Battery device and balancing method

Abstract

A plurality of positive pole switches are respectively connected between positive terminals of the plurality of battery packs and a first node, and a plurality of negative pole switches are respectively connected between negative terminals of the plurality of battery packs and a second node. A first switch is connected between the first node and a positive pole link terminal, and a second switch is connected between the second node and a negative pole link terminal. A third switch and a resistor are connected in series between the first node and the second node. A processor controls the positive pole switch, the negative pole switch, the first switch, the second switch, and the third switch to perform balancing among at least some of the plurality of battery packs.

Description

[Technical field]

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0168956 dated November 30, 2021, and all contents disclosed in the documents of the Korean Patent Application are incorporated herein by reference.

[0002] The disclosure relates to a battery device and a balancing method. [Background technology]

[0003] Electric vehicles are vehicles that are powered by driving a motor using a battery as a power source, and research into them is being actively conducted as an alternative that can solve the pollution and energy problems of internal combustion engine vehicles. In addition, rechargeable batteries are used in various external devices other than electric vehicles.

[0004] Recently, as batteries having high output and large charging capacity are required, battery devices in which a plurality of battery packs are connected in parallel are being used. When a voltage difference occurs between battery cells in a battery pack, the voltage difference can be reduced through cell balancing, but balancing to reduce the voltage difference between battery packs is not used. In addition, since the balancing operation takes a long time, it is necessary to solve the problem of not being able to supply power from the battery packs while balancing between the battery packs is being performed. Summary of the Invention [Problem to be solved by the invention]

[0005] One embodiment may provide a battery device and a balancing method capable of balancing between battery packs. [Means for solving the problem]

[0006] According to one embodiment, a battery device may be provided that includes a positive link terminal and a negative link terminal connected to an external device, a plurality of battery packs including a first battery pack and a second battery pack, a plurality of positive switches respectively connected between the positive terminals of the plurality of battery packs and a first node, a plurality of negative switches respectively connected between the negative terminals of the plurality of battery packs and a second node, a first switch connected between the first node and the positive link terminal, a second switch connected between the second node and the negative link terminal, a third switch and a resistor connected in series between the first node and the second node, and a processor. The processor may control the plurality of positive switches, the plurality of negative switches, the first switch, the second switch, and the third switch to perform balancing among at least some of the plurality of battery packs.

[0007] In one embodiment, when a first predetermined condition is satisfied, the processor may open the first switch and the second switch, close the third switch, and close a negative switch connected to negative terminals of the first battery pack and the second battery pack among the plurality of negative switches, and a positive switch connected to positive terminals of the first battery pack and the second battery pack among the plurality of positive switches, to perform balancing between the first battery pack and the second battery pack.

[0008] In one embodiment, the first predetermined condition may include a condition that a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

[0009] In one embodiment, the first battery pack may be a battery pack having a highest voltage among the plurality of battery packs, and the second battery pack may be a battery pack having a lowest voltage among the plurality of battery packs.

[0010] In one embodiment, the first predetermined condition may include a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required.

[0011] In one embodiment, the processor may terminate the balancing if a second predetermined condition is satisfied.

[0012] In an embodiment, the second predetermined condition may include a condition that a voltage difference between the first battery pack and the second battery pack is less than a predetermined voltage.

[0013] In one embodiment, the second predetermined condition may include a condition in which the battery device is in a mode that requires the battery device to supply power to the external device.

[0014] According to another embodiment, a battery device may be provided that includes a positive link terminal and a negative link terminal connected to an external device, a plurality of battery packs including a first battery pack and a second battery pack, a plurality of positive switches respectively connected between the positive terminals of the plurality of battery packs and a first node, a plurality of negative switches respectively connected between the negative terminals of the plurality of battery packs and a second node, a balancing circuit, and a processor. The balancing circuit may be connected to the first node, the second node, the positive link terminal, and the negative link terminal. The processor may control the balancing circuit to perform balancing between at least some of the battery packs of the plurality of battery packs.

[0015] In one embodiment, when a first predetermined condition is satisfied, the processor controls the balancing circuit to cut off a connection between the first node and the positive link terminal and a connection between the second node and the negative link terminal, and closes a negative switch among the plurality of negative switches connected to the negative terminals of the first battery pack and the second battery pack, and a positive switch among the plurality of positive switches connected to the positive terminals of the first battery pack and the second battery pack, thereby performing balancing between the first battery pack and the second battery pack.

[0016] In an embodiment, the balancing circuit may further include a resistor coupled between the first node and the second node when performing the balancing.

[0017] In one embodiment, the first predetermined condition may include a condition that a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

[0018] In an embodiment, the first predetermined condition may further include a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required.

[0019] In one embodiment, the processor may terminate the balancing if a second predetermined condition is satisfied.

[0020] In an embodiment, the second predetermined condition may include a condition that a voltage difference between the first battery pack and the second battery pack is less than a predetermined voltage.

[0021] In one embodiment, the second predetermined condition may include a condition in which the battery device is in a mode that requires the battery device to supply power to the external device.

[0022] According to another embodiment, a balancing method for a battery device including a positive link terminal and a negative link terminal connected to an external device, a plurality of battery packs including a first battery pack and a second battery pack, a plurality of positive switches respectively connected between the positive terminals of the plurality of battery packs and a first node, and a plurality of negative switches respectively connected between the negative terminals of the plurality of battery packs and a second node may be provided. The balancing method may include, when a predetermined condition is satisfied, cutting off a connection between the positive switch and the positive link terminal and a connection between the negative switch and the negative link terminal, connecting a resistor in parallel to the first battery pack and the second battery pack, and closing a negative switch connected to the negative terminals of the first battery pack and the second battery pack among the plurality of negative switches and a positive switch connected to the positive terminals of the first battery pack and the second battery pack among the plurality of positive switches to supply a current from the first battery pack to the second battery pack and the resistor.

[0023] In one embodiment, the predetermined condition may include a condition that a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

[0024] In one embodiment, the predetermined condition may further include a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required. Effect of the Invention

[0025] According to one embodiment, a higher voltage battery pack can charge a lower voltage battery pack, thereby allowing balancing between the battery packs. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 illustrates an example of a battery device according to one embodiment. [Diagram 2] FIG. 13 is a diagram showing an example of a battery device according to another embodiment. [Diagram 3] 3 is a diagram showing an example of switching timing of the battery pack shown in FIG. 2. [Figure 4] 1 is a flowchart illustrating an example of a battery pack balancing method of a battery device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not necessary for the explanation are omitted, and similar parts are designated by similar reference numerals throughout the specification.

[0028] When a component is said to be "connected" to another component, it should be understood that the component may be directly connected to the other component, but there may also be other components in between. Conversely, when a component is said to be "directly connected" to another component, it should be understood that there are no other components in between.

[0029] In the following description, expressions described as singular can be interpreted as singular or plural, unless expressly stated otherwise, such as "one" or "single".

[0030] In the flowcharts described with reference to the figures, the order of operations may be changed, various operations may be combined or certain operations may be separated, and certain operations may not be performed.

[0031] FIG. 1 is a diagram illustrating an example of a battery device according to an embodiment.

[0032] Referring to FIG. 1, the battery device 100 has a structure that can be electrically connected to an external device 10 through a positive link terminal DC(+) and a negative link terminal DC(-). In one embodiment, the battery device 100 can be connected to the external device 10 through the positive link terminal DC(+) and the negative link terminal DC(-). When the external device 10 is a load, the battery device 100 can operate as a power source that supplies power to the load and can be discharged. When the external device 10 is a charger, the battery device 100 can be charged by receiving external power through the charger 10. In one embodiment, the external device 10 operating as a load can be, for example, an electronic device, a vehicle, or an energy storage system (ESS), and the vehicle can be, for example, an electric vehicle, a hybrid vehicle, or a smart mobility vehicle.

[0033] The battery device 100 includes a plurality of battery packs 110, a plurality of switching circuits 120, a balancing circuit 130, and a processor 140.

[0034] The battery packs 110 are connected in parallel to link terminals DC(+) and DC(-) through the switching circuits 120. The switching circuits 120 correspond to the battery packs 110, respectively. That is, each switching circuit 120 is connected to a corresponding battery pack 110 among the battery packs 110. Each battery pack 110 includes a plurality of battery cells (not shown) and has a positive terminal PV(+) and a negative terminal PV(-). In one embodiment, the battery cells may be rechargeable secondary batteries. In one embodiment, a predetermined number of battery cells are connected in series in the battery pack 110 to configure a battery module and supply a desired power. In another embodiment, a predetermined number of battery modules are connected in series or in parallel in the battery pack 110 to supply a desired power.

[0035] Each switching circuit 120 includes a positive switch 121 and a negative switch 122. The positive switch 121 is connected between a positive terminal PV(+) of the corresponding battery pack 110 and a node N1. The node N1 can be connected to a positive link terminal DC(+) of the battery device 100 through a balancing circuit 130. The negative switch 122 is connected between a negative terminal PV(-) of the corresponding battery pack 110 and a node N2. The node N2 can be connected to a negative link terminal DC(-) of the battery device 100 through the balancing circuit 130. The switches 121 and 122 can be controlled by the processor 140 to control the electrical connection between the battery pack 110 and the external device 10. In one embodiment, the switches 121 and 122 can each include a contactor including a relay. In one embodiment, the switches 121 and 122 can each include an electrical switch such as a transistor. In one embodiment, the switching circuit 120 may further include a driving circuit (not shown) that drives the switches 121 and 122, respectively, in response to a control signal from the processor 140. When the positive switch 121 and the negative switch 122 are closed, power can be supplied from the battery pack 110 to the external device 10, or power can be supplied from the external device 10 to the battery pack 110. Closing the switch may be expressed as turning the switch on, and opening the switch may be expressed as turning the switch off.

[0036] The balancing circuit 130 is connected between the nodes N1, N2 and the link terminals DC(+), DC(-). During balancing, the balancing circuit 130 cuts off the connection between the node N1 and the positive link terminal DC(+) and the connection between the node N2 and the negative link terminal DC(-), and performs balancing between the selected battery packs 110. The balancing circuit 130 can perform balancing such that the battery pack 110 with a lower voltage is charged by the battery pack 110 with a higher voltage. When balancing is not performed, the balancing circuit 130 connects the node N1 to the positive link terminal DC(+) and the node N2 to the negative link terminal DC(-). Thus, when the positive switch 121 and the negative switch 122 are closed, power can be supplied from the battery pack 110 to the external device 10, or power can be supplied from the external device 10 to the battery pack 110.

[0037] The processor 140 controls the multiple switching circuits 120 and the balancing circuit 130. In one embodiment, the processor 140 may include, for example, a microcontroller unit (MCU). The processor 140 performs balancing among at least some of the multiple battery packs 110 when a predetermined condition (or a "first predetermined condition") is satisfied. During balancing, the processor 140 may control the balancing circuit 130 to close the positive switch 121 and the negative switch 122 of the battery pack 110 selected for balancing among the multiple battery packs 110, and to cut off the connection between the node N1 and the positive link terminal DC(+) and the connection between the node N2 and the negative link terminal DC(-). When balancing is not performed, the processor 140 may control the balancing circuit 130 to connect the node N1 to the positive link terminal DC(+) and connect the node N2 to the negative link terminal DC(-).

[0038] In one embodiment, the predetermined condition may include a condition in which a voltage difference between the battery packs to be balanced exceeds a critical voltage. In one embodiment, the processor 140 may select the battery pack 110 with the highest voltage and the battery pack 110 with the lowest voltage among the plurality of battery packs 110 as the battery packs 110 for balancing. In one embodiment, when the processor 140 selects the battery pack 110 with the highest voltage, the processor 140 may select one or more battery packs 110 with the highest voltage among the plurality of battery packs 110. When the processor 140 selects the battery pack 110 with the lowest voltage, the processor 140 may select one or more battery packs 110 with the lowest voltage among the plurality of battery packs 110. When the processor 140 selects the battery pack 110 with the lowest voltage, the processor 140 may perform balancing between the battery pack 110 with the highest voltage and the battery pack 110 with the lowest voltage when the difference between the highest voltage and the lowest voltage exceeds a critical voltage.

[0039] In one embodiment, the predetermined condition may include a condition that the battery device 100 is in a balancing mode. In one embodiment, the balancing circuit 130 may perform balancing under the control of the processor 140 in the balancing mode. In one embodiment, the balancing circuit 130 may not perform balancing under the control of the processor 140 in the power supply mode. In one embodiment, the balancing mode is a mode in which power supply from the battery device 100 to the external device 10 is not required, and may include a sleep period of the battery device 100. The power supply mode may be a mode in which the battery device 100 operates as a power supply that supplies power to the external device 10. In one embodiment, the sleep period may include a pre-sleep mode immediately before the battery management system including the processor 140 enters a sleep mode. In one embodiment, when the external device 10 is a vehicle, the balancing mode may include a parking mode in which the vehicle is parked, and the power supply mode may include a driving mode in which the vehicle is driving.

[0040] In one embodiment, the battery device 100 may further include a monitoring circuit that monitors the voltage of the battery pack 110. The processor 140 may receive the monitoring result from the monitoring circuit and detect the voltage of the battery pack 110.

[0041] According to the embodiment described above, since the battery pack 110 with a higher voltage can charge the battery pack 110 with a lower voltage, balancing can be performed between the battery packs 110. In one embodiment, balancing can be performed stably by performing balancing in a balancing mode including a parking mode.

[0042] Fig. 2 is a diagram showing an example of a battery device according to another embodiment, and Fig. 3 is a diagram showing an example of switching timing of the battery device shown in Fig. 2. For convenience of explanation, two battery packs selected for balancing are shown in Fig. 2. For convenience of explanation, the enable level of the control signal is shown as a high level, and the disable level of the control signal is shown as a low level in Fig. 3.

[0043] Referring to FIG. 2, the battery device 200 includes a plurality of battery packs 210a, 210b, a plurality of switching circuits 220a, 220b, a balancing circuit 230, and a processor 240.

[0044] 1, the switching circuit 220a includes a positive switch 221a and a negative switch 222a, and the switching circuit 220b includes a positive switch 221b and a negative switch 222b. The positive switch 221a is connected between the positive terminal PV(+) of the battery pack 210a and a node N1, and the negative switch 222a is connected between the negative terminal PV(-) of the battery pack 210a and a node N2. The positive switch 221b is connected between the positive terminal PV(+) of the battery pack 210b and the node N1, and the negative switch 222b is connected between the negative terminal PV(-) of the battery pack 210b and a node N2.

[0045] The balancing circuit 230 includes a balancing switch 231, a balancing resistor 232, and coupling switches 233 and 234. The balancing switch 231 and the balancing resistor 232 are connected in series between a node N1 and a node N2. In one embodiment, the coupling switch 233 is connected between the node N1 and the positive link terminal DC(+) and is used to couple the positive switches 221a and 221b to the positive link terminal DC(+). The coupling switch 234 is connected between the node N2 and the negative link terminal DC(-) and is used to couple the negative switches 222a and 222b to the negative link terminal DC(-).

[0046] In one embodiment, the switches 221a, 221b, 222a, 222b, 231, 233, and 234 may each include a contactor including a relay. In one embodiment, the switches 221a, 221b, 222a, 222b, 231, 233, and 234 may each include an electrical switch, such as a transistor. In one embodiment, the balancing resistor 232 may include a cement resistor.

[0047] 2 and 3, in the balancing mode, the processor 240 transmits a control signal C4 having a disable level to the connection switches 233 and 234, and the connection switches 233 and 234 are opened in response to the control signal C4 having the disable level. When the connection switches 233 and 234 are opened, the connection between the node N1 and the link terminal DC(+) and the connection between the node N2 and the link terminal DC(-) are interrupted.

[0048] In addition, the processor 240 transmits a control signal C3 having an enable level to the balancing switch 231, and the balancing switch 231 is closed in response to the control signal C3 having the enable level. When the balancing switch 231 is closed, the node N1 and the node N2 are connected through the balancing resistor 232. That is, the balancing resistor 232 is connected in parallel to the battery packs 210a and 210b.

[0049] In addition, the processor 240 transmits control signals C1, C2 having an enable level to the switching circuits 220a, 220b of the battery packs 210a, 210b selected for balancing, the negative switches 222a, 222b of the battery packs 210a, 210b are closed in response to the control signal C2 having the enable level, and the positive switches 221a, 221b of the battery packs 210a, 210b are closed in response to the control signal C1 having the enable level. The processor 240 transmits control signals having a disable level to the switching circuits of the remaining battery packs, and the positive and negative switches of the battery packs not selected for balancing are kept open in response to the control signal having the disable level.

[0050] As a result, a current flows from a battery pack with a higher voltage (e.g., 210a) to the balancing resistor 232 and a battery pack with a lower voltage (e.g., 210b). In this case, a current flows from the battery pack 210a to the battery pack 210b and the balancing resistor 232 according to a ratio between the internal resistance of the battery pack 210b and the balancing resistor 232, and the battery pack 210b can be charged by the current supplied to the battery pack 210b. Therefore, the voltage of the battery pack 210b increases, and balancing can be performed between the battery packs 210a and 210b. In this case, the balancing resistor 232 can limit the current supplied to the battery pack 210b to prevent an excessive current from being supplied to the battery pack 210b.

[0051] To end the balancing mode, the processor 240 transmits a control signal C3 having a disable level to the balancing switch 231 and transmits a control signal C4 having an enable level to the coupling switches 233 and 234.

[0052] The balancing switch 231 is opened in response to the control signal C3 having a disable level, and the connection switches 233 and 234 are closed in response to the control signal C4 having an enable level. As a result, the balancing between the battery packs 210a and 210b is completed, and the nodes N1 and N2 can be connected to the link terminals DC(+) and DC(-), respectively. In addition, the processor 240 transmits the control signals C1 and C2 having a disable level to the switching circuits 220a and 220b of the battery packs 210a and 210b, and the positive switches 221a and 221b and the negative switches 222a and 222b of the battery packs 210a and 210b are opened in response to the control signals C1 and C2 having a disable level. In one embodiment, the processor 240 may output the control signals C1 and C2 having a disable level before outputting the control signal C3 having a disable level.

[0053] In one embodiment, when the difference between the voltage of battery pack 210a and the voltage of battery pack 210b becomes less than a predetermined voltage, processor 240 may terminate the balancing mode. In one embodiment, when battery packs 210a, 210b supply power to external device 20, processor 240 may terminate the balancing mode.

[0054] FIG. 4 is a flowchart illustrating an example of a battery pack balancing method for a battery device according to an embodiment.

[0055] 4, when the battery device satisfies a predetermined condition (or a "first predetermined condition") (S410, S420), the processor 240 performs pack balancing between at least some of the battery packs (S430-S490). In one embodiment, when the battery device enters a period in which balancing is possible (e.g., a balancing mode) (S410), the processor (e.g., 240 in FIG. 2) of the battery device detects the voltages of the battery packs included in the battery device and compares the difference between the highest and lowest voltages of the voltages of the battery packs with a critical voltage (S420). When the difference between the highest and lowest voltages exceeds the critical voltage (S420), the processor 240 may perform pack balancing between the battery pack having the highest voltage (e.g., 210a in FIG. 1) and the battery pack having the lowest voltage (e.g., 210b in FIG. 1) (S430-S490). That is, the first predetermined condition may include a condition in which the battery device is in a period in which balancing is possible (e.g., a condition in which the battery device is in a mode in which power supply from the battery device to an external device is not required). Alternatively, the first predetermined condition may include a condition in which a difference between a maximum voltage and a minimum voltage exceeds a critical voltage. In one embodiment, the processor 240 may perform pack balancing between one or more battery packs having a maximum voltage and one or more battery packs having a minimum voltage.

[0056] The processor 240 opens a connection switch (e.g., 233 in FIG. 2) for connecting the positive switch (e.g., 221a, 221b in FIG. 2) to the positive link terminal (e.g., DC(+) in FIG. 2) and a connection switch (e.g., 234 in FIG. 2) for connecting the negative switch (e.g., 222a, 222b in FIG. 2) to the negative link terminal (e.g., DC(-) in FIG. 2) (S430). The processor 240 opens the connection switches 233, 234 to cut off the connection between the positive switches 221a, 221b and the positive link terminal DC(+) and the connection between the negative switches 222a, 222b and the negative link terminal DC(-) (S430).

[0057] The processor 240 closes a balancing switch (e.g., 231 in FIG. 2) (S440). The processor 240 closes the balancing switch 231 to connect a balancing resistor (e.g., 232 in FIG. 2) in parallel to the battery packs 210a and 210b.

[0058] The processor 240 also closes the negative switch 222a and the positive switch 221a of the battery pack 210a having the highest voltage and the negative switch 222b and the positive switch 221b of the battery pack 210b having the lowest voltage (S440).The processor 240 also keeps the negative and positive switches of the remaining battery packs open, except for the battery packs 210a and 210b having the highest and lowest voltages among the plurality of battery packs (S450).

[0059] As a result, a current flows from the battery pack 210a having the highest voltage to the battery pack 210b having the lowest voltage and the balancing resistor 232, so that the battery pack 210b having the lowest voltage is charged (S470).

[0060] If a predetermined condition (or a "second predetermined condition") is satisfied (S480), the processor 240 terminates the balancing (S490). In one embodiment, the processor 240 may monitor the difference between the voltage of the battery pack 210a and the voltage of the battery pack 210b as the battery pack 210b having the lowest voltage is charged (S480). If the difference between the voltage of the battery pack 210a and the voltage of the battery pack 210b becomes smaller than a predetermined voltage (S480), the processor 240 terminates the pack balancing (S490). The predetermined voltage is a voltage lower than a critical voltage. That is, the predetermined condition may include a condition in which the difference between the voltage of the battery pack 210a and the voltage of the battery pack 210b becomes smaller than a predetermined voltage. In one embodiment, even if the condition in which the difference between the voltage of the battery pack 210a and the voltage of the battery pack 210b is smaller than the predetermined voltage is not satisfied, the processor 240 may terminate the pack balancing if the battery device is switched to a power supply mode (S490). When it is necessary to supply power from the battery device to the external device, the processor 240 can terminate pack balancing and supply power to the external device. That is, the predetermined condition can include a condition in which the battery device is in a mode in which it is necessary to supply power from the battery device to the external device.

[0061] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. A positive link terminal and a negative link terminal connected to an external device; a plurality of battery packs including a first battery pack and a second battery pack; a plurality of positive pole switches respectively connected between positive pole terminals of the plurality of battery packs and a first node; a plurality of negative pole switches respectively connected between negative pole terminals of the plurality of battery packs and a second node; a first switch connected between the first node and the positive link terminal; a second switch connected between the second node and the negative link terminal; a third switch and a resistor connected in series between the first node and the second node; a processor that controls the plurality of positive pole switches, the plurality of negative pole switches, the first switch, the second switch, and the third switch to perform balancing among at least some of the plurality of battery packs; A battery device including:

2. If a first predetermined condition is satisfied, the processor: opening the first switch and the second switch; closing the third switch; closing a negative switch connected to the negative terminals of the first battery pack and the second battery pack among the plurality of negative switches and a positive switch connected to the positive terminals of the first battery pack and the second battery pack among the plurality of positive switches; The battery device according to claim 1 , wherein balancing is performed between the first battery pack and the second battery pack.

3. The battery device according to claim 2 , wherein the first predetermined condition includes a condition in which a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

4. the first battery pack is a battery pack having a highest voltage among the plurality of battery packs; The battery device according to claim 3 , wherein the second battery pack is a battery pack having a lowest voltage among the plurality of battery packs.

5. 5. The battery device according to claim 4, wherein the first predetermined condition includes a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required.

6. The battery device according to claim 2 , wherein the processor terminates the balancing if a second predetermined condition is satisfied.

7. The battery device according to claim 6 , wherein the second predetermined condition includes a condition that a voltage difference between the first battery pack and the second battery pack is smaller than a predetermined voltage.

8. 7. The battery device according to claim 6, wherein the second predetermined condition includes a condition in which the battery device is in a mode requiring power supply from the battery device to the external device.

9. A positive link terminal and a negative link terminal connected to an external device; a plurality of battery packs including a first battery pack and a second battery pack; a plurality of positive pole switches respectively connected between positive pole terminals of the plurality of battery packs and a first node; a plurality of negative pole switches respectively connected between negative pole terminals of the plurality of battery packs and a second node; a balancing circuit connected to the first node, the second node, the positive link terminal, and the negative link terminal; a processor that controls the balancing circuit to perform balancing among at least some of the battery packs of the plurality of battery packs; A battery device including:

10. If a first predetermined condition is satisfied, the processor: controlling the balancing circuit to cut off a connection between the first node and the positive link terminal and a connection between the second node and the negative link terminal; closing a negative switch connected to the negative terminals of the first battery pack and the second battery pack among the plurality of negative switches and a positive switch connected to the positive terminals of the first battery pack and the second battery pack among the plurality of positive switches; The battery device according to claim 9 , wherein balancing is performed between the first battery pack and the second battery pack.

11. The battery device of claim 10 , wherein the balancing circuit further comprises a resistor coupled between the first node and the second node when performing the balancing.

12. The battery device according to claim 10 or 11, wherein the first predetermined condition includes a condition that a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

13. The battery device according to claim 12 , wherein the first predetermined condition further includes a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required.

14. The battery device according to claim 10 or 11, wherein the processor terminates the balancing if a second predetermined condition is satisfied.

15. The battery device according to claim 14 , wherein the second predetermined condition includes a condition that a voltage difference between the first battery pack and the second battery pack is smaller than a predetermined voltage.

16. The battery device according to claim 14 , wherein the second predetermined condition includes a condition in which the battery device is in a mode requiring power supply from the battery device to the external device.

17. A method for balancing a battery device, the method comprising: a positive link terminal and a negative link terminal connected to an external device; a plurality of battery packs including a first battery pack and a second battery pack; a plurality of positive switches respectively connected between positive terminals of the plurality of battery packs and a first node; and a plurality of negative switches respectively connected between negative terminals of the plurality of battery packs and a second node, If a predetermined condition is satisfied, disconnecting a connection between the positive switch and the positive link terminal and a connection between the negative switch and the negative link terminal; connecting a resistor in parallel to the first battery pack and the second battery pack; closing a negative switch connected to the negative terminals of the first battery pack and the second battery pack among the plurality of negative switches and a positive switch connected to the positive terminals of the first battery pack and the second battery pack among the plurality of positive switches to supply a current from the first battery pack to the second battery pack and the resistor; A balancing method comprising:

18. The balancing method of claim 17, wherein the predetermined condition includes a condition in which a voltage difference between the first battery pack and the second battery pack exceeds a critical voltage.

19. The balancing method according to claim 18 , wherein the predetermined conditions further include a condition in which the battery device is in a mode in which power supply from the battery device to the external device is not required.

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