Battery management device, battery pack, battery management method, and battery management program

Abstract

In a battery management device (11) according to an embodiment, a control unit (13) calculates, on the basis of the full charge capacity and the remaining capacity of a battery pack (10), the charge capacity required when the battery pack (10) is charged at a constant voltage (CV). Furthermore, the control unit (13) generates a charging current transition on the basis of the charging current at the start of CV charging and the charging current at the time of full charging of the assembled battery (10), the charging current transition assuming that the charging current decreases at a constant speed. In addition, the control unit (13) estimates the charging time when the CV is charged on the basis of the required charging capacity and the charging current pass.

Description

Technical Field

[0001] This disclosure relates to a battery management device, battery pack, battery management method, and battery management program for managing the charging of batteries. Background Technology

[0002] Constant current constant voltage (CC-CV) charging has become widely used as a charging method for battery packs (see, for example, Patent Document 1). In typical CC-CV charging, when the SOC (State of Charge) is around 80% to 90%, the charging current gradually decreases as the charging method switches from CC charging to CV charging.

[0003] The charging capacity is calculated using the product of the charging current and time. During CC charging, the time until the end of charging is determined by dividing the charging capacity until full charge by the charging current. As mentioned above, in CC-CV charging, CC charging occurs when the battery voltage is low, but when the battery voltage exceeds the set voltage, it switches to CV charging, and the charging current gradually decreases. Therefore, in CV charging, simply dividing the charging capacity until full charge by the charging current cannot calculate the time until the end of charging.

[0004] Therefore, we consider determining the relationship between the State of Charge (SOC) during CV charging and the time until charging is complete through experiments and simulations, and defining it in a table. Specifically, we create a table describing the following relationships: SOC = 81% - Time to end of charging = 88 minutes, SOC = 82% - Time to end of charging = 86 minutes, ..., SOC = 99% - Time to end of charging = 3 minutes. Additionally, we also consider determining the relationship between the charging current during CV charging and the time until charging is complete through experiments and simulations, and defining it in a table.

[0005] However, the relationship between the State of Charge (SOC) during CV charging and the time until charging ends, or the relationship between the charging current and the time until charging ends, is affected by factors such as temperature and State of Health (SOH). For example, the lower the SOH (the more severe the degradation), the greater the error in the relationship defined in the table, and the greater the deviation between the estimated time until charging ends and the actual time until charging ends. To reduce this deviation, a multi-dimensional table that considers changes in temperature and SOH needs to be created. In this case, the program size increases.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-39400 Summary of the Invention

[0009] This disclosure provides a technique for estimating the time from the start of CV charging to the end of charging with relatively high accuracy and ease.

[0010] A battery management device according to a certain aspect of this disclosure includes a control unit that estimates the charging time when the battery pack is fully charged. The control unit calculates the required charging capacity for CV charging of the battery pack based on the full-charge capacity and remaining capacity of the battery pack. Furthermore, the control unit generates a charging current shift assuming a uniform decrease in charging current based on the charging current at the start of CV charging and the charging current when the battery pack is fully charged. Finally, the control unit estimates the charging time for CV charging based on the required charging capacity and the charging current shift.

[0011] Furthermore, any combination of the above-mentioned constituent elements, and any manner in which the present disclosure is manifested in apparatus, system, method, computer program, etc., are also valid as forms of the present disclosure.

[0012] According to this disclosure, the time from the start of CV charging to the end of charging can be estimated with relatively high accuracy and ease. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating the structure of the battery pack and charger involved in the implementation method.

[0014] Figure 2 This is a schematic diagram illustrating the time-varying charging current during CC-CV charging.

[0015] Figure 3 This is a graph showing the required charging capacity during CV charging.

[0016] Figure 4 This demonstrates how to obtain the area using the trapezoidal approximation. Figure 3 A diagram illustrating an example of the required charging capacity during CV charging.

[0017] Figure 5 This is a graph illustrating an example of the charging current and the state of charge (SOC) of the battery pack during CC-CV charging over time. Detailed Implementation

[0018] Figure 1This diagram illustrates the structure of the battery pack 1 and charger 2 according to the embodiment. In this embodiment, the battery pack 1 is envisioned as being mounted on an electric mobile vehicle (e.g., an electric bicycle, an electric motorcycle, an electric scooter, etc.). The battery pack 1 can be a detachable, portable type, or it can be fixed to a vehicle. In the former case, the battery pack 1 is charged by being fitted into the charging slot of the charger 2; in the latter case, the battery pack 1 is charged by being connected to the charger 2 via a charging cable.

[0019] The battery pack 1 includes a battery array 10 and a battery management device 11. The battery array 10 includes multiple cells E1-En connected in series. The number of cells connected in series is determined by the load specifications. For the cells E1-En, lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, etc., can be used. Hereinafter, in this specification, a lithium-ion battery cell (nominal voltage: 3.6-3.7V) is envisioned as an example of using a single cell E1-En. Furthermore, in order to increase the capacity, multiple cells can also be connected in parallel within the series stage of each cell.

[0020] A switch SW1 is inserted into the power line connecting the battery pack 10 and the charger 2 to switch the charger 2 on / off state. A semiconductor switch or a relay can be used for switch SW1.

[0021] The battery management device 11 includes a measurement unit 12 and a control unit 13. The measurement unit 12 is composed of an AFEIC (Analog Front-End Integrated Circuit) or an ASIC (Application Specific Integrated Circuit). The control unit 13 is composed of a microcontroller.

[0022] The measurement unit 12 is connected to each node of multiple individual cells E1-En connected in series via multiple voltmeter measurement lines. By measuring the voltage between two adjacent voltmeter measurement lines, the voltage of each individual cell E1-En is measured.

[0023] The measurement unit 12 includes a multiplexer and an A / D (Analog-to-Digital) converter. The multiplexer outputs the voltages of multiple individual units E1-En in a given order to the A / D converter. The A / D converter converts the analog voltages input from the multiplexer into digital values. The measurement unit 12 transmits the converted digital voltage values ​​of each individual unit E1-En to the control unit 13 via a communication interface.

[0024] The measurement unit 12 measures the current flowing through the battery pack 10. A shunt resistor Rs is connected in the power line connecting the battery pack 10 and the charger 2. A differential amplifier (not shown) amplifies the voltage across the shunt resistor Rs and outputs it to the A / D converter within the measurement unit 12. The A / D converter converts the analog voltage representing the current flowing through the battery pack 10, which is input from the differential amplifier, into a digital value. The measurement unit 12 then sends the converted digital current value to the control unit 13 via a communication interface.

[0025] A temperature sensor T1 (e.g., a thermistor) is disposed on the surface of the battery pack 10. The voltage divided by the temperature sensor T1 and a voltage divider resistor (not shown) is input to the measurement unit 12. An A / D converter within the measurement unit 12 converts the input analog voltage representing the temperature into a digital value. The measurement unit 12 transmits the converted temperature value to the control unit 13 via a communication interface.

[0026] The control unit 13 manages the state of each cell E1-En based on the voltage value of each cell E1-En, the current value flowing through the battery pack 10, and the temperature value of the battery pack 10 received from the measurement unit 12. When the control unit 13 detects any of the following: overcharge, over-discharge, overcurrent, high temperature abnormality, or low temperature abnormality, it sends a cut-off signal to the measurement unit 12 to turn off the switch SW1.

[0027] The control unit 13 executes firmware and other programs within the microcontroller to perform the following functions. The control unit 13 combines the OCV (Open Circuit Voltage) method and the current accumulation method to estimate the State of Charge (SOC). The OCV method estimates the SOC based on the measured OCV of a single cell and the SOC-OCV curve of that cell. The SOC-OCV curve of the single cell is pre-created based on characteristic tests conducted by the battery manufacturer and is registered in the control unit 13 at the time of shipment.

[0028] The current accumulation method estimates the state of charge (SOC) based on the initial charge-discharge velocity (OCV) of a single cell and the cumulative value of the measured current. However, in this method, the measurement error accumulates as the charging / discharging time increases. Therefore, it is preferable to use a weighted average of the SOC estimated by the current accumulation method and the SOC estimated by the OCV method.

[0029] The control unit 13 can convert the SOC of each cell E1-En into actual capacity, combine these actual capacities to calculate the actual capacity of the battery pack 1, and estimate the SOC of the battery pack 1 based on the actual capacity and the current full charge capacity (FCC: Full Charge Capacity) of the battery pack 1.

[0030] The control unit 13 can estimate the current FCC of the battery pack 1 by dividing the accumulated current value within the operating SOC range by the operating SOC range. The control unit 13 can estimate the SOH by dividing the current FCC by the initial FCC.

[0031] Charger 2 includes: an AC (Alternating Current) / DC (Direct Current) converter 21, a DC / DC converter 22, a control unit 23, and a display unit 24. The AC / DC converter 21 converts AC power supplied from the commercial power system 3 into DC power. When the commercial power system 3 does not have reverse power flow capability, the AC / DC converter 21 can be configured using a combination of a rectifier and a filter. When the commercial power system 3 has reverse power flow capability, a bidirectional converter is used for the AC / DC converter 21.

[0032] With battery pack 1 and charger 2 connected, DC / DC converter 22 controls the voltage or current of the DC power supplied from AC / DC converter 21 and outputs it to battery pack 10. If the commercial power system 3 does not have reverse power flow capability, DC / DC converter 22 can be a unidirectional DC / DC converter. If the commercial power system 3 has reverse power flow capability, a bidirectional DC / DC converter is used for DC / DC converter 22.

[0033] The control unit 23 is composed of a microcontroller. The control unit 23 of the charger 2 and the control unit 13 of the battery pack 1 are connected via signal lines, and a given serial communication is performed between the two. When the battery pack 1 is connected to the charger 2, the control unit 23 of the charger 2 receives the constant current value, constant voltage value, and current value at full charge (charging termination current value) during CC-CV charging from the control unit 13 of the battery pack 1.

[0034] The control unit 23 of the charger 2 performs CC charging when the voltage of the battery pack 10 is lower than the received constant voltage value, and performs CV charging when the voltage of the battery pack 10 is higher than the constant voltage value. During CC charging, the control unit 23 generates a current command value to maintain the measured output current of the DC / DC converter 22 at the received constant current value. When the measured output current of the DC / DC converter 22 is greater than the received constant current value, the control unit 23 generates a current command value to reduce the output of the DC / DC converter 22; when the measured output current of the DC / DC converter 22 is less than the received constant current value, it generates a current command value to increase the output of the DC / DC converter 22.

[0035] During CV charging, the control unit 23 generates a voltage command value to maintain the measured output voltage of the DC / DC converter 22 at the received constant voltage value. When the measured output voltage of the DC / DC converter 22 is higher than the received constant voltage value, the control unit 23 generates a voltage command value to decrease the output of the DC / DC converter 22; when the measured output voltage of the DC / DC converter 22 is lower than the received constant voltage value, it generates a voltage command value to increase the output of the DC / DC converter 22. The DC / DC converter 22 performs switching operations based on the drive signal based on the generated current command value or voltage command value.

[0036] Figure 2 This is a schematic diagram illustrating the time progression of the charging current during CC-CV charging. The charging period in CC-CV charging is defined by the total of the CC charging period and the CV charging period. In this embodiment, the control unit 13 of the battery pack 1 has the function of estimating the charging time required to fully charge the battery pack 10.

[0037] When performing CC-CV charging on the battery pack 10, the control unit 13 calculates the required charging capacity during CC charging and the required charging capacity during CV charging based on the battery pack 10's FCC, remaining capacity (RC: Remaining Charge), and capacity when switching from CC charging to CV charging. The capacity when switching from CC charging to CV charging can also be preset as a fixed value (e.g., 80%) in a non-volatile memory area within the control unit 13. Alternatively, the capacity when switching from CC charging to CV charging can also use a value notified from the charger 2.

[0038] The timing for switching from CC charging to CV charging is determined by the point in time when the voltage of the battery pack 10 reaches a set constant voltage value during CC charging based on the DC / DC converter 22, and the charging current decreases by more than the tolerance. The control unit 13 of the battery pack 1 can store the capacity at the point in time when the switch from CC charging to CV charging actually occurs in a non-volatile memory area. The control unit 13 can also use the capacity stored in the non-volatile memory area at the point in time when the switch from CC charging to CV charging occurs, measured during the previous charging, as the capacity at the time of the switch.

[0039] As shown in Equation 1 below, the control unit 13 estimates the charging time during CC charging based on the required charging capacity and constant current value during CC charging.

[0040] CC charging time = Required charging capacity during CC charging / Constant current value (Equation 1)

[0041] Required charging capacity during CC charging = (FCC × Capacity when switching to CV charging (%) - RC)

[0042] As shown in Equation 2 below, the control unit 13 estimates the charging time during CV charging based on the required charging capacity and the shift in charging current during CV charging. The control unit 13 generates the shift in charging current during CV charging based on the charging current at the start of CV charging and the charging current when the battery pack 10 is fully charged, using a linear approximation assuming that the charging current decreases at a uniform rate.

[0043] CV charging time = Required charging capacity during CV charging × 2 / (Charging current at the start of CV charging + Charging current at full charge) (Equation 2)

[0044] Required charging capacity during CV charging = (FCC × (100 - capacity (%) when switching to CV charging) - RC)

[0045] The charging current at the start of CV charging is essentially a constant current value. The charging current at which the battery pack 10 is fully charged can also be preset as a fixed value (e.g., 360mA) in the non-volatile memory region within the control unit 13. The control unit 13 can store the charging current at which the battery pack 10 actually reaches full charge in the non-volatile memory region. The control unit 13 can also use the charging current at which the battery pack 10 reaches full charge, measured during the previous charging cycle, stored in the non-volatile memory region, as the charging current at which the battery pack 10 reaches full charge.

[0046] Furthermore, if the SOC of battery pack 10 at the start of charging is greater than the capacity (%) at which CV charging is switched, the CC charging period is omitted, and CV charging is implemented from the start of charging. In this case, the charging current at the start of CV charging is essentially the same as the measured current at the start of CV charging.

[0047] Figure 3 This is a graph showing the required charging capacity during CV charging. Figure 4 This demonstrates how to obtain the area using the trapezoidal approximation. Figure 3 A graph illustrating an example of the required charging capacity during CV charging. Figure 3 , Figure 4 The example shown is an instance where the capacity is SOC = 80% when switching from CC charging to CV charging.

[0048] like Figure 3 As shown, the charging capacity is obtained by integrating the charging current over time. However, it is difficult to predict in advance the charging current at each time point during CV charging, which gradually decreases due to factors such as temperature and cell degradation. Therefore, in this embodiment, as shown in Equation 3 below, the charging capacity during CV charging is approximated by the area of ​​a trapezoid.

[0049] The charging capacity during CV charging = (charging current at the start of CV charging + charging current at full charge) × CV charging time / 2 (Equation 3)

[0050] Equation 2 is derived from Equation 3.

[0051] The control unit 13 adds the charging time during CC charging and the charging time during CV charging to estimate the charging time for CC-CV charging. Before charging begins, the control unit 13 estimates the charging time required to fully charge the battery pack 10 via CC-CV charging. After charging begins, the control unit 13 calculates the remaining time until charging ends.

[0052] For example, during CC charging, the control unit 13 acquires the RC of the battery pack 10 in real time, calculates (Equation 1) + (Equation 2) as described above, and updates the remaining time until the end of charging. For example, whenever the SOC of the battery pack 10 increases, the control unit 13 recalculates the remaining time until the end of charging. In addition, the remaining time until the end of charging can also be recalculated periodically (e.g., once every 1 minute or once every 5 minutes).

[0053] At the point when switching from CC charging to CV charging, the control unit 13 subtracts the RC at that point from the FCC of the battery pack 10 to calculate the remaining required charging capacity. The control unit 13 sets the remaining required charging capacity as the required charging capacity during CV charging, calculates the above (Equation 2), and recalculates the remaining time until the end of charging.

[0054] During CV charging, the control unit 13 acquires the RC and charging current values ​​of the battery pack 10 in real time. The control unit 13 subtracts the RC at each time point from the FCC and recalculates the remaining required charging capacity. The control unit 13 sets the remaining required charging capacity as the required charging capacity during CV charging, sets the current measured charging current as the charging current at the start of CV charging, and calculates the above (Equation 2) to recalculate the remaining time until the end of charging. Furthermore, during CV charging, due to variations in the charging current, the remaining time until the end of charging fluctuates significantly. Therefore, during CV charging, the control unit 13 can also calculate the remaining time until the end of charging by subtracting the elapsed time from the time of switching to CV charging from the CV charging switching time.

[0055] Furthermore, in the case where the remaining time until the end of charging is not recalculated during charging, the control unit 13 subtracts the elapsed time from the start of charging from the charging time estimated before charging begins, and obtains the remaining time until the end of charging.

[0056] The control unit 13 sends the remaining time until the end of charging to the control unit 23 of the charger 2 via a signal line. The control unit 23 of the charger 2 causes the display unit 24 to display the remaining time until the end of charging. The display unit 24 can be a 7-segment display, a liquid crystal display, an organic EL (Electro Luminescence) display, etc.

[0057] Furthermore, the control unit 13 can also display the remaining time until charging is complete on other user interfaces. For example, if the battery pack 1 itself is equipped with a display unit such as a 7-segment display, an LCD display, or an OLED display, the control unit 13 can make the display unit of the battery pack 1 display the remaining time until charging is complete. In addition, the control unit 13 can also convert the ratio of the remaining time until charging is complete to the charging time into the number of LEDs lit on the battery pack 1, thereby changing the number of LEDs lit.

[0058] Furthermore, when the battery pack 1 is fixed to the vehicle and connected to the instrument panel of the vehicle, such as the steering wheel, by a signal wire, the control unit 13 can make the vehicle's instrument panel display the remaining time until charging is finished.

[0059] Figure 5 This is a graph illustrating an example of the charging current during CC-CV charging and the time-varying SOC of battery pack 10. Assume that battery pack 10 has an FCC of 16051 mAh, a constant current of 4000 mA, a temperature of 25°C, an SOC of 80% when switching from CC charging to CV charging, a charging current of 360 mA at full charge, and an RC of 0 mAh at the start of charging.

[0060] According to Equation 1 above, the CC charging period is (16051×0.8-0) / 4000×60≈193 minutes. According to Equation 2 above, the CV charging period is (16051×0.2-0)×2 / (4000+360)×60≈88 minutes. Therefore, the total charging time is 281 minutes.

[0061] As explained above, according to this embodiment, by approximating the charging capacity during CV charging with a trapezoidal area, the time until the end of CV charging can be estimated with high accuracy and ease. Since the current FCC is used, the influence of SOH reduction can be eliminated. Furthermore, since a constant current value and a full-charge current value are used, the influence of current variations caused by temperature changes can be minimized. In particular, when the measured value from the previous charge is used as the full-charge current value, a full-charge current value corresponding to the current state of the battery pack 10 can be adapted. Additionally, since it is not necessary to prepare a multi-dimensional table considering temperature and SOH variations, the increase in program size can be suppressed. Furthermore, even in cases where conditions are not defined in the multi-dimensional table, flexible solutions can be provided.

[0062] The present disclosure has been described above based on the embodiments. The embodiments are illustrative, and those skilled in the art should understand that various modifications are possible in the combination of these constituent elements and processing procedures, and such modifications are also within the scope of the present disclosure.

[0063] In the above embodiment, an example of charging control via the DC / DC converter 22 within the charger 2 is shown. In this case, with both a DC / DC converter and an AC / DC converter built into the battery pack 1, the battery pack 1 can be directly connected to the AC outlet of the commercial power system 3 using a flexible cord with an AC plug. In this case, charging control is performed via the DC / DC converter within the battery pack 1.

[0064] In the above embodiments, an example of the battery pack 1 according to this disclosure being mounted on an electric mobile body has been described. In this respect, the battery pack 1 according to this disclosure can also be mounted on civilian electronic devices (e.g., laptop PCs, smartphones, tablets), EVs (Electric Vehicles), multi-rotor aircraft (drones), and fixed-location energy storage systems.

[0065] In addition, the implementation method can also be determined by the following items.

[0066] [Project 1]

[0067] The battery management device (11) of Project 1 includes a control unit (13) that estimates the charging time when the battery pack (10) is fully charged. The control unit (13) calculates the required charging capacity for CV charging of the battery pack (10) based on the full-charge capacity and remaining capacity of the battery pack (10). Furthermore, the control unit (13) generates a charging current shift assuming a uniform decrease in charging current based on the charging current at the start of CV charging and the charging current when the battery pack (10) is fully charged. Additionally, the control unit (13) estimates the charging time for CV charging based on the required charging capacity and the charging current shift.

[0068] Therefore, it is possible to estimate the time from the start of CV charging to the end of charging with relatively high accuracy and ease.

[0069] [Project 2]

[0070] In the battery management device (11) of Project 2, in the battery management device (11) described in Project 1, the control unit (13) calculates the required charging capacity × 2 / (charging current at the start of CV charging + charging current at full charge) and estimates the charging time during CV charging.

[0071] Therefore, based on the approximation of the trapezoidal area, the charging time during CV charging can be estimated with high accuracy and ease.

[0072] [Project 3]

[0073] In the battery management device (11) of Project 3, in the battery management device (11) described in Project 1, the control unit (13) uses the charging current measured by the full charge timer during the previous charging of the battery pack (10) when it is fully charged.

[0074] Accordingly, a charging current suitable for the current state of the battery pack (10) during full charge can be used.

[0075] [Project 4]

[0076] In the battery management device (11) of Project 4, in the battery management device (11) described in Project 1, when performing CC-CV charging on the battery pack (10), the control unit (13) calculates the required charging capacity during CC charging and the required charging capacity during CV charging based on the full charge capacity, remaining capacity, and capacity when switching from CC charging to CV charging of the battery pack (10). Furthermore, the control unit (13) estimates the charging time during CC charging based on the required charging capacity and constant current value during CC charging. Additionally, the control unit (13) estimates the charging time during CV charging based on the required charging capacity and charging current shift during CV charging. Finally, the control unit (13) adds the charging time during CC charging and the charging time during CV charging to estimate the charging time during CC-CV charging.

[0077] Therefore, it is possible to estimate the time from the start of CC-CV charging to the end of charging with relatively high accuracy and ease.

[0078] [Project 5]

[0079] In the battery management device (11) of Project 5, in the battery management device (11) described in Project 4, the control unit (13) uses the capacity measured at the time of switching from CC charging to CV charging when switching from CC charging to CV charging during the previous charging.

[0080] Accordingly, the capacity when switching from CC charging to CV charging can be used, which is suitable for the current state of the battery pack (10).

[0081] [Project 6]

[0082] The battery pack (1) of Project 6 includes: a battery pack (10) and a battery management device (11) as described in any one of Projects 1 to 5.

[0083] Accordingly, a battery pack (1) can be made that can estimate the time from the start of CV charging to the end of charging with relatively high accuracy and ease.

[0084] [Project 7]

[0085] The battery management method of Project 7 includes the following steps: calculating the required charging capacity for CV charging of the battery pack (10) based on its full charge capacity and remaining capacity. Additionally, the battery management method of Project 7 includes the following steps: generating a charging current shift assuming a uniform decrease in charging current based on the charging current at the start of CV charging and the charging current at full charge of the battery pack (10). Furthermore, the battery management method of Project 7 includes the following steps: estimating the charging time during CV charging based on the required charging capacity and the charging current shift.

[0086] Therefore, it is possible to estimate the time from the start of CV charging to the end of charging with relatively high accuracy and ease.

[0087] [Project 8]

[0088] The battery management program of Project 8 causes the computer to perform the following processing: based on the full charge capacity and remaining capacity of the battery pack (10), calculate the required charging capacity for CV charging of the battery pack (10). Additionally, the battery management program of Project 8 causes the computer to perform the following processing: based on the charging current at the start of CV charging and the charging current at full charge of the battery pack (10), generate a charging current shift assuming a uniform decrease in charging current. Furthermore, the battery management program of Project 8 causes the computer to perform the following processing: based on the required charging capacity and the charging current shift, estimate the charging time during CV charging.

[0089] Therefore, it is possible to estimate the time from the start of CV charging to the end of charging with relatively high accuracy and ease.

[0090] Symbol Explanation

[0091] 1 Battery Pack

[0092] 10 battery packs

[0093] 11 Battery Management Device

[0094] 12 Measurement Department

[0095] 13 Control Department

[0096] 2 Chargers

[0097] 21 AC / DC converter

[0098] 22 DC / DC converters

[0099] 23 Control Department

[0100] 24 Display Section

[0101] 3. Commercial Power Systems

[0102] E1 monomer

[0103] E2 monomer

[0104] En monomer

[0105] Rs Shunt resistor

[0106] SW1 switch

[0107] T1 Temperature sensor.

Claims

1. A battery management device comprising a control unit that estimates the charging time when a battery pack is fully charged. The control unit performs the following processing: Based on the full-charge capacity and remaining capacity of the battery pack, the required charging capacity for constant-voltage (CV) charging of the battery pack is calculated. Based on the charging current at the start of CV charging and the charging current when the battery pack is fully charged, a charging current shift is generated assuming the charging current decreases at a constant rate. Based on the required charging capacity and the shift in charging current, the charging time during CV charging is estimated.

2. The battery management device according to claim 1, wherein, The control unit calculates the required charging capacity × 2 / (charging current at the start of CV charging + charging current at full charge) and estimates the charging time during CV charging.

3. The battery management device according to claim 1, wherein, The control unit uses the charging current measured by the full charge timer during the previous charging cycle for the charging current of the battery pack when it is fully charged.

4. The battery management device according to claim 1, wherein, The control unit performs the following processing: When performing CC-CV charging on the battery pack, the required charging capacity during CC charging and the required charging capacity during CV charging are calculated based on the battery pack's full charge capacity, remaining capacity, and capacity when switching from CC charging to CV charging. Here, CC represents a constant current. Based on the required charging capacity and constant current value during CC charging, the charging time during CC charging is estimated. Based on the required charging capacity and the shift in charging current during the CV charging period, the charging time during the CV charging period is estimated. The charging time during CC charging is added together with the charging time during CV charging to estimate the charging time during CC-CV charging.

5. The battery management device according to claim 4, wherein, The control unit uses the capacity measured at the time of switching from CC charging to CV charging during the previous charging cycle to determine the capacity at the point in time when switching from CC charging to CV charging.

6. A battery pack, comprising: The battery management device according to any one of claims 1 to 5; and The battery pack.

7. A battery management method comprising the following steps: Based on the full charge capacity and remaining capacity of the battery pack, calculate the required charging capacity for CV charging of the battery pack. Based on the charging current at the start of CV charging and the charging current when the battery pack is fully charged, a charging current shift is generated assuming a uniform decrease in charging current; and Based on the required charging capacity and the shift in charging current, the charging time during CV charging is estimated.

8. A battery management program that causes a computer to perform the following processing: Based on the full charge capacity and remaining capacity of the battery pack, calculate the required charging capacity for CV charging of the battery pack. Based on the charging current at the start of CV charging and the charging current when the battery pack is fully charged, a charging current shift is generated assuming a uniform decrease in charging current; and Based on the required charging capacity and the shift in charging current, the charging time during CV charging is estimated.

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