JP2006190520A - Battery pack and cover for connecting battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack capable of easily increasing and decreasing battery capacity without damaging the efficiency of usage and productivity, and to provide a cover for connecting a battery pack. <P>SOLUTION: The battery pack 1 is constituted by housing a cell 11 and a circuit board 16 in an outer packaging case 10, and has electrodes 12, 13 of the cell 11 and battery terminals 17, 18 electrically connected to the electrodes 12, 13. The battery pack 1 is equipped with connectors 19, 20 connectable from the outside of the outer packaging case 10 and electrically connected to the battery terminal 17, and connectors 21, 22 connectable from the outside of the outer packaging case 10 and electrically connected to the battery terminal 18. At least two battery packs 1 can electrically be connected in parallel through the connectors 19, 20 and the connectors 21, 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack and a battery pack connection cover, and more particularly to a battery pack and a battery pack connection cover that can efficiently use a plurality of cells.

  Battery packs are used as power sources for portable electronic devices and the like. A battery pack usually has a configuration in which cells are housed in an outer case together with a circuit board on which a protection circuit and the like are formed. With reference to FIG. 10, the structure of a conventional one-cell battery pack will be described. 10A is a top view of the circuit board 116 in the outer case of the battery pack, FIG. 10B is a left side view of the circuit board 116, and FIG. 10C is a right side view of the circuit board 116. FIG. 10D is a front view showing the periphery of the circuit board 116 in the outer case of the battery pack.

  The cell 111 is a cell (unit cell) such as a lithium ion battery. The electrodes 112 and 113 of the cell 111 are electrically connected to the circuit board 116 via tabs 114 and 115, respectively. For example, the electrodes 112 and 113 and the tabs 114 and 115 and the tabs 114 and 115 and the circuit board 116 are connected by soldering. An electric circuit such as a protection circuit is formed on the circuit board 116. Further, the circuit board 116 is provided with battery terminals 117 and 118 that can be electrically connected to the outside through an exterior case (not shown). The tabs 114 and 115 are electrically connected to the battery terminals 117 and 118 via the protection circuit of the circuit board 116, respectively.

  Next, a circuit configuration of a conventional one-cell battery pack will be described with reference to FIG. The circuit of the battery pack 101 includes a cell 111, battery terminals 117 and 118, a control IC (Integrated Circuit) 119 that forms a protection circuit, and a switch circuit 120.

  The positive side of the cell 111 is connected to the battery terminal 117, and the negative side of the cell 111 is connected to the battery terminal 118 via the switch circuit 120.

  The control IC 119 controls the switch circuit 120 in order to prevent overdischarge, overcharge, overcurrent, etc. of the cell 111. The switch circuit 120 cuts off the charge / discharge current based on the control of the control IC 119. The switch circuit 120 includes a charge control switch and a discharge control switch made of, for example, an FET (Field Effect Transistor).

  The control IC 119 measures the voltage of the cell 111, and when the voltage becomes equal to or higher than a predetermined value, the control IC 119 controls the charge control switch of the switch circuit 120 to cut off the charging current and becomes a voltage lower than the predetermined value. In addition, the discharge current is cut off by controlling the discharge control switch.

  Thereby, when the battery terminals 117 and 118 are attached to the charging device and the load device, the battery pack 101 is connected between the charging device and the load device and the cell 111 when the voltage of the cell 111 is within a predetermined range. The charging / discharging current can be input / output.

  The battery pack may include a plurality of cells. With reference to FIG. 12, a circuit configuration of a two-cell battery pack connected in parallel will be described. The battery pack 102 mainly includes cells 111a and 111b, battery terminals 117 and 118, a control IC 119, and a switch circuit 120.

  Both the cells 111a and 111b are cells such as lithium ion batteries. The cells 111 a and 111 b are electrically connected in parallel, the positive electrode side is connected to the battery terminal 117, and the negative electrode side is connected to the battery terminal 118 via the switch circuit 120. The circuit configuration of the battery pack 101 is the same as that described above except that the cell 111 shown in FIG. 11 is configured by cells 111a and 111b electrically connected in parallel.

  Thus, the battery capacity of a battery pack can be increased by setting it as the structure by which the some cell was electrically connected in parallel.

  Patent Document 1 below can be stored in a space occupied by a plurality of smaller battery (battery) packs, and has a terminal at the same position as one battery pack in the smaller battery pack, There is described a battery pack in which a plurality of battery packs having different capacities can be installed together in an electronic device by providing a hole at a position corresponding to a terminal of another battery pack.

Japanese Patent Laid-Open No. 11-288699

  However, the conventional battery pack described above has the following problems. When a plurality of cells are electrically connected in parallel to increase the battery capacity of the battery pack, the battery pack producer produces a battery pack in which the cells are electrically connected in parallel inside the outer case, It was necessary to supply to consumers. The customer had to own a plurality of battery packs with different battery capacities, and had to use them properly according to the application. For this reason, there are battery packs that are not used due to proper use.

  Although the battery pack described in Patent Document 1 described above can be used in combination with battery packs having different capacities, the producer needs to produce a plurality of types of battery packs having different capacities for each type. There was a problem that production efficiency was not good.

  Accordingly, an object of the present invention is to provide a battery pack and a battery pack connection cover that can easily increase or decrease the battery capacity without impairing the efficiency of use and productivity.

  In order to solve the above-described problem, a first embodiment of the present invention includes a cell, a circuit board, and an outer case that houses the cell and the circuit board, and is electrically connected to the positive electrode and the negative electrode of the cell, respectively. The battery pack is provided with at least a positive electrode terminal and a negative electrode terminal that are connectable from the outside of the outer case, and are electrically connected to the positive electrode terminal and connected to the positive electrode side in parallel. A negative electrode side parallel connection connector electrically connected to the negative electrode terminal, and at least two battery packs are electrically connected via the positive electrode side parallel connection connector and the negative electrode side parallel connection connector, respectively. The battery pack can be connected in parallel.

  According to a second aspect of the present invention, there is provided a positive electrode terminal and a negative electrode terminal each having a cell, a circuit board, and an outer case for housing the cell and the circuit board, and electrically connected to the positive electrode and the negative electrode of the cell, respectively. Is provided at least, is connectable from the outside of the outer case, is connected to the positive side parallel connection connector electrically connected to the positive terminal, and is connectable from the outer side of the outer case, and is electrically connected to the negative terminal. A battery pack connection cover that is detachable from at least two battery packs each having a negative electrode side parallel connection connector, and electrically connects each of the positive electrode side parallel connection connectors of a plurality of battery packs. And a connection plug for electrically connecting each of the negative electrode side parallel connection connectors of the plurality of battery packs, and the positive terminal and the negative electrode of the plurality of battery packs. Among children, a battery pack connection cover, wherein at least one of the positive and negative terminals is an external electrically connectable structure.

  In this invention, since at least two battery packs can be electrically connected in parallel via the positive electrode side parallel connection connector and the negative electrode side parallel connection connector, the battery capacity can be increased. Since the battery pack is already in a product state, the user can increase the battery capacity according to the application. Moreover, since the protection circuit acts on the cells of the individual battery packs, the safety of the product is improved. When the battery pack connection cover electrically connects the positive electrode side parallel connection connectors of the plurality of battery packs and electrically connects the negative electrode side parallel connection connectors of the plurality of battery packs respectively. The increase in capacity by the combination corresponding to the battery pack connection cover can be easily achieved.

  As a result, the user can easily increase or decrease the battery capacity simply by possessing one type of battery pack, and can properly use it according to the application. The producer only has to produce and supply one type of battery pack, which facilitates production, inventory and shipping management, and improves production efficiency.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the structure of a battery pack according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 shows an example of the structure of a battery pack 1 according to an embodiment of the present invention. 1A is a top view of the battery pack 1, FIG. 1B is a left side view of the battery pack 1, FIG. 1C is a right side view of the battery pack 1, and FIG. 1D is a line shown in FIG. 1A. It is sectional drawing between AA '.

  FIG. 2 is a view for explaining the structure inside the outer case 10 of the battery pack 1. 2A is a top view of the circuit board 16, FIG. 2B is a left side view of the circuit board 16, and FIG. 2C is a right side view of the circuit board 16. FIG. 2D is a front view of the battery pack 1 excluding the outer case 10.

  The battery pack 1 is configured such that the cells 11 and the circuit board 16 are housed in an outer case 10. The outer case 10 is made of, for example, an insulating resin material. The outer case 10 has a substantially square shape, and has openings for battery terminals 17 and 18 and openings for connectors 19, 20, 21, and 22.

  The cell 11 is a cell (unit cell) such as a lithium ion battery. The positive and negative electrodes 12 and 13 of the cell 11 are electrically connected to the electric circuit of the circuit board 16 via the tabs 14 and 15, respectively. For example, the electrodes 12 and 13 and the tabs 14 and 15 and the tabs 14 and 15 and the circuit board 16 are connected by soldering.

  The circuit board 16 is disposed on the upper part of the battery pack 1 so as to face the upper surface of the outer case 10. An electric circuit such as a protection circuit is formed on the circuit board 16. Battery terminals 17 and 18 and connectors 19, 20, 21, and 22 are provided on the surface of the circuit board 16 that faces the upper surface of the outer case 10. The tabs 14 and 15 are electrically connected to the battery terminals 17 and 18 through the protection circuit of the circuit board 16, respectively. Further, the positive side connector 19, 20 for parallel connection is electrically connected to the battery terminal 17 by the wiring pattern of the circuit board 16, and the negative side connector 21, 22 is connected to the battery terminal 18. And are electrically connected.

  The battery terminals 17 and 18 are configured to be electrically connected to the outside of the battery pack 1. The battery terminals 17 and 18 are configured such that their outer surfaces are substantially the same as the outer surface of the outer case 10 or slightly protrude from the outer surface of the outer case 10 as shown.

  The battery terminals 17 and 18 may be constituted by terminals made of copper foil or the like provided on the circuit board 16, or may be constituted by terminals of components arranged on the circuit board 16.

  Further, in the example shown in the figure, when the battery pack 1 is overlapped in the short side direction (thickness direction) shown in FIG. The battery terminal 18 is provided so as to be located on the right side, and the battery terminal 18 is provided so as to be located substantially in the center of the upper surface of the battery pack 1. You may arrange | position in other positions, such as arrange | positioning or arrange | positioning symmetrically on either side.

  The connectors 19, 20, 21, and 22 are for electrically connecting a plurality of battery packs 1 in parallel by a connection cover that will be described later. The connectors 19, 20, 21, and 22 are arranged so that the fitting portions are exposed through the connector openings provided in the outer case 10 so that the connectors 19, 20, 21, and 22 can be connected from the outside of the outer case 10. In the example shown in the figure, the connector 19 and the connector 20 are disposed symmetrically about the line AA ′ that is the center line in the thickness direction of the battery pack 1. Further, the connector 21 and the connector 22 are arranged symmetrically with respect to the line AA ′.

  In order to facilitate electrical connection to the battery terminals 17 and 18, the connectors 19 and 20 are arranged in the vicinity of the battery terminal 17 so as to sandwich the battery terminal 17, and the connectors 21 and 22 are It arrange | positions in the vicinity of the battery terminal 18 so that the battery terminal 18 may be pinched | interposed. In this way, by arranging the connectors 19 and 20 and the connectors 21 and 22 on both sides of the battery terminals 17 and 18, respectively, different battery packs 1 can be used regardless of whether the other battery packs 1 are stacked in the thickness direction. The connector 19 and the connector 20 and the connector 21 and the connector 22 can be connected in the same way, and the order of stacking does not have to be taken into consideration. The connectors 19, 20, 21, and 22 are arranged at positions where the connectors 19 and 20 of the different battery packs 1 and the connectors 21 and 22 are electrically connected to each other by connection covers described later. If it is, it will not specifically limit, You may arrange | position in another position.

  As the connectors 19, 20, 21, and 22, for example, a connector 30 shown in FIG. 3 can be used. 3A is a front view of the connector 30, FIG. 3B is a top view of the connector 30, and FIG. 3C is a right side view of the connector 30.

  The connector 30 electrically connects the conductor inserted in the fitting portion and the electric circuit of the circuit board 16. The main body portion 31 is made of, for example, a metal such as nickel, and is configured such that the fitting portion has elasticity. The insertion port 32 is configured to be bent inward, and when the conductor is inserted from the insertion port 32, the contact portion 33 sandwiches the conductor, and the conductor and the main body 31. Are configured to be electrically connected reliably. A notch 34 is provided at the center of the main body 31.

  In addition, metal lead terminals 35 and 36 are provided on the bottom of the main body 31. For example, the lead terminals 35 and 36 are inserted into through holes provided in the circuit board 16, fixed to the circuit board 16 by soldering or the like, and electrically connected to the wiring pattern of the circuit board 16.

  The connectors 19, 20, 21, and 22 are not limited to those shown in FIG. 3, and have a configuration that electrically connects the conductor inserted in the fitting portion and the electric circuit of the circuit board 16. If it is a thing, the connector of various other shapes can be used. For example, the connector 30 is an insertion mounting type component, but may be a surface mounting type component. Although the main body 31 is made of metal, it is made of a resin material having moderate elasticity and rigidity such as polycarbonate, and electrically connects the conductor and the lead terminals 35 and 36 when the conductor is inserted. The structure which arranged the conductive contact part to connect may be sufficient.

  Further, the connectors 19, 20, 21, and 22 may not have the same shape. For example, the connector 19 and the connector 20, and the connector 21 and the connector 22 may have the same shape. Furthermore, the connectors 19, 20, 21, and 22 can be configured only by terminals made of copper foil or the like provided on the circuit board without using components such as the connector 30.

  The battery pack connection cover according to an embodiment is used by being attached to two or more battery packs 1. When the battery pack 1 is attached to a plurality of battery packs 1, each battery pack 1 is electrically connected. It has the structure connected in parallel. Note that the number of battery packs 1 to be used can be appropriately changed by the user as long as it is within the number supported by the battery pack connection covers.

  FIG. 4 is an example of a circuit configuration when the battery pack connection cover is applied. The circuit of the battery pack 1 includes a cell 11, battery terminals 17 and 18, a control IC (Integrated Circuit) 39 and a switch circuit 40 that form a protection circuit.

  The positive electrode side of the cell 11 is connected to the positive battery terminal 17, and the negative electrode side of the cell 11 is connected to the negative battery terminal 18 via the switch circuit 40.

  The control IC 39 controls the switch circuit 40 in order to prevent overdischarge, overcharge, overcurrent, etc. of the cell 11. The switch circuit 40 cuts off the charge / discharge current based on the control of the control IC 39. The switch circuit 40 includes a charge control switch and a discharge control switch made of, for example, an FET (Field Effect Transistor).

  When the control IC 39 measures the voltage of the cell 11 and becomes a voltage equal to or higher than a predetermined value, the control IC 39 controls the charge control switch of the switch circuit 40 to cut off the charging current and becomes a voltage lower than the predetermined value. In addition, the discharge current is cut off by controlling the discharge control switch.

  When the battery pack connection cover is used, the first battery pack 1 and the second battery pack 1 are electrically connected in parallel between the protection circuits and the battery terminals. Thus, when at least one of the battery terminal 17 and the battery terminal 18 is attached to the charging device and the load device, the voltage of each cell 11 is within a predetermined range, and the charging device, the load device and each cell 11 The charging / discharging current can be input / output between. In consideration of the balance during charging / discharging, the cells 11 of the first battery pack 1 and the cells 11 of the second battery pack 1 preferably have the same battery characteristics such as battery capacity.

  Thus, battery capacity can be increased by setting it as the structure by which each cell 11 is electrically connected in parallel. In addition, since a protection circuit is provided for each cell 11, safety can be improved.

  Next, the structure of the battery pack connection cover will be described with reference to FIGS. 5 and 6. FIG. 5 shows the battery pack connection covers attached to the two battery packs 1, and FIG. 6 shows the state of the battery pack 1 in the battery pack connection cover. 5A and 6A are top views, FIGS. 5B and 6B are left side views, and FIGS. 5C and 6C are right side views.

  The connection cover 41 is configured such that the two battery packs 1 can be freely attached and detached. As shown in FIG. 6, the connection cover 41 includes a connector 20 of the first battery pack 1 (upper battery pack 1 in the figure) and a connector of the second battery pack 1 (lower battery pack 1 in the figure). 19 and the terminal surfaces of the first and second battery packs 1 overlapped so that the connector 22 of the first battery pack 1 and the connector 21 of the second battery pack 1 are adjacent to each other. It is attached to. In the example shown in the figure, the first and second battery packs 1 are stacked so that there is no gap in order to make the shape after the connection cover 41 is mounted smaller. If the battery packs 1 can be stably fixed, a gap may be formed.

  The connection cover 41 integrates the first and second battery packs 1 and electrically connects the first battery pack 1 and the second battery pack 1 in parallel. An example of the configuration of the connection cover 41 will be described with reference to FIGS. 7 and 8. 7A is a top view of the connection cover 41, FIG. 7B is a rear view of the connection cover 41, and FIG. 7C is a right side view of the connection cover 41. FIG. 8 is a cross-sectional view taken along line BB ′ shown in FIG. 7A.

  The connection cover 41 is made of a resin material such as polycarbonate, for example, and has a structure that is attached to the upper part on the terminal surface side of the first and second battery packs 1 overlapped as shown in FIG. is doing. Openings 42 and 43 are respectively provided in the portions where the battery terminals 17 and 18 of the second battery pack 1 are located, and even when the connection cover 41 is attached, the second battery pack is provided. One battery terminal 17, 18 is configured to be electrically connectable to the outside. That is, when the battery terminals 17 and 18 of the second battery pack 1 are both electrically connected to a load device and a charging device (not shown), charging and discharging of each cell 11 of the first and second battery packs 1 is performed. Done.

  In addition, without providing the openings 42 and 43 in the connection cover 41, by electrically connecting the metal terminal member separately provided in the connection cover 41 and the battery terminals 17 and 18, The battery terminals 17 and 18 may be configured to be electrically connected to the outside. The openings 42 and 43 are not limited to being provided on the second battery pack 1 side, but are provided on the first battery pack 1 side or both the first battery pack 1 and the second battery pack 1. It may be provided.

  Connection plugs 44 and 45 made of a metal such as copper or nickel are insert-molded on the inner surface of the connection cover 41. The connection plug 44 electrically connects the connector 20 of the first battery pack 1 and the connector 19 of the second battery pack 1, and the connection plug 45 is connected to the connector 22 of the first battery pack 1. The connector 21 of the second battery pack 1 is electrically connected.

  As shown in FIG. 8, the connection plug 45 has a U-shaped cross section including an insertion pin 46, an insertion pin 47, and a connection portion 48 that electrically connects the insertion pin 46 and the insertion pin 47. Have. When the connection cover 41 is attached to the first battery pack 1 and the second battery pack 1, the insertion pin 46 of the connection plug 45 is fitted into the connector 22 of the first battery pack 1 as shown in FIG. 9. The insertion pin 47 is inserted into the connector 21 of the second battery pack 1. As a result, the connector 22 of the first battery pack 1 and the connector 21 of the second battery pack 1 are electrically connected. When the connection portion 48 protrudes from the inner surface of the connection cover 41, the battery terminals 17 and 18 are protruded from the outer surface of the outer case 10 as described above by the length of the protrusion. And a gap between the connection cover 41 and the terminals 17 and 18 can be prevented.

  As shown in FIG. 7, the connection plug 44 has the same structure as the connection plug 45. That is, the connection plug 44 has a U-shaped cross section including an insertion pin 46, an insertion pin 47, and a connection portion 48 that electrically connects the insertion pin 46 and the insertion pin 47. When the connection cover 41 is attached to the first battery pack 1 and the second battery pack 1, the insertion pin 46 of the connection plug 44 is inserted into the connector 20 of the first battery pack 1, and the insertion pin 47 is The connector 19 of the second battery pack 1 is inserted. As a result, the connector 22 of the first battery pack 1 and the connector 21 of the second battery pack 1 are electrically connected.

  Thus, when the connection cover 41 is attached to the first battery pack 1 and the second battery pack 1, the first battery pack 1 and the second battery pack 1 are electrically connected by the connection plugs 44 and 45. Thus, the first battery pack 1 and the second battery pack 1 are integrally fixed together. Since the first battery pack 1 and the second battery pack 1 completed as a product can be electrically connected in parallel, the user can easily increase the battery capacity by making a two-cell structure. it can.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, the connection cover 41 described above is configured to connect two battery packs 1, but may be configured to connect three or more battery packs 1.

  In addition, the battery pack 1 described above has the upper surface as a terminal surface, and the battery terminals 17 and 18 and the connectors 19, 20, 21, and 22 are arranged on the upper part of the battery pack 1. The upper portion of the battery pack 1 is not limited to the upper portion of the battery pack 1 and may be arranged at other positions such as the lower portion and the lateral portion of the battery pack 1. Further, the battery pack 1 is not limited to a rectangular one.

  In the above-described embodiment, the electrodes 12 and 13 and the battery terminals 17 and 18 are electrically connected so that the battery terminal 17 becomes a positive terminal and the battery terminal 18 becomes a negative terminal. The connection may be made so that 18 is a positive terminal and the battery terminal 17 is a negative terminal.

  Further, the terminals provided in the battery pack 1 are not limited to the battery terminals 17 and 18 but may be provided with a cell type, a battery capacity identifying terminal, a communication terminal, and the like. Further, the battery pack 1 may be configured to include a safety circuit such as a thermistor or a thermal fuse.

  In the above-described embodiment, the connection cover 41 is configured to be attached to the upper part of the battery pack 1, but the connection cover 41 may be configured to surround the entire battery pack 1.

It is a figure which shows an example of the structure of the battery pack by one Embodiment of this invention. It is a figure for demonstrating the structure in the exterior case of a battery pack. It is a figure for demonstrating the structure of the connector applicable to one Embodiment. It is a figure which shows an example of the circuit structure at the time of applying the battery pack connection cover by one Embodiment. It is a figure which shows the cover for a connection with which two battery packs were mounted | worn. It is a figure which shows the state of the battery pack in the cover for connection. It is a figure which shows an example of a structure of the cover for connection by one Embodiment. It is sectional drawing between line BB 'shown to FIG. 7A. It is a figure for demonstrating the connection by a connection plug. It is a figure which shows an example of the structure of the conventional 1 cell battery pack. It is a figure for demonstrating the circuit structure of the conventional 1 cell battery pack. It is a figure for demonstrating the circuit structure of the conventional 2 cell battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery pack 10 ... Outer case 11 ... Cell 12, 13 ... Electrode 14, 15 ... Tab 16 ... Circuit board 17, 18 ... Battery terminal 19, 20, 21 22 ... Connector 39 ... Control IC
40: Switch circuit 41 ... Connection cover 44, 45 ... Connection plug

Claims (5)

A battery pack having a cell, a circuit board, and an outer case for housing the cell and the circuit board, and at least a positive electrode terminal and a negative electrode terminal electrically connected to the positive electrode and the negative electrode of the cell, respectively Because
Connectable from the outside of the outer case, a positive side parallel connection connector electrically connected to the positive terminal,
It can be connected from the outside of the outer case, and includes a negative electrode side parallel connection connector electrically connected to the negative electrode terminal,
A battery pack, wherein at least two battery packs can be electrically connected in parallel through the positive electrode side parallel connection connector and the negative electrode side parallel connection connector. In claim 1,
The battery pack, wherein the positive electrode side parallel connection connector is disposed in the vicinity of the positive electrode terminal, and the negative electrode side parallel connection connector is disposed in the vicinity of the negative electrode terminal. In claim 1,
The positive side parallel connection connector is configured by two connectors disposed on both sides of the positive terminal, and the negative side parallel connection connector is configured by two connectors disposed on both sides of the negative terminal. A battery pack characterized by having In claim 1,
Each of the positive side parallel connection connectors of the plurality of exterior cases is electrically connected by a connection plug provided on the inner surface of the battery pack connection cover in which the plurality of exterior cases are detachable. The battery pack is characterized in that each of the negative electrode side parallel connection connectors of the plurality of exterior cases is electrically connected. A cell, a circuit board, and an outer case for housing the cell and the circuit board, and at least a positive electrode terminal and a negative electrode terminal electrically connected to a positive electrode and a negative electrode of the cell, respectively, are provided; A positive-side parallel connection connector that can be connected from the outside of the outer case and electrically connected to the positive terminal, and a negative electrode that can be connected from the outside of the outer case and electrically connected to the negative terminal A battery pack connection cover that is detachable from at least two battery packs each having a side parallel connection connector,
A connection plug is provided for electrically connecting each of the positive side parallel connection connectors of the plurality of battery packs and electrically connecting each of the negative side parallel connection connectors of the plurality of battery packs. A battery pack connection cover, wherein at least one positive electrode terminal and negative electrode terminal of the plurality of battery packs is electrically connectable to the outside. .

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