JP2018198181A - Connecting stem for battery pack, and battery pack - Google Patents

Abstract

To provide a connecting stem for battery pack which comprises a fuse function and is easy to produce, and a battery pack effectively utilizing the connecting stem for battery pack.SOLUTION: A connecting stem 1 for battery pack comprises: first and second connecting ends 3 and 4 connected to electrodes of a unit cell; and a main body 2 conducting the first and second connecting ends via fusible parts 2d and 2e that are fused by overcurrent. The fusible parts have a smaller cross-sectional area than an end portion of the main body connected to the first and second connecting ends. The fusible parts have a cross-sectional area of 30 mm2 or more and 120 mm2 or less, such that Joule heat is generated in the fusible parts by overcurrent flowing to the main body and that the fusible parts are fused thereby. A battery pack 10 using the connecting stem 1 for battery pack represents a fuse function by fusing the fusible parts in response to overcurrent, thereby preventing overcurrent.SELECTED DRAWING: Figure 1

Description

  The present invention provides an assembled battery connection stem for electrically connecting a plurality of unit cells each having a pair of electrodes to form an assembled battery, and a unit cell electrically connected by the assembled battery connection stem. The present invention relates to an assembled battery.

  For example, electric forklifts and plug-in electric vehicles are cargo handling vehicles that transport and load cargo by driving an electric motor, and are particularly in demand because they are clean vehicles that do not emit exhaust gas. An assembled battery is used as a power source for driving the electric motor.

  An assembled battery is generally configured by connecting single cells in series. Here, the electrodes of each unit cell are connected by a connection trunk (also called a bus bar) (see, for example, Patent Document 1).

  Here, if an overcurrent flows through the assembled battery, a failure may occur in the battery or the driven vehicle. Conventionally, no fuse is provided in any of the cables connecting these batteries, such as a battery, a driven vehicle, and the like, and the possibility that an overcurrent flows in the assembled battery cannot be denied.

  Therefore, Patent Documents 1 and 2 disclose an assembled battery in which a fuse is provided in addition to a connection trunk. However, since a fuse is separately provided, the number of parts increases.

  In this regard, Patent Document 3 discloses a connection trunk having a fuse function. However, since it has a fuse function, it becomes a connecting trunk with a complicated shape, and production is not easy.

Japanese Patent Laying-Open No. 2015-041586 JP, 2015-141801, A JP 2014-154337 A

  It is an object of the present invention to provide an assembled battery connection trunk that has a fuse function and is easy to produce, and an assembled battery that utilizes the assembled battery connection trunk.

The connection trunk of the present invention is
A battery pack connection trunk for electrically connecting a plurality of unit cells each having a pair of electrodes to form a battery pack,
First and second connection ends respectively connected to a first electrode of a first unit cell and a second electrode of a second unit cell included in the plurality of unit cells;
A main body that conducts between the first and second connection ends via a fusing part that is fused by an overcurrent; and
With
The body is made of an alloy of lead and antimony;
The fusing part has a substantially rectangular shape whose long side is twice or less the length of the short side in a cross section perpendicular to the line connecting the first and second connection ends, and is a cut of about 30 mm2 or more and 120 mm2 or less. It has an area.

  According to this feature, the main body has an overcurrent between the first and second connection ends connected to the first electrode of the first unit cell and the second electrode of the second unit cell included in the plurality of unit cells, respectively. Conduction is performed through a fusing portion that is fused. Since the fusing part has a small cross-sectional area, Joule heat is generated in the fusing part due to an overcurrent flowing through the main body, thereby fusing. Therefore, when a current flows through the main body between the first and second unit cells to which the first and second connection ends are connected, the fusing part is blown in response to an overcurrent, and the fuse function is expressed. Overcurrent can be prevented.

  The first and second connection ends can be configured as substantially cylindrical holes provided in a plate-like connection trunk. The production process of the connection trunk is not complicated.

  Here, a stress that disturbs the form of the assembled battery is generated in the assembled battery (unit cell constituting the battery) due to thermal expansion or external force during power generation. It is preferable that the connecting trunk body has rigidity sufficient to withstand such stress. Therefore, it is known to use an alloy of lead and antimony instead of lead that has conductivity but lacks rigidity. An alloy of lead and antimony has a lower melting point than lead and is suitable for developing a fuse function.

  The fuse function needs to be blown in a short time in the case of an overcurrent (each cell does not break down) without being blown by a normally flowing current. The time required for fusing depends on the amount of heat generated by the conductor in the fusing part (varies depending on the temperature of the fusing part), the surface area, the outside air temperature, and the like, and thus cannot be easily calculated. The applicant has an approximately rectangular shape in which the fusing part has a long side whose length is not more than twice the length of the short side and has a cross-sectional area of 30 mm2 or more and 120 mm2 or less. Then, it discovered that it melts in a short time. In addition, when providing a some fusing part so that it may mention later, suppose that the cross-sectional area of the whole fusing part is the sum of the cross-sectional areas of each fusing part.

The connection trunk of the present invention is
When the current flows through the main body, the fusing part does not melt with respect to a current of 400 A, but melts within 30 seconds with respect to a current of 2000 A.

  According to this feature, the battery pack is not blown at 400A which is a general rated current of an assembled battery used in an electric forklift or a plug-in electric vehicle, and is blown out in a short time at 2000A which is an obvious overcurrent. The assembled battery can be protected.

The connection trunk of the present invention is
The fusing part is characterized by fusing within 10 seconds for a current of 1000 A.

  According to this feature, even a small overcurrent melts in a short time. The assembled battery can be protected more reliably.

The connection trunk of the present invention is
The main body is characterized in that a hollow part is formed in a cross-sectional area of the fusing part.

  According to this feature, by providing the hollow portion, it is possible to reduce the cross-sectional area of the melted portions at both ends thereof. In addition, since the fusing part is configured without reducing the width of the main body, the rigidity of the whole main body can be maintained without being reduced so much as compared with the case where the center of the main body is thinned to form the fusing part. The hollow portion can be a simple shape such as a columnar hole, and the production process of the connection trunk is not complicated.

  According to the shape of the connection end and the shape of the hollow portion described above, the connection trunk can be produced by die processing.

The connection trunk of the present invention is
The hollow part of the main body is filled with a nonconductive member having a higher rigidity than the main body.

  According to this feature, the rigidity of the entire main body can be sufficiently obtained by filling the hollow portion with the non-conductive member having a high rigidity.

The connection trunk of the present invention is
A covering portion that covers the fused portion is provided,
The covering portion is formed of a heat-shrinkable tube, and is not conductive at the melting point temperature of the fusing portion for 2 seconds or more, and is non-conductive.

  According to this feature, when the fusing part is blown by covering the fusing part with a non-conductive covering part that is constituted by a heat-shrinkable tube and is not divided for 3 seconds or more at the melting point temperature of the fusing part. A possible spark can be confined. Here, “dividing” means the general separation into two or more parts, and includes fusing by heat and breaking by mechanical deformation.

The connection trunk of the present invention is
The said coating | coated part coat | covers the said cutting part except the part of the said cutting part which opposes via the said hollow part, It is characterized by the above-mentioned.

  According to this feature, the coating part covers the melted part except for the part of the melted part facing through the hollow part, so that the spark that can be generated when the melted part melts can be confined in the hollow part. it can.

The assembled battery of the present invention is
A battery pack in which cells are connected in series,
A battery pack connecting trunk of the present invention;
A plurality of unit cells including at least first and second unit cells electrically connected by the battery pack connection trunk;
It is characterized by providing.

  According to this, at least the first and second unit cells among the plurality of unit cells connected in series are electrically connected by the connection trunk for the assembled battery having a fuse function, so that the assembled battery is protected from overcurrent. The whole can be protected.

  The battery pack connection trunk of the present invention provides a battery pack connection trunk that has a fuse function and is easy to produce.

  According to the assembled battery of the present invention, an assembled battery that prevents overcurrent is provided.

FIG. 1 is a diagram illustrating a configuration of a battery pack connection trunk. FIG. 2 is a diagram showing an energization test of the battery pack connection trunk. FIG. 3 is a diagram illustrating a configuration of the assembled battery. FIG. 4 is a diagram showing the configuration of the battery pack connection trunk.

  Examples of the present invention will be described below.

  The present embodiment shows a basic configuration of a battery pack connection trunk.

  FIG. 1 is a diagram showing a configuration of an assembled battery connection trunk (also simply referred to as a connection trunk) 1. Here, FIG. 1A is a top view, and FIG. 1B is a cross-sectional view with respect to a reference line BB in FIG. The connection trunk 1 is a connection tool for electrically connecting a plurality of single cells to form an assembled battery, and includes a first and second connection ends 3 and 4, a main body 2, and a nonconductive member 5. Is done.

  The first and second connection ends 3 and 4 are members that electrically connect the electrodes of the unit cell, and are formed into a ring shape using a conductive metal such as lead or an alloy such as lead-antimony alloy, for example. . The 1st and 2nd connection ends 3 and 4 have the hole parts 3a and 4a in which the electrode of a cell is inserted (or inserted), respectively. As an example, the outer diameter (diameter) W is 32.5 mm, the inner diameter (diameter of the holes 3a and 4a) w is 19 mm, and the thickness H is 8 mm. The first and second connection ends 3 and 4 are positioned on one side (left side in the drawing) and the other side (right side in the drawing), for example, with a center distance L = 70 mm apart.

  The main body 2 is a member that connects the first and second connection ends 3 and 4 and energizes between them, and is formed using the same conductive material as the first and second connection ends 3 and 4. The main body 2 has a uniaxial direction (left-right direction in the drawing) as a longitudinal direction, and a hollow portion 2a having a substantially rectangular shape is formed at the center, and concave surfaces 2b and 2c having arc shapes in top view are formed at both ends. Here, the width D of the main body 2 is 27.5 mm, the thickness h is 7 mm, the length s in the uniaxial direction (horizontal direction in the drawing) of the hollow portion 2a is 30 mm, and the width in the direction orthogonal to the uniaxial direction (up and down direction in the drawing). d is 19 mm, the corner radius of curvature is 7.5 mm, and the concave radius of curvature is W / 2. The main body 2 joins the two concave surfaces 2b and 2c to the side surfaces of the first and second connection ends 3 and 4 and connects them. The main body 2 may be integrally formed with the first and second connection ends 3 and 4.

  In the main body 2 having the above-described configuration, the hollow portion 2a is formed at the center, so that two current paths for passing a current between the two concave surfaces 2c and 2d, that is, between the first and second connection ends 3 and 4 can be obtained. Provided. The two current paths are located on the upper side and the lower side of the drawing, respectively, and the fusing part 2d, having a smaller cross-sectional area than the ends of the main body (that is, the concave surfaces 2c and 2d) connected to the first and second connection ends 3 and 4, respectively. 2e is included. Here, the fusing parts 2d and 2e have a non-zero electric resistance based on the size of the respective cross-sectional areas and the resistivity of the conductive material constituting the main body 2, so that Joule heat is generated when an overcurrent is applied. The fuse function is manifested by fusing with the heat.

  The widths C1 and C2 of the fusing parts 2d and 2e are C1 + C2 = D−d, but C1 = C2. That is, C1 = C2 = (D−d) /2=4.25 mm.

  By forming the hollow part 2a in the main body 2 as described above, the main body 2 can be provided with the fusing parts 2d and 2e having a small cross-sectional area without reducing the width D of the main body 2 to the extent of the width of the fusing part. Here, the number of the hollow portions 2 a is not limited to one, and a plurality of hollow portions 2 a may be formed in the main body 2. For example, two or more current paths may be formed in the vertical direction of the drawing to form three or more current paths. Also, two or more may be formed side by side in the horizontal direction of the drawing.

  The cross-sectional areas of the fusing parts 2d and 2e (C1 × h, C2 × h: in this example, 29.75 mm 2 each, and the cross-sectional area of the whole fusing part is 59.5 mm 2) It will be determined accordingly. As a condition of the fuse function, for example, when an electric current is passed through the main body 2, the fusing parts 2d and 2e are not blown with respect to a current of 400A, but within 30 seconds with respect to a current of 2000A, more preferably a current of 1000A. The fusing shall be performed within 10 seconds. As a result, the fusing parts 2d and 2e flow a rated current of 400 A or less through the main body 2 without fusing, within 30 seconds for a current of 2000 A exceeding the rated current, and for a current of 1000 A under more preferable conditions. The battery pack can be protected from overcurrent by fusing within seconds.

  The nonconductive member 5 is a member for reinforcing the main body 2 and is filled in the hollow portion 2 a of the main body 2. The non-conductive member 5 can be provided in the hollow portion 2a by, for example, filling the hollow portion 2a with a silicone resin and curing it. The non-conductive member 5 is not limited to silicon, and a material having a strength equal to or higher than that of the main body 2 (particularly, the fusing parts 2d and 2e), such as ceramics, can be used. Thereby, the hollow part 2a is formed and the main body 2 having a low resistance to stress is reinforced. In addition, when the main body 2 has sufficient tolerance with respect to stress, the nonelectroconductive member 5 does not need to be provided in the hollow part 2a.

  An energization test was performed on the connection trunk 1 by applying a voltage between the first and second connection ends 3 and 4, energizing the main body 2, and testing the fusing of the main body 2. Here, a connection stem manufactured according to the above-described design was adopted as the sample 1, and a connection stem manufactured according to the above-mentioned design was adopted except that the non-conductive member 5 was not filled in the hollow portion 2a as the sample 2. The room temperature during the test was 24 ° C.

  FIG. 2 is a diagram showing an energization test of the battery pack connection trunk. FIG. 2A shows the status of the test. The connection trunk 1 is fixed to a conductive current test base 6 and connected to a controller (not shown) via a current test cable 7. The controller applies a voltage to the two energization test bases 6 (connection trunk 1) so as to obtain a constant current.

The results of the energization test are shown in Table 1. Sample 1 is the above-described connection trunk 1 and does not have the non-conductive member 5, and sample 2 is the above-described connection trunk 1 and the non-conductive member 5 is a silicon resin. The material of the connection trunk 1 was an alloy of 90% lead and 10% antimony.

  In the energization of 1000 A, the main body 2 (melting portions 2d and 2e) is melted about 6.0 seconds after the energization of the sample 1 is started, and the main body 2 (melting out) is about 7.9 seconds after the energization is started for the sample 2. The parts 2d and 2e) were melted. In addition, it is thought that it is because heat dissipation improved because the time which reached the fusing of the sample 2 with respect to the sample 1 was filled with the silicon resin 5 in the hollow part 2a.

  With respect to 150 A energization, both Samples 1 and 2 did not melt even after 2 hours had passed since the start of energization. In both Samples 1 and 2, their temperatures were saturated to 97 ° C. in about 1 hour after the start of energization from the temperature 24 ° C. before the start of the test. That is, since the temperature is saturated at a temperature lower than the melting point of the main body 2, even if energization is performed for a long time, it does not melt.

  From the above results, it was found that the connection trunk 1 did not melt even when a current of 150 A was applied, and the melted portions 2 d and 2 e were melted within 10 seconds for a current of 1000 A. According to this, it was found that the assembled connection trunk 1 does not melt in normal use of the battery, and can protect the assembled battery by melting in a short time of 10 seconds or less when an overcurrent of 1000 A flows.

  As described above in detail, the battery pack connection trunk 1 according to the present embodiment includes the first and second connection ends 3 and 4 and the first and second connection ends 3 and 3 connected to the electrodes of the unit cell, respectively. 4 is provided with a main body 2 that is electrically connected through fusing parts 2d and 2e that are fused by overcurrent, and the fusing parts 2d and 2e are connected to the first and second connection ends 3 and 4, respectively. It has a smaller cross-sectional area. The first and second connection ends 3 and 4 that are respectively connected to the electrodes of the unit cell are electrically connected by the main body 2 via fusing parts 2d and 2e that are fused by overcurrent. The fusing parts 2 d and 2 e have a smaller cross-sectional area than the end of the main body 2 connected to the first and second connection ends 3 and 4, so that Joule heat is generated in the fusing parts 2 d and 2 e due to overcurrent flowing through the main body 2. Occurs and thereby blows. Therefore, when current flows through the main body 2 between the unit cells to which the first and second connection ends 3 and 4 are connected, the fusing parts 2d and 2e are blown in response to the overcurrent, so that a fuse function is exhibited. In addition, the assembled battery can be protected from overcurrent.

  The present embodiment shows a battery pack connection trunk 1 provided with a covering member 8.

  FIG. 4 is a diagram showing the configuration of the connection trunk 1. Here, FIG. 4A is a top view, and FIG. 4B is a cross-sectional view related to the reference line BB in FIG. 4A. The connection trunk 11 includes first and second connection ends 3 and 4, a main body 2, and a covering member 8. The first and second connection ends 3 and 4 and the main body 2 are configured in the same manner as those in the connection trunk 1 described above.

  The covering member 8 is a member that covers the fusing parts 2 d and 2 e of the connection trunk 1. The covering member 8 is formed in a cylindrical shape from, for example, a non-conductive heat-shrinkable tube, and covers the entire hollow portion 2a between the fusing portions 2d and 2e by inserting the main body 2 inside thereof. . Sparks that can be generated when the fusing parts 2d and 2e are fused can be confined in the hollow part 2a by the covering member 8 to prevent ignition to hydrogen gas, oxygen gas, or the like.

By making the covering member 8 a heat shrinkable tube, the covering member 8 contracts and continues to cover the fusing parts 2d and 2e even if the temperature of the fusing parts 2d and 2e rises. The covering member 8 shall have heat resistance that does not divide for 2 seconds or more, preferably 3 seconds or more at the melting point temperature of the fusing parts 2d and 2e. For example, since the melting point temperature of an alloy of lead and antimony is around 230 ° C., it is preferable to use a heat shrinkable tube that can be used continuously at that temperature. Moreover, if the continuous useable temperature of a heat-shrinkable tube is 100 degreeC or more, the thickness can be adjusted and it shall not divide | segment for 2 seconds or more, Preferably it is 3 seconds or more.

  When the fusing parts 2d and 2e are fused, the fusing part becomes thin and the electrical resistance increases. On the other hand, the voltage applied to the part does not decrease. As a result, a current also flows in a portion other than the fusing portions 2d and 2e (for example, air having some conductivity including water vapor around the fusing portions 2d and 2e). Such an electric current generates a spark. If there is a flammable gas around the spark, there is a risk that the gas will explode.

  The unit cells connected by the connection trunk 1 may be those that generate hydrogen gas, oxygen gas, or the like (for example, lithium ion batteries). Doing so may ignite the spark. By covering the fusing parts 2d and 2e with the covering member 8, the flammable gas is separated from the spark.

  The covering member 8 is formed into an arbitrary size and shape as long as it covers the fusing parts 2d and 2e facing each other through the hollow part 2a, that is, the upper surface, the lower surface, and the outer surface excluding the inner surface. May be. For example, the covering member 8 may be formed in a U shape to cover the upper surface, the lower surface, and the outer surface of each of the fusing parts 2d and 2e. Since the portions of the fusing portions 2d and 2e facing each other through the hollow portion 2a are not covered, the conductivity of the portion facing through the hollow portion 2a is higher than the other portions, and a spark is generated in the hollow portion 2a. . Sparks that can be generated when the fusing parts 2d and 2e are fused can be confined in the hollow part 2a by the covering member 8.

  As described in detail above, the battery pack connection trunk 1 according to the present embodiment can separate the spark generated when the fusing parts 2d and 2e are fused by the covering member 8 from the combustible gas. .

  The present embodiment shows an assembled battery using the connection trunk for the assembled battery.

  FIG. 3 is a diagram illustrating a configuration of the assembled battery. The assembled battery 10 includes a plurality of single cells 10 a to 10 x, a plurality of connection trunks 1, and two cables 11.

  The plurality of unit cells 10a to 10x is, for example, 24 rectangular batteries. The unit cells 10a to 10x have positive electrodes 10a + to 10x + and negative electrodes 10a− to 10x− near one end and the other end of the upper surface, respectively.

  The plurality of connection trunks 1 are members that electrically connect the single cells 10a to 10x by inserting (or fitting) the electrodes of the single cells 10a to 10x into the holes 3a and 4a. 23 connection trunks 1 are included corresponding to the number of 10a to 10x. Of these, the first connection trunk 1 connects the negative electrode 10a- of the unit cell 10a and the positive electrode 10b + of the unit cell 10b. The second connection trunk 1 connects the negative electrode 10b− of the unit cell 10b and the positive electrode 10c + of the unit cell 10c. Hereinafter, similarly, the negative electrode and the positive electrode of adjacent unit cells are connected, and the unit cells 10a to 10d are connected in series.

  Any of the connection trunks 1 shown in the first and second embodiments can be used. Here, when the unit cells 10a to 10x are, for example, lithium ion batteries, and hydrogen gas, oxygen gas, or the like is generated around the electrodes, in order to prevent ignition of sparks generated during fusing, the embodiment It is preferable to use the one shown in 2.

  In the assembled battery 10, the single cells 10a to 10x are connected in series, and one single cell has a voltage of 2V and generates a voltage of 48V. A potential difference of 48 V is generated between the two cables 11 connected to the positive electrode 10a + of the unit cell 10a and the negative electrode 10b- of the unit cell 10x. The assembled battery 10 further includes a housing (not shown) that stores the cells 10a to 10x, and is mounted on a vehicle body such as an electric forklift. The vehicle body is driven by connecting the two cables 11 to an electric motor (not shown) in the vehicle body (not shown).

  According to the assembled battery 10, the plurality of single cells 10a to 10d are electrically connected by the connection trunk 1 having a fuse function. Thereby, when the overcurrent is energized, the connection trunk 1 is melted, so that the assembled battery 10 can be protected from the overcurrent.

  Note that the connection trunk 1 of the present invention in which all the connection trunks are fused may not be used. In the case of the connection trunk 1 of the present invention in which at least one connection trunk is fused, all currents of the plurality of single cells 10a to 10x connected in series are cut off by the fusion of the connection trunk.

  As described above in detail, the assembled battery 10 according to the present embodiment includes the first and second unit cells electrically connected by the assembled battery connection trunk 1 and the assembled battery connection trunk 1 of the present embodiment. A plurality of unit cells 10a to 10x are included. Among the plurality of unit cells, at least the first and second unit cells are electrically connected by the assembled battery connection trunk 1 having a fuse function, so that the assembled battery 10 can be protected from overcurrent.

  In the present embodiment, the assembled battery 10 is mounted on a vehicle body such as a forklift and used as a power source for driving an electric motor. However, the use of the assembled battery 10 is not limited to this, and any electric device can be used. It can be arbitrarily used as a power source for supplying power.

  The connection trunk for assembled battery of the present invention has a fuse function and is easy to produce. The assembled battery of the present invention prevents overcurrent. Many of them are considered to be used by assembled battery producers and assembled battery using product producers.

1 Connection trunk for battery pack (connection trunk)
2 Main body 2a Hollow part 2b Concave surface 2c Concave surface 2d Fusing part 2e Fusing part 3 Connection end 3a Hole part 4 Connection end 4a Hole part 5 Non-conductive member 6 Electricity test base part 7 Electricity test cable 8 Covering member 10 Battery 10a -10x cell 10a + -10x + positive electrode 10a--10x- negative electrode 11 cable

Claims (8)

A battery pack connection trunk for electrically connecting a plurality of unit cells each having a pair of electrodes to form a battery pack,
First and second connection ends respectively connected to a first electrode of a first unit cell and a second electrode of a second unit cell included in the plurality of unit cells;
A main body that conducts between the first and second connection ends via a fusing part that is fused by an overcurrent; and
With
The body is made of an alloy of lead and antimony;
In the cross section perpendicular to the line connecting the first and second connection ends, the fusing part has a substantially rectangular shape with a length of the long side being not more than twice the length of the short side, and a cross-sectional area of 30 mm2 or more and 120 mm2 or less. A connection stem for an assembled battery, comprising:   2. The set according to claim 1, wherein when the current flows through the main body, the fusing part does not blow with respect to a current of 400 A, but blows within 30 seconds with respect to a current of 2000 A. Battery connection trunk.   3. The battery pack connection trunk according to claim 2, wherein the fusing part is fused within 10 seconds with respect to a current of 1000 A. 4.   The battery pack connection trunk according to any one of claims 1 to 3, wherein the main body has a hollow portion formed in the fusing portion.   5. The assembled battery connection trunk according to claim 4, wherein the hollow portion of the main body is filled with a nonconductive member having a higher rigidity than that of the main body. A covering portion that covers the fused portion is provided,
5. The battery pack connection trunk according to claim 4, wherein the covering portion is constituted by a heat-shrinkable tube, is not divided for 2 seconds or more at the melting point temperature of the fusing portion, and is non-conductive.   The battery pack connection trunk according to claim 6, wherein the covering portion covers the fusing portion except for a portion of the fusing portion facing through the hollow portion. A battery pack in which cells are connected in series,
A battery pack connection trunk according to any one of claims 1 to 7,
A plurality of unit cells including at least first and second unit cells electrically connected by the battery pack connection trunk;
An assembled battery comprising: