Traction battery pack thermal management system providing primary and secondary cooling paths

Abstract

The present disclosure provides a traction battery pack thermal management system providing a primary cooling path and a secondary cooling path. A thermal management system for a traction battery pack is provided. An exemplary thermal management system may include a primary cooling system configured to direct a first cooling fluid through a first interior volume of one or more battery modules; and an auxiliary cooling system configured to direct a second cooling fluid through a second interior volume of the housing assembly that accommodates the one or more battery modules. The primary cooling system may establish a primary cooling path for thermal management of battery cells of the one or more battery modules, and the secondary cooling system may establish a secondary cooling path for thermal management of terminals and / or bus bars of the one or more battery modules.

Description

Technical Field

[0001] The present disclosure relates generally to electrified vehicle traction battery packs and, more particularly, to a thermal management system for a traction battery pack. Background Art

[0002] An electrified vehicle includes a traction battery pack for powering the vehicle's electric motor and other electrical loads. The traction battery pack includes a plurality of battery cells and various other battery internal components that support electric vehicle propulsion. Summary of the invention

[0003] A traction battery pack according to an exemplary aspect of the present disclosure includes, among other things: a housing assembly; a plurality of battery modules housed within the housing assembly; a primary cooling system configured to direct a first cooling fluid through a first interior volume of each of the plurality of battery modules; and an auxiliary cooling system configured to direct a second cooling fluid through a second interior volume of the housing assembly.

[0004] In yet another non-limiting embodiment of the foregoing traction battery pack, each of the plurality of battery modules includes a battery subassembly and an external cover.

[0005] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the battery subassembly includes a plurality of battery cells held between a first frame and a second frame.

[0006] In yet another non-limiting embodiment of any of the foregoing traction battery packs, adjacent battery cells of the plurality of battery cells are at least partially separated by sealing strips of the first frame and the second frame.

[0007] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the exterior cover includes four sides and two open ends.

[0008] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the first frame is positioned at one of the two open ends of the exterior cover, and the second frame is positioned at the other of the two open ends.

[0009] In a further non-limiting embodiment of any of the foregoing traction battery packs, the first cooling fluid cools the plurality of battery cells and the second cooling fluid cools bus bars or terminals located outside of the first interior volume.

[0010] In a further non-limiting embodiment of any of the foregoing traction battery packs, the first cooling fluid cools at least one battery cell of each of the plurality of battery modules, and the second cooling fluid cools bus bars or terminals of each of the plurality of battery modules.

[0011] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the primary cooling system includes: an inlet duct; a delivery line fluidly connected to the inlet duct and to an inlet tube of at least one of the plurality of battery modules; an outlet duct; and a receiving line fluidly connected to an outlet tube of the at least one of the plurality of battery modules and the outlet duct.

[0012] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the first interior volume is located between the inlet tube and the outlet tube.

[0013] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the auxiliary cooling system includes an inlet pipe mounted to a first end wall of the housing assembly and an outlet pipe mounted to a second end wall of the housing assembly. The second interior volume is located between the inlet pipe and the outlet pipe.

[0014] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the first cooling fluid is a coolant, and the second cooling fluid is an air flow or a dielectric fluid.

[0015] According to another exemplary aspect of the present disclosure, a traction battery pack includes a battery module, wherein the battery module includes a battery cell, a terminal and a bus bar. A thermal management system establishes a main cooling path for thermal management of the battery cell and an auxiliary cooling path for thermal management of the terminal and the bus bar.

[0016] In yet another non-limiting embodiment of the foregoing traction battery pack, the primary cooling path extends through an interior volume of the battery module.

[0017] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the primary cooling path extends between the battery cell and a second battery cell, and further, between the battery cell and an external cover of the battery module.

[0018] In yet another non-limiting embodiment of any of the foregoing traction battery packs, a sealing strip of a frame of the battery module at least partially separates the battery cell from the second battery cell.

[0019] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the auxiliary cooling path extends through an interior volume of the housing assembly housing the battery module.

[0020] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the primary cooling path is configured to circulate a first cooling fluid through: an inlet duct; a delivery line fluidly connected to the inlet duct; an inlet tube of the battery module fluidly connected to the delivery line; an interior volume of the battery module; an outlet tube of the battery module; a receiving line fluidly connected to the outlet tube; and an outlet duct fluidly connected to the receiving line.

[0021] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the auxiliary cooling path is configured to circulate a second cooling fluid through a channel between the battery module and a second battery module.

[0022] In yet another non-limiting embodiment of any of the foregoing traction battery packs, the second cooling fluid comprises a dielectric fluid or an air flow.

[0023] The embodiments, examples and alternatives of the preceding paragraphs, claims or the following description and drawings (including any of their various aspects or corresponding individual features) may be adopted independently or in any combination. Features described in conjunction with one embodiment apply to all embodiments, unless such features are incompatible.

[0024] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 An electrified vehicle is schematically shown.

[0026] Figure 2 A traction battery pack including a thermal management system is shown.

[0027] Figure 3 Shows Figure 2 An exemplary battery module for a traction battery pack.

[0028] Figure 4 yes Figure 3 An exploded view of the battery module.

[0029] Figure 5 yes Figure 3 A cross-sectional view of a battery module and schematically illustrates the main cooling path of the traction battery pack thermal management system.

[0030] Figure 6 The auxiliary cooling path of the traction battery pack thermal management system is schematically shown. DETAILED DESCRIPTION

[0031] The present disclosure details a thermal management system for a traction battery pack. An exemplary thermal management system may include: a primary cooling system configured to direct a first cooling fluid through a first interior volume of one or more battery modules; and an auxiliary cooling system configured to direct a second cooling fluid through a second interior volume of a housing assembly that houses the one or more battery modules. The primary cooling system may establish a primary cooling path for thermally managing battery cells of the one or more battery modules, and the auxiliary cooling system may establish an auxiliary cooling path for thermally managing terminals and / or bus bars of the one or more battery modules. These and other features are discussed in more detail in the following paragraphs of this detailed description.

[0032] Figure 1 An electrified vehicle 10 is schematically shown. The electrified vehicle 10 may include any type of electrified powertrain. In an embodiment, the electrified vehicle 10 is a battery electric vehicle (BEV). However, the concepts described herein are not limited to BEVs and may be extended to other electrified vehicles, including but not limited to hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, and the like. Therefore, although not specifically shown in the exemplary embodiment, the powertrain of the electrified vehicle 10 may be equipped with an internal combustion engine, which may be employed alone or in combination with other power sources to propel the electrified vehicle 10.

[0033] In the illustrated embodiment, the electrified vehicle 10 is depicted as an automobile. However, the electrified vehicle 10 may alternatively be a sport utility vehicle (SUV), a van, a pickup truck, or any other vehicle configuration. Although specific component relationships are shown in the drawings of the present disclosure, the drawings are not intended to limit the present disclosure. The placement and orientation of the various components of the electrified vehicle 10 are schematically shown and may vary within the scope of the present disclosure. In addition, the various drawings attached to the present disclosure are not necessarily drawn to scale, and some features may be enlarged or minimized to emphasize certain details of a particular component or system.

[0034] In the illustrated embodiment, the electrified vehicle 10 is a pure electric vehicle that is propelled solely by electricity, such as by one or more electric machines 12, without assistance from an internal combustion engine. The electric machines 12 may operate as electric motors, generators, or both. The electric machines 12 receive electricity and may convert the electricity into torque for driving one or more wheels 14 of the electrified vehicle 10.

[0035] Voltage bus 16 may electrically couple electric machine 12 to traction battery pack 18. Traction battery pack 18 is an exemplary electrified vehicle battery. Traction battery pack 18 may be a high voltage traction battery pack assembly that includes a plurality of battery cells capable of outputting electrical power to power electric machine 12 and / or other electrical loads of electrified vehicle 10. Other types of energy storage devices and / or output devices may alternatively or additionally be used to power electrified vehicle 10.

[0036] The traction battery pack 18 may be secured to an underbody 20 of the electrified vehicle 10 . However, the traction battery pack 18 may be located elsewhere on the electrified vehicle 10 within the scope of the present disclosure.

[0037] Figure 2 Shown with Figure 1 The traction battery pack 18 of the electrified vehicle 10 may include a plurality of battery modules 22 (e.g., a battery assembly or group of rechargeable battery cells 24) capable of outputting electrical power to power the electric machine 12 and / or other electrical loads of the electrified vehicle 10.

[0038] The battery cells 24 may be stacked side-by-side along a stacking axis to construct a group of battery cells 24 , sometimes referred to as a “cell stack.” The total number of battery modules 22 and battery cells 24 provided within the traction battery pack 18 is not intended to be limiting of the present disclosure.

[0039] In an embodiment, the battery cells 24 of each battery module 22 are prismatic lithium-ion cells. However, within the scope of the present disclosure, battery cells having other geometries (cylindrical, pouch, etc.), other chemistries (nickel metal hydride, lead acid, etc.), or both may alternatively be utilized.

[0040] The battery modules 22 may be arranged in multiple rows within the traction battery pack 18. For example, the battery modules 22 may be arranged in a first row R1, a second row R2 laterally adjacent to the first row R1, and a third row R3 laterally adjacent to the second row R2. In an embodiment, each of the first row R1, the second row R2, and the third row R3 includes five battery modules 22 (a total of fifteen battery modules 22), and each battery module 22 includes four battery cells 24 (a total of sixty battery cells 24). However, other configurations are possible, and thus the traction battery pack 18 may include a greater or lesser number of rows, battery modules, and battery cells within the scope of the present disclosure.

[0041] The battery modules 22 and various other battery internal components (e.g., bus electrical center, battery electrical control module, wiring, connectors, etc.) can be housed within the interior of the housing assembly 28 of the traction battery pack 18. Although shown schematically, the housing assembly 28 can embody a single-piece design or a multi-piece design (e.g., a housing cover and a housing tray that are combined together to establish an interior for housing the battery modules 22). The size, shape, and overall configuration of the housing assembly 28 are not intended to limit the present disclosure. In an embodiment, the housing assembly 28 provides a sealed enclosure around the battery modules 22 and other battery internal components of the traction battery pack 18.

[0042] Each battery module 22 can be completely separated from the other battery modules 22 of the traction battery pack 18. For example, the battery modules 22 can be spaced apart from each other in each of the first row R1, the second row R2, and the third row R3. In addition, the channel 30 can extend between the first row R1 and the second row R2 and between the second row R2 and the third row R3 to separate the battery modules 22 of each corresponding row. The channel 30 can extend longitudinally between the opposite end walls 26 of the housing assembly 28. The side wall 31 of the housing assembly 28 is connected between the end walls 26.

[0043] The traction battery pack 18 may additionally include a thermal management system 32 . As explained further below, the thermal management system 32 may establish both primary and secondary cooling paths for thermally managing the battery modules 22 and / or other electrical components of the traction battery pack 18 .

[0044] The thermal management system 32 may include a primary cooling system 34 and an auxiliary cooling system 36. The primary cooling system 34 may be configured to cool individual surfaces of the battery cells 24 by introducing a first cooling fluid F1 into each battery module 22, and the auxiliary cooling system 36 may be configured to cool components (e.g., terminals, bus bars, etc.) at least partially external to the battery modules 22 by introducing a second cooling fluid F2 into the housing assembly 28 of the traction battery pack 18.

[0045] The main cooling system 34 may include an inlet duct 38, an outlet duct 40, a plurality of delivery lines 42, and a plurality of receiving lines 44. The inlet duct 38 and the outlet duct 40 may extend to the exterior of the housing assembly 28, and at least a portion of the delivery lines 42 and the receiving lines 44 may extend through the interior of the housing assembly 28. The delivery lines 42 may be fluidly connected to the inlet duct 38, and the receiving lines 44 may be fluidly connected to the outlet duct 40. Each delivery line 42 may also be fluidly connected to an inlet pipe 46 of one or more of the battery modules 22, and each receiving line 44 may also be fluidly connected to an outlet pipe 48 of one or more of the battery modules 22.

[0046] The main cooling system 34 may be configured to deliver a first cooling fluid F1 for managing heat generated by the battery cells 24 of the battery module 22 during operation of the traction battery pack 18. In an embodiment, the first cooling fluid F1 is a conventional type of coolant mixture, such as water mixed with ethylene glycol. However, other coolants, including gases, are contemplated within the scope of the present disclosure.

[0047] The inlet conduit 38 may be fluidly connected to a fluid source (not shown) storing the first cooling fluid F1. The fluid source may be part of the main cooling system of the electrified vehicle 10, or may be a dedicated fluid source for the traction battery pack 18. The first cooling fluid F1 may be delivered through the inlet conduit 38 before being separated into a plurality of delivery lines 42. The first cooling fluid F1 may then enter the interior volume of each battery module 22 through the inlet pipe 46 (see, e.g., Figure 5 As the first cooling fluid F1 flows through the interior volume of each battery module 22, the first cooling fluid may absorb heat from the battery cells 24, thereby removing excess heat and stabilizing the temperature of the battery cells 24.

[0048] The first cooling fluid F1 may exit through the outlet tube 48 of each battery module 22 and then enter the receiving line 44 before merging into the outlet conduit 40, which may then be exhausted from the traction battery pack 18. The first cooling fluid F1 may be returned to the fluid source as part of a closed loop system via the outlet conduit 40. Although not shown, the first cooling fluid F1 may be delivered to a radiator or some other heat exchange device for cooling before being returned to the fluid source.

[0049] The auxiliary cooling system 36 may include an inlet duct 50 and an outlet duct 52. The inlet duct 50 and the outlet duct 52 may each be mounted to the housing assembly 28 of the traction battery pack 18. For example, the inlet duct 50 may be mounted to one of the end walls 26 and the outlet duct 52 may be mounted to the other of the end walls 26 of the housing assembly 28. However, other configurations are also contemplated within the scope of the present disclosure.

[0050] The auxiliary cooling system 36 may be configured to deliver the second cooling fluid F2 through the interior volume 76 of the housing assembly 28 (see Figure 2 and Figure 6) for managing heat generated by certain components of the traction battery pack 18. In an embodiment, the second cooling fluid F2 is an airflow or a dielectric fluid. The second cooling fluid F2 may enter the interior volume 76 of the housing assembly 28 through the inlet tube 50. The second cooling fluid F2 may then circulate through various open spaces of the interior volume 76 before being discharged from the traction battery pack 18 through the outlet tube 52. For example, the second cooling fluid F2 may flow through each of the channels 30, through an open space between the side wall 31 and the first row R1 of the battery modules 22, through another open space between the side wall 31 and the third row R3 of the battery modules 22, and so on, for managing heat generated within the traction battery pack 18.

[0051] Figure 3 , Figure 4 and Figure 5 Shows Figure 1 and Figure 2 1. An exemplary design of a battery module 22 of a traction battery pack 18. Each battery module 22 of the traction battery pack 18 may include Figure 3 , Figure 4 and Figure 5 The battery module 22 shown in FIG. 1 is of the same design or a similar design in that its electrical connections to adjacent battery modules may be varied in order to complete the necessary circuit of the traction battery pack 18 .

[0052] The battery module 22 may include a plurality of battery cells 24 stacked between a first frame 54 and a second frame 56. The battery cells 24, the first frame 54, and the second frame 56 may together establish a battery subassembly 58 (in Figure 4 ). The battery subassembly 58 may be received within the exterior cover 60 to establish the battery module 22.

[0053] The battery cells 24 may be held together by the first frame 54 and the second frame 56 in a desired position relative to each other. The first frame 54 and the second frame 56 may each include a plurality of sealing strips 62 that at least partially separate the battery cells 24 of the battery subassembly 58 from each other. The sealing strips 62 may be configured to exert a relatively small amount of compression on the battery cells 24 in order to maintain their position within the battery module 22.

[0054] In an embodiment, the first frame 54 and the second frame 56 are constructed of a high temperature polymer and are square in shape. However, other materials and shapes are also contemplated within the scope of the present disclosure.

[0055] Each battery cell 24 may include a pair of terminals 64. The terminals 64 of adjacent battery cells 24 may be connected by internal bus bars 66 to electrically connect the battery cells 24 of the battery subassembly 58. External bus bars 68 may be provided for electrically connecting the battery subassembly 58 of the battery module 22 to adjacent battery modules of the traction battery pack 18.

[0056] The terminals 64, the internal bus bars 66, and the external bus bars 68 may be disposed at a common side of the battery subassembly 58. Thus, in the exemplary embodiment, the terminals 64, the internal bus bars 66, and the external bus bars 68 are all disposed adjacent to the second frame 56. However, other configurations are also contemplated within the scope of the present disclosure.

[0057] The external cover 60 may be configured as a sleeve including four sides 70 and two open ends 72. The battery subassembly 58 may be inserted into the external cover 60 such that the first frame 54 is located at one of the open ends 72 and the second frame 56 is located at the opposite open end 72. Once the battery subassembly 58 is received within the external cover 60, the sealing strips 62 of the first frame 54 and the second frame 56 are arranged to seal gaps between adjacent battery cells 24 and gaps between the battery cells 24 and the sides 70 of the external cover 60. Thus, the open ends 72 are filled with the battery cells 24, the sealing strips 62, and the remainder of the first frame 54 and the second frame 56 such that the interior volume of the battery module 22 is sealed relative to the external environment surrounding the battery module 22.

[0058] The inlet tube 46 and the outlet tube 48 may extend parallel to the sealing strip 62. The inlet tube 46 may be attached to one of the sides 70 of the outer cover 60 (here, at the top side of the outer cover 60). The outlet tube 48 may be attached to the other of the sides 70 (here, at the bottom side of the outer cover 60). However, other configurations are also contemplated within the scope of the present disclosure.

[0059] Figure 3 and Figure 4 The internal volume 74 of the battery module 22 is Figure 5 Schematically shown in FIG. A main cooling path P1 of the main cooling system 34 of the thermal management system 32 may extend through the internal volume 74 for cooling the battery cells 24 of the battery module 22. When the first cooling fluid F1 circulates along the main cooling path P1, the first cooling fluid may flow over the main surface of each battery cell 24 of the battery module 22 to provide increased cooling performance.

[0060] exist Figure 6Schematically illustrated is an interior volume 76 of the traction battery pack 18. An auxiliary cooling path P2 of the auxiliary cooling system 36 of the thermal management system 32 may extend through the interior volume 76 for cooling components such as the terminals 64, the internal bus bars 66, and the external bus bars 68. A second cooling fluid F2 may be introduced into the interior volume 76 for cooling these and / or other internal battery components.

[0061] The auxiliary cooling system 36 can be configured to automatically introduce the second cooling fluid F2 into the interior volume 76 to flow along the auxiliary cooling path P2 during a battery thermal event. A battery thermal event may occur, for example, during an overcharge condition, an overdischarge condition, or other condition, and may cause one or more of the battery cells 24 to vent battery ventilation byproducts, which may include gases, effluent particles, and / or other ventilation byproducts.

[0062] A temperature sensor 78 may be provided in or near the outlet duct 52 of the housing assembly 28. The temperature sensor 78 may be operably connected to a control module 80 of the thermal management system 32 and may be configured to sense a temperature of the second cooling fluid F2. The temperature sensor 78 may provide an input signal to the control module 80 when the temperature sensed by the temperature sensor 78 exceeds a predefined threshold. In response to receiving the input signal, the control module 80 may command the auxiliary cooling system 36 to begin circulating the second cooling fluid F2 through the interior volume 76 along the second cooling path P2 in order to limit heat propagation during a battery thermal event.

[0063] An exemplary traction battery pack of the present disclosure includes a thermal management system having both a primary cooling system and an auxiliary cooling system. The primary cooling system may provide a compartmentalized / modular design with internal coolant flow to maximize heat transfer from the battery surface to the coolant, and the auxiliary cooling system may provide a battery pack level design with cooling fluid flow for maximizing heat transfer from the battery terminals and / or internal / external bus bars to the cooling fluid.

[0064] Although different non-limiting embodiments are shown as having specific components or steps, the embodiments of the present disclosure are not limited to these specific combinations. Some of the components or features from any one of the non-limiting embodiments may be used in combination with features or components from any one of the other non-limiting embodiments.

[0065] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings.It should be understood that although particular component arrangements are disclosed and shown in these exemplary embodiments, other arrangements may also benefit from the teachings of the present disclosure.

[0066] The above description should be interpreted as illustrative and not in any limiting sense. It will be appreciated by those skilled in the art that certain modifications may occur within the scope of the present disclosure. For these reasons, the attached claims should be studied to determine the true scope and content of the present disclosure.

Claims

1. A traction battery pack, comprising: Housing assembly; a plurality of battery modules, the plurality of battery modules being housed within the housing assembly; a primary cooling system configured to direct a first cooling fluid through a first interior volume of each of the plurality of battery modules; and A secondary cooling system is configured to direct a second cooling fluid through the second interior volume of the housing assembly.

2. The traction battery pack of claim 1 , wherein each of the plurality of battery modules comprises a battery subassembly and an external cover, and optionally wherein the battery subassembly comprises a plurality of battery cells held between a first frame and a second frame. 3 . The traction battery pack of claim 2 , wherein adjacent battery cells in the plurality of battery cells are at least partially separated by sealing strips of the first frame and the second frame.

4. The traction battery pack of claim 2, wherein the external cover includes four sides and two open ends, and optionally, wherein the first frame is positioned at one of the two open ends of the external cover and the second frame is positioned at the other of the two open ends.

5. The traction battery pack of claim 2, the first cooling fluid cooling the plurality of battery cells, and the second cooling fluid cooling bus bars or terminals located outside the first interior volume.

6. A traction battery pack as claimed in any preceding claim, wherein the first cooling fluid cools at least one battery cell of each of the plurality of battery modules and the second cooling fluid cools bus bars or terminals of each of the plurality of battery modules.

7. A traction battery pack as claimed in any preceding claim, wherein the primary cooling system comprises: Inlet pipe; a delivery line fluidly connected to the inlet conduit and to an inlet tube of at least one of the plurality of battery modules; Export pipeline; and a receiving line fluidly connected to an outlet tube of the at least one of the plurality of battery modules and to the outlet conduit, and optionally wherein the first interior volume is located between the inlet tube and the outlet tube.

8. The traction battery pack of any preceding claim, wherein the auxiliary cooling system comprises an inlet duct mounted to a first end wall of the housing assembly and an outlet duct mounted to a second end wall of the housing assembly, and further wherein the second interior volume is located between the inlet duct and the outlet duct.

9. A traction battery pack as claimed in any preceding claim, wherein the first cooling fluid is a coolant and the second cooling fluid is an air flow or a dielectric fluid.

10. A traction battery pack, comprising: A battery module, the battery module comprising battery cells, terminals and bus bars; as well as A thermal management system is provided to establish a primary cooling path for thermally managing the battery cells and an auxiliary cooling path for thermally managing the terminals and the bus bar.

11. The traction battery pack of claim 10, wherein the primary cooling path extends through an interior volume of the battery module.

12. A traction battery pack according to claim 10 or 11, wherein the main cooling path extends between the battery cell and a second battery cell and further, between the battery cell and an external cover of the battery module, and optionally wherein a sealing strip of a frame of the battery module at least partially separates the battery cell from the second battery cell.

13. The traction battery pack of any one of claims 10 to 12, wherein the auxiliary cooling path extends through an interior volume of the housing assembly housing the battery module.

14. The traction battery pack of any one of claims 10 to 13, wherein the primary cooling path is configured to circulate a first cooling fluid through: an inlet duct; a delivery line, the delivery line being fluidly connected to the inlet duct; an inlet pipe of the battery module, the inlet pipe being fluidly connected to the delivery line; an interior volume of the battery module; an outlet pipe of the battery module; a receiving line fluidly connected to the outlet pipe; and an outlet conduit fluidly connected to the receiving line.

15. The traction battery pack of any one of claims 10 to 14, wherein the auxiliary cooling path is configured to circulate a second cooling fluid through a channel between the battery module and a second battery module, and optionally wherein the second cooling fluid comprises a dielectric fluid or an air flow.

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