Cooling architecture for a swappable battery pack

Abstract

A swappable battery pack includes an outer housing defining an inner surface and including a protrusion extending outwardly from the inner surface, and a cell module assembly disposed within the outer housing and including a plurality of battery cells, each defining a positive side and a negative side, and a thermal filler material engaged between a portion of one of the plurality of battery cells and the protrusions, so that a conductive path is formed between the one of the battery cells and the outer housing.

Description

COOLING ARCHITECTURE FOR A SWAPPABLE BATTERY PACKCROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit of and priority to U. S. Provisional Patent Application No. 63 / 671,606, filed on July 15, 2025, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Battery packs may be implemented to provide power to indoor and outdoor power equipment. The battery pack may be removed and replaced after the battery pack is discharged, which enables continued use of the power equipment without having to wait for a single battery back to be recharged.SUMMARY

[0003] In some aspects, the present disclosure relates to a swappable battery pack including: an outer housing defining an inner surface and including a protrusion extending outwardly from the inner surface; a cell module assembly disposed within the outer housing and including a plurality of battery cells, each defining a positive terminal and a negative terminal, wherein the protrusion is aligned with a portion of one of the plurality of battery cells; and a thermal filler material engaged between the portion of the one of the plurality of battery cells and the protrusion, so that a thermally conductive path is formed between the one of the plurality of battery cells and the outer housing.

[0004] In some aspects, the present disclosure relates to a swappable battery pack including: an outer housing defining an interior cavity; a cell module assembly disposed within the interior cavity, the cell module assembly including: a plurality of cell carriers, each cell carrier of the plurality of cell carriers defining a plurality of cell openings arranged in a row that extends in a lateral direction, the plurality of cell carriers being stacked together along a longitudinal direction that is substantially perpendicular to the lateral direction; and a plurality of battery cells disposed within the plurality of cell openings; and an electrically insulative material disposed between the cell module assembly and the outer housing.

[0005] In some aspects, the present disclosure relates to a swappable battery pack including: an outer housing defining an interior cavity; a cell module assembly disposed within the interior cavity, the cell module assembly including: a plurality of cell carriers, each cell carrier of the plurality of cell carriers defining a plurality of cell openings arranged in a row that extends in a lateral direction, the plurality of cell carriers stacked together along a longitudinal direction that is substantially perpendicular to the lateral direction; and a plurality of battery cells disposed within the plurality of cell openings; and a plurality of fans stacked along at least one of the lateral direction or the longitudinal direction and oriented to move air across the cell module assembly.

[0006] This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.BRIEF DESCRIPTION OF THE FIGURES

[0001] The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:

[0002] FIG. 1 is a perspective view of a swappable battery pack, according to an embodiment;

[0003] FIG. 2 is an exploded view of a cell module assembly for a swappable battery pack, according to an embodiment;

[0004] FIG. 3 is a front perspective view of a cell module assembly including a two-piece module frame, according to an embodiment;

[0005] FIG. 4 is a side perspective view of the cell module assembly of FIG. 3;

[0006] FIG. 5 is a perspective view of a cell module assembly including an extruded core, according to an embodiment;

[0007] FIG. 6 is a perspective view of a cell carrier of a cell module assembly, according to an embodiment;

[0008] FIG. 7 is a perspective view of the cell carrier of FIG. 6 after application of a conductive material to the cell carrier, according to an embodiment;

[0009] FIG. 8 is a top view of a single-cell portion of the cell carrier of FIG. 6;

[0010] FIG. 9 is a perspective view of a cell module assembly including a plurality of cell carriers of FIG. 6;

[0011] FIG. 10A is a top view of a cell module assembly of FIG. 9 including electrical connections between the battery cells, according to an embodiment;

[0012] FIG. 10B is a perspective view of a portion of the cell module assembly of FIG. 10A, showing the electrical connections between cells of the core module assembly;

[0013] FIG. 11 is a top perspective view of a cell module assembly including a plurality of cell carriers, according to another embodiment;

[0014] FIG. 12 is a perspective view of a first cell carrier of the cell module assembly of FIG. 11;

[0015] FIG. 13 is a perspective view of a second cell carrier of the cell module assembly of FIG. 11;

[0016] FIG. 14 is a top perspective view of a core module assembly that includes heat transfer elements incorporated into busbars to facilitate heat transfer between opposing ends of the core module assembly, according to an embodiment;

[0017] FIG. 15 is a bottom perspective view of the core module assembly of FIG. 14;

[0018] FIG. 16 is a side view of a core module assembly that includes heat transfer elements to facilitate heat transfer between opposing ends of the core module assembly, according to another embodiment;

[0019] FIG. 17 is a perspective view of a core module assembly for a swappable battery pack that includes internal stirring fans, according to an embodiment;

[0020] FIG. 18 is a perspective view of a heat transfer model of the core module assembly of FIG. 17;

[0021] FIG. 19 is a top view of a contour plot generated using the heat transfer model of FIG. 18, shown with the stirring fans deactivated;

[0022] FIG. 20 is a perspective view of the contour plot of FIG. 19;

[0023] FIG. 21 is a top view of a contour plot generated using the heat transfer model of FIG.18, shown with the stirring fans activated;

[0024] FIG. 22 is a perspective view of the contour plot of FIG. 21;

[0025] FIG. 23 is a perspective view of a swappable battery pack that includes an air flow circulation system, according to an embodiment;

[0026] FIG. 24 is a perspective view of a swappable battery pack that includes an external air circulation system, according to an embodiment;

[0027] FIG. 25 is a perspective view of a swappable battery pack that includes a cooling system that is configured to selectively vent an outer housing of the battery pack to an external environment, according to an embodiment; and

[0028] FIGS. 26-30 are charts showing battery cell temperature as a function of operating time under different operating conditions for multiple different swappable battery pack configurations, according to various embodiments.

[0029] FIG. 31 is a top view of a swappable battery pack including a thermal filler material arranged within a holding plate, according to an embodiment;

[0030] FIG. 32 is a bottom perspective view of a housing of a housing of a swappable battery pack, according to an embodiment;

[0031] FIG. 33 is a schematic illustration of a cell module assembly arranged within the housing of FIG. 32 and including a thermal filler material; and

[0032] FIG. 34 is a schematic illustration of a cell module assembly arranged within the housing of FIG. 32 and including a thermal filler material.DETAILED DESCRIPTION

[0033] Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology setforth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting.

[0034] Battery packs can be used to provide power to a variety of products, including outdoor power equipment, standby generators, and other applications. Some battery packs are “swappable”, meaning that the battery pack can be easily removed from and replaced on the products (e.g., for charging, replacement with a charged battery pack). These swappable battery packs are self-contained units that can be charged remotely from the power equipment, and enable continued use of the power equipment through replacement of the battery packs. Existing swappable battery packs typically include a durable outer housing that is sealed from the outside environment to reduce the risk of water and particulate ingestion during use and to prevent damage to the battery cells contained within the outer housing. However, such sealed housing construction can cause difficulties with managing the temperature of the battery cells during use and / or recharging.

[0035] Referring to the figures generally, systems and methods for improving cooling performance of swappable battery packs are shown, according to various embodiments. In some embodiments, the swappable battery pack includes a cell module assembly that supports the battery cells and facilitates heat transfer between the battery cells and an environment surrounding the housing. For example, the cell module assembly may include cell carriers made from a metallic material that extend along the length of the cells to facilitate heat transfer from the battery cells to the wall(s) of the outer housing. In this way, the outer housing forms part of the cooling system and dissipates heat from the battery cells to an environment surrounding the outer housing. In some embodiments, the cell carriers may be formed using an extrusion operation, which can provide a more uniform cross section for heat transfer along the axial direction between opposing ends of each battery cell. Such designs can also provide weight savings by eliminating excess materials along the perimeter of each battery cell. In such arrangements, the battery cells may all be oriented along the same direction within the outer housing, with at least one side of the cell carriers bonded to the outer housing, which can reduce thermal resistance between the battery cells and the outer housing, and reduce the average operating temperature of the battery cells.

[0036] In some embodiments, the swappable battery pack includes fans positioned within the outer housing and arranged to recirculate air across the battery cells. Such an arrangement can also improve air flow across the inner surface of the outer housing, and provide convective heat transfer between the cells and the outer housing. In some embodiments, at least one fan is positioned to recirculate air through a conduit or passage external of the outer housing, which can increase the surface area available for heat transfer to the surroundings, and reduce flow restriction upstream of the fan(s). In at least one embodiment, the battery pack may further include at least one vent flap that is configured to selectively allow transfer of ambient air external to the housing, through the outer housing, and across the battery cells. In such embodiments, the battery pack may include a battery pack controller that is configured to selectively actuate the vent flap to enable exchange of ambient air during certain periods, such as during charging (and / or coordinated with other activities associated with greater than average heat generation). Such an arrangement can reduce the operating temperature of the battery cells during periods of large heat generation, while maintaining sealing requirements during use of the battery pack with power equipment.

[0037] In still further embodiments, the swappable battery pack includes metallic extrusions / standoffs within the cell module assembly and / or sealed openings through the outer housing to facilitate heat transfer between the cell module assembly and the outer housing, as will be further described.

[0038] Among other benefits, the various cooling systems and methods disclosed herein can enable sustained operation of the swappable battery pack at greater charge / discharge rates without damaging the battery cells. The cooling systems and methods of the present disclosure can also enable a more uniform charge / discharge rate without exceeding temperature limits. For example, various implementations and combinations disclosed herein can enable charge rates of the swappable battery pack of approximately 1C or greater at 25°C.

[0039] Referring now to FIG. 1, a swappable battery pack 100 is shown with improved heat transfer performance is shown, according to an exemplary embodiment. In some embodiments, the battery pack 100 is configured to be removably coupled to a piece of power equipment, and may be recharged separately from the power equipment. For example, the battery pack 100 may be configured to be inserted (e.g., dropped, lowered, placed) into a receptacle integrated with a piece of power equipment and / or a charging station. In some embodiments, the battery pack 100is configured to provide electrical power to a power equipment, such as any type of equipment, machine, or vehicle that may be used to perform a chore (e.g., an outdoor chore, an indoor chore, lawn care, etc.). For example, the power equipment may include a motor, a pump, an actuator, a compressor, and / or another device that is electrically powered to operate some function of the power equipment to facilitate performing a chore.

[0040] The battery pack 100 can be installed into a piece of equipment vertically, horizontally, and / or at any angle. In some embodiments, the battery pack 100 may include a Lithium-ion battery. However, other battery types are contemplated, such as nickel-cadmium (NiCD), lead- acid, nickel-metal hydride (NiMH), lithium polymer, etc. In some embodiments, the battery pack 100 yields a voltage of between approximately 12 and approximately 200 Volts (V), or for example, 48V, and a capacity between approximately 200 and approximately 2000 Watt-hours (Wh) of energy. In some embodiments, the battery pack 100 may have a peak discharge current of 80 A, 100 A, 125 A, or greater. The battery pack 100 may be sized differently depending on application requirements. For example, the battery pack 100 may include a capacity that is between about 1000 Wh and about 2000 Wh, or between about 1100 Wh and about 1900 Wh, or between about 1200 Wh and 1800 Wh, or any range between and including any two of the foregoing values.

[0041] Referring to FIGS. 1-2, the battery pack 100 includes an outer housing 102 (e.g., a battery case, a case wall, etc.), and a cell module assembly 104 housed within the outer housing 102. The outer housing 102 includes a plurality of sidewalls, shown as outer walls 105 (e.g., exterior walls, sidewalls, etc.) that together define an interior cavity. The outer housing 102 is fabricated from a die cast aluminum material. In some embodiments (see FIG. 1), the outer housing 102 is a multi-piece housing assembly that includes at least two side portions that are sealingly engaged with one another. For example, the two-piece housing may be welded together, and / or may include sealing materials (e.g., O-rings, gaskets, etc.) to prevent water and particulate ingestion from an environment surrounding the outer housing 102 into the interior cavity. The outer housing 102 fluidly seals the interior cavity and provides an ingress protection (IP) rating of 55 (i.e., IP55 defined by the International Electrotechnical Commission) or greater (e.g., IP66, etc.).

[0042] Referring to FIG. 2, the cell module assembly 104 is configured to support a plurality of battery cells 110 within the outer housing 102 and to facilitate heat transfer between the battery cells 110 and the outer housing 102. The cell module assembly 104 is configured to be positioned within the internal cavity of the outer housing 102. In the embodiment of FIG. 2, the cell module assembly 104 includes a cell carrier 106, a heat collection member 108, the plurality of battery cells 110, and a plurality of cell sleeves 112. In other embodiments, the cell module assembly 104 may include additional, fewer, and / or different components.

[0043] The cell carrier 106 is configured to support the battery cells 110 in an array within the outer housing 102. The cell carrier 106 defines a plurality of cell openings 114 arranged in a row that extends in a lateral direction 1 16 along the outer housing 102 (see also FIG. 1) and between opposing ends of the outer housing 102. The cell carrier 106 has a length along an axial direction 117 (e.g., parallel to a central axis of the battery cells 110) to support the battery cells 110 and to electrically insulate the battery cells 110 from one another. In some embodiments, the length of the cell carrier 106 is greater than half the length of the battery cells 110, which can improve electrical isolation therebetween and provide greater support against vibrational loading.

[0044] In some embodiments, the cell carrier 106 is formed from a plastic material or another electrically insulative material, which prevents electrical shorting between the battery cells 110.

[0045] The heat collection member 108 is engageable with the cell carrier 106 and couples the cell carrier 106 to the outer housing 102 (see also FIG. 1). In the embodiment of FIG. 2, the heat collection member 108 is a second portion of the cell carrier 106 having a similar construction as the cell carrier 106. The heat collection member 108 defines a plurality of member openings 118 that align with the cell openings 114 of the cell carrier 106 when the heat collection member 108 is coupled to the cell carrier 106. In some embodiments, the member openings 118 define pockets (e g., recessed areas, etc.) that are engageable with axial ends of the battery cells 110, and that maintain separation between the battery cells 110 and the outer housing 102. In other embodiments, the member openings 118 are through-hole openings that extend through the entire thickness of the heat collection member 108.

[0046] The heat collection member 108 also engages the battery cells 110 along a length of the battery cells 110. The heat collection member 108 has a length along the axial direction 117 (e g., parallel to a central axis of the battery cells 110) to allow for heat conduction from the batterycells 110 at multiple locations along the length of the battery cells 1 10. Such an arrangement can increase heat transfer performance by increasing the effective cross-sectional area for heat transfer between axial ends of the battery cells 110.

[0047] In some embodiments, the heat collection member 108 is formed from a metallic material (e.g., aluminum, etc.) by an extrusion operation, which ensures a uniform cross-sectional area for heat transfer along the axial length of the heat collection member 108. In other embodiments, the heat collection member 108 may be formed from a casting and / or machining operation.

[0048] In some embodiments, the heat collection member 108 is electrically insulated from the outer housing 102 by a pad 120 of electrically insulative material. The pad 120 may be made from a material with high electrical resistivity while having a low thermal resistance. For example, the pad 120 may be made from an Kapton® tape, fish paper, or another type of insulative paper or layer (e.g., Nomex® 410, etc.), a glass-reinforced epoxy laminate material (e.g., FR4, etc.), a thermally conductive glue or adhesive that provides heat transfer without conducting electricity (e g., an adhesive including alumina, etc ). In some embodiments, the pad 120 extends across the entire heat collection member 108 along both the lateral direction 116 and a longitudinal direction that is perpendicular to the lateral direction 116. In such embodiments, the pad 120 completely insulates the heat collection member 108 from the outer housing 102.

[0049] The plurality of cell sleeves 112 are configured to couple the battery cells 110 to the cell carrier 106. The cell sleeves 112 also provide thermal coupling between an outer perimeter wall of the battery cells 110 and the heat collection member 108. In the embodiment of FIG. 2, the plurality of cell sleeves 112 each include a hollow cylindrical sleeve made from a metallic material (e.g., 304 stainless steel, etc.). An axial end of each cell sleeve 112 is engageable with the member openings 118 of the heat collection member 108 and are configured to thermally couple the battery cells 110 to the heat collection member 108. Such an arrangement increases the cross-sectional area available for heat transfer along the axial direction 117, and reduces thermal resistance between opposing axial ends of the battery cells 110.

[0050] The battery cells 110 are disposed within the cell sleeves 112 and are configured to output power to operate a piece of power equipment. In some embodiments, the battery cells 110 may be lithium-ion battery cells. In some embodiments, the battery cells 110 are tab-less batterycells in which the terminals are formed along an entire length of a conductive substrate at either end, which can further reduce resistive heating across the battery cells 110. In some embodiments, the battery cells 110 are grouped in subsets or groups along the lateral direction 116 that are connected in a parallel configuration. Each of the groups may then be connected in a series configuration to achieve a desired voltage. In some embodiments, the battery cells 110 may be electrically connected to one another using electrical connectors (e.g., conducting wires) and common conductors (e.g., collector plates, etc.).

[0051] The design and arrangement of the cell module assembly 104 described with reference to FIGS. 1-2 should not be considered limiting and various changes are possible without departing from the inventive principles disclosed herein. For example, referring to FIGS. 3-4, a cell module assembly 204 is shown that includes a cell carrier 206 made from a thermally conductive material, according to an embodiment. The cell carrier 206 is a multi-piece assembly that includes a first frame element 222 and a second frame element 224 engaging opposite axial ends of the battery cells 210. The first frame element 222 and the second frame element 224 nestably engage one another to support the battery cells 210.

[0052] The first frame element 222 is configured to support a first axial end 226 of the battery cells 210. The second frame element 224 is configured to engage with and support a second axial end 228 of the battery cells 210. In some embodiments, the first frame element 222 and / or the second frame element 224 define a plurality of cell openings 214 extending axially therethrough that are configured to receive an axial end of the battery cells 210 and to maintain spacing between the axial ends of the battery cells 210.

[0053] In the embodiment of FIGS. 3-4, the first frame element 222 includes a first base panel 230 and a first plurality of support panels 232 extending substantially perpendicular to the first base panel 230. The first base panel 230 extends across an axial end (e.g., the first axial end 226) of each one of the battery cells 210. In some embodiments, the first base panel 230 is a planar wall that extends normal to a central axis of each of the battery cells 210.

[0054] The first base panel 230 defines a first plurality of cell openings 214a that are configured to receive the first axial end 226 of each of the battery cells 210 therein. In some embodiments, the first plurality of cell openings 214a define a first plurality of cell pockets that support the first axial end 226 so that the first axial end 226 of the battery cells 210 are spacedapart from an outer housing of the battery pack (which prevents electrical shorting between the battery cells 210 and the outer housing). In other embodiments, the first plurality of cell openings 214a are through-hole openings that extend through an entire thickness of the first base panel 230.

[0055] The first plurality of support panels 232 extend away from a surface of the first base panel 230 on a battery-facing side of the first base panel 230. In the embodiment of FIGS. 3-4, each support panel of the first plurality of support panels 232 extends axially away from a respective one of the first plurality of cell openings 214a. The first plurality of support panels 232 each define an arcuate support surface that extends across a first perimeter portion of a respective one of the battery cells 210. In some embodiments, as shown in FIG. 3, at least one of the support panels 232 defines multiple arcuate support surfaces disposed between adjacent ones of the battery cells 210.

[0056] In the embodiment of FIGS. 3-4, the first frame element 222 also includes a plurality of compression limiters 234 that are configured to facilitate coupling between the first frame element 222 and the second frame element 224. The plurality of compression limiters 234 are disposed in approximately equal intervals along an outer perimeter of the first frame element 222. The compression limiters 234 extend parallel to the first plurality of support panels 232 and toward the second frame element 224.

[0057] In some embodiments, the first base panel 230, the first plurality of support panels 232, and the compression limiters 234 are integrally formed as a monolithic body from a single piece of material. In other embodiments, at least one of the first plurality of support panels 232 and the compression limiters 234 are formed separately from the first base panel 230 and are welded, fastened, or otherwise secured to the first base panel 230. In yet other embodiments, at least one of the compression limiters 234 is integrally formed with the second frame element 224, or portions of a single compression limiter 234 are formed on each of the first frame element 222 and the second frame element 224.

[0058] In some embodiments, the second frame element 224 has a similar design as the first frame element 222. In some embodiments, the second frame element 224 is symmetric with the first frame element 222. In other embodiments, the design of the first frame element 222 and the second frame element 224 are different. In the embodiment of FIGS. 3-4, the second frame element 224 includes a second base panel 236 and a second plurality of support panels 238extending away from a batery-facing side of the second base panel 236 in substantially perpendicular orientation with respect to the second base panel 236.

[0059] In the embodiment of FIGS. 3-4, each support panel of the second plurality of support panels 238 extends axially away from a respective one of the second plurality of cell openings 214b. The second plurality of support panels 238 each define an arcuate support surface that extends across a second perimeter portion of a respective one of the battery cells 210. In some embodiments, the second perimeter portion is disposed at an opposite side of the battery cells 210 as the first perimeter portion, which prevents movement of the battery cells 210 relative to the cell openings when the first frame element 222 is coupled to the second frame element 224. The first perimeter portion and the second perimeter portion together define a cylindrical passage that is configured to receive a respective one of the battery cells 210 therein.

[0060] In some embodiments, the first perimeter portion and the second perimeter portion are spaced apart from one another by a circumferential gap, which prevents electrical shorting between the two frame elements. In the embodiment of FIGS. 3-4, a radius of curvature of each of the arcuate surfaces of the first perimeter portion and the second perimeter portion are approximately equal. In some embodiments, the radius of curvature of each of the arcuate surfaces is a few degrees smaller than a radius of curvature of the battery cells 210. Such an arrangement can facilitate engagement between the support panels and the outer wall of the batery cells 210, which can reduce thermal resistance due to conduction therebetween.

[0061] Referring to FIG. 5, a cell module assembly 304 for a swappable battery pack is shown that includes a plurality of cell carriers 306 that are stacked or otherwise arranged together to support the battery cells 310 in substantially parallel rows.

[0062] In the embodiment of FIG. 5, the cell module assembly 304 includes three cell carriers 306 that are similar to one another (e.g., identical to one another). Each cell carrier of the plurality of cell carriers 306 includes a body 322 defining a plurality of cell openings 314 arranged in a row that extends in a lateral direction 316 across the swappable battery pack (e.g., the outer housing, the interior cavity, etc.). In the embodiment of FIG. 5, the body 322 is a rectangular prism having a rectangular cross- section. In other embodiments, the shape of the body 322 is different.

[0063] In some embodiments, the cell openings 314 are arranged in a substantially linear row across the body 322. In the embodiment of FIG. 5, the cell carriers 306 are machined, cast,extruded, or otherwise formed from a metallic material such as aluminum, or another material with high thermal conductivity. In this way, the cell carriers 306 can provide a greater cross-sectional area for conduction between axial ends of the battery cells 210, and can also allow for radial conduction of heat away from the battery cells 210 along their length.

[0064] The cell carriers 306 are stacked together along a longitudinal direction 318 that is substantially perpendicular to the lateral direction 316. The cell carriers 306 are arranged parallel to one another and together define substantially parallel rows of cell openings 314. In some embodiments, the battery cells 310 are arranged in the same direction within each cell carrier 306 (e g., the axial orientation of each of the battery cells 310 within the cell carrier 306 is the same) so that each cell carrier 306 can define part of a parallel electronic circuit for the swappable battery pack. The battery cells 310 are bonded or otherwise secured to the cell carriers 306 using a thermally conductive material. Adjacent ones of the cell carriers 306 may be electrically connected to one another in series so that a cathode (e.g., a negative terminal) is disposed on a first longitudinal end 324 of the cell module assembly 304 and an anode (e.g., a positive terminal) is disposed on a second longitudinal end 326 of the cell module assembly 304 opposite the first longitudinal end 324.

[0065] In some embodiments, the cell module assembly 304 also includes electrically insulative materials to prevent shorting between adjacent ones of the plurality of cell carriers 306. For example, the cell module assembly 304 may include insulating tape 328 (e.g., Kapton® tape, etc.), and / or another one of the electrically insulative materials discussed herein. The insulating tape 328 may be applied in between adjacent ones of the cell carriers 306, as well as between an axial end surface of the cell carriers 306 and a heat collection member 308 (e.g., an end plate, an outer wall of the outer housing, etc.). In such an embodiment, a first axial end of the cell module assembly 304 may be bonded to the heat collection member 308, which can further improve heat transfer performance by spreading out the heat generated by the battery cells 210 across the outer housing.

[0066] Referring to FIGS. 6-9, and FIGS. 10A-10B, a cell module assembly 404 is shown that includes a plurality of cell carriers 406 made from a metallic material by an extrusion operation. Referring to FIG. 6, each cell carrier is formed as a single monolithic piece having approximately uniform wall thickness. Such an arrangement can reduce weight of the overall cellmodule assembly 404 without significantly reducing heat transfer performance. The cell carriers 406 can also include outer flanges, which can be used to define an electrical circuit between the battery cells 410 in each cell carrier and the cell carrier body.

[0067] In the embodiment of FIG. 6, the cell module assembly 404 includes a busbar 422 for each cell carrier that electrically couples the battery cells 410 in each cell carrier together. In some embodiments, the busbar 422 is mechanically stabilized to a respective one of the cell carriers 406 using a vibration reducing adhesive, such as a room temperature vulcanizing (RTV) silicone. In such an arrangement, the busbar 422 may provide an electrical connection between a button of each of the battery cells 410 (e.g., a header, a cathode, etc.) along the length of the cell carrier. In the embodiment of FIG. 6, lateral ends of each busbar 422 extend into a channel 424 defined by core tabs at opposing lateral ends of the cell carrier. In some embodiments, the busbars are slidably engaged with the cell carriers 406 at the channels 424 along the axial direction. Such an arrangement can accommodate expansi on / contracti on of the battery cells 410 during operation by enabling relative movement between the busbars and the cell carriers 406.

[0068] Referring to FIG. 7, the cell carriers 406 may be coated with varnish or another electrically insulative material to prevent electrical shorting between adjacent ones of the cell carriers 406. In other embodiments, another type of electrically insulative material may be used to prevent electrical connections between the cell carriers 406, while still promoting heat transfer between adjacent cell carriers 406. Referring to FIG. 8, an electrically insulative resin, varnish, and / or another electrically insulative material may also be used to secure the battery cells 410 to the cell carriers 406, while at the same time reducing thermal resistance between the battery cells 410 and the cell carriers 406.

[0069] Referring still to FIG. 8, the cell carriers 406 may also include anti-rotation features within the cell openings 414 to prevent relative movement between the battery cells 410 and the cell carriers 406 during operation. In some embodiments, the anti-rotation features may include at least one rib 426 protruding radially into the cell openings 414 that are configured to engage an outer surface of a respective one of the battery cells 410. For example, the anti-rotation feature may include a pair of diametrically opposed ribs within each cell opening to prevent relative movement between the battery cells 410 and the cell carriers 406. It should be understood that the size, shape, and arrangement of ribs may be different in various embodiments.

[0070] Referring to FIG. 9 and FIGS. 10A-10B, the plurality of cell carriers 406 are stacked together along a longitudinal direction 418 between opposing ends of the swappable battery pack (e.g., the internal cavity). In at least one embodiment, the cell module assembly 404 also includes electrical connections, such as wires, between the battery cells 410 and other components of the cell module assembly 404 (e.g., the busbar(s), the cell carrier(s), etc.).

[0071] The number and diameter of the electrical connections, including wires and wire bonds, are selected to reduce resistive heating of the swappable battery pack during operation. For example, electrical connections may include multiple bonds to reduce electrical resistance, and may use larger diameter wires and / or ribbons in place of wires in at least portions of the cell module assembly to reduce resistive heating during recharging / discharging of the battery cells.

[0072] Referring to FIG. 11 , another cell module assembly 450 is shown that includes multiple different cell carrier structures, shown as a first cell carrier 452 and a second cell carrier 454. Each of the first cell carrier 452 and the second cell carrier 454 include greater wall thickness than the cell carrier described with reference to FIGS. 10A-10B, which can increase the area available for heat transfer, and reduce the heat transfer resistance along the radial and axial directions, through the first cell carrier 452 and the second cell carrier 454 (e.g., between opposing axial ends of the first cell carrier 452 and the second cell carrier 454). The structure of the first cell carrier 452 and the second cell carrier 454 can also provide greater structural support for the battery cells.

[0073] In the embodiment of FIG. 11, the cell module assembly includes a single second cell carrier 454. In other embodiments, the cell module assembly includes a plurality of second cell carriers that are stacked together. The first cell carrier 452 is one of a pair of first cell carriers that are disposed at opposing ends of the second cell carrier 454 or a stack of second cell carriers.

[0074] Referring to FIG. 12, the first cell carrier 452 includes a first cell carrier body 456 (e.g., a first cell carrier block, etc.). The first cell carrier body 456 includes a plurality of arcuate surfaces defining a plurality of grooves 458 (e.g., channels, passages, etc.) extending along an axial direction from a first axial end of the first cell carrier body 456 and through a second axial end of the first cell carrier body 456. The plurality of grooves 458 each extend parallel to one another and define a half portion of a cell opening. The plurality of grooves 458 are shaped complementary to the battery cells (e.g., a semi-circular shape, etc.) and are configured to nestably engage arespective one of a plurality of battery cells along an outer surface of the battery cells to reduce heat transfer resistance between the battery cells and the first cell carrier 452.

[0075] Referring to FIG. 13, the second cell carrier 454 includes a second cell carrier body 460. The second cell carrier body 460 is shaped similar to the first cell carrier body 456 (see FIG. 12) on one side of the second cell carrier body 460. The second cell carrier body 460 includes a first plurality of arcuate surfaces defining a first plurality of grooves 462 (e.g., channels, passages, etc.) extending along an axial direction from a first axial end of the second cell carrier body 460 and through a second axial end of the second cell carrier body 460. The first plurality of grooves 462 each extend parallel to one another and define a half portion of a cell opening. The second cell carrier body 460 also includes a second plurality of arcuate surfaces defining a second plurality of grooves 464 on an opposing side of the second cell carrier body 460 as the first plurality of grooves 462. In some embodiments, the second cell carrier body 460 is symmetric about an axial reference plane extending through the second cell carrier body 460.

[0076] Referring again to FIG. 11, the first plurality of grooves 462 from one of the second cell carriers is aligned with the plurality of grooves 458 of a respective one of the first cell carriers to define a plurality of cell openings 466 therebetween. In some embodiments, the first cell carrier 452 and / or the second cell carrier 454 are machined, cast, extruded, or otherwise formed from a metallic material such as aluminum, or another material with high thermal conductivity. In some embodiments, the cell module assembly 450 also includes a pad 468 that is “sandwiched” or otherwise disposed between (i) the first cell carrier 452 and the second cell carrier 454, and (ii) a lower frame element. The pad 468 is configured to reduce heat transfer resistance between the cell carriers and the lower frame element while also electrically insulating the ends of the first cell carrier 452 and the second cell carrier 454. In some embodiments, the pad 468 is a soft, conformable, thermally conductive and electrically insulative pad, such as a Sil Pad® produced by Henkel Adhesive Technologies. The pad 468 may include fiberglass and / or silicone rubber.

[0077] Other electrical components of the cell module assembly may also facilitate heat transfer between the battery cells and the outer housing. For example, referring to FIGS. 14-15, a cell module assembly 504 is shown that includes a plurality of busbars 522 that extend axially between opposing frame elements of a cell carrier structure. The busbars 522 are configured to electrically connect the battery cells to one another and / or to electrical terminals of the swappablebattery pack. In the embodiment of FIGS. 14-15, the busbars 522 include heat pipes that transfer heat between the frame elements. For example, at least one of the busbars 522 may include an outer tube or conduit made from an electrically conductive material, such as aluminum or copper. The at least one busbar may also include a wick (e.g., an absorbent material, etc.) lining at least a portion of an inner surface of the outer tube and extending between opposing axial ends of the outer tube. The outer tube and the wick may define a vapor cavity configured to receive a working fluid therein (e.g., alcohol, etc.) to facilitate heat transfer between opposing ends of the busbar.

[0078] Referring to FIG. 16, a side view of a cell module assembly 550 is shown, according to another embodiment. The cell module assembly 550 includes a first frame element 552 (e.g., an upper frame element as shown in FIG. 16), a second frame element 554 (e.g., a lower frame element as shown in FIG. 16), a pad 556, and a plurality of connector elements 558. The first frame element 552 and the second frame element 554 are configured to support the battery cells 560 and to maintain uniform spacing between the battery cells 560. The first frame element 552 and the second frame element 554 are spaced apart from one another to define an axial gap therebetween. The first frame element 552 and the second frame element 554 extend parallel to one another and across each of the plurality of battery cells 560.

[0079] The first frame element 552 defines a plurality of cell openings 562 that are structured to nestably receive the battery cells 560 therein. In at least one embodiment, the first frame element 552 is formed from a metallic material with high electrical conductivity to transfer heat from the ends of the battery cells 560 to the plurality of connector elements 558.

[0080] The plurality of connector elements 558 couple the first frame element 552 to the second frame element 554. In the embodiment of FIG. 16, the plurality of connector elements 558 are bolts that are disposed along a perimeter of the first frame element 552 and the second frame element 554 and that extend from the first frame element 552 to the second frame element 554. The bolts are formed from a metallic material with high electrical conductivity to transfer heat between the first frame element 552 and the second frame element 554.

[0081] The pad 556 is engaged with and coupled to the second frame element 554. The pad 556 extends across an upper surface of the second frame element 554. In some embodiments, the pad 556 is made from the same or similar material as described with respect to the pad 468 of FIG. 11. The pad 556 extends between the battery cells 560 and the second frame element 554 andelectrically insulates adjacent battery cells 560 from one another and the second frame element 554.

[0082] In some embodiments, the swappable battery pack includes a plurality of conductive extrusions to increase heat transfer performance of the swappable battery pack. For example, the swappable battery pack may include at least one heat pipe disposed in an unused one of the cell openings to increase heat transfer between opposing axial ends of the cell module assembly, and / or between the cell carrier and the outer housing. In other embodiments, at least one of the cell openings in the cell module assembly (e.g., the cell carrier) is configured to receive a solid metallic (e g., aluminum, copper, etc.) standoff in the middle of the cell module assembly, which can provide both heat transfer and an additional structural support for the swappable battery pack.

[0083] In some embodiments, the swappable battery pack includes a plurality of heat pipes and / or thermally conductive standoffs spaced at approximately equal intervals across the cell module assembly (e.g., three standoffs down the middle (vertically), four or more standoffs arranged in a square or circular arrangement that surround a central one of the cell openings, etc.), or another arrangement of metallic standoffs. In yet other embodiments, the standoff(s) may include a cantilevered metallic post extending from one side of outer housing and that is fastened to the other side of the outer housing via a bolt or another mechanical fastener. In yet further embodiments, the cell module assembly includes two diametrically opposed standoffs extending from opposing sidewalls of the outer housing, and that facilitate heat transfer to opposing sides of the outer housing. In such embodiments, the standoffs need not engage one another, as each will enhance heat transfer to a respective side of the outer housing.

[0084] In yet other embodiments, the cell module assembly includes additional electrically conductive materials that are embedded into the cell carrier, and / or that are connected between the cell carrier and the outer housing. For example, the cell module assembly may include strips of aluminum between rows of cells that thermally couple the cell carrier to the outer housing. Such features can significantly reduce the average battery cell temperature during operation, and can thereby enable continuous discharge rates at greater currents than in existing swappable battery pack designs.

[0085] Referring to FIGS. 17-18, a swappable battery pack 600 is shown that includes a plurality of fluid drivers 608 (e.g., fans, blowers, etc.) configured to recirculate air across aplurality of battery cells 210 within an outer housing 602 of the battery pack 600. The fluid drivers 608 are coupled to a cell module assembly 604 of the battery pack 600 and may form part of the cell module assembly 604. In other embodiments, the fluid drivers 608 are directly coupled to the outer housing 602, such as to at least one sidewall of the outer housing 602.

[0086] In the embodiment of FIGS. 17-18, the plurality of fluid drivers 608 are stacked within an interior cavity 603 of the outer housing 602, and along a lateral direction and / or a longitudinal direction between opposing ends of the outer housing 602. For example, the fluid drivers 608 may be stacked parallel to at least one sidewall of the outer housing 602. The fluid drivers 608 are arranged to direct air across the plurality of battery cells 610 in a direction that is substantially perpendicular to the at least one sidewall. In some embodiments, the fluid drivers 608 are spaced apart from the at least one sidewall by a gap 620, which can reduce flow restriction at an upstream end of the fluid drivers 608 and increase the overall flow rate of air across the battery cells 610 and outer housing 602. In some embodiments, at least one end of the cell module assembly 604 is also be spaced apart from the outer housing 602, which can increase the flow rate of air across an exterior wall of the outer housing 602, thereby increasing convective heat transfer to the outer housing 602.

[0087] In some embodiments, the battery pack 600 (e.g., the outer housing 602, the cell module assembly 604, etc.) includes at least one baffle that is configured to increase the flow rate of air across different surfaces of the outer housing 602. The baffles can also reduce areas of flow recirculation or “dead zones” within the interior cavity 603. For example, and referring to FIG. 18, the baffles may include flow directing louvers 622 on a sidewall of the outer housing that is opposite from the plurality of fluid drivers 608. The flow directing louvers 622 redirect the flow from the fans across upper and lower exterior walls of the outer housing 602. In other embodiments, the baffles may include ribs, flanges, and / or another flow directing structure to enhance heat transfer performance.

[0088] In some embodiments, the outer housing 602 defines at least one flow passage that extends through the cell module assembly 604. Such an arrangement can increase the surface area of the outer housing 602 and can also reduce resistance to conductive heat transfer between the cell module assembly 604 and the outer housing 602. In some embodiments, the battery pack 600further includes a heat pipe disposed within the at least one flow passage, or a fluid driver configured to direct air through the at least one flow passage.

[0089] Referring to FIGS. 19-22, various contour plots from a finite element analysis of a swappable battery pack that includes a plurality of internal fluid drivers are shown. The contour plots in compare heat transfer performance of the swappable battery pack 600 of FIGS. 17-18 with the fluid drivers 608 deactivated (FIGS. 19-20) and activated (FIGS. 21-22). In particular, FIG. 19 and FIG. 21 compare the heat transfer performance of the two operating modes during 5 minutes of battery cell operation at 100 A discharge, starting at an average battery cell temperature of 27°C. FIG. 20 and FIG. 22 compare the heat transfer performance of the two operating modes after a 5- minute period of fan operation starting with a battery temperature of approximately 50°C. As shown, the fluid drivers 608 significantly improve overall cooling performance of the swappable battery pack 600, providing a reduction of approximately 4°C during battery operation (comparing FIG. 19 and FIG. 21), and increase heat rejection from the case by over 200% (comparing FIG. 20 and FIG. 22).

[0090] Referring to FIG. 23, a swappable battery pack 700 is shown that includes an air flow circulation system 704 (e.g., a cooling system, etc.) disposed at least partially exterior to an outer housing 702 of the battery pack 700. The air flow circulation system 704 includes a pair of fluid drivers 708 (e.g., a fan, a blower, etc.) disposed outside of the outer housing 702 on opposing sides of the outer housing 702. The fluid drivers 708 are fluidly coupled to an interior cavity of the outer housing 702 through outer sidewalls 710 (e.g., an exterior wall, a sidewall, etc.) at opposing ends of the outer housing 702. Each of the fluid drivers 708 is fluidly coupled to the interior cavity by a U-shaped conduit 712 that extends from opposing lateral ends of a respective one of the outer sidewalls 710. The fluid drivers 708 are configured to circulate air from the interior cavity through pass throughs 714 (e.g., flanges, etc.) that fluidly couple the conduits 712 to the outer housing 702. Such an arrangement can reduce flow resistance by separating the fluid drivers 708 from the outer sidewalls, which can increase the overall flow rate of air through the interior cavity. The conduits 712 also increase the surface area of the swappable battery pack 700 that is available for heat transfer to the environment surrounding the outer housing 702.

[0091] It should be understood that the number and / or arrangement of fluid drivers may be different in various embodiments. For example, referring to FIG. 24, an air flow circulation system804 is shown that is configured to selectively introduce vent air from the environment surrounding the outer housing 802 into an interior cavity of the outer housing 802. The air flow circulation system 804 includes a pair of fluid drivers 808 that are configured to direct vent air into the outer housing 802 through a pair of U-shaped conduits 812 that are similar in construction to those described in FIG. 23. In other embodiments, the design, shape, and / or number of conduits may be different. In some embodiments, the air flow circulation system 804 includes at least one fluid driver that is directly coupled to the housing, such as along an interior surface of a sidewall of the outer housing 802. For example, referring to FIG. 24, at least one fluid driver may be disposed within an interior cavity of the outer housing 902 and may be configured to receive vent air through at least one vent opening 906 disposed on the outer housing 902.

[0092] In the embodiment of FIG. 23, the fluid drivers 808 are disposed on opposite ends of the battery pack 800 at respective ones of an upstream end and a downstream end of the air flow circulation system 804. In other embodiments, the air flow circulation system 804 includes only a single fluid driver along the flow path defined by the pair of U-shaped conduits 812.

[0093] In some embodiments, the air flow circulation system is configured to coordinate the exchange of vent air with certain operating conditions of the swappable battery pack. For example, and referring again to FIG. 24, the air flow circulation system 904 includes at least one vent flap 908 (e.g., a pair of vent flaps including an inlet vent flap and an outlet vent flap) coupled to the outer housing 902 and configured to selectively actuate to fluidly couple the interior cavity to an environment surrounding the outer housing 902. The vent flaps 908 may be disposed along an inner or outer surface of the outer sidewall adjacent to a respective one of the vent openings 906 and may be configured to selectively cover the vent opening 906 to selectively seal the vent opening 906 from flow therethrough.

[0094] The air flow circulation system 904 also includes a controller 910 that is configured to coordinate operation of the vent flap(s) 908 and / or the fluid driver(s) based on operating conditions of the swappable battery pack 900. For example, the controller 910 may be communicably coupled to a battery control module and / or at least one sensor generating a control signal that is indicative of an operating condition of the battery pack 900. The controller 910, responsive to the control signal, may be configured to selectively open the vent flap(s) 908 and / or activate the fluid driver(s) to circulate vent air through the interior cavity. For example, the controller 910 may be configuredto actuate the vent flap(s) 908 in response to a control signal that indicates that a charger has been connected to the battery pack 900, and / or in response to control signals indicating that the battery is being charged. Among other benefits, such an arrangement can enable higher charge rates by providing additional cooling to the battery cells. Such an arrangement also enables weatherproofing of the outer housing 902 during periods when the battery pack 900 is connected to chore and / or other power equipment.

[0095] Referring to FIGS. 26-30 various charts of performance simulations using various implementations of the swappable battery pack are shown, including a baseline design with no additional cooling system, a solid core design (corresponding to the cell carrier designs described with reference to FIGS. 6-9), a stirring fan design (corresponding to the air flow circulation system designs described with reference to FIGS. 17 and 18), and a charger cooling design (corresponding to the controlled air flow circulation system described with reference to FIG. 25). In particular, FIGS. 26-30 show how the average operating temperature of the battery cells various with time under different operating conditions, and as a function of different arrangements of the cooling system for the swappable battery pack. FIG. 26 shows how the average battery cell temperature changes during system operation with 100 A continuous rate of discharge (or a 1C charge from 45°C). FIG. 27 shows how the average battery cell temperature changes during system operation with a 1C 100% charge staring from 0% charge at 25°C. FIG. 28 shows variation in the average battery cell temperature during system operation under 1C charge (or 1C discharge) conditions. FIG. 29 shows variation in the average battery cell temperature with the average battery cell temperature starting at 55°C, and with ambient conditions (i.e., 25°C air temperature) external to the outer housing of the battery pack. FIG. 30 show variation in the average battery cell temperature as a function of system operating time with the average battery temperature starting at 50°C and with ambient conditions (i.e., 25°C air temperature) external to the outer housing of the battery pack.

[0096] In some embodiments, a swappable battery pack (e.g., the battery pack 100, the battery pack 600, etc.) includes a thermal filler material that provides a conductive path between a subset or all of the battery cell and the housing. For example, the thermal filler material may be aligned with a portion of one of the battery cells (e.g., a negative side / terminal) and engaged between the portion of the one of the battery cells and the housing. The thermal filler material acts to remove heat from the battery cells and into the housing, which is fabricated from aluminum and expels theheat from the battery cells to the surroundings. Tn general, the incorporation of the thermal filler material into the swappable battery pack provides heat removal and cooling to the battery cells with a longer time constant (e.g., 1-2 hours) and aids in maintaining the swappable battery pack in an operational state (e.g., continuous charging / discharging) for long periods of time.

[0097] FIG. 31 shows a cell module assembly 1000 of a swappable battery pack (e.g., the battery pack 100, etc.) that includes a holder plate 1002 arranged on a side (e.g., a top side, a bottom side, etc.) of the cell module assembly 1000. Specifically, the holder plate 1002 is supported on a side of the cell module assembly 1000 that is exposed to an end of the battery cells 1004. The holder plate 1002 includes a plurality of cutouts 1006 formed within the holder plate 1002 and that extend completely through the holder plate 1002. The plurality of cutouts 1006 are placed in particular locations that overlap with and provide access to a subset of the battery cells 1004. In an exemplary embodiment, the plurality of cutouts 1006 overlap with and provide access to a negative side or end of the battery cells 1004. In some embodiments, the negative side of each of the battery cells 1004 is aligned with a corresponding one of the plurality of cutouts 1006.

[0098] Each of the plurality of cutouts 1006 is filled with a thermal filler material 1008. In some embodiments, the thermal filler material 1008 is a low durometer elastomer or rubber material that is filled or doped with thermally conductive particles that act to increase the thermal conductivity of the material (e.g., a silicone material that is filled or doped with alumina). When the cell module assembly 1000 is assembled within a swappable battery pack (e.g., the battery pack 100), the thermal filler material 1008 provides a thermally conductive path between the subset of the battery cells 1004 and a housing of the battery pack 100 (e.g., the outer housing 102). Specifically, the thermal filler material 1008 is in direct contact with both the subset of the battery cells 1004 (e g., the negative terminals / sides) and an inner surface of the housing (e.g., the outer housing 102). As described herein, the housing of the battery pack 100, which may incorporate the cell module assembly 1000, is fabricated from aluminum and is, therefore, a good conductor of heat. Accordingly, the thermally conductive path between the subset of the battery cells 1004 and the housing provided by the thermal filler material 1008 acts to expel heat from the battery cells 1004 to the housing, and then to the atmosphere. With the heat transfer from the battery cells 1004 to the housing being via conduction, the time constant for the cooling occurs on the order of hours and provides prolonged cooling to the battery cells 1004, which aids in allowing theswappable battery pack to continuously operated (e g., charging or discharging) over long periods of time.

[0099] FIGS. 32 and 33 show an exemplary embodiment of the thermal fdler material 1008 being incorporated into the cell module assembly 1000 without the holder plate 1002. In the illustrated embodiment, the outer housing 102 of the battery pack 100 includes a plurality of pillars, posts, or tabs, shown as protrusions 1010, each extending outwardly from an inner surface 1012 of the outer housing 102. As described herein, the outer housing 102 may be a multi -piece design. In the illustrated embodiment, the outer housing 102 includes a first housing section 1014 and a second housing section 1016, each including the protrusions 1010. For example, each of the first housing section 1014 and the second housing section 1016 includes at least one of the protrusions 1010.

[0100] Each of the protrusions 1010 is positioned on the first housing section 1014 and the second housing section 1016 to align with a subset of the battery cells 1004. For example, each of the protrusions 1010 is aligned with (e.g., axially aligned along a cell axis) and faces a negative side / terminal of each of the battery cells 1004, as shown in the exemplary embodiment of FIG. 33. Accordingly, a pattern defined by the protrusions 1010 on the outer housing 102 corresponds with the arrangement of the negative sides / terminals of the battery cells 1004 within the cell module assembly 1000, which ensures contact between the protrusions 1010 and the thermal filler material 1008 during assembly of the outer housing 102. In the illustrated embodiment, each of the protrusions 1010 is in the form of a cylindrical protrusion, which corresponds to the shape defined by the battery cells 1004.

[0101] The thermal filler material 1008 is arranged between each aligned pair of the negative sides / terminals of the subset of the battery cells 1004 and the protrusions 1010. Specifically, the thermal filler material 1008 is in direct contact with each of the negative sides / terminals of the battery cells 1004 and the protrusions 1010 to form a thermally conductive path between the battery cells 1004 and the outer housing 102. Heat generation in the battery cells 1004 primarily occurs in at the negative sides / terminals, so removing heat from these locations on the battery cells 1004 provides efficient cooling of the cell module assembly 1000. During assembly, the thermal filler material 1008 is placed on each of the negative sides / terminals of each of the battery cells 1004 and the outer housing 102, including the protrusions 1010, is then installed on the cell moduleassembly 1000. The distance that the protrusions 1010 extend outwardly from the inner surfaces of the first housing section 1014 and the second housing section 1016 ensures that each of the protrusions 1010 engage the thermal filler material 1008 placed on each of the battery cells 1004. By installing the thermal filler material 1008 on each of the negative sides / terminals of the battery cells 1004, discrete thermally conductive paths are formed by the thermal filler material 1008 throughout the cell module assembly 1000. In other words, the thermal filler material 1008 is not installed in a continuous layer over the side of the cell module assembly 1000, and rather individually installed on each of the negative sides / terminals of the battery cells 1004 in approximately cylindrical dollops that are engaged by the protrusions 1010.

[0102] In an exemplary embodiment, the thermal filler material 1008 is arranged all of the negative sides / terminals of the battery cells 1004 and a portion of the positive sides of the battery cells 1004, as shown in FIG. 34. For example, the thermal filler material 1008 may be installed on at least one of the positive sides / terminals of the battery cells 1004, or at least one of the positive sides within each parallel grouping of the battery cells 1004 within the cell module assembly 1000 (e.g., about 14 of the positive sides / terminals). In some embodiments, the thermal filler material 1008 may be installed on each of the positive sides / terminals of the battery cells 1004 and each of the negative sides / terminals of the battery cells 1004.

[0103] It should be appreciated that any of cooling system designs described herein may be combined with other designs, and that all such implementations are contemplated as part of the present disclosure. For example, the cell carrier structure described with reference to FIGS. 6-9, FIGS. 10A-10B, and FIGS. 11-13 may be combined with any of the air flow circulation system designs described in FIGS. 17-18 and FIGS. 24-25, and / or combined with the thermal filler solution described with reference to FIG. 31, or FIGS. 32-34. Other combinations and implementations are also contemplated, and none of the designs disclosed herein should be understood as precluding the use of other cooling system components or design implementations in other embodiments.

[0104] As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “substantially,” and similar terms generally mean + / - 10% of the disclosed values. When the terms “approximately,” “about,” “substantially,” and similar terms are applied to a structural feature (e.g., to describe its shape, size, orientation, direction, etc.), these terms are meant to coverminor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.

[0105] It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0106] The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.

[0107] References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0108] The hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry that is specific to a given function. The memory (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and / or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, the memory is communicably connected to the processor via a processing circuit and includes computer code for executing (e.g., by the processing circuit or the processor) the one or more processes described herein.

[0109] The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of theabove are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0110] Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.

[0111] It is important to note that the construction and arrangement of the swappable battery pack as shown in the various exemplary embodiments is illustrative only. Additionally, any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein. Although only one example of an element from one embodiment that can be incorporated or utilized in another embodiment has been described above, it should be appreciated that other elements of the various embodiments may be incorporated or utilized with any of the other embodiments disclosed herein.

Claims

WHAT IS CLAIMED IS:

1. A swappable battery pack comprising: an outer housing defining an inner surface and including a protrusion extending outwardly from the inner surface; a cell module assembly disposed within the outer housing and including a plurality of battery cells, each defining a positive terminal and a negative terminal, wherein the protrusion is aligned with a portion of one of the plurality of battery cells; and a thermal filler material engaged between the portion of the one of the plurality of battery cells and the protrusion, so that a thermally conductive path is formed between the one of the plurality of battery cells and the outer housing.

2. The swappable battery pack of claim 1, wherein the thermal filler material is an elastomer material filled with alumina particles.

3. The swappable battery pack of claim 1, wherein the portion of the one of the plurality of battery cells includes the positive terminal or the negative terminal.

4. The swappable battery pack of claim 1, wherein the portion of the one of the plurality of battery cells includes the negative terminal.

5. The swappable battery pack of claim 1, wherein the thermal filler material is in direct contact with both the portion of the one of the plurality of battery cells and the protrusion.

6. The swappable battery pack of claim 1, further comprising a plurality of protrusions, each extending outwardly from the inner surface, wherein each of the plurality of protrusions is aligned with a portion of a corresponding one of the plurality of battery cells.

7. The swappable battery pack of claim 6, wherein the thermal filler material is arranged between each corresponding pair of the portions of the plurality of battery cells and the plurality of protrusions.

8. The swappable battery pack of claim 1, wherein the outer housing includes a first housing section and a second housing section.

9. The swappable battery pack of claim 8, wherein the protrusion is arranged on the first housing section or the second housing section.

10. The swappable battery pack of claim 8, further comprising a plurality of protrusions, wherein each of the first housing section and the second housing section include at least one of the plurality of protrusions.

11. The swappable battery pack of claim 1, wherein the outer housing is fabricated from die cast aluminum.

12. A swappable battery pack comprising: an outer housing defining an interior cavity; a cell module assembly disposed within the interior cavity, the cell module assembly including: a plurality of cell carriers, each cell carrier of the plurality of cell carriers defining a plurality of cell openings arranged in a row that extends in a lateral direction, the plurality of cell carriers being stacked together along a longitudinal direction that is substantially perpendicular to the lateral direction; and a plurality of battery cells disposed within the plurality of cell openings; and an electrically insulative material disposed between the cell module assembly and the outer housing.

13. The swappable battery pack of claim 12, wherein at least one cell carrier of the plurality of cell carriers is formed from a metallic material.

14. The swappable battery pack of claim 13, wherein the metallic material is formed by an extrusion operation.

15. The swappable battery pack of claim 12, wherein the cell module assembly further comprises an electrically insulating material between adjacent pairs of the plurality of cell carriers.

16. The swappable battery pack of claim 12, further comprising a plurality of fans disposed within the interior cavity, the plurality of fans stacked along at least one of the lateral direction or the longitudinal direction and oriented to move air across the cell module assembly.

17. The swappable battery pack of claim 16, wherein the outer housing fluidly seals the interior cavity from an environment surrounding the outer housing.

18. The swappable battery pack of claim 12, further comprising a fan fluidly coupled to the interior cavity through an outer wall of the outer housing, the fan being configured to circulate air from the interior cavity through the outer wall.

19. The swappable battery pack of claim 12, wherein the outer housing defines an inner surface and includes a protrusion extending outwardly from the inner surface, and wherein a thermal filler material is engaged between a portion of one of the plurality of battery cells and the protrusion, so that a thermally conductive path is formed between the one of the plurality of battery cells and the outer housing.

20. The swappable battery pack of claim 12, wherein the plurality of battery cells are each oriented along the same direction so that a cathode end of each of the plurality of battery cells is arranged adjacent to a first sidewall of the outer housing and an anode end of each of the plurality of battery cells is arranged adjacent to a second sidewall of the outer housing opposite the first sidewall.21 . The swappable battery pack of claim 12, further comprising a vent flap coupled to the outer housing and configured to selectively actuate to fluidly couple the interior cavity to an environment surrounding the outer housing.

22. A swappable battery pack comprising: an outer housing defining an interior cavity; a cell module assembly disposed within the interior cavity, the cell module assembly including: a plurality of cell carriers, each cell carrier of the plurality of cell carriers defining a plurality of cell openings arranged in a row that extends in a lateral direction, the plurality of cell carriers stacked together along a longitudinal direction that is substantially perpendicular to the lateral direction; and a plurality of battery cells disposed within the plurality of cell openings; and a plurality of fans stacked along at least one of the lateral direction or the longitudinal direction and oriented to move air across the cell module assembly.

23. The swappable battery pack of claim 22, wherein the plurality of fans are disposed within the interior cavity.

24. The swappable battery pack of claim 22, wherein the plurality of fans are fluidly coupled to the interior cavity through an outer wall of the outer housing, the plurality of fans being configured to circulate air from the interior cavity through the outer wall.

25. The swappable battery pack of claim 22, wherein the outer housing defines an inner surface and includes a protrusion extending outwardly from the inner surface, and wherein a thermal filler material is engaged between a portion of one of the plurality of battery cells and the protrusion, so that a thermally conductive path is formed between the one of the plurality of battery cells and the outer housing.

26. The swappable battery pack of claim 22, further comprising an electrically insulative material disposed between the cell module assembly and the outer housing.

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