Battery pack, electrical device, and system

Abstract

To provide a battery pack, an electrical device, and a system that are highly convenient, utilizing USB.SOLUTION: A battery pack 1 that can be attached to and detached from a device body 4 includes a first cell unit 11 and a second cell unit 12, a USB port 17 capable of connecting an external device, and an MCU 19 for controlling input or output of power via the USB port 17. The MCU 19 can arbitrarily switch from an external source between a first state in which it powers external devices from the first cell unit 11 and the second cell unit 12 via the USB port 17 and a second state in which it receives power from external devices via the USB port 17 to the first cell unit 11 and the second cell unit 12 (charging the first cell unit 11 and the second cell unit 12).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery pack, an electric device, and a system.

Background Art

[0002] Patent Document 1 discloses providing a USB connector (USB: Universal Serial Bus) on a device body and supplying power to a portable device or a smartphone as an external device via a USB cable. Patent Document 2 discloses providing a USB connector on a device body and charging a built-in battery from an external power source via the USB connector. On the other hand, USB devices used for power supply in various electric devices have an expanded power function of USB Type-C with the power supply standard USB Power Delivery (USB-PD), and a supply of up to 240 W (48 V / 5 A) is possible.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a highly convenient battery pack, electric device, and system using USB.

Means for Solving the Problems

[0005] One aspect of the present invention is a battery pack. This battery pack is a battery pack detachable from a device body, a battery cell, A USB connector capable of connecting an external device, a control unit that controls input or output of power via the USB connector, and is provided with The control unit is configured to be arbitrarily switchable from the first state of supplying power from the battery cell to the external device via the USB connector to the second state of receiving power from the external device to the battery cell via the USB connector from the outside.

[0006] Another aspect of the present invention is an electric device. This electric device the battery pack, a device body that detachably mounts the battery pack, and is an electric device provided with The device body has a load unit that is driven by power supplied from the battery pack.

[0007] Another aspect of the present invention is an electric device. This electric device is an electric device provided with a device body that detachably mounts a battery pack or incorporates a battery pack, a USB connector capable of connecting an external device, a control unit that controls input or output of power via the USB connector, and is provided with The control unit is configured to be arbitrarily switchable from the first state of supplying power from the battery pack to the external device via the USB connector to the second state of receiving power from the external device to the battery pack via the USB connector from the outside.

[0008] Another aspect of the present invention is a system in which an external device is electrically connected to the USB connector of the battery pack or the electric device.

[0009] The electric device of the present invention may be expressed as a "working machine", "power tool", etc., and those so expressed are also effective as aspects of the present invention.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a highly convenient battery pack, an electric device, and a system using USB.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0012] This embodiment relates to an electric device having a battery pack 1 detachable from a device main body 4, a device main body 2 for detachably mounting a battery pack 3, and a system in which the battery pack 1 or the device main body 2 is connected to an external device by a USB cable 9.

[0013] Fig. 1(A) is an external view of a system in which two battery packs 1 mounted on a device main body 4 are electrically connected to each other by a USB cable 9. The circuit block diagram corresponding to this system is Fig. 4. In Fig. 4, the two battery packs 1 are distinguished as battery packs 1A and 1B.

[0014] Fig. 1(B) is an external view of a system in which a battery pack 1 mounted on a device main body 4 and a device main body 2 with a battery pack 3 mounted thereon are electrically connected to each other by a USB cable 9. The circuit block diagram corresponding to this system is Fig. 7.

[0015] FIG. 1(C) is an external view of a system in which two device main bodies 2 each equipped with a battery pack 3 are electrically connected to each other by a USB cable 9. The circuit block diagram corresponding to this system is shown in FIG. 8. In FIG. 8, the two device main bodies 2 are distinguished as device main bodies 2A and 2B.

[0016] FIG. 1(D) is an external view of a system in which a battery pack 1 mounted on a device main body 4 and a battery pack 1 mounted on a connection device 6 are electrically connected to each other by a USB cable 9. Although the illustration of the circuit block diagram corresponding to this system is omitted, the circuit block diagram of a state in which the battery pack 1 and the connection device 6 are combined is shown in FIG. 3(B).

[0017] FIG. 1(E) is an external view of a system in which a battery pack 1 mounted on a device main body 4 and an external device 7 are electrically connected to each other by a USB cable 9. The circuit block diagram corresponding to this system is shown in FIG. 10.

[0018] FIG. 1(F) is an external view of a system in which a battery pack 1 mounted on a connection device 6 and an external device 7 are electrically connected to each other by a USB cable 9. The illustration of the circuit block diagram corresponding to this system is omitted

[0019] FIG. 1(G) is an external view of a system in which a device main body 2 equipped with a battery pack 3 and an external device 7 are electrically connected to each other by a USB cable 9. The circuit block diagram corresponding to this system is shown in FIG. 11.

[0020] In the illustrated example, the device main bodies 2 and 4 are impact drivers, but they may be the main bodies of working machines (power tools) other than impact drivers, or the main bodies of electrical devices other than working machines.

[0021] FIG. 2 is a circuit block diagram of the battery pack 1 according to an embodiment of the present invention. The battery pack 1 includes a first cell unit 11 (first bank), a second cell unit 12 (second bank), a resistor 13, a current detection circuit 14, a bridge circuit 15, a buck-boost circuit 16, a USB port 17, a display unit 18, an MCU 19, and a USB PD controller IC 20 (USB power delivery controller).

[0022] The first cell unit 11 and the second cell unit 12 each include at least one secondary battery cell. The first cell unit 11 and the second cell unit 12 each have a nominal voltage (rated voltage) of, for example, 18V and are equal to each other. The voltage V1 of the positive terminal and the voltage V3 of the negative terminal of the first cell unit 11, and the voltage V2 of the positive terminal and the voltage V4 of the negative terminal of the second cell unit 12 are transmitted to the MCU 19.

[0023] The first cell unit 11 and the second cell unit 12 are in a non-connected state with each other when the battery pack 1 is not attached to a counterpart device such as the device main body 4 or the connected device 6 (when the terminals of the battery pack 1 are in an open state), and are in a connected state with each other when the battery pack 1 is attached to the counterpart device. As will be described later, the first cell unit 11 and the second cell unit 12 may be connected in series or in parallel with each other depending on the terminal structure of the counterpart device to which the battery pack 1 is attached.

[0024] The resistor 13 is provided in the discharge path from the first cell unit 11 and the second cell unit 12 to the USB port 17. The current detection circuit 14 detects the discharge current from the first cell unit 11 and the second cell unit 12 to the USB port 17 (hereinafter referred to as "USB discharge current") based on the voltage of the resistor 13 and transmits it to the MCU 19.

[0025] The bridge circuit 15 includes FETs 21 to 24 that are bridge-connected between the positive terminal of the first cell unit 11 and the VBUS terminal of the USB port 17, and switches whether to connect the positive terminal of the first cell unit 11 and the VBUS terminal of the USB port 17 to either the input side or the output side of the buck-boost circuit 16, respectively. When FETs 21 and 23 are on and FETs 22 and 24 are off, the positive terminal of the first cell unit 11 is connected to the input side of the buck-boost circuit 16, and the VBUS terminal of the USB port 17 is connected to the output side of the buck-boost circuit 16. When FETs 21 and 23 are off and FETs 22 and 24 are on, the positive terminal of the first cell unit 11 is connected to the output side of the buck-boost circuit 16, and the VBUS terminal of the USB port 17 is connected to the input side of the buck-boost circuit 16. In the bridge circuit 15, the FETs 21 to 24 may be switching elements other than FETs, such as IGBTs or relays.

[0026] The buck-boost circuit 16 is a DCDC converter circuit capable of boosting and bucking the input voltage. The USB port 17 is a USB connector connectable to an external device, such as a USB Type-C port, and is compatible with USB PD. The battery pack 1 can be in a first state of supplying power to an external device from the first cell unit 11 and the second cell unit 12 via the USB port 17, and a second state of receiving power (charging the first cell unit 11 and the second cell unit 12) from the external device via the USB port 17. The display unit 18 displays the remaining capacity of the battery pack 1 and the enable / disable of a short-range wireless communication function such as Bluetooth (registered trademark) according to the control of the MCU 19.

[0027] The MCU 19, together with the USB PD controller IC 20, constitutes a control unit that controls the overall operation of the battery pack 1. The MCU 19 and the USB PD controller IC 20 communicate with each other. The MCU 19 and the USB PD controller IC 20 are not limited to being separate from each other as shown in the figure, and may be integrated with each other.

[0028] The MCU 19 monitors the voltage V1 at the positive terminal and the voltage V3 at the negative terminal of the first cell unit 11, as well as the voltage V2 at the positive terminal and the voltage V4 at the negative terminal of the second cell unit 12. The MCU 19 monitors the USB discharge current. The MCU 19 controls the on / off states of FETs 21 to 24. The MCU 19 controls the driving of the buck-boost circuit 16. The MCU 19 has a function as a wireless communication unit and can communicate with a portable device 8 (Fig. 8) such as a smartphone or a tablet terminal by short-range wireless communication such as Bluetooth (registered trademark). Note that a wireless communication unit separate from the MCU 19 may be provided.

[0029] The USB PD controller IC 20 is a controller that controls power reception and supply by USB PD. The USB PD controller IC 20 communicates with an external device connected to the USB port 17, determines the power to be received from the external device at the USB port 17 (hereinafter referred to as "USB planned received power") or the power to be supplied to the external device via the USB port 17 (hereinafter referred to as "USB planned discharge power"), and transmits it to the MCU 19. The MCU 19 controls the buck-boost circuit 16 according to the USB planned received power or the USB planned discharge power.

[0030] Fig. 3(A) is a circuit block diagram of an electric device with the device main body 4 connected to the battery pack 1. When the battery pack 1 is attached to the device main body 4, the terminals of the battery pack 1 and the device main body 4, that is, the battery-side terminals and the device-side terminals, are electrically and mechanically connected to each other.

[0031] The device main body 4 includes a motor 31 as a load unit, an inverter 32, an inverter drive circuit 33, a magnetic sensor 34, a rotor position detection circuit 35, a resistor 36, a current detection circuit 37, a trigger switch 38, a switch detection circuit 39, a display unit 40, an MCU (control unit) 41, and a short bar 42.

[0032] The motor 31 is, for example, a three-phase brushless motor. The inverter 32 includes switching elements such as FETs or IGBTs connected in a three-phase bridge, and converts the DC input from the battery pack 1 into AC and supplies it to the motor 31. The inverter drive circuit 33 outputs drive signals for turning on and off each switching element of the inverter 32. The magnetic sensor 34 is, for example, a Hall IC, and outputs a signal corresponding to the rotational position of the rotor of the motor 31. The rotor rotational position detection circuit 35 detects the rotor rotational position based on the output signal of the magnetic sensor 34 and transmits it to the MCU 41.

[0033] The resistor 36 is provided in the path of the current flowing through the motor 31. The current detection circuit 37 detects the current flowing through the motor 31 based on the voltage of the resistor 36 and transmits it to the MCU 41. The trigger switch 38 is an operation switch for the user to switch between driving and stopping the motor 31, and includes a mechanical switch provided in the path of the current flowing through the motor 31. The switch detection circuit 39 detects the on / off state of the trigger switch 38 and transmits it to the MCU 41. The display unit 40 displays the drive mode and the like of the device main body 4 according to the control of the MCU 41.

[0034] The MCU 41 is a control unit that controls the overall operation of the device main body 4. Based on the current flowing through the motor 31, the rotational position of the rotor of the motor 31, and the operation of the trigger switch 38, the MCU 41 controls the drive of the inverter 32 via the inverter drive circuit 33 to control the drive of the motor 31. The MCU 41 communicates (wired communication) with the MCU 19 of the battery pack 1. The MCU 41 can communicate with the portable device 8 (Fig. 8) via the MCU 19 of the battery pack 1.

[0035] The short bar 42 is a short-circuit member that short-circuits between the positive terminal of the second cell unit 12 and the negative terminal of the first cell unit 11 of the battery pack 1. When the battery pack 1 is attached to the device main body 4, the first cell unit 11 and the second cell unit 12 are connected in series with each other.

[0036] Figure 3(B) is a circuit block diagram of the state where the connection device 6 is connected to the battery pack 1. The connection device 6 is an example of the device body. When the battery pack 1 is attached to the connection device 6, the terminals of the battery pack 1 and the connection device 6, that is, the battery-side terminal and the device-side terminal, are electrically and mechanically connected to each other.

[0037] The connection device 6 has a short bar 45 which is a short-circuit member that short-circuits between the positive terminal of the second cell unit 12 and the negative terminal of the first cell unit 11 of the battery pack 1. When the battery pack 1 is attached to the connection device 6, the first cell unit 11 and the second cell unit 12 are connected in series with each other. As another example, the terminal structure of the connection device 6 may be one that short-circuits the positive terminals and the negative terminals of the first cell unit 11 and the second cell unit 12, respectively. In this case, the first cell unit 11 and the second cell unit 12 are connected in parallel with each other. The connection device 6 has resistors 46 and 47 connected in series between the positive terminal of the first cell unit 11 and the negative terminal of the second cell unit 12, and transmits the voltages of the resistors 46 and 47 to the MCU 19 of the battery pack 1.

[0038] Figure 4 is a circuit block diagram of a system in which the USB ports 17 of the battery packs 1A and 1B (having the same configuration as the battery pack 1) attached to the device body 4 are electrically connected to each other by a USB cable 9. Figure 5 is a circuit block diagram in which the arrows indicating the flow of current when charging the battery pack 1B from the battery pack 1A are added to Figure 4.

[0039] When charging battery pack 1B from battery pack 1A, the MCU 19 of battery pack 1A turns on FETs 21 and 23 and turns off FETs 22 and 24. The MCU 19 of battery pack 1B turns off FETs 21 and 23 and turns on FETs 22 and 24. As shown in Fig. 5, the current flows through the positive terminal of the first cell unit 11, FET 21, the buck-boost circuit 16, FET 23, and the USB port 17 in sequence on the battery pack 1A side, and is supplied to the battery pack 1B side via the USB cable 9. Then, on the battery pack 1B side, the current flows through the USB port 17, FET 24, the buck-boost circuit 16, FET 22, the first cell unit 11, the short bar 42, the second cell unit 12, the buck-boost circuit 16, and the USB port 17 in sequence, and returns to the battery pack 1A side via the USB cable 9. Then, on the battery pack 1A side, the current flows through the USB port 17, the buck-boost circuit 16, the second cell unit 12, the short bar 42, and the first cell unit 11 in sequence.

[0040] On the battery pack 1A side, the voltage between the positive terminal of the first cell unit 11 and the input terminal of the buck-boost circuit 16 is, for example, 36V, and varies in the range of 40V to 28V according to the remaining capacity of battery pack 1A. The output voltage of the buck-boost circuit 16 is determined according to the USB discharge planned power and is, for example, 36V. The output voltage of the buck-boost circuit 16 of battery pack 1A is input to the buck-boost circuit 16 of battery pack 1B via the USB cable 9. On the battery pack 1B side, the buck-boost circuit 16 converts the input voltage into the charging voltage for the first cell unit 11 and the second cell unit 12 and outputs it. The charging voltage is, for example, 36V and is gradually increased according to the progress of charging.

[0041] FIG. 6 is a circuit block diagram of a system in which the USB ports 17 of the battery pack 1A mounted on the device main body 5 and the battery pack 1B mounted on the device main body 4 are electrically connected to each other by a USB cable 9, and is a circuit block diagram showing the arrows of the current flow when charging the battery pack 1B from the battery pack 1A. The device main body 5 is different from the device main body 4 in that it does not have a short bar 42 and has a terminal structure that short-circuits the positive electrodes and the negative electrodes of the first cell unit 11 and the second cell unit 12 of the battery pack 1A, and is the same in other respects. When the battery pack 1A is mounted on the device main body 5, the first cell unit 11 and the second cell unit 12 are connected in parallel to each other. On the battery pack 1A side, the voltage from the positive terminal of the first cell unit 11 to the input terminal of the buck-boost circuit 16 is, for example, 18V, and changes in the range of, for example, 20V to 14V according to the remaining capacity of the battery pack 1A. The output voltage of the buck-boost circuit 16 is determined according to the USB discharge planned power and is, for example, 36V. The voltage after the buck-boost circuit 16 is the same as in the case of FIG. 5.

[0042] FIG. 7 is a circuit block diagram of a system in which the battery pack 1 mounted on the device main body 4 and the device main body 2 equipped with the battery pack 3 are electrically connected to each other by a USB cable 9. In FIG. 7, the motor and the motor peripheral circuit 30 are a block that combines the motor 31, the inverter 32, the inverter drive circuit 33, the magnetic sensor 34, the rotor position detection circuit 35, the resistor 36, and the current detection circuit 37.

[0043] The battery pack 3 corresponds to the battery pack 1 with the USB port 17 and its related configuration removed. The battery pack 3 includes a first cell unit 51 (first bank), a second cell unit 52 (second bank), a display unit 58, and an MCU 59.

[0044] The first cell unit 51 and the second cell unit 52 each include at least one secondary battery cell. The first cell unit 51 and the second cell unit 52 each have a nominal voltage (rated voltage) of, for example, 18V and are equal to each other.

[0045] When the battery pack 3 is not attached to a counterpart device such as the device main body 2 (when the terminals of the battery pack 3 are in an open state), the first cell unit 51 and the second cell unit 52 are in a non-connected state with each other, and when the battery pack 3 is attached to the counterpart device, they are in a connected state with each other. As will be described later, depending on the terminal structure of the counterpart device to which the battery pack 3 is attached, the first cell unit 51 and the second cell unit 52 may be connected in series or in parallel with each other.

[0046] The display unit 58 displays, according to the control of the MCU 59, the remaining capacity of the battery pack 3 and the enable / disable of a short-range wireless communication function such as Bluetooth (registered trademark). The MCU 59 is a control unit that controls the overall operation of the battery pack 3. The MCU 59 communicates (wired communication) with the MCU 79 of the device main body 2. The MCU 59 has a function as a wireless communication unit and can communicate with a portable device 8 (Fig. 8) such as a smartphone or a tablet terminal by short-range wireless communication such as Bluetooth (registered trademark). Note that a wireless communication unit separate from the MCU 59 may be provided.

[0047] The device main body 2 corresponds to the device main body 4 with a USB port 17 and related configurations added thereto. The device main body 2 includes a motor and a motor peripheral circuit 60, a trigger switch 68, a switch detection circuit 69, a short bar (short circuit member) 70, a bridge circuit 75, a boost-buck circuit 76, a USB port 77, a display unit 78, an MCU 79, and a USB PD controller IC 80 (USB power delivery controller).

[0048] The motor and the motor peripheral circuit 60 have the same configuration as the motor and the motor peripheral circuit 30 of the device main body 4. The trigger switch 68 is an operation switch for the user to switch the drive and stop of the motor in the motor and the motor peripheral circuit 60, and includes a mechanical switch provided in the current path flowing through the motor. The switch detection circuit 69 detects the on / off of the trigger switch 68 and transmits it to the MCU 79.

[0049] The short bar 70 is a short - circuit member that short - circuits between the positive - terminal of the second cell unit 52 and the negative - terminal of the first cell unit 51 of the battery pack 3. When the battery pack 3 is mounted on the device main body 2, the first cell unit 51 and the second cell unit 52 are connected in series with each other. Although not shown in the figure, when the battery pack 3 is mounted on the device main body 5 shown in FIG. 6, the first cell unit 51 and the second cell unit 52 are connected in parallel with each other.

[0050] The bridge circuit 75 includes FETs 71 - 74 that are bridge - connected between the positive - terminal of the device main body 2 and the VBUS terminal of the USB port 77, and switches whether to connect the positive - terminal of the device main body 2 (the positive - terminal of the first cell unit 51 of the battery pack 3) and the VBUS terminal of the USB port 77 to either the input - side or the output - side of the buck - boost circuit 76. When FETs 71, 73 are on and FETs 72, 74 are off, the positive - terminal of the device main body 2 is connected to the input - side of the buck - boost circuit 76, and the VBUS terminal of the USB port 77 is connected to the output - side of the buck - boost circuit 76. When FETs 71, 73 are off and FETs 72, 74 are on, the positive - terminal of the device main body 2 is connected to the output - side of the buck - boost circuit 76, and the VBUS terminal of the USB port 77 is connected to the input - side of the buck - boost circuit 76. In the bridge circuit 75, the FETs 71 - 74 may be switching elements other than FETs, such as IGBTs or relays.

[0051] The buck - boost circuit 76 is a DCDC converter circuit capable of boosting and bucking the input voltage. The USB port 77 is a USB connector connectable to an external device, for example, a USB Type - C port, and is compatible with USB PD. The device main body 2 can supply power to an external device via the USB port 77 from the first cell unit 51 and the second cell unit 52 of the battery pack 3 mounted on itself, and can receive power (charge the first cell unit 51 and the second cell unit 52) from the external device via the USB port 77 to the first cell unit 51 and the second cell unit 52. The display unit 78 displays the drive mode etc. of the device main body 2 according to the control of the MCU 79.

[0052] The MCU 79, together with the USB PD controller IC 80, constitutes a control unit that controls the overall operation of the device body 2. The MCU 79 and the USB PD controller IC 80 communicate with each other. The MCU 79 and the USB PD controller IC 80 are not limited to being separate from each other as shown in the figure, and they may be integrated with each other. The MCU 79 controls the on / off of the FETs 71 to 74. The MCU 79 controls the driving of the buck-boost circuit 76. The MCU 79 controls the driving of the motor in the same way as the MCU 41 of the device body 4. The MCU 79 communicates (by wired communication) with the MCU 59 of the battery pack 3. The MCU 79 can communicate with the portable device 8 (Figure 8) via the MCU 59 of the battery pack 3.

[0053] The USB PD controller IC 80 is a controller that controls power reception and supply by USB PD. The USB PD controller IC 80 communicates with an external device connected to the USB port 77, determines the power received from the external device at the USB port 77 or the power supplied to the external device via the USB port 77, and transmits it to the MCU 79. The MCU 79 controls the buck-boost circuit 76 according to the received information from the USB PD controller IC 80.

[0054] Figure 8 is a circuit block diagram of a system in which device bodies 2A and 2B each connected with a battery pack 3 are electrically connected to each other by a USB cable 9. Figure 9 is a circuit block diagram showing the arrows of the current flow when charging the battery pack 3 connected to the device body 2B from the battery pack 3 connected to the device body 2A in Figure 8. Figures 8 and 9 show an example in which the MCU 59 of the battery pack 3 mounted on the device body 2A communicates with a portable device 8 such as a smartphone or a tablet terminal by short-range wireless communication such as Bluetooth (registered trademark). However, the MCU 59 of the battery pack 3 mounted on the device body 2B may communicate with the portable device 8 by short-range wireless communication, and in other circuit block diagrams, the MCU 19 of the battery packs 1, 1A, 1B, the MCU 59 of the battery pack 3, or the MCU 99 of the external device 7 (Figure 11) may communicate with the portable device 8 by short-range wireless communication.

[0055] The mobile device 8 has a management application (hereinafter referred to as "management app") installed therein for managing battery packs, electrical devices, etc. The mobile device 8 includes a display unit 82, an operation unit 83, and an MCU 84. The display unit 82 performs screen display of the management app and the like. The operation unit 83 receives operations by the user on the management app and the like. When the display unit 82 is a touch panel, the function of the operation unit 83 is included in the display unit 82. The MCU 84 executes various functions of the management app and the like.

[0056] When charging the battery pack 3 connected to the device body 2B from the battery pack 3 connected to the device body 2A, the MCU 79 of the device body 2A turns on the FETs 71 and 73 and turns off the FETs 72 and 74. The MCU 79 of the device body 2B turns off the FETs 71 and 73 and turns on the FETs 72 and 74. As shown in FIG. 9, the current flows in the order of the positive terminal of the first cell unit 51, the FET 71, the buck-boost circuit 76, the FET 73, and the USB port 77 on the device body 2A side, and is supplied to the device body 2B side via the USB cable 9. Thereafter, the current flows in the order of the USB port 77, the FET 74, the buck-boost circuit 76, the FET 72, the first cell unit 51, the short bar 70, the second cell unit 52, the buck-boost circuit 76, and the USB port 77 on the device body 2B side, and returns to the device body 2A side via the USB cable 9. Thereafter, the current flows in the order of the USB port 77, the buck-boost circuit 76, the second cell unit 52, the short bar 70, and the first cell unit 51 on the device body 2A side.

[0057] On the device body 2A side, the voltage between the positive terminal of the first cell unit 51 and the input terminal of the buck-boost circuit 76 is, for example, 36V, and changes in the range of, for example, 40V to 28V according to the remaining capacity of the battery pack 3. The output voltage of the buck-boost circuit 76 is, for example, 36V. The output voltage of the buck-boost circuit 76 of the device body 2A is input to the buck-boost circuit 76 of the device body 2B via the USB cable 9. On the device body 2B side, the buck-boost circuit 76 converts the input voltage into a charging voltage for the first cell unit 51 and the second cell unit 52 and outputs it. The charging voltage is, for example, 36V, and is sequentially increased according to the progress of charging.

[0058] FIG. 10 is a circuit block diagram of a system in which a battery pack 1 mounted on a device main body 4 and an external device 7 are electrically connected to each other by a USB cable 9. FIG. 11 is a circuit block diagram of a system in which a device main body 2 equipped with a battery pack 3 and an external device 7 are electrically connected to each other by a USB cable 9.

[0059] The external device 7 is an electric device incorporating a cell unit 90 including at least one secondary battery cell. Although not shown, the external device 7 may be a power tool or a working machine having a motor as a load section. The external device 7 includes a bridge circuit 95, a step-up / down circuit 96, a USB port 97, a display section 98, an MCU 99, and a USB PD controller IC 100 (USB power delivery controller).

[0060] The bridge circuit 95 includes FETs 91 to 94 bridged between the positive terminal of the cell unit 90 and the VBUS terminal of the USB port 97, and switches whether to connect the positive terminal of the cell unit 90 and the VBUS terminal of the USB port 97 to either the input side or the output side of the step-up / down circuit 96, respectively. When FETs 91 and 93 are on and FETs 92 and 94 are off, the positive terminal of the cell unit 90 is connected to the input side of the step-up / down circuit 96, and the VBUS terminal of the USB port 97 is connected to the output side of the step-up / down circuit 96. When FETs 91 and 93 are off and FETs 92 and 94 are on, the positive terminal of the cell unit 90 is connected to the output side of the step-up / down circuit 96, and the VBUS terminal of the USB port 97 is connected to the input side of the step-up / down circuit 96. In the bridge circuit 95, the FETs 91 to 94 may be switching elements other than FETs, such as IGBTs or relays.

[0061] The buck-boost circuit 96 is a DC-DC converter circuit capable of boosting and bucking the input voltage. The USB port 97 is a USB connector connectable to an external device, for example, a USB Type-C port, and is compatible with USB PD. The external device 7 can supply power from the cell unit 90 incorporated therein to other devices (the battery pack 1 and the device main body 2) via the USB port 97, and can receive power (charge the cell unit 90) from other devices to the cell unit 90 via the USB port 97. The display unit 98 displays the state of the external device 7 and the like according to the control of the MCU 99.

[0062] The MCU 99, together with the USB PD controller IC 100, constitutes a control unit that controls the overall operation of the external device 7. The MCU 99 and the USB PD controller IC 100 communicate with each other. The MCU 99 and the USB PD controller IC 100 are not limited to being separate from each other as shown in the figure, and may be integrated with each other. The MCU 99 controls the on / off of the FETs 91 to 94. The MCU 99 controls the driving of the buck-boost circuit 96. The MCU 99 has a function as a wireless communication unit and can communicate with a portable device 8 (Fig. 8) such as a smartphone or a tablet terminal by short-range wireless communication such as Bluetooth (registered trademark). Note that a wireless communication unit separate from the MCU 99 may be provided.

[0063] The USB PD controller IC 100 is a controller that controls power reception and supply by USB PD. The USB PD controller IC 100 communicates with other devices connected to the USB port 97, determines the power to be received from other devices at the USB port 97 or the power to be supplied to other devices via the USB port 97, and transmits it to the MCU 99. The MCU 99 controls the buck-boost circuit 96 according to the received information from the USB PD controller IC 100.

[0064] Fig. 12(A) is a control flowchart of the source / sink setting of the battery pack 1.

[0065] When an external device is connected to the USB port 17 (S1), the MCU 19 acquires the battery information of the external device through communication between the USB ports (S3). The battery information includes the battery type such as the nominal voltage (rated voltage), and the current battery voltage. When the battery pack 1 is designated as either a source or a sink by the management app of the portable device 8 in S5 (YES in S5), the MCU 19 sets the battery pack 1 as either a source or a sink according to the designation of the management app (S7), and transmits the set content to the management app (S23).

[0066] When the battery pack 1 is not designated as either a source or a sink by the management app of the portable device 8 in S5 (NO in S5), and the battery type of the battery pack 1 is the same as that of the external device (YES in S9), if the battery voltage of the battery pack 1 is higher than the battery voltage of the external device in S11 (YES in S11), the MCU 19 sets the battery pack 1 as a source (S13), and transmits the set content to the management app (S23). If the battery voltage of the battery pack 1 is not higher than the battery voltage of the external device in S11 (NO in S11), the MCU 19 sets the battery pack 1 as a sink (S15), and transmits the set content to the management app (S23).

[0067] When the battery type of the battery pack 1 is not the same as that of the external device in S9 (NO in S9), if the nominal voltage of the battery pack 1 is higher than the nominal voltage of the battery of the external device in S17 (YES in S17), the MCU 19 sets the battery pack 1 as a sink (S19), and transmits the set content to the management app (S23). If the nominal voltage of the battery pack 1 is not higher than the nominal voltage of the battery of the external device in S17 (NO in S17), the MCU 19 sets the battery pack 1 as a source (S21), and transmits the set content to the management app (S23).

[0068] The function of setting the source / sink according to the flowchart shown in Fig. 12(A) is the same in the MCU 79 of the device main body 2 and the MCU 99 of the external device 7. In the case of the device main body 2, the battery pack attached to the device main body 2 is the target for source / sink setting. In the case of the external device 7, the cell unit 90 built into the external device 7 is the target for source / sink setting.

[0069] Fig. 12(B) is a sequence diagram showing the flow of source / sink setting using the management app of the mobile device 8. The operation target device (the target for setting), which is the target of the management app's operation, communicates with the partner device connected to its own USB port via the USB port to obtain the battery information of the partner device (S31). The operation target device transmits the connection information via USB (information such as the product type, model number, and battery information of the partner device) to the management app by short-range wireless communication (S32). The user operates the management app and transmits a wireless signal for specifying the operation target device as either a source or a sink to the operation target device (S34). The operation target device sets itself as one of the source and the sink according to the specification of the management app and sets the partner device to be the other of the source and the sink by communication between the USB ports (S35), and transmits the set source / sink information to the management app (S36). The management app displays the set source / sink information on the display unit 82 to notify the user (S37).

[0070] Fig. 13 is a control flowchart of the battery pack 1, which is a control flowchart regarding power reception and supply via the USB port 17.

[0071] In the startup state (S41), when the voltage V2 of the positive terminal of the second cell unit 12 is not equal to the voltage V3 of the negative terminal of the first cell unit 11 (NO in S43), and the voltage V1 of the positive terminal of the first cell unit 11 is not equal to the voltage V2 of the positive terminal of the second cell unit 12 or the voltage V3 of the negative terminal of the first cell unit 11 is not equal to the voltage V4 of the negative terminal of the second cell unit 12 (NO in S45), the input and output of power via the USB port 17 are prohibited, and it waits while monitoring the voltages V1 to V4. That is, when the battery pack 1 is not attached to the counterpart device, the input and output of power via the USB port 17 are prohibited.

[0072] When the voltage V2 of the positive terminal of the second cell unit 12 is equal to the voltage V3 of the negative terminal of the first cell unit 11 (YES in S43), or when the voltage V1 of the positive terminal of the first cell unit 11 is equal to the voltage V2 of the positive terminal of the second cell unit 12 and the voltage V3 of the negative terminal of the first cell unit 11 is equal to the voltage V4 of the negative terminal of the second cell unit 12 (YES in S45), at least one of the input and output of power via the USB port 17 is permitted, and it communicates with the MCU of the device (e.g., the device main body 4 or the device main body 5, hereinafter referred to as the "attached device") to which the battery pack 1 is attached (S47). Although not shown in the figure, in the case of YES in S43 or YES in S45, the MCU 19 permits the output of power via the USB port 17 if the battery voltage of the battery pack 1 is not below the reference value for over-discharge protection, and permits the input of power via the USB port 17 if the battery voltage of the battery pack 1 is not above the reference value corresponding to full charge.

[0073] When the trigger switch of the wearable device is on (YES in S49), the MCU 19 returns to S47. When the trigger switch of the wearable device is not on (NO in S49), the MCU 19 communicates with the USB PD controller IC 20 (S51). When no external device is connected to the USB port 17 (NO in S53), the MCU 19 returns to S47. When an external device is connected to the USB port 17 (YES in S53), the MCU 19 executes processing related to the source / sink setting of the battery pack 1 and the external device according to the flowchart shown in FIG. 12(A) (S55).

[0074] The MCU 19 executes boost / buck discrimination processing in the buck-boost circuit 16 according to the USB power reception planned power or the USB power discharge planned power (S57), switches the connection by the bridge circuit 15 (S59), and outputs a drive signal for the buck-boost circuit 16 (S61). When the battery pack 1 is discharging (source) and the battery voltage of the battery pack 1 is not below the over-discharge protection reference value (NO in S63), or when the battery pack 1 is charging (sink) and the battery voltage of the battery pack 1 is not above the reference value corresponding to full charge (NO in S63), the MCU 19 communicates with the MCU of the wearable device (S65). If the trigger switch of the wearable device is not on (NO in S67), the MCU 19 returns to S63 to continue discharging or charging. When the trigger switch of the wearable device is on (YES in S67), the MCU 19 turns off all of the FETs 21 to 24 of the bridge circuit 15 (S69), stops the drive signal of the buck-boost circuit 16 (S71), and returns to S47.

[0075] In S63, when the battery pack 1 is discharging (source) and the battery voltage of the battery pack 1 is below the over-discharge protection reference value (YES in S63), or when the battery pack 1 is charging (sink) and the battery voltage of the battery pack 1 is above the reference value corresponding to full charge (YES in S63), the MCU 19 stops discharging or charging (S69, S71) and returns to S47. Although not shown, when both conditions of S43 and S45 are not satisfied during the execution of discharging or charging via the USB port 17, the MCU 19 stops discharging or charging (S69, S71) and returns to S43.

[0076] FIG. 14 and FIG. 15 are diagrams showing examples of screen displays related to source / sink settings in the management application of the mobile device 8.

[0077] During the execution of the management application, the display unit 82 of the mobile device 8 includes an operation target device display unit 85, a USB-connected device display unit 86, a remaining amount display unit 87, a source / sink display unit 88, and a source / sink switching button 89.

[0078] FIG. 14(A) shows a state in which the management application is connected to an operation target device (here, an electrical device with a battery pack attached) by short-range wireless communication. FIG. 14(B) shows a state in which a partner device (here, an electrical device with a battery pack attached) is connected to the USB port of the operation target device (the connection of the partner device is detected) from the state of FIG. 14(A).

[0079] FIGS. 14(C) and (D) show a state in which power reception and supply are being performed between the operation target device and the partner device after the processing related to the source / sink setting is completed from the state of FIG. 14(B). FIG. 14(C) corresponds to the case where the operation target device is the source (discharge side), and FIG. 14(D) corresponds to the case where the operation target device is the sink (power reception side).

[0080] FIGS. 15(A) and (B) are obtained by changing the partner device to a battery pack in FIGS. 14(C) and (D), respectively. FIGS. 15(C) and (D) are obtained by changing the operation target device to a battery pack in FIGS. 15(A) and (B), respectively.

[0081] The present embodiment has the following operational effects.

[0082] (1) In the battery pack 1, when the battery pack 1 is connected to the device main body (device main body 4 or connected device 6), the MCU 19 permits power input or output via the USB port 17 (charging or discharging of the first cell unit 11 and the second cell unit 12), and when the battery pack 1 is not connected to the device main body, prohibits power input or output via the USB port 17. For this reason, it is suppressed that power input or output via the USB port 17 is performed while the first cell unit 11 and the second cell unit 12 remain unconnected to each other, and an increase in the imbalance between the first cell unit 11 and the second cell unit 12 is suppressed. Thereby, a highly convenient battery pack 1 using USB is realized.

[0083] (2) The MCU 19 determines whether the battery pack 1 is connected to the device main body based on at least any one of the voltage V1 of the positive terminal and the voltage V3 of the negative terminal of the first cell unit 11, and the voltage V2 of the positive terminal and the voltage V4 of the negative terminal of the second cell unit 12. For this reason, communication with the device main body is unnecessary, quick determination is possible, and determination is possible even if the device main body has no communication function. Thus, a highly convenient battery pack 1 using USB is realized.

[0084] (3) When discharging from the battery pack 1 to the device main body or charging the battery pack 1 from the device main body (for example, a charger), the MCU 19 prohibits power input or output via the USB port 17. For this reason, it is suppressed that the discharge current from the first cell unit 11 and the second cell unit 12 becomes excessive, or the charging current from the first cell unit 11 and the second cell unit 12 becomes excessive, or that the control becomes complicated to prevent them.

[0085] (4) The MCU 19 can be arbitrarily switched externally by the management app of the portable device 8 as to whether the battery pack 1 acts as a source or a sink in power reception and supply via the USB port 17. That is, the MCU 19 can be arbitrarily switched externally between a first state in which power is supplied from the first cell unit 11 and the second cell unit 12 to an external device via the USB port 17, and a second state in which power is received (the first cell unit 11 and the second cell unit 12 are charged) from the external device to the first cell unit 11 and the second cell unit 12 via the USB port 17. Therefore, the user can flexibly set whether the battery pack 1 acts as a source or a sink according to the usage status of the battery pack 1. Also, since the switching between the first state and the second state is performed by a wireless signal from the portable device 8, a wired connection to the portable device 8 is not required. Further, the battery pack 1 can be charged by the received power via the USB port 17 while being attached to the device body 4, and there is no need to remove the battery pack 1 from the device body 4. Thus, a highly convenient battery pack 1 using USB is realized.

[0086] (5) The MCU 19 can transmit to the portable device 8 whether the battery pack 1 is acting as a source or a sink in power reception and supply via the USB port 17. Therefore, the user can visually confirm the current source / sink setting status, for example, as shown in FIGS. 14(C), (D) or FIGS. 15(A)-(D), by the management app of the portable device 8. Thus, a highly convenient battery pack 1 using USB is realized.

[0087] (6) When there is no source / sink designation by the management app of the portable device 8, and when the nominal voltages of the batteries of the battery pack 1 and the partner device connected to the USB port 17 are the same, the MCU 19 sets the battery pack 1 as a source when the remaining capacity (battery voltage) of the battery pack 1 is greater (higher) than the remaining capacity (battery voltage) of the battery of the partner device, and sets the battery pack 1 as a sink otherwise. Thereby, when there is no designation by the management app, the battery with the larger remaining capacity can automatically charge the battery with the smaller remaining capacity, which is highly convenient.

[0088] (7) When there is no source / sink specified by the management app of the mobile device 8, if the nominal voltages of the batteries of the battery pack 1 and the device on the other side connected to the USB port 17 are not the same, when the nominal voltage of the battery pack 1 is higher than the nominal voltage of the battery of the device on the other side, the battery pack 1 is set as a sink, and when it is not, the battery pack 1 is set as a source. Thereby, when there is no specification by the management app, the battery with a lower nominal voltage can automatically charge the battery with a higher nominal voltage, which is highly convenient.

[0089] (8) In the device main body 2, the MCU 79 can be arbitrarily switched externally by the management app of the mobile device 8 as to whether the battery pack 3 attached to the device main body 2 becomes a source or a sink in power supply and reception via the USB port 77. That is, the MCU 79 can be arbitrarily switched externally between a first state in which power is supplied from the first cell unit 51 and the second cell unit 52 of the battery pack 3 to an external device via the USB port 77, and a second state in which power is received (the first cell unit 51 and the second cell unit 52 are charged) from the external device via the USB port 77 to the first cell unit 51 and the second cell unit 52. Therefore, the user can flexibly set whether the battery pack 3 becomes a source or a sink according to the usage status of the battery pack 3. Also, since the switching between the first state and the second state is performed by a wireless signal from the mobile device 8, a wired connection to the mobile device 8 is not required. Further, the battery pack 3 can be charged by the received power via the USB port 77 while being attached to the device main body 2, and there is no need to remove the battery pack 3 from the device main body 2. Thus, a highly convenient device main body 2 using USB is realized.

[0090] (9) The MCU 79 can transmit to the mobile device 8 whether the battery pack 3 attached to the device main body 2 is a source or a sink in power supply and reception via the USB port 77. Therefore, the user can visually confirm the current source / sink setting status, for example, as shown in FIGS. 14(C), (D) or FIGS. 15(A) to (D), by the management app of the mobile device 8. Thus, a highly convenient device main body 2 using USB is realized.

[0091] (10) When there is no source / sink designation by the management application of the mobile device 8, if the nominal voltages of the battery pack 3 attached to the device main body 2 and the battery of the counterpart device connected to the USB port 77 are the same, and the remaining capacity (battery voltage) of the battery pack 3 is greater (higher) than the remaining capacity (battery voltage) of the battery of the counterpart device, the battery pack 3 is used as a source; otherwise, the battery pack 3 is used as a sink. Thereby, when there is no designation by the management application, the battery with the smaller remaining capacity can be automatically charged from the battery with the larger remaining capacity, which is highly convenient.

[0092] (11) When there is no source / sink designation by the management application of the mobile device 8, if the nominal voltages of the battery pack 3 and the battery of the counterpart device connected to the USB port 77 are not the same, and the nominal voltage of the battery pack 3 is higher than the nominal voltage of the battery of the counterpart device, the battery pack 3 is used as a sink; otherwise, the battery pack 3 is used as a source. Thereby, when there is no designation by the management application, the battery with the higher nominal voltage can be automatically charged from the battery with the lower nominal voltage, which is highly convenient.

[0093] As described above, the present invention has been described by taking the embodiments as examples, but the present invention is not limited to the embodiments. Various modifications are possible within the scope described in the claims for each matter specifically described in the embodiments.

[0094] In the battery pack 1, the buck-boost circuit 16 may be a bidirectional DCDC converter circuit, and the bridge circuit 15 may be omitted. The same applies to the device main body 2 and the external device 7.

[0095] The battery pack 1 is provided with a connection part for connecting the positive terminals and the negative terminals of the first cell unit 11 and the second cell unit 12 to each other via switches such as relays. When starting power reception and supply via the USB port 17, the MCU 19 turns on the switch, so that the voltage V1 of the positive terminal of the first cell unit 11 is equal to the voltage V2 of the positive terminal of the second cell unit 12 and the voltage V3 of the negative terminal of the first cell unit 11 is equal to the voltage V4 of the negative terminal of the second cell unit 12, and it may be possible to proceed to YES in S45 of FIG. 13 without connecting to the device body.

[0096] The battery pack 1 is provided with a connection part for connecting the negative terminal of the first cell unit 11 and the positive terminal of the second cell unit 12 to each other via a switch such as a relay. When starting power reception and supply via the USB port 17, the MCU 19 turns on the switch, so that the voltage V2 of the positive terminal of the second cell unit 12 is equal to the voltage V3 of the negative terminal of the first cell unit 11, and it may be possible to proceed to YES in S43 of FIG. 13 without connecting to the device body.

[0097] In the battery pack 1, the MCU 19 may be configured to prohibit discharging to the device body on which the battery pack 1 is mounted or charging from the device body when power is being input or output via the USB port 17. In this case, when detecting the turning on of the trigger switch at S67 in FIG. 13, the user may be notified that the mounted device cannot be driven by blinking the display unit or the like, and the input or output of power via the USB port 17 may be continued. Also, in FIGS. 14 and 15, it may be possible to display the nominal voltage of the battery pack, information on the counterpart device connected to the device to be operated, etc., and the display content may be arbitrarily set.

[0098] The number of cell units (banks) exemplified as specific numerical values in the embodiment, the voltage values of each part, etc. do not limit the scope of the invention in any way and can be arbitrarily changed according to the required specifications.

Explanation of Signs

[0099] 1… Battery pack, 2… Equipment main body, 3… Battery pack, 4… Equipment main body, 5… Equipment main body, 6… Connected equipment, 7… External equipment, 8… Portable equipment, 9… USB cable, 11… First cell unit (first bank), 12… Second cell unit (second bank), 13… Resistor, 14… Current detection circuit, 15… Bridge circuit, 16… Buck-boost circuit (DCDC converter), 17… USB port, 18… Display unit, 19… MCU, 20… USB PD controller IC, 21~24… FET (switching element), 30… Motor and motor peripheral circuit, 31… Motor, 32… Inverter, 33… Inverter drive circuit, 34… Magnetic sensor, 35… Rotor position detection circuit, 36… Resistor, 37… Current detection circuit, 38… Trigger switch, 39… Switch detection circuit, 40… Display unit, 41… MCU (control unit), 42… Short bar (short circuit member), 45… Short bar (short circuit member), 51… First cell unit (first bank), 52… Second cell unit (second bank), 58… Display unit, 59… MCU, 60… Motor and motor peripheral circuit, 68… Trigger switch, 69… Switch detection circuit, 70… Short bar (short circuit member), 71~74… FET (switching element), 75… Bridge circuit, 76… Buck-boost circuit (DCDC converter), 77… USB port, 78… Display unit, 79… MCU (control unit), 80… USB PD controller IC, 82… Display unit, 83… Operation unit, 84… MCU, 85… Operation target device display unit, 86… USB connected device display unit, 87… Remaining amount display unit, 88… Source / sink display unit, 89… Source / sink changeover button, 90… Cell unit, 91~94… FET (switching element), 95… Bridge circuit, 96… Buck-boost circuit (DCDC converter), 97… USB port, 98… Display unit, 99… MCU (control unit), 100… USB PD controller IC.

Claims

1. A battery pack detachable from a machine body, comprising a battery cell, a USB connector capable of connecting to an external device, and a control unit for controlling input or output of power via the USB connector, wherein the control unit is configured to be externally and arbitrarily switchable between a first state of supplying power from the battery cell to the external device via the USB connector and a second state of receiving power from the external device to the battery cell via the USB connector. A battery pack characterized by the above.

2. The battery pack according to Claim 1, comprising a wireless communication unit capable of receiving a wireless signal from the outside, wherein the control unit switches between the first state and the second state according to the wireless signal. A battery pack characterized by the above.

3. The battery pack according to Claim 2, wherein the current state of either the first state or the second state can be transmitted from the wireless communication unit to the outside. A battery pack characterized by the above.

4. The battery pack according to any one of Claims 1 to 3, wherein when an external device that is a battery pack different from the battery pack or incorporates or mounts a battery pack different from the battery pack is connected to the USB connector and no designation of the first state or the second state is made from the outside, and when the nominal voltages of the battery pack and the different battery pack are the same, the battery pack enters the first state when the remaining capacity of the battery pack is greater than the remaining capacity of the different battery pack, and enters the second state when the remaining capacity of the battery pack is smaller than the remaining capacity of the different battery pack. A battery pack characterized by the above.

5. The battery pack according to any one of Claims 1 to 3, wherein when an external device that is a battery pack different from the battery pack or incorporates or mounts a battery pack different from the battery pack is connected to the USB connector and no designation of the first state or the second state is made from the outside, and when the nominal voltage of the battery pack is lower than the nominal voltage of the different battery pack, the battery pack enters the first state, and when the nominal voltage of the battery pack is higher than the nominal voltage of the different battery pack, the battery pack enters the second state. A battery pack characterized by the above.

6. An electric device comprising the battery pack according to any one of Claims 1 to 3, and a machine body on which the battery pack is detachably mounted, wherein the machine body has a load unit driven by power supplied from the battery pack. An electrical device characterized by the following.

7. An electrical device comprising a device body with a detachable battery pack or a built-in battery pack, a USB connector capable of connecting an external device, a control unit for controlling the input or output of power via the USB connector, and comprising: the control unit is configured to be externally and arbitrarily switchable between a first state in which power is supplied from the battery pack to the external device via the USB connector and a second state in which power is received from the external device to the battery pack via the USB connector, An electrical device characterized by the following.

8. The electrical device according to claim 7, comprising a wireless communication unit capable of receiving a wireless signal from the outside, the control unit switches between the first state and the second state according to the wireless signal, An electrical device characterized by the following.

9. The electrical device according to claim 8, the current state of either the first state or the second state can be transmitted from the wireless communication unit to the outside, An electrical device characterized by the following.

10. The electrical device according to any one of claims 7 to 9, when an external device with a battery pack different from the battery pack or a built-in or attached battery pack different from the battery pack is connected to the USB connector and there is no designation of the first state or the second state from the outside, and when the nominal voltages of the battery pack and the other battery pack are the same, if the remaining capacity of the battery pack is greater than the remaining capacity of the other battery pack, it is in the first state, and if the remaining capacity of the battery pack is less than the remaining capacity of the other battery pack, it is configured to be in the second state, An electrical device characterized by the following.

11. The electrical device according to any one of claims 7 to 9, when an external device with a battery pack different from the battery pack or a built-in or attached battery pack different from the battery pack is connected to the USB connector and there is no designation of the first state or the second state from the outside, and when the nominal voltage of the battery pack is lower than the nominal voltage of the other battery pack, it is in the first state, and when the nominal voltage of the battery pack is higher than the nominal voltage of the other battery pack, it is configured to be in the second state, An electrical device characterized by the following.

12. The electrical device according to any one of claims 7 to 9, comprising the battery pack detachably attached to the device body, The machine body includes the USB connector, the control unit, and a load unit driven by power supplied from the battery pack. An electrical device characterized by the above. **Claim 13** A system in which an external device is electrically connected to the USB connector of the battery pack according to Claim 1 or the electrical device according to Claim 7.

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