge / discharge unit, and an AC / DC adapter. For example, the power supply circuit 33 converts a DC voltage supplied from an external power source such as an AC adapter (not shown) or a battery 40 into a plurality of voltages required to operate the electronic device 10. The power supply circuit 33 also supplies power to each unit of the electronic device 10 based on the control from the embedded controller 31.

[0031] The battery 40 is, for example, a secondary battery such as a lithium ion battery. When power is supplied from an external power source to the electronic device 10, the battery 40 is charged via the power supply circuit 33. When power is not supplied from an external power source to the electronic device 10, the battery 40 outputs the accumulated power via the power supply circuit 33 as operating power for the electronic device 10.

[0032] The embedded controller 31 is a one-chip microcomputer that monitors and controls various devices (peripheral devices, sensors, etc.) regardless of the system state of the electronic device 10. The embedded controller 31 includes a CPU, ROM, RAM, A / D input terminals for multiple channels, a D / A output terminal, a timer, and digital input / output terminals (not shown). An input unit 32, a power supply circuit 33, etc. are connected to the digital input / output terminals of the embedded controller 31, and the embedded controller 31 controls the operations of these. The embedded controller 31 also controls changes in the clock frequency of the CPU 11 via the chipset 21.

[0033] 2 shows an example of the configuration of the battery 40 according to this embodiment. The battery 40 has a battery 41, a BMU (Battery Management Unit) 42, and a battery capacity calculation device 43. The battery capacity calculation device 43 may be included in the BMU 42.

[0034] For example, the battery 41 is a lithium ion battery. The BMU 42 monitors various states of the battery 41 and acquires information relating to the various states from the battery 41. For example, the BMU 42 acquires the voltage value, current value, temperature, and the like of the battery 41 from the battery 41.

[0035] The battery capacity calculation device 43 includes a controller 44 and a memory 45. The controller 44 includes a micro processing unit (MPU) etc. The memory 45 includes a storage medium such as a RAM.

[0036] The controller 44 has, as functional components for the processes executed by the MPU, a status acquisition unit 440, an impedance value calculation unit 441, a battery capacity calculation unit 442, a memory control unit 443, and a charge control unit 444. The functions of the controller 44 may be implemented in battery firmware.

[0037] The status acquisition unit 440 acquires information on various statuses of the battery 41 from the BMU 42. The impedance value calculation unit 441 calculates the impedance value of the battery 41 by using the information acquired from the BMU 42. The battery capacity calculation unit 442 calculates the full charge capacity of the battery 41 by using the information acquired from the BMU 42 and the impedance value calculated by the impedance value calculation unit 441. The memory control unit 443 controls reading and writing of data between the controller 44 and the memory 45. The charging control unit 444 controls charging of the battery 41 via the BMU 42.

[0038] The impedance value calculation process executed by the controller 44 will be described with reference to Fig. 3. Fig. 3 shows an example of the impedance value calculation process according to this embodiment. The controller 44 executes the impedance value calculation process shown in Fig. 3 while the battery 41 is being charged.

[0039] (Step S100) The state acquisition unit 440 acquires information on the SoC (State of Charge) of the battery 41 from the BMU 42 every time a predetermined time elapses. The SoC indicates the state of charge of the battery 41. When the battery 41 is fully charged, the SoC is 100%, and when the battery 41 is completely discharged, the SoC is 0%. The state acquisition unit 440 determines whether the state of charge indicated by the SoC is a predetermined state. The predetermined state corresponds to a state in which the electronic device 10 is operating by receiving power from the battery 41 and the impedance of the battery 41 is stable. For example, the predetermined state corresponds to an SoC of 60%, 65%, 70%, 75%, or 80%.

[0040] When the charging state of the battery 41 is not in the predetermined state, the controller 44 executes step S100 again. When the charging state of the battery 41 is in the predetermined state, the controller 44 executes the following step S101.

[0041] When the SoC is 60%, 65%, 70%, 75%, or 80%, the controller 44 calculates the impedance value of the battery 41 as follows: Therefore, the controller 44 can calculate the impedance value of the battery 41 frequently.

[0042] (Step S101) The status acquisition unit 440 acquires information on the voltage value V1, the current value I1, and the temperature T of the battery 41 from the BMU .

[0043] (Step S102) After step S101 is executed, the charging control unit 444 stops charging of the battery 41 for one minute. The time period for which the charging control unit 444 stops charging is not limited to one minute.

[0044] (Step S103) After step S102 is executed, the state acquisition unit 440 acquires information on the voltage value V2 of the battery 41 from the BMU 42.

[0045] (Step S104) After step S103 is executed, the impedance value calculation unit 441 uses the voltage value V1, the voltage value V2, and the current value I1 to calculate the impedance value of the battery 41. In addition, the impedance value calculation unit 441 uses the temperature T to correct the impedance value and obtain a corrected impedance value.

[0046] 4 and 5, a method in which the impedance value calculation unit 441 calculates the impedance value of the battery 41 will be described. Fig. 4 shows an example of a change in the voltage of the battery 41 during charging. Fig. 5 is an enlarged view of a part of Fig. 4.

[0047] The horizontal axis of the graph in FIG. 4 indicates the SoC, and the vertical axis of the graph indicates the voltage. Line L1 in FIG. 4 indicates the closed circuit voltage (CCV) of battery 41 during charging. Points P1 to P5 on line L2 in FIG. 4 indicate the open circuit voltage (OCV) of battery 41 after charging of battery 41 has stopped for one minute. When SoC is 60%, the open circuit voltage of battery 41 is at point P1. When SoC is 65%, the open circuit voltage of battery 41 is at point P2. When SoC is 70%, the open circuit voltage of battery 41 is at point P3. When SoC is 75%, the open circuit voltage of battery 41 is at point P4. When SoC is 80%, the open circuit voltage of battery 41 is at point P5.

[0048] Fig. 5 shows the voltage of the battery 41 in the vicinity of point P1 in Fig. 4. Point P0 on line L1 shown in Fig. 5 shows the voltage of the battery 41 in step S100. The status acquisition unit 440 acquires a voltage value V1 and a current value I1 at point P0. Point P1 on line L2 shown in Fig. 5 shows the voltage of the battery 41 in step S103. The status acquisition unit 440 acquires a voltage value V2 at point P1.

[0049] The impedance value calculation unit 441 calculates the impedance value of the battery 41 by dividing the difference (V1-V2) between the voltage value V1 and the voltage value V2 by the current value I1. The impedance value calculation unit 441 also multiplies the impedance value by a correction coefficient according to the temperature T to calculate a corrected impedance value.

[0050] FIG. 6 shows an example of the impedance of a battery configured similarly to battery 41. The horizontal axis of the graph in FIG. 6 shows the voltage of the battery when the SoC is 60%, and the vertical axis of the graph shows the impedance of the battery. Line L3 in FIG. 6 shows the impedance at a temperature of 45° C. Line L4 in FIG. 6 shows the impedance at a temperature of 35° C. Line L5 in FIG. 6 shows the impedance at a temperature of 25° C. Line L6 in FIG. 6 shows the impedance at a temperature of 15° C.

[0051] For example, by using a battery configured similarly to battery 40, the same processes as steps S101 to S103 are executed to calculate the impedance value. The impedance values ​​at various temperatures are calculated, and the data of the graph shown in Fig. 6 is obtained. By using the data, a correction coefficient according to the temperature is calculated.

[0052] FIG. 7 shows an example of the correction coefficient. In this example, the reference temperature is 25° C., and the correction coefficient at the reference temperature is set to 1.00. The correction coefficient at each temperature other than the reference temperature is the ratio of the impedance value at each temperature to the impedance value at the reference temperature. The correction coefficients shown in FIG. 7 are pre-recorded in the memory 45.

[0053] As the temperature increases, the correction coefficient increases. For example, when the temperature is a reference temperature (25°C), the impedance value calculation unit 441 multiplies the impedance value by a predetermined correction coefficient (1.00). When the temperature is lower than the reference temperature, the impedance value calculation unit 441 multiplies the impedance value by a correction coefficient smaller than the predetermined correction coefficient. When the temperature is higher than the reference temperature, the impedance value calculation unit 441 multiplies the impedance value by a correction coefficient larger than the predetermined correction coefficient.

[0054] (Step S105) After step S104 is executed, the memory control unit 443 records the correction impedance value in the memory 45. The memory control unit 443 may update the correction impedance value previously recorded in the memory 45 with the newly calculated correction impedance value. The memory control unit 443 may record the newly calculated correction impedance value in the memory 45 in a state in which it can be distinguished from the correction impedance value calculated in the past. After that, the controller 44 executes step S100 again.

[0055] The capacity calculation process executed by the controller 44 will be described with reference to Fig. 8. Fig. 8 shows an example of the capacity calculation process according to this embodiment. The controller 44 executes the capacity calculation process shown in Fig. 8 at any timing. The controller 44 may execute the capacity calculation process while the battery 41 is being charged, or may execute the capacity calculation process when the battery 41 is not being charged.

[0056] (Step S200) Every time a predetermined time elapses, the memory control unit 443 determines whether or not a new corrected impedance value has been recorded in the memory 45. If a new corrected impedance value has not been recorded in the memory 45, the controller 44 executes step S200 again. If a new corrected impedance value has been recorded in the memory 45, the controller 44 executes the following step S201.

[0057] (Step S201) The battery capacity calculation unit 442 calculates the corrected impedance increase. The corrected impedance increase is a ratio between the corrected impedance value recorded in the memory 45 and the initial impedance value. The initial impedance value is the impedance value of the battery 41 before use of the battery 41 starts (before the initial charging of the battery 41 starts). The impedance value of the battery 41 gradually increases from the initial impedance value over time. The initial impedance value is recorded in advance in the memory 45.

[0058] (Step S202) The status acquisition unit 440 acquires information regarding the number of cycles and the high temperature and high pressure time from the BMU 42 .

[0059] One cycle corresponds to the period from when the battery 41 goes from a completely discharged state to a fully charged state, and then when the battery 41 goes back to a completely discharged state again. The battery 41 stores the number of cycles from when the battery 41 started to be used inside the battery 41.

[0060] The high temperature and high pressure time is the time (hours) during which the temperature of the battery 41 is within a predetermined temperature range and the output voltage value of the battery 41 is within a predetermined voltage range. For example, the predetermined temperature range is 45° C. or higher and 70° C. or lower. For example, the predetermined voltage range is 4.4 V or higher and 4.5 V or lower.

[0061] (Step S203) After step S202 is executed, the battery capacity calculation unit 442 calculates the full charge capacity of the battery 41 by using the number of cycles, the high temperature and high pressure time, and the corrected impedance increase. The memory control unit 443 records the full charge capacity in the memory 45. After this, the controller 44 executes step S200 again.

[0062] An example of a method for calculating the full charge capacity of the battery 41 will be described. Fig. 9 shows an example of the relationship between the number of cycles and the capacity maintenance rate, and the relationship between the number of cycles and the impedance growth. As described above, the capacity maintenance rate is obtained by dividing the full charge capacity by the design capacity. The impedance growth is the ratio between the current impedance value and the initial impedance value.

[0063] The horizontal axis of the graph in FIG. 9 indicates the number of cycles, and the vertical axis of the graph indicates the capacity retention rate and the impedance increase. Line L10 shown in FIG. 9 indicates the relationship between the number of cycles and the capacity retention rate. Line L11 shown in FIG. 9 indicates the relationship between the number of cycles and the impedance increase. As shown in FIG. 9, as the number of cycles increases, the capacity retention rate decreases and the impedance increase increases. In other words, as the impedance increases, the full charge capacity decreases. Battery capacity calculation unit 442 calculates the full charge capacity based on the relationship between the full charge capacity and the impedance.

[0064] Fig. 10 shows an example of the relationship between impedance increase and capacity retention rate of a battery configured similarly to battery 41. The horizontal axis of the graph in Fig. 10 represents impedance increase, and the vertical axis of the graph represents capacity retention rate.

[0065] The graph in Figure 10 shows the measurement results of impedance and full charge capacity obtained by degrading a battery in three different test environments, where the test environment temperatures are 25°C, 45°C, and 60°C. As shown in Figure 10, it is estimated that the relationship between impedance and full charge capacity can be approximated by a straight line.

[0066] Fig. 11 shows three straight lines that approximate the measurement results shown in Fig. 10. Line L7 approximates the measurement results in degradation mode 1 (test environment temperature 25°C). Line L8 approximates the measurement results in degradation mode 2 (test environment temperature 45°C). Line L9 approximates the measurement results in degradation mode 3 (test environment temperature 60°C).

[0067] As shown in Fig. 11, the relationship between impedance and full charge capacity can be approximated by a straight line, and the relationship depends on temperature. Also, as shown in Fig. 9, the relationship between the cycle number and the capacity maintenance rate can be approximated by a straight line. Taking these factors into consideration, the full charge capacity FCC of the battery 41 is expressed by the following formula (1) that uses the cycle number CYC, the high temperature and high pressure time HTVT, and the corrected impedance increase IMP. FCC=1.0+a*CYC+b*HTVT+c*IMP ···(1)

[0068] In formula (1), a, b, and c are predetermined coefficients. By using a battery configured similarly to battery 41, impedance values ​​and full charge capacities at various temperatures are measured, and the number of cycles and high-temperature, high-pressure time are obtained. The results are subjected to, for example, the least squares method to calculate coefficients a, b, and c. These coefficients are stored in advance in memory 45. Controller 44 calculates the full charge capacity by using formula (1).

[0069] As described above, the controller 44 acquires the first voltage value (V1) and the charging current value (I1) of the battery 41 while the battery 41 is being charged. The controller 44 acquires the second voltage value (V2) of the battery 41 while the charging of the battery 41 is paused. The controller 44 calculates the impedance value of the battery 41 by using the first voltage value, the second voltage value, and the charging current value. The controller 44 calculates an impedance increase, which is a ratio between the impedance value and an initial impedance value previously recorded in the memory 45. The controller 44 acquires the number of cycles of the battery 41. The controller 44 acquires the time (high temperature and high pressure time) during which the temperature of the battery 41 is within a predetermined temperature range and the output voltage value of the battery 41 is within a predetermined voltage range. The controller 44 calculates the full charge capacity of the battery 41 by using the number of cycles, the impedance increase, and the high temperature and high pressure time.

[0070] In this embodiment, the charge and discharge amounts of the battery 41 required to calculate the full charge capacity are small, so the controller 44 can calculate the full charge capacity frequently.

[0071] The controller 44 calculates the full charge capacity according to the above formula (1). The controller 44 can calculate the full charge capacity by using a simple formula.

[0072] The controller 44 may calculate the full charge capacity without using the high temperature and high pressure time. In this case, the controller 44 does not need to acquire the high temperature and high pressure time from the BMU 42. The controller 44 calculates the full charge capacity by using the following formula (2) which is a modification of formula (1). FCC = 1.0 + a * CYC + c * IMP (2)

[0073] The controller 44 corrects the impedance value according to the temperature during charging of the battery 41. The controller 44 calculates the full charge capacity by using the corrected impedance increase according to the temperature, so that the controller 44 can calculate the full charge capacity with high accuracy.

[0074] Second Embodiment A second embodiment of the present invention will be described. In the second embodiment, a battery 40a shown in FIG. 12 is used instead of the battery 40 shown in FIG. 2. FIG. 12 shows an example of the configuration of the battery 40a according to this embodiment. Only configurations different from the configuration shown in FIG. 2 will be described, and descriptions of the same configurations as those shown in FIG. 2 will be omitted.

[0075] A battery capacity calculation device 43a shown in Fig. 12 is used in place of the battery capacity calculation device 43 shown in Fig. 2. In the battery capacity calculation device 43a, a controller 44a is used in place of the controller 44 shown in Fig. 2.

[0076] The controller 44a has a life estimation unit 445 in addition to the state acquisition unit 440, the impedance value calculation unit 441, the battery capacity calculation unit 442, the memory control unit 443, and the charge control unit 444 shown in Fig. 2. The life estimation unit 445 calculates the time until the full charge capacity of the battery 41 becomes equal to or less than a predetermined capacity.

[0077] The controller 44a executes a capacity calculation process shown in Fig. 13 instead of the capacity calculation process shown in Fig. 8. Fig. 13 shows an example of the capacity calculation process according to this embodiment. Only the process different from the process shown in Fig. 8 will be described, and the description of the same process as the process shown in Fig. 8 will be omitted.

[0078] Steps S200 to S203 shown in FIG. 13 are the same as steps S200 to S203 shown in FIG.

[0079] (Step S204) After step S203 is executed, the life estimation unit 445 judges whether the full charge capacity (FCC) calculated in step S203 is less than 80%. If the full charge capacity is 80% or more, the controller 44a executes step S200. If the full charge capacity is less than 80%, the controller 44a executes the following step S205.

[0080] (Step S205) The full charge capacity calculated in step S203 and time information indicating the date on which the full charge capacity was calculated are recorded in memory 45. Using the full charge capacity and the time information recorded in memory 45, life estimation unit 445 calculates the time until the full charge capacity reaches the reference capacity.

[0081] Fig. 14 shows an example of the change over time in the full charge capacity of a battery configured similarly to battery 41. The horizontal axis of the graph in Fig. 14 represents time, and the vertical axis represents the full charge capacity.

[0082] The full charge capacity gradually decreases with time. The relationship between time and the full charge capacity can be approximated by a straight line. On a day indicated by T1, the full charge capacity is 80%. Then, on a day indicated by T2, the full charge capacity is 60% which is the reference capacity. The life estimation unit 445 calculates the time between T1 and T2.

[0083] Specifically, the life estimation unit 445 calculates an equation for an approximate straight line indicating the relationship between time and the full charge capacity by using the past full charge capacity recorded in the memory 45. The life estimation unit 445 uses the equation to calculate the time it takes for the full charge capacity to change from 80% to 60%. This time serves as a guide for when the user should replace the battery 41. The life estimation unit 445 may calculate the number of cycles corresponding to this time.

[0084] In the above example, the threshold value in step S204 is 80%, but the threshold value may be a value other than 80%. In the above example, the reference capacity is 60%, but the reference capacity may be a value other than 60%.

[0085] The time calculated by the life estimation unit 445 may be output to the CPU 11. The CPU 11 may execute a notification process for notifying the user of the time. For example, the CPU 11 may display information indicating the time on the display unit 14. The CPU 11 may generate a sound corresponding to the information from a speaker not shown in FIG. 1. The CPU 11 may transmit the information to another device via the WLAN card 25.

[0086] As described above, the controller 44 records the calculated full charge capacity and the time information at which the full charge capacity was calculated in the memory 45. The controller 44 uses the full charge capacity and the time information recorded in the memory 45 to calculate the time until the full charge capacity of the battery 41 becomes equal to or less than a predetermined capacity. The controller 44 can predict the life of the battery 41.

[0087] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above embodiment, and design modifications and the like that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0088] 10 Electronic device, 11 CPU, 12 Main memory, 13 Video subsystem, 14 Display unit, 21 Chipset, 22 BIOS memory, 23 Storage medium, 24 Audio system, 25 WLAN card, 26 USB connector, 31 Embedded controller, 32 Input unit, 33 Power supply circuit, 40, 40a Battery, 41 Battery, 42 BMU, 43, 43a Battery capacity calculation device, 44, 44a Controller, 45 Memory, 440 Status acquisition unit, 441 Impedance value calculation unit, 442 Battery capacity calculation unit, 443 Memory control unit, 444 Charging control unit, 445 Life estimation unit

Claims

1. A controller is provided. The controller: obtaining a first voltage value and a charging current value of the battery while the battery is being charged; obtaining a second voltage value of the battery during a pause in charging the battery; calculating an impedance value of the battery using the first voltage value, the second voltage value, and the charging current value; Calculating an impedance increase, which is the ratio of the impedance value to an initial impedance value previously stored in memory; Obtaining a cycle count for the battery; obtaining a time during which the temperature of the battery is within a predetermined temperature range and the output voltage value of the battery is within a predetermined voltage range; Calculating the full charge capacity of the battery using the number of cycles, the impedance increase, and the time. Battery capacity calculation device.

2. The controller calculates the full charge capacity according to the formula: FCC=1.0+a*CYC+b*HTVT+c*IMP; In the above formula, FCC is the full charge capacity, CYC is the cycle number, HTVT is the time, IMP is the impedance increase, and a, b, and c are predetermined coefficients. The battery capacity calculation device according to claim 1 .

3. The controller corrects the impedance value according to the temperature during charging of the battery. The battery capacity calculation device according to claim 1 or 2.

4. The controller: Recording the calculated full charge capacity and time information at the time when the full charge capacity was calculated in a memory; By using the full charge capacity and the time information recorded in the memory, the time until the full charge capacity of the battery becomes equal to or less than a predetermined capacity is calculated. The battery capacity calculation device according to claim 1 or 2.

5. A controller is provided. The controller: obtaining a first voltage value and a charging current value of the battery while the battery is being charged; obtaining a second voltage value of the battery during a pause in charging the battery; calculating an impedance value of the battery using the first voltage value, the second voltage value, and the charging current value; Calculating an impedance increase, which is the ratio of the impedance value to an initial impedance value previously stored in memory; Obtaining a cycle count for the battery; Calculate the full charge capacity of the battery using the number of cycles and the impedance increase. Battery capacity calculation device.

6. obtaining a first voltage value and a charging current value of the battery while the battery is being charged; obtaining a second voltage value of the battery during a pause in charging the battery; calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; calculating an impedance increase which is a ratio between the impedance value and an initial impedance value previously stored in a memory; obtaining a cycle count of the battery; acquiring a time during which the temperature of the battery is within a predetermined temperature range and the output voltage value of the battery is within a predetermined voltage range; calculating a full charge capacity of the battery using the number of cycles, the impedance increase, and the time; A battery capacity calculation method comprising:

7. obtaining a first voltage value and a charging current value of the battery while the battery is being charged; obtaining a second voltage value of the battery during a pause in charging the battery; calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; calculating an impedance increase which is a ratio between the impedance value and an initial impedance value previously stored in a memory; obtaining a cycle count of the battery; calculating a full charge capacity of the battery using the number of cycles and the impedance increase; A battery capacity calculation method comprising:

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