Energy storage apparatus and collision load detection method for energy storage apparatus

Abstract

To provide a power storage device capable of detecting a collision load to the power storage device, and a collision load detection method to the power storage device.SOLUTION: The power storage device 10 includes a plurality of battery cells 14, a battery case 12 that accommodates the battery cells 14, a conductive portion 34 that is disposed with respect to a lower wall portion 12C constituting a part of the battery case 12 so as to overlap the battery cells 14 as viewed from a predetermined direction and to which a predetermined voltage is applied, and a collision detection portion 32 that includes an insulator-made covering portion 36 that covers a portion of the conductive portion 34 overlapping the lower wall portion 12C and the battery cells 14 as viewed from the predetermined direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric storage device and a method for detecting a collision load on an electric storage device. [Background technology]

[0002] Patent Document 1 below discloses an invention related to a vehicle control device. In this vehicle control device, when the detected value of an acceleration sensor is greater than a predetermined acceleration, an airbag ECU (Electronic Control Unit) determines that the vehicle has collided, and the power stored in the power storage device is discharged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-129367 Summary of the Invention [Problem to be solved by the invention]

[0004] However, what the acceleration sensor detects is mainly the acceleration of the vehicle body, and the prior art has room for improvement in terms of detecting the collision load input to the power storage device.

[0005] In consideration of the above, an object of the present invention is to provide an electric storage device capable of detecting a collision load on an electric storage device and a method for detecting a collision load on an electric storage device. [Means for solving the problem]

[0006] The energy storage device of the first aspect includes a plurality of battery cells, a battery case that houses the battery cells, a conductive portion that is arranged against a wall that forms part of the battery case, is arranged so as to overlap the battery cells when viewed from a predetermined direction, and has a collision detection unit that includes an insulating covering portion that covers the portion of the conductive portion that overlaps both the wall and the battery cells when viewed from the predetermined direction.

[0007] The power storage device according to the first aspect includes a plurality of battery cells, and by mounting the power storage device on a vehicle, for example, it is possible to supply power from these battery cells to various devices mounted on the vehicle.

[0008] Generally, acceleration sensors are installed in the front or rear of a vehicle, and although they can detect collision loads on the vehicle body, it is difficult for these acceleration sensors to detect whether or not a collision load has been input to an electric storage device mounted on the vehicle.

[0009] In this embodiment, a collision detection unit is disposed on a wall portion that forms part of the battery case that houses the battery cells, and this collision detection unit makes it possible to detect whether or not a collision load is being input to the storage device.

[0010] Specifically, the collision detection unit includes a conductive portion and an insulating covering portion. The conductive portion is arranged to overlap the battery cell when viewed from a predetermined direction, and a predetermined voltage is applied to the conductive portion.

[0011] On the other hand, the covering portion covers the portion of the conductive portion that overlaps with both the wall portion of the battery case and the battery cell when viewed from the predetermined direction, thereby insulating the conductive portion from the wall portion and the battery cell.

[0012] Therefore, in this aspect, when a collision load is input to the power storage device, the conductive portion is ruptured or deformed in accordance with the deformation of the covering portion, and the voltage output from the conductive portion decreases. In other words, in this aspect, it is possible to determine whether a collision load has been input to the power storage device based on the voltage output from the conductive portion.

[0013] The energy storage device of the second aspect is the energy storage device of the first aspect, further comprising a cooling section arranged against the wall section, the collision detection section being arranged between the battery cell and the cooling section, and heat being transferred between the battery cell and the cooling section via the covering section.

[0014] In the energy storage device according to the second aspect, the cooling unit is disposed on the wall of the battery case, and the collision detection unit is disposed between the battery cell and the cooling unit, and heat is transferred between the battery cell and the cooling unit via the covering unit.

[0015] Therefore, in this aspect, when the cooling section cools the battery cells, heat exchange between the cooling section and the battery cells is promoted, and the cooling efficiency of the battery cells can be improved.

[0016] A power storage device according to a third aspect is the power storage device according to the second aspect, wherein the covering portion is in contact with the battery cell.

[0017] In the power storage device according to the second aspect, the covering portion and the battery cell are in contact with each other, and the collision load input to the battery cell and the collision load input to the collision detection portion can be made similar to each other.

[0018] A fourth aspect of the present invention is the power storage device according to the second or third aspect, wherein the covering portion is in contact with the cooling portion.

[0019] According to the energy storage device of the fourth aspect, the collision detection unit and the cooling unit are in contact with each other, and the conductive unit can be cooled by the cooling unit, thereby preventing the resistance value of the conductive unit from changing due to heat from the battery cell.

[0020] A fifth aspect of the energy storage device is the energy storage device of the third aspect, wherein the distance from the surface of the covering portion facing the battery cell to the conductive portion is set longer than the distance from the surface of the covering portion facing the cooling portion to the conductive portion.

[0021] In the energy storage device according to the fifth aspect, the distance from the surface of the covering part facing the battery cell to the conductive part is set longer than the distance from the surface of the covering part facing the cooling part to the conductive part, which makes it difficult for the conductive part to come into contact with the battery cell when the conductive part is broken or deformed when a collision load is applied to the energy storage device.

[0022] The energy storage device according to a sixth aspect is the energy storage device according to any one of the first to fifth aspects, further comprising a monitoring unit that monitors the state of the battery cells, and the monitoring unit receives the voltage output from the conductive portion.

[0023] According to the energy storage device of the sixth aspect, the monitoring unit can monitor the state of the battery cells. Furthermore, in this aspect, the voltage output from the conductive part can be input to the monitoring unit, so the monitoring unit can also monitor for breakage or deformation of the conductive part. Therefore, in this aspect, the number of parts can be reduced compared to a configuration in which a separate component is provided to monitor the voltage output from the conductive part.

[0024] A seventh aspect of the method for detecting a collision load on an energy storage device includes disposing a collision detection unit on a battery cell and a wall portion that forms part of a battery case that houses the battery cell, the collision detection unit including a conductive portion that is arranged to overlap the battery cell when viewed from a predetermined direction and to which a predetermined voltage is applied, and an insulating covering portion that covers the portion of the conductive portion that overlaps with both the wall portion and the battery cell when viewed from the predetermined direction, and measuring the voltage drop of the conductive portion to estimate whether a collision load has been input to the battery case.

[0025] According to the method for detecting a collision load on an electricity storage device according to the seventh aspect, the same effects as those of the first aspect described above are achieved.

[0026] The method for detecting a collision load on an electric storage device according to the eighth aspect is the same as the method for detecting a collision load on an electric storage device according to the seventh aspect, in which it is determined that a collision load has been input to the battery case side when the voltage drop is greater than a threshold value.

[0027] According to the method for detecting a collision load on an energy storage device relating to the eighth aspect, it is determined that a collision load has been input to the battery case side when the voltage drop of the conductive part is greater than a threshold value, thereby ensuring accuracy in determining whether a collision load has been input to the battery case side. [Effects of the Invention]

[0028] As described above, the power storage device and the method for detecting a collision load on a power storage device according to the present invention have the excellent effect of being able to detect a collision load on the power storage device. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a plan view schematically showing the configuration of a power storage device according to a first embodiment. [Figure 2] 1 is a cross-sectional view (a cross-sectional view showing a state cut along line 2-2 in FIG. 1) that schematically shows the configuration of the electricity storage device according to the first embodiment. [Figure 3] 3 is a plan view schematically showing the configuration of a collision detection unit provided in the power storage device according to the first embodiment. FIG. [Figure 4] 1 is a perspective view schematically illustrating a configuration of a power storage device according to a first embodiment. [Figure 5] 10 is a cross-sectional view (corresponding to FIG. 2) that schematically shows the configuration of a power storage device according to a second embodiment. [Figure 6] 10 is a cross-sectional view (a cross-sectional view corresponding to FIG. 2) that schematically shows the configuration of a power storage device according to a third embodiment. [Figure 7] FIG. 10 is a plan view schematically showing the configuration of a power storage device according to a third embodiment. [Figure 8] FIG. 10 is a side view showing the configuration of an electricity storage device according to a fourth embodiment. [Figure 9] FIG. 11 is a plan view schematically showing the configuration of a collision detection unit provided in a power storage device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] First Embodiment Hereinafter, an electricity storage device according to a first embodiment of the present invention will be described with reference to Figures 1 to 4. The "electricity storage device 10" according to this embodiment can be mounted on the underside of the floor of a vehicle (not shown), such as a hybrid car, a plug-in hybrid car, or an electric car. As shown in Figures 1 and 2, this electricity storage device 10 holds a "battery case 12" that forms its outer shell, and a plurality of "battery cells 14" housed in the battery case 12.

[0031] In each drawing, arrow FR indicates the front side of the power storage device 10 in the front-rear direction, arrow UP indicates the upper side of the power storage device 10 in the height direction, and arrow LH indicates the left side of the power storage device 10 in the width direction. In the following, unless otherwise specified, the front-rear direction of the power storage device 10 will be simply referred to as the front-rear direction, the height direction of the power storage device 10 will be simply referred to as the height direction, and the width direction of the power storage device 10 will be simply referred to as the width direction, respectively. Furthermore, the front-rear direction of the power storage device 10 coincides with the front-rear direction of the vehicle, the height direction of the power storage device 10 coincides with the height direction of the vehicle, and the width direction of the power storage device 10 coincides with the width direction of the vehicle.

[0032] 1 and 2, the battery case 12 is made of, for example, an aluminum alloy. The battery case 12 includes a pair of side walls 12A that form the outer portions in the width direction, a front wall (not shown) that forms the front portion in the front-to-rear direction, a rear wall (not shown) that forms the rear portion in the front-to-rear direction, a bottom wall 12C that forms the lower portion in the height direction, and multiple partition walls 12D that connect the pair of side walls 12A and extend in the width direction.

[0033] A storage section 12E is provided between the partition walls 12D in the battery case 12, and this storage section 12E houses the main part of a battery stack 16 formed by stacking battery cells 14 in the width direction. The battery cells 14 are supported by the bottom wall section 12C via insulating legs 17 made of an insulating material that are located below the battery cells 14 in the height direction on both front-rear sides.

[0034] Each battery cell 14 is provided with external terminals (not shown) on the positive and negative sides, and as shown in FIG. 4, the external terminals of the same polarity of adjacent battery cells 14 in the width direction are electrically connected in the width direction by bus bars 18. These bus bars 18 are held in place by a case 20. In the following, an assembly of multiple bus bars 18 and a case 20 will be referred to as a bus bar module 21.

[0035] The busbar module 21 configured as described above is electrically connected to a monitoring board unit 22. This monitoring board unit 22 is made up of a flexible printed circuit (FPC) and, as shown in Fig. 1, is electrically connected to a "Satellite Battery Module (SBM) 26" serving as a monitoring unit via a connector 24 provided at an end of the monitoring board unit 22. In other words, each of the multiple battery cells 14 is electrically connected to the SBM 26 via the busbar module 21 and the monitoring board unit 22.

[0036] The SBM 26 is capable of acquiring various data relating to the battery cells 14, such as data relating to voltage values, current values, and temperature, and transmitting this data to a control unit 40 such as an ECU mounted on the vehicle.

[0037] 2, a "cooling section 28" is disposed below the lower wall section 12C of the battery case 12 in the height direction. This cooling section 28 is made of an aluminum alloy, for example, and has a flow path section 28A formed therein through which a heat transfer medium such as cooling water flows. The cooling section 28 is attached to the lower wall section 12C via an attachment member (not shown).

[0038] Furthermore, a heat conducting portion 30 made of a clay-like heat conducting material is interposed between the lower wall portion 12C and the cooling portion .

[0039] Here, this embodiment is characterized in that a "collision detection unit 32" is disposed between the battery cells 14 and the lower wall portion 12C, on the height direction upper side of the lower wall portion 12C of the battery case 12. The configuration of the collision detection unit 32 will be described in detail below.

[0040] As shown in Figures 2 and 3, one collision detection unit 32 is arranged for each battery stack 16, and is composed of a metal "conductive portion 34" and an insulating "covering portion 36."

[0041] The conductive portion 34 is a signal line made of a single metal wire, such as nichrome wire, that has a relatively high electrical resistance and a wire diameter of approximately 100 μm, and is arranged so that it partially overlaps the battery cell 14 when viewed from the height direction. The conductive portion 34 is U-shaped when viewed from the height direction and includes a pair of widthwise extending portions 34A that extend in the width direction and a front-rear extending portion 34B that connects the widthwise extending portions 34A in the front-rear direction.

[0042] The conductive portion 34 may include, for example, four widthwise extending portions 34A and three front-rear extending portions 34B connecting them, and may be configured such that the signal line is bent in a serpentine manner when viewed from the height direction, or may be configured from metal foil.

[0043] On the other hand, the covering portion 36 is, for example, a rectangular sheet made of epoxy resin or the like with the width direction as the longitudinal direction when viewed from the height direction, and the main part of the conductive portion 34 is embedded inside it. In other words, the covering portion 36 covers the part of the conductive portion 34 that overlaps with the bottom wall portion 12C of the battery case 12 and the battery cells 14 when viewed from the height direction.

[0044] The covering portion 36 is in direct contact with the bottom wall portion 12C of the battery case 12 and the battery cells 14, and is joined to these via a joint (not shown) using a highly thermally conductive insulating adhesive or the like. In other words, the covering portion 36, together with the heat conducting portion 30 and the like, constitutes part of the heat transfer path between the battery cells 14 and the cooling portion 28.

[0045] In addition, the conductive portion 34 is positioned relative to the covering portion 36 so that the distance D1 from the surface of the covering portion 36 facing the battery cell 14, i.e., the "upper surface 36A," to the conductive portion 34 is longer than the distance D2 from the surface of the covering portion 36 facing the cooling portion 28, i.e., the "lower surface 36B," to the conductive portion 34.

[0046] 4, the conductive portion 34 extends from the covering portion 36 and is integrated into a detection board 38 made of an FPC, and the detection board 38 is electrically connected to the connector 24. In other words, the conductive portion 34 is electrically connected to the SBM 26 via the detection board 38.

[0047] In this embodiment, the SBM 26 applies a predetermined voltage to each conductive part 34 at predetermined time intervals under the control of a control part 40 mounted on the vehicle. Data on the voltage value of each conductive part 34 is acquired by the SBM 26 and transmitted to the control part 40.

[0048] On the other hand, the control unit 40 compares the voltage values ​​of the conductive part 34 at predetermined time intervals, and if the voltage drop from the previously acquired voltage value to the most recently acquired voltage value is greater than a threshold value, it determines that a collision load has been input to the battery case 12 side.

[0049] (Actions and Effects of This Embodiment) Next, the operation and effects of this embodiment will be described.

[0050] In this embodiment, as shown in FIG. 2, a plurality of battery cells 14 are provided, and by mounting the power storage device 10 on a vehicle, for example, it is possible to supply power from these battery cells 14 to various devices mounted on the vehicle.

[0051] Generally, an acceleration sensor is installed in the front or rear of a vehicle body, and although it can detect a collision load on the vehicle body, it is difficult for this acceleration sensor to detect whether or not a collision load has been input to the energy storage device 10 mounted on the vehicle.

[0052] In this embodiment, a collision detection unit 32 is disposed on the lower wall portion 12C that forms part of the battery case 12 that houses the battery cells 14, and this collision detection unit 32 makes it possible to detect whether or not a collision load is input to the energy storage device 10.

[0053] More specifically, the collision detection unit 32 includes a conductive portion 34 and an insulating covering portion 36. The conductive portion 34 is arranged to overlap the battery cell 14 when viewed from the height direction, and a predetermined voltage is applied to the conductive portion 34.

[0054] On the other hand, the covering portion covers the portion of the conductive portion that overlaps with the bottom wall 12C of the battery case 12 and the battery cells when viewed from the height direction, and insulates the conductive portion from the bottom wall 12C and the battery cells .

[0055] Therefore, in this embodiment, for example, when a collision load is input from the underside of the vehicle to the power storage device 10 from an object on the road surface, the conductive portion 34 is ruptured or deformed in accordance with the deformation of the covering portion 36, and the voltage output from the conductive portion 34 decreases. That is, in this embodiment, it is possible to determine whether a collision load has been input to the power storage device 10 based on the voltage output from the conductive portion 34.

[0056] In this embodiment, the cooling unit 28 is disposed on the bottom wall 12C of the battery case 12, and the collision detection unit 32 is disposed between the battery cells 14 and the cooling unit 28. Heat is transferred between the battery cells 14 and the cooling unit 28 via the covering unit 36.

[0057] Therefore, in this embodiment, when the cooling section 28 cools the battery cells 14, heat exchange between the cooling section 28 and the battery cells 14 is promoted, and the cooling efficiency of the battery cells 14 can be improved.

[0058] Furthermore, in this embodiment, the covering portion 36 and the battery cell 14 are in contact with each other, and the collision load input to the battery cell 14 and the collision load input to the collision detection portion 32 can be made similar to each other.

[0059] Furthermore, in this embodiment, the distance D1 from the upper surface 36A of the covering portion 36 on the battery cell 14 side to the conductive portion 34 is set to be longer than the distance D2 from the lower surface 36B of the covering portion 36 on the cooling portion 28 side to the conductive portion 34. Therefore, when the conductive portion 34 is torn or deformed when a collision load is input to the energy storage device 10, it is possible to make it less likely for the conductive portion 34 to come into contact with the battery cell.

[0060] 1, in this embodiment, the state of the battery cells 14 can be monitored by the SBM 26. In this embodiment, the voltage output from the conductive parts 34 can be input to the SBM 26, so the SBM 26 can also monitor for fractures or deformation of the conductive parts 34. Therefore, in this embodiment, the number of parts can be reduced compared to a configuration in which a separate component is provided to monitor the voltage output from the conductive parts 34. Note that in this specification, "monitoring" refers to a state in which the device to be monitored (the battery cells 14 or the conductive parts 34 in the above example) and the device that monitors it (the SBM 26, particularly the circuit boards inside the SBM 26 in the above example) are electrically connected or connected by communication means.

[0061] Furthermore, in this embodiment, the control unit 40 measures the voltage drop of the conductive part 34 based on the data acquired from the SBM 26, thereby estimating whether or not a collision load has been input to the battery case 12 side.

[0062] Specifically, in this embodiment, when the voltage drop of the conductive part 34 is greater than a threshold value, the control unit 40 determines that a collision load has been input to the battery case 12 side, thereby ensuring accuracy in determining whether or not a collision load has been input to the battery case 12 side.

[0063] As described above, in this embodiment, the collision load on the electricity storage device 10 can be detected.

[0064] Second Embodiment A power storage device 50 according to a second embodiment of the present invention will be described below with reference to Fig. 5. Note that the same components as those in the first embodiment described above are given the same reference numerals, and descriptions thereof will be omitted.

[0065] This electricity storage device 50 has a configuration basically similar to that of the first embodiment described above, but the positions of the heat conduction unit 30 and the collision detection unit 32 are interchanged. That is, in this embodiment, the covering unit 36 ​​of the collision detection unit 32 is in contact with the cooling unit 28.

[0066] This configuration basically achieves the same functions and effects as the first embodiment. Furthermore, in this embodiment, the collision detection unit 32 and the cooling unit 28 are in contact with each other, and the conductive unit 34 can be cooled by the cooling unit 28, so that changes in the resistance value of the conductive unit 34 due to heat from the battery cells 14 can be suppressed.

[0067] <Third embodiment> Hereinafter, a "power storage device 60" according to a third embodiment of the present invention will be described with reference to Figures 6 and 7. Note that the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

[0068] This electricity storage device 60 has a configuration similar to that of the first embodiment described above, but the "conductive portion 64" of the "collision detection portion 62" is a coated wire coated with vinyl resin. Also, the "coating portion 66" in which the conductive portion 64 is embedded is formed by pouring molten resin between the bottom wall portion 12C of the battery case 12 and the battery cell 14.

[0069] More specifically, in this embodiment, the battery case 12 has slits 68 provided between the side wall 12A and the partition 12D and between the rear wall and the partition 12D.

[0070] Then, with the battery cell 14 and the conductive portion 64 placed in the battery case 12, molten resin is poured between the battery cell 14 and the battery case 12, and the resin passes through each slit portion 68 and solidifies while spreading over the entire upper surface of the lower wall portion 12C, thereby forming the covering portion 66.

[0071] This configuration basically achieves the same functions and effects as those of the first embodiment. Furthermore, this embodiment can reduce the number of parts compared to a configuration in which a collision detection unit 32 is provided for each battery stack 16.

[0072] <Fourth embodiment> A power storage device 70 according to a fourth embodiment of the present invention will be described below with reference to Fig. 8. Note that the same components as those in the first embodiment described above are given the same reference numerals, and descriptions thereof will be omitted.

[0073] This energy storage device 70 is basically configured in the same manner as the first embodiment described above, but a "collision detection unit 72" configured in the same manner as the collision detection unit 32 is attached to the side wall portion 12A of the battery case 12.

[0074] Specifically, the collision detection section 72 is configured to include a "conductive section 74" and a "covering section 76", and is disposed on the surface of the side wall section 12A opposite to the battery cell 14 with its longitudinal direction aligned in the front-to-rear direction.

[0075] This configuration basically achieves the same functions and effects as those of the first embodiment. In this embodiment, a collision detection unit 72 is provided on the side wall 12A of the battery case 12, and the collision detection unit 72 can be used to detect the input of a collision load to the electricity storage device 70 in the vehicle width direction.

[0076] Fifth Embodiment A "power storage device 80" according to a fifth embodiment of the present invention will be described below with reference to Fig. 9. Note that the same components as those in the first embodiment described above are given the same reference numerals, and descriptions thereof will be omitted.

[0077] This energy storage device 80 is basically configured in the same manner as the first embodiment described above, but has a long hole 82 extending in the front-to-rear direction at the end of the covering portion 36, and the front-to-rear extending portion 34B of the conductive portion 34 is exposed inside this long hole 82.

[0078] In addition, in this embodiment, the SBM 26 is capable of detecting a short circuit between the conductive part 34 and the battery case 12, and the control unit 40 is configured to determine that a leakage current has occurred within the battery case 12 when the SBM 26 detects a short circuit between the conductive part 34 and the battery case 12.

[0079] This configuration provides the same functions and effects as those of the first embodiment. In addition, in this embodiment, when water accumulates in the elongated hole 82 due to water droplets forming inside the battery case 12, the conductive portion 34 and the battery case 12 are short-circuited, and the control unit 40 can detect a leakage current inside the battery case 12 based on information acquired from the SBM 26.

[0080] That is, in this embodiment, the input of a collision load to the electricity storage device 80 and a leakage current in the battery case 12 can be detected using the same component.

[0081] <Supplementary explanation of the above embodiment> (1) In the above-described embodiment, the conductive portion provided in the collision detection unit is connected to the SBM 26 via the connector 24 connected to the bus bar module 21. However, depending on the vehicle specifications, etc., a configuration may be adopted in which the conductive portion is connected to a connector dedicated to the conductive portion, and this connector is then connected to the SBM 26.

[0082] (2) In addition, in the above-described embodiment, the battery case 12 and the cooling section 28 were separate entities. However, depending on the vehicle specifications, etc., a configuration may be adopted in which the lower wall portion 12C of the battery case 12 and the cooling section 28 are integrated. [Explanation of symbols]

[0083] 10. Energy storage device 12 Battery case 12A Side wall (wall) 12C Lower wall (wall) 14 battery cells 26 SBM (Monitoring Department) 28 Cooling section 32 Collision detection unit 34 Conductive part 36 Covering part 36A Top surface (battery cell side) 36B bottom surface (cooling section side surface) 50 Electricity storage device 60 Electricity storage device 62 Collision detection unit 64 Conductive part 66 Covering part 70 Electricity storage device 72 Collision detection unit 74 Conductive part 76 Covering part 80 Electricity storage device

Claims

1. A plurality of battery cells; a battery case that houses the battery cell; a collision detection unit including: a conductive portion that is disposed against a wall portion that constitutes a part of the battery case, that is disposed so as to overlap with the battery cell when viewed from a predetermined direction, and that has a predetermined voltage applied thereto; and a covering portion made of an insulating material that covers the portion of the conductive portion that overlaps with both the wall portion and the battery cell when viewed from the predetermined direction; A power storage device having the above structure.

2. a cooling portion disposed relative to the wall portion; the collision detection unit is disposed between the battery cell and the cooling unit, and heat is transferred between the battery cell and the cooling unit via the covering unit. The power storage device according to claim 1 .

3. The covering portion is in contact with the battery cell. The power storage device according to claim 2 .

4. The covering portion is in contact with the cooling portion. The power storage device according to claim 2 .

5. a distance from a surface of the covering portion facing the battery cell to the conductive portion is set to be longer than a distance from a surface of the covering portion facing the cooling portion to the conductive portion; The power storage device according to claim 3 .

6. a monitoring unit that monitors the state of the battery cell; The monitoring unit receives the voltage output from the conductive unit. The power storage device according to any one of claims 1 to 5.

7. a collision detection unit is disposed on a battery cell and a wall portion constituting a part of a battery case that houses the battery cell, the collision detection unit including a conductive portion that is arranged to overlap the battery cell when viewed from a predetermined direction and to which a predetermined voltage is applied, and a covering portion made of an insulating material that covers the portion of the conductive portion that overlaps both the wall portion and the battery cell when viewed from the predetermined direction; By measuring a voltage drop in the conductive part, it is estimated whether or not a collision load has been input to the battery case. A method for detecting a collision load on an electric storage device.

8. If the voltage drop is greater than a threshold value, it is determined that a collision load has been input to the battery case. The method for detecting a collision load on an electric storage device according to claim 7.

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