Patent Publication Number: US-2022219798-A1

Title: Integrated electric outboard motor assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application No. 63/135,491, filed Jan. 8, 2021, which is incorporated by reference in its entirety herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to electric vehicles and, in particular embodiments, to electric outboard motors. 
     BACKGROUND 
     Known electric boat motors range from small trolling motors to larger outboard motors. Trolling motors are designed to be portable, light weight, low power units. They are typically powered by small cylindrical batteries located in their upper unit that power a small motor in the lower unit that directly drives a propeller. These electric trolling motors typically provide a power range in the order of 0.5-3 HP. 
     Larger electric outboard motors that provide a greater power range are typically broken up into two components, with the electric motor located outboard of the boat and the battery pack located inboard on the boat itself. The large electric motor is typically housed in the upper unit of the outboard device with a shaft coupled to the propeller located in the lower unit. Alternatively, a motor in the lower unit may be coupled to an inverter and other power electronics located in the upper unit. With either design the battery pack is located on the boat itself, typically hidden within the hull of the boat. Often times, this requires a specially designed boat hull to accommodate the large battery pack. 
     SUMMARY 
     Some embodiments of the present disclosure provide an outboard motor having a battery pack, motor assembly and propeller assembly that are conveniently provided as a single integrated assembly for connection to a boat. This integrated outboard motor assembly may eliminate the need to store a battery pack within the hull of a boat, thereby making the outboard motor assembly more versatile for use with a variety of different boat designs. Further, the assembly provides an architecture that accommodates relatively high-power motors and/or relatively high energy density battery packs. 
     One example provides an electric outboard motor assembly having a battery pack located in an upper unit, a propeller assembly located in a lower unit and a motor assembly located in a middle unit between the upper unit and the lower unit. 
     In one example, an outboard motor housing includes a first portion that houses the battery pack and a second portion that houses the motor assembly. In one example, the first portion of the housing defines a first interior volume and the second portion of the housing defines a second interior volume, the first interior volume being greater than the second interior volume. In one example, the outboard motor assembly defines a longitudinal axis extending from the upper unit to the lower unit, wherein a first circumferential measurement of the first portion of the housing at a mid-point of the upper unit along the longitudinal axis is greater than a second circumferential measurement of the second portion of the housing at a mid-point of the middle unit along the longitudinal axis. 
     In one example, the outboard motor housing includes an inboard end operative for facing inboard of the watercraft and an outboard end operative for facing outboard of the watercraft, the inboard end of the second portion of the housing being indented in relation to the inboard end of the first portion of the housing. In one example, a transom mount is attachable to one of the second portion of the housing and an internal support structure of the outboard motor at a location beneath the upper unit. 
     In one example, the first portion of the housing and the second portion of the housing are at least partially integrally formed together. In one example, at least part of the first portion of the housing enables access to the battery pack. In one example, at least part of the second portion of the housing enables access to the motor assembly. In one example, a seam separates the first portion of the housing from the second portion of the housing. In one example, the first portion of the housing and the second portion of the housing are joined together at the seam. 
     In one example, battery pack includes a plurality of battery modules, which may be prismatic battery modules. In one example, each battery module includes a plurality of battery cells, which may be pouch battery cells. 
     In one example, each battery module includes at least one battery cell. In one example, the battery pack includes a first stack of prismatic battery modules and a second stack of prismatic battery modules, where the first stack is positioned over the second stack. In one example, the first stack of prismatic battery modules are oriented in a first orientation and the second stack of prismatic battery modules are oriented in a second orientation different than the first orientation. In one example, the first orientation is at 90 degrees with respect to the second orientation. 
     In one example, the motor assembly is an integrated motor assembly with an inverter and an alternating current (AC) motor contained within a common motor assembly housing. In one example, the propeller assembly includes a propeller drive shaft, and where a motor drive shaft of the motor assembly is perpendicular to the propeller drive shaft. In one example, a gear mechanism is coupled between the motor assembly and the propeller assembly. 
     In one example, a thermal management system is in fluid communication with the battery pack and the outboard motor assembly. In one example, the thermal management system comprises a closed-loop liquid cooling system. 
     In one example, the electric outboard motor assembly has a center of gravity located between the battery pack and the motor assembly. 
     Another example provides an electric outboard motor assembly including an outboard motor housing, a battery pack including a plurality of battery modules, the battery pack located within the outboard motor housing, and a motor assembly located within the outboard motor housing. The battery modules may include a plurality of battery cells, such as pouch cells, for example. 
     In one example, the outboard motor housing includes a first housing portion and a second housing portion, where the battery pack is positioned within the first housing portion. 
     In one example, the battery pack includes a first stack of battery modules and a second stack of battery modules, where the first stack is positioned over the second stack. In one example, the first stack of battery modules are oriented in a first orientation and the second stack of battery modules are oriented in a second orientation different than the first orientation. 
     Another example provides an electric outboard motor assembly including an outboard motor housing, a battery pack, a motor assembly having an inverter and outboard motor, and a thermal management system in fluid communication with the battery pack and the motor assembly, where at least two of the battery pack, the motor assembly and the thermal management system are located within the outboard motor housing. 
     In one example, the battery pack, motor assembly and thermal management system are all at least partially located within the outboard motor housing. In one example, the thermal management system comprises a closed-loop liquid system. In one example, the thermal management system includes a coolant pump and a reservoir tank, in fluid communication with the battery pack and the motor assembly. In one example, the reservoir tank is located adjacent the battery pack. In one example, the thermal management system further includes a heat exchanger. In one example, the heat exchanger includes a raw water inlet and outlet to aid in removing rejected heat from coolant moving therethrough. 
     Additional and/or alternative features and aspects of examples of the present technology will become apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a boat assembly having an electric outboard motor assembly, according to one example of the present disclosure. 
         FIG. 2  is a side view of an electric outboard motor assembly showing a schematic arrangement of components, according to one example of the present disclosure. 
         FIG. 3  is an end view of the electric outboard motor assembly of  FIG. 2 . 
         FIG. 4  is a side view of an outboard motor housing according to one example of the present disclosure. 
         FIG. 5  is a top perspective view of an electric outboard motor assembly without a housing according to one example of the present disclosure. 
         FIG. 6  is another top perspective view of the electric outboard motor assembly of  FIG. 5 . 
         FIG. 7  is a bottom perspective view of the electric outboard motor assembly of  FIG. 5 . 
         FIG. 8  is another bottom perspective view of the electric outboard motor assembly of  FIG. 5 . 
         FIG. 9  is a side view of the electric outboard motor assembly of  FIG. 5   
         FIG. 10  is an end view of the electric outboard motor assembly of  FIG. 5 . 
         FIG. 11  is a perspective view of a battery pack for use in an electric outboard motor assembly according to one example of the present disclosure. 
         FIG. 12  is a side view of a motor assembly for use in an electric outboard motor assembly according to one example of the present disclosure. 
         FIG. 13  is a partial view of a motor assembly for use in an electric outboard motor assembly according to one example of the present disclosure. 
         FIG. 14  is a partial mechanical diagram of an electric outboard motor assembly according to one example of the present disclosure. 
         FIG. 15  is a block diagram of a thermal management system including a closed-loop system for use with an electric outboard motor assembly according to one example of the present disclosure. 
         FIG. 16  is a side view illustrating an electric outboard motor assembly including a thermal management system according to one example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise. 
       FIG. 1  is a perspective view illustrating one example of a boat assembly  100  having an electric outboard motor assembly  110  attached to a boat  112 . The electric outboard motor assembly  110  is an example of an integrated electric outboard motor assembly that includes a battery pack and motor assembly located within the same housing. As will be described below, the battery pack and motor assembly provide high power and high energy density to the electric outboard motor assembly  110  such that it is able to provide a non-limiting power range of between at least 120-180HP. Since the battery pack and motor assembly are integrated into the same housing, the electric outboard motor assembly  110  can be used with differently sized boats and boat hulls. It is no longer necessary to locate a large battery pack in a specially designed boat hull in order to achieve high motor horsepower designs. 
       FIG. 2  is a side view of one example of an electric outboard motor assembly  110 , showing a schematic positioning of the motor assembly components.  FIG. 3  is an end view of the electric outboard motor assembly  110  of  FIG. 2 . The electric outboard motor assembly  110  includes an upper unit  114 , a middle unit  116  and a lower unit  118 . A battery pack  120  is located in the upper unit  114 . A propeller assembly  122  is located in the lower unit  118 . A motor assembly  124  is located in the middle unit  116  between the upper unit  114  and the lower unit  118 . 
     The terms “upper”, “lower” and “middle” used herein may refer to relative positions along a longitudinal axis of the electric outboard motor assembly  110  extending between an upper end  102  and a lower end  104  of the electric outboard motor assembly  110 . The upper end  102  of the electric outboard motor assembly  110  may face vertically upwards when the electric outboard motor assembly  110  is positioned for use. The lower end  104  of the electric outboard motor assembly  110  may face vertically downwards when the electric outboard motor assembly  110  is positioned for use. 
     The upper unit  114 , middle unit  116  and lower unit  118  may also be considered an upper portion, middle portion and lower portion, respectively. Each of the units  114 ,  116 ,  118  may define respective compartments or volumes to store components of the electric outboard motor assembly  110 . In some examples, there is at least some separation between the compartments defined by the units  114 ,  116 ,  118  using, for example, walls or dividers. However, there need not always be separation between compartments defined by the units  114 ,  116 ,  118 . Two or more of the units  114 ,  116 ,  118  may define compartments that are joined or otherwise integrated. In this way, the upper unit  114 , middle unit  116  and lower unit  118  might not be individual physical elements of the electric outboard motor assembly  110 , but may simply identify the relative positioning of the units in relation to each other. In some cases, the upper unit  114 , middle unit  116  and lower unit  118  may be delineated by the location of the battery pack  120 , motor assembly  124  and propeller assembly  122  along a longitudinal axis of the electric outboard motor assembly  110 . 
     In some examples, the upper unit  114 , the middle unit  116  and the lower unit  118  do not overlap along a longitudinal axis of the electric outboard motor assembly  110 . For example, the battery pack  120  and the motor assembly  124  may be spaced apart along a longitudinal axis of the electric outboard motor assembly  110 . Alternatively or additionally, the motor assembly  124  and the propeller assembly  122  may be spaced apart along a longitudinal axis of the electric outboard motor assembly  110 . In other examples, the upper unit  114  may partially overlap with the middle unit  116  and/or the lower unit  118  may partially overlap with the middle unit  116 . For example, the battery pack  120  and the motor assembly  124  may be partially coincident along a longitudinal axis of the electric outboard motor assembly  110 , and/or the motor assembly  124  and the propeller assembly  122  may be partially coincident along a longitudinal axis of the electric outboard motor assembly  110 . 
     In one example, a gear assembly  126  is positioned within the lower unit  118 . In other examples, the gear assembly  126  can be located in the middle unit  116 . Alternatively, the electric outboard motor assembly  110  may be a direct drive unit and may not include the gear assembly  126 . 
     A transom mount  128  is configured to couple the electric outboard motor assembly  110  to the transom of a boat. The transom mount  128  may include fasteners (e.g., bolts and screws) and/or clamps to mount to the transom of the boat. The transom mount  128  is rotatably connected to the electric outboard motor assembly  110 . The transom mount  128  connection mechanisms allow the transom mount  128  to be rotated horizontally side to side (e.g., for steering the boat). In one example, the transom mount  128  includes a pivot point  130 . The electric outboard motor assembly  110  is movable or can be ‘pivoted” side to side at the pivot point  130  (relative to the transom mount  128 ) about a pivot axis  132 , as indicated by rotational arrows  134 ,  136 . The pivot axis  132  may generally correspond to a longitudinal axis of the electric outboard motor assembly  110 . Additionally, the electric outboard motor assembly  110  can be moved vertically up and down to “trim” the motor for boating between shallow water areas and deep water areas or during trailering of the boat. The trim can also be used to adjust the attitude of the boat in the water. In one example operation, the electric outboard motor assembly  110  can be rotated upward or downward, indicated by rotational arrows  140 ,  142  about a trim axis (not shown) running through pivot point  130 . The transom mount  128  can be moved or rotated either manually or through a boat control system. In other embodiments, the electric outboard motor assembly  110  can be part of an inboard/outboard boating system and can be operated entirely by the boat control system. 
     In some examples, the electric outboard motor  110  may include a mount to couple to portions of a boat other than the transom, such as the bow, for example. 
     As shown in  FIGS. 2-3 , the electric outboard motor assembly  110  includes an outboard motor housing  150 . According to an example of the present disclosure, both the battery pack  120  and the motor assembly  124  are housed within the outboard motor housing  150 . The outboard motor housing  150  may be designed to have substantially similar dimensions as traditional combustion engine outboard motors. As shown, the outboard motor housing  150  extends at least partially over the battery pack  120  and the motor assembly  124 . In one example, the outboard motor housing  150  extends entirely over the battery pack  120  and the motor assembly  124 . The outboard motor housing  150  may be made of a rigid polymeric (i.e., plastic) material. In other examples, the outboard motor housing may be made of other materials, such as metal or a composite material. 
     Reference is also made to  FIG. 4 , which is a diagram further illustrating the outboard motor housing  150 . In one example, the outboard motor housing  150  includes a first portion  152  associated with the upper unit  114  of the electric outboard motor assembly  110  and a second portion  154  associated with the middle unit  116  of the electric outboard motor assembly  110 . The first portion  152  of the housing  150  houses the battery pack  120  and the second portion  154  houses the motor assembly  124 . The first portion  152  defines a first interior volume  156  and the second portion  154  defines a second interior volume  158 , the first interior volume  156  being greater than the second interior volume  158 . 
     In accordance with a non-limiting example, in order to provide sufficient energy density to the electric outboard motor assembly  110 , the battery pack  120  may take up a larger volumetric space than the motor assembly  124 . Accordingly, the battery pack  120  may be housed within the first portion  152  of the housing  150  associated with the upper unit  114  that traditionally provides a larger volumetric space than the second portion  152  of the housing  150  associated with the middle unit  116 . This configuration of housing the battery pack  120  above the motor assembly  124  allows the components of the electric outboard motor assembly  110  to fit within a housing having substantially similar dimensions as traditional combustion engine outboard motors. While the Figures illustrate an outboard motor housing  150  having a shape and configuration similar to those of traditional outboard motors, it is possible for the electric outboard motor assembly  110  to have a housing  150  having any shape and configuration suitable for housing the battery pack  120  and the motor assembly  124  in the manners described herein. 
     In accordance with a non-limiting example, the first portion  152  of the housing  150  may have a height H 1  between 35-65 cm, a width W 1  between 40-70 cm and a depth D 1  between 80-120 cm. The second portion  154  of the housing  150  may have a height H 2  between 60-100 cm, a width W 2  between 40-70 cm and a depth D 2  between 80-120 cm. 
     In other examples, the first interior volume  156  is substantially the same or less than the second interior volume  158 . In this example, the electric outboard motor assembly  110  may be rated for operation at a lower horsepower and as such may require housing for fewer and/or smaller battery modules. In other examples, the first portion  152  of the housing  150  houses the motor assembly  124  and the second portion  154  of the housing  150  houses the battery pack  120 . In this example, the second portion  154  may have a second interior volume  158  that is larger than the first interior volume  156  of the first portion  152 . 
     With reference to  FIG. 4 , the outboard motor housing  150  includes an inboard end  180  operative for facing inboard of a watercraft and an outboard end  182  operative for facing outboard of a watercraft, the inboard end  180  of the second portion  154  of the housing  150  is indented in relation to the inboard end  180  of the first portion  152  of the housing  150 . This indentation provides a space for receiving the transom mount  128  described above. In one example, the transom mount  128  is attachable to the inboard end  180  of the second portion  154  of the housing  150 . In a further non-limiting example, the transom mount  128  is positioned beneath the upper unit  114  of the electric outboard motor assembly  110 . The transom mount  128  may be attached to an internal support structure of the electric outboard motor assembly  110  that supports the motor assembly  124  and battery pack  120 , among other components. 
     As described above, a shape of the second portion  154  of the housing  150  may comprise an indentation or recess to accommodate the attachment of the transom mount  128 . Accordingly, a cross-sectional area or circumference of the second portion  154  of the housing  150  may be less than a cross-sectional area or circumference of the first portion  154  of the housing. More specifically, in a non-limiting example, the electric outboard motor assembly  110  defines a longitudinal axis  170  extending from the upper unit  114  to the lower unit  118 . A first circumferential measurement  172  of the first portion  152  of the housing  150  at a mid-point  176  of the upper unit  114  along the longitudinal axis  170  is greater than a second circumferential measurement  179  of the second portion  154  of the housing  150  at a mid-point  178  of the middle unit  116  along the longitudinal axis  170 . 
     In one example, at least part of the first portion  152  of the housing  150  and the second portion  154  of the housing  150  are integrally formed together. A seam  190  may define a transition between the first portion  152  of the housing  150  and the second portion  154  of the housing  150 . In one example, seam  190  is defined as a bend or indent in the housing  150 . The seam  190  may be a molded demarcation in an integrally formed housing  150 , or the seam  190  may be a physical separation between the first portion  152  and second portion  154 . In such an example, the first portion  152  and the second portion  154  may be separate pieces that are connected together to form housing  150 , and may be physically joined together at the seam  190  via fasteners (e.g., nuts, bolts, screws and/or rivets), adhesives, welds and/or a snap-fit arrangement. In yet a further alternative, the seam  190  may be absent such that there is no physical or visual demarcation between the first portion  152  of the housing  150  and the second portion  154  of the housing. In such a case, the transition between the first portion  152  of the housing  150  and the second portion  154  of the housing may occur at any position along the longitudinal axis  170  between the battery pack  120  and the motor assembly  124 . 
     In another example, at least part of the first portion  152  of the housing  150  is removable or openable for access to the battery pack  120 . This removeable and/or openable access to the battery pack  120  may enable components of the battery pack  120 , such as battery modules, to be replaced. In a further example, at least part of the second portion  154  of the housing  150  is removable or openable for access to the motor assembly  124 . For example, the first portion  152  and/or the second portion  154  of the housing  150  may define a hatch or door for providing access to the battery pack  120  and/or motor assembly  124 . In one example, the entire housing  150  is at least partially removable or openable as a single unit for access to the battery pack  120  and/or the motor assembly  124 . 
       FIG. 5  is a top side perspective view of the electric outboard motor assembly  110  according to one example of the present disclosure.  FIG. 6  is another top side perspective view of the electric outboard motor assembly  110 . In both  FIG. 5  and  FIG. 6 , the electric outboard motor assembly  110  is illustrated with the outboard motor housing  150  removed. 
     The battery pack  120  is made up of one or more battery stacks  200  located within the upper unit  114 . The motor assembly  124  and the transom mount  128  are located within the middle unit  116 . The propeller assembly  122  and the gear assembly  126 , along with fins  138  are illustrated in the lower unit  118 . 
     In one example, the electric outboard motor assembly  110  includes a support structure  210 . The support structure  210  is defined as a support frame system that provides support to one or more of the battery pack  120 , motor assembly  124 , transom mount  128 , propeller assembly  122 , gear assembly  126  and fins  138 . The support structure  210  aids in retaining the elements that make up the electric outboard assembly  110  together as a single unit. In one example, the support structure  210  is made of a rigid, polymeric material. In other examples the support structure  210  is made of other materials, such as metal. Welds and/or fasteners, for example, may be used to assemble the support structure  210  and couple the support structure  210  to the battery pack  120 , motor assembly  124 , transom mount  128 , propeller assembly  122 , gear assembly  126  and/or fins  138 . 
     Additional reference is made to  FIG. 7  and  FIG. 8 .  FIG. 7  is a bottom side perspective view of the electric outboard motor assembly  110  according to one example of the present disclosure.  FIG. 8  is another bottom end perspective view of the electric outboard motor assembly  110  according to one example of the present disclosure. In these figures, additional elements illustrated in other views are not labeled for clarity. 
     Support structure  210  includes a battery rack  212 , a motor rack  214 , and propeller assembly support  216 . The battery rack  212  is positioned within the upper unit  114  and includes a first platform  218  and second platform  220 . The first platform  218  and the second platform  220  may be rigid frames or plates for supporting, and optionally coupling to, battery modules. In the non-limiting embodiment shown, the battery stack  120  includes a first stack of battery modules  222  and a second stack of battery modules  224 . The first stack  222  is positioned over the second stack  224 . The first stack  222  is positioned on the first platform  218 , and the second stack  224  is positioned on the second platform  220 . The first platform  218  is connected to the second platform  220  via vertical support members  226 . The support members  226  may be rigid beams or bars connected to the first platform  218  and the second platform  220 . Further, the support members  226  are sized such that when the first stack  222  is positioned on the first platform  218  and the second stack  224  is positioned on the second platform  220 , the first stack  222  is spaced from the second stack  224 , as indicated by space  228 . The space  228  is formed between the first stack  222  and the second stack  224  along a longitudinal axis of the electric outboard motor assembly  110 . Although two stacks of battery modules  222 ,  224  are shown, the battery pack may comprise a single battery stack, or multiple battery stacks, among other possibilities. As battery technology evolves, different arrangements, orientations and positioning of the battery modules can be envisaged. 
     Additional reference is made to  FIG. 9  and  FIG. 10 .  FIG. 9  is a side view of the electric outboard motor assembly  110  according to one example of the present disclosure.  FIG. 10  is an end view of the electric outboard motor assembly  110  according to one example of the present disclosure. The motor rack  214  includes a motor platform  230  and support members  232 . The motor assembly  124  is positioned on the motor platform  230 . The motor platform  230  may be a rigid frame or plate with connection points to couple to the motor assembly  124 . The support members  232  extend between the motor platform  230  and the second platform  220  of the battery rack  212 . The support members  232  may be rigid beams or bars that connect to the motor platform  230  and the second platform  220 . The transom mount  128  is coupled to the motor rack  214 . In one example, the transom mount  128  is coupled to and supported by the support members  232 . The propeller assembly support  216  includes the propeller assembly  122  being coupled to the electric outboard motor assembly  110  via the gear assembly  126 . 
       FIG. 11  is a perspective view of battery pack  120  for use in the electric outboard motor assembly  110  according to one example of the present disclosure. The battery pack  120  includes one or more battery stacks  200  made up of battery modules. The battery modules are electrically connected to form a high voltage circuit that drives the outboard motor assembly  110 . In the illustrated example, the battery pack  120  includes the first stack of battery modules  222  and the second stack of battery modules  224 . In other examples, the battery pack  120  may only include a single stack of battery modules or more than two stacks of battery modules. The first stack of battery modules  222  is positioned over the second stack of battery modules  224 . The first stack of battery modules  222  is oriented in a first orientation  300  and the second stack of battery modules  224  is oriented in a second orientation  302  that is different from the first orientation  300 . In this way, each battery module in the first stack of battery modules  222  may have a different orientation than the battery modules in the second stack of battery modules  224 . In one example, the first orientation  300  is oriented at 90 degrees with respect to the second orientation  302 . In other examples, the first stack of battery modules  222  may be oriented in the same direction as the second stack of battery modules  224 . 
     In one example, the battery pack  120  is made up of multiple battery modules, where each battery module includes one or more battery cells. In one example, the battery modules are prismatic battery modules. The battery modules may comprise one or more cylindrical battery cells, one or more pouch battery cells and/or one or more prismatic battery cells. In one example, a battery module includes 12 pouch battery cells. The battery cells may be rechargeable. In one or more examples, the battery cells are rechargeable lithium-ion battery cells. 
     In one example, battery stacks  200  include multiple battery modules  310  connected together via cartridge assemblies  320 . The number of battery modules  310  in the first stack of battery modules  222  may be the same as, less than, or more than the number of battery modules in the second stack of battery modules  224 . In one example, the first stack of battery modules  222  includes 16 battery modules and the second stack of battery modules  224  includes 24 battery modules. In a non-limiting example, each battery module  310  comprises at least a first pouch battery cell, a second pouch battery cell and a cooling panel positioned between the first and second pouch battery cells. The cooling panel may include multiple layers of film or foil that define cooling channels to circulate a coolant between the pouch battery cells. One or more examples of a battery stack, a battery cartridge, a battery module and a battery cooling panel assembly suitable for use in the electric outboard motor assembly  110  are disclosed in U.S. patent application Ser. No. 17/091,777 titled Battery Cooling Panel for Electric Vehicles filed Nov. 6, 2020, the entire contents of which are incorporated herein by reference. 
     The use of pouch battery cells allows the construction of battery modules that have a relatively compact size for the amount of energy they are able to provide. In accordance with a non-limiting example, the battery modules  120  may provide an energy density in the range of 0.03-0.3 kWh/kg and a specific energy in the range of 100-300 kWh/m 3 . At this energy density level, a battery pack  120  may have a relatively small volumetric size (allowing it to be housed in the upper unit  114  of an outboard motor housing  150 ) while providing sufficient energy to a motor capable of providing between 90-180HP, and in some cases between 130-180HP. In some examples, the battery pack  120  may be configured to output electric power at a voltage of between 300-400 volts, or up to 800 volts, for example. 
     It should be understood that as battery technology evolves, an even higher energy density range may be achievable for a battery pack having a volumetric size suitable for being positioned within an upper unit  114  of an outboard motor housing  150 . As such, a configuration for an electric outboard motor assembly  110  having a battery pack  120  located in the upper unit  114 , a propeller assembly  122  located in the lower unit  118  and a motor assembly  124  located in the middle unit  116  that is able to provide 350HP is included within the present application. 
     The battery pack  120  may be contained within a watertight enclosure. In one example, the housing  150  previously detailed herein provides the watertight enclosure. In another example, battery pack  120  is contained within a separate watertight enclosure (not illustrated), that is in turn positioned within the housing  150 . In another example, each of the battery stacks  200  are contained within one or more waterproof enclosures. In one example, the first stack of battery modules  222  are contained in a watertight first battery enclosure and the second stack of battery modules  224  are contained in a watertight second battery enclosure separate from the first battery enclosure. 
     In one example, the electric outboard motor assembly  110  includes a battery management system (not shown) that may monitor battery modules contained in battery pack  120 . A central battery management controller may communicate with battery module controllers on the battery modules to manage each of the battery modules. The central battery management controller may be responsible for making sure the battery is operating within its safe operating conditions, monitoring its state of charge (SoC) and state of health (SoH), and balancing the operation of the battery cells within each battery module. The battery management system may also monitor battery operating parameters such as battery module voltage and temperature. One battery management system suitable for use in electric outboard motor assembly  110  is disclosed in U.S. Patent Application No. 63/135,452, Attorney Docket Number T1670.108.101/TPA012 titled Electric Vehicle Having A Modular Distributed Battery Management System, the entire contents of which are incorporated herein by reference. 
     In one example, the electric outboard motor assembly  110  may include a high-voltage module that selectively connects or disconnects the battery pack  120  to other components of the outboard motor assembly  110 . The selective connection and disconnection of the battery pack  120  may be done according to instructions or algorithms executed by a control system. 
     In one example, the electric outboard motor assembly  110  may include one or more heating modes (including battery heating circuits) for the battery stacks  200  and individual battery modules. The battery heating modes may allow the electric outboard motor assembly  110  to warm the battery pack  120  and run in cold conditions. One thermal management system that includes battery heating modes suitable for use in electric outboard motor assembly  110  is disclosed in U.S. patent application Ser. No. 17/091,625 titled Thermal Management System for Electric Vehicle filed Nov. 6, 2020, the entire contents of which are incorporated herein by reference. 
       FIG. 12  illustrates generally at  400  a view of the motor assembly  124  positioned in the electric outboard motor assembly  110  according to one example of the present disclosure.  FIG. 13  is a partial close-up view of the motor assembly  124  illustrated in  FIG. 12 . In one example, the motor assembly  124  includes an alternating current (AC) motor  410  coupled to an inverter  412 . The motor assembly  124  is an integrated motor assembly where the inverter  412  is integrated into a common housing  414  with the motor  110 . In this example, a footprint of the housing  414  is generally cylindrically shaped. The motor  410  includes a motor drive shaft  420 . The motor  410  is mechanically coupled to the gear assembly  126  for driving the propeller assembly  122 . The motor  410  may be a permanent magnet synchronous motor. In an alternative embodiment, any electric motor suitable for providing sufficient HP and having dimensions suitable for being housed within the middle unit  116  of the electric outboard motor assembly  110  may be used. In some examples, the motor assembly  124  includes a brushless direct current (DC) motor. 
     One motor assembly including a motor coupled to an inverter, suitable for use in the present electric outboard motor assembly, is disclosed in U.S. Patent Application No. 63/135,466 (Attorney Docket No. T1670.109.101/TPA013), titled DRIVE UNIT FOR ELECTRIC VEHICLE, filed Jan. 8, 2021, the entire contents of which are incorporated herein by reference. 
       FIG. 14  is a partial mechanical diagram of the electric outboard motor assembly  110  further illustrating a mechanical operation of the motor assembly  124  for driving the propeller assembly  122 . The motor drive shaft  420  extends vertically down from motor  410 , and is mechanically coupled to the gear assembly  126 . The gear assembly  126  may be a belt driven gear assembly, indicated at  500 . A gear shaft  510  extends from the belt driven gear assembly  500  downward to the propeller assembly  122 . The propeller assembly  122  includes a propeller drive shaft  512  coupled to a propeller  514 . The gear shaft  510  includes a bevel gear  520  at one end that interacts with a bevel gear  522  coupled to the propeller drive shaft  512 . In operation, the motor  410  is operated to rotate the motor drive shaft  420 , indicated at  540 . The belt gear  500  is activated by the motor drive shaft  420  (indicated at  542 ), which in turn operates the gear shaft  510  (indicated at  544 ). The gear drive  510  drives the propeller drive  512  (indicated at  546 ) via gear interaction between the bevel gears  520 ,  522 . The propeller drive shaft  512  is direct coupled to propeller  514 . 
     In this example, the motor assembly  124  is mounted vertically within the middle unit  116 . The motor drive shaft  420  is substantially perpendicular to the propeller drive shaft  512 . However, other configurations are also contemplated. For example, the motor drive shaft  420  may be parallel to the propeller drive shaft  512  and may directly drive the propeller drive shaft  512  in some cases. The motor assembly  124  can be operated in a first or a second direction, operating the propeller  514  in forward or reverse. 
       FIG. 15  is a block diagram of a thermal management system  500  for use with the electric outboard motor assembly  110  according to one example of the present disclosure. The thermal management system  500  operates to provide cooling during operation of the electric outboard motor assembly  110 . The thermal management system  500  may be located integral to the electric outboard motor assembly  110 , and provides cooling of the battery pack  120  and/or motor assembly  124 . More specifically, the thermal management system  500  may be housed at least partially within the housing  150  of the electric outboard motor assembly  110 . In one example, the thermal management system  500  is a closed-loop liquid cooling system. In one or more examples, the thermal management system  500  may additionally or alternatively include the use of an open-loop system and/or a hybrid cooling system that uses both a closed-loop and an open-loop system. The thermal management system  500  may also comprise a cooling plate for providing additional cooling to the electric outboard motor assembly  110 . 
     In a non-limiting example, thermal management system  500  is a closed-loop liquid cooling system that includes one or more coolant tanks  510 ,  512 , a heat exchanger  514 , and a pump  516 . The battery pack  120  and the motor assembly  124  include coolant paths  518  and  520  routed therethrough. For example, the coolant paths  518  may include channels within cooling panels of battery modules in the battery pack  120 . The coolant paths  520  may include channels formed within one or more walls of the housing  410  for the motor assembly  124 . As illustrated, the coolant reservoir or tank  510  is in fluid communication  540  with the battery pack  120 ; the battery pack  120  is in fluid communication  542  with the motor assembly  124 , including the motor  410  and inverter  412 ; the motor assembly  124  is in fluid communication  544  with the coolant tank  512 ; the coolant tank  512  is in fluid communication  546  with the heat exchanger  514 ; the heat exchanger  514  is in fluid communication  548  with the pump  516 ; and the pump  516  is in fluid communication  550  with the coolant tank  510 . However, this is only one example arrangement of a thermal management system. The various components of the electric outboard motor assembly  110  could be fluidly interconnected by a thermal management system in other ways. Further, more or fewer coolant tanks could be implemented in a thermal management system. 
     The thermal management system  500  is operated through activation of the pump  516  by a control system  560 . The pump  516  operates to move liquid coolant through the system  500 , including through conduits implemented at  540 ,  542 ,  544 ,  546 ,  548 ,  550 . Coolant is pumped from the coolant tank  510  through the battery pack  120  and the motor assembly  124  to remove heat that occurs during operation of the outboard motor assembly  110 . As a result, the temperature of coolant leaving the battery pack  120  (indicated at  542 ) is higher than the temperature of entering the battery pack  120  (indicated at  540 ). The temperature of coolant leaving the motor assembly  124  (indicated at  544 ) is higher than the temperature of the coolant entering the motor assembly  124  (indicated at  542 ). Coolant may be temporarily stored in the coolant tank  512 , prior to entering the heat exchanger  514 . The heat exchanger  514  operates to remove heat from the liquid coolant entering the heat exchanger  514  (indicated at  546 ) such that it exits the heat exchanger  514  at a cooler temperature (indicated at  548 ). 
     Additional cooling of liquid coolant located with the closed-loop system  500  can be accomplished using a secondary cooling system. In one example, the secondary cooling system is a raw water (i.e., water to water) cooling system indicated at  570 . Raw water is brought into the heat exchanger  514  at a raw water inlet  572 , used to remove heat from the liquid coolant passing through the heat exchanger  514 , and exits at an outlet  574  at a higher temperature. In another example, the secondary cooling system includes a cooling plate  580  to aid in cooling liquid coolant in the closed-loop system, including liquid coolant passing through the heat exchanger  514 . 
       FIG. 16  is a side view of the electrical outboard motor assembly  110  illustrating one or more examples of physical locations of elements of the thermal management system  500 . In one example, the coolant tank  510  is located above and/or adjacent to the battery pack  120  within the upper unit  114 . For example, the coolant tank  510  may be located immediately adjacent to the battery pack  120 . The coolant pump  516  may be located immediately adjacent or on one side of the battery pack  120 . For example, the pump  516  may be located to one side of the first stack  222  and above the second stack  224 . In one example, the coolant tank  510  or the coolant tank  512  may be located in the middle unit  116 , above or adjacent the motor assembly  124 . The coolant pump  516  may also be located within the middle unit  116  adjacent the motor assembly  124 . In one example, the heat exchanger  514  may be located in the lower unit  118  near the propeller assembly  122 , although it may also be located within the middle unit  116 . The coolant tank  510  or  512  can also be located within the lower unit  118 . In other examples, the coolant path may be routed through cooling channels  580  integrally formed within the lower unit  118  including within the fin  138 . 
     The electric outboard motor assembly  110  disclosed herein provides an integrated electric outboard motor assembly that has a battery pack and motor assembly housed in the same housing. This results in a more conveniently packaged electric outboard motor assembly that can be used on boats and watercraft of differing sizes. The high energy density battery modules that can be packaged in a relatively small volumetric space enable the electric outboard motor assembly to power much larger boats than has traditionally been possible with integrated electric outboard motor assemblies. The integrated electric outboard motor assembly can further provide an integrated thermal management system that is a closed loop liquid cooling system for cooling the battery pack and motor assembly during operation of the electric outboard motor assembly. The electric outboard motor assembly can be used with a variety of sized boats having hulls with many different shapes and sizes. 
     Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This disclosure is intended to cover any adaptations or variations of the specific examples discussed herein. 
     Various example embodiments will now be provided. 
     Example embodiment 1: An electric outboard motor assembly comprising: a battery pack located in an upper unit; a propeller assembly located in a lower unit; and a motor assembly located in a middle unit between the upper unit and the lower unit. 
     Example embodiment 2: The assembly of example embodiment 1, comprising an outboard motor housing, where the outboard motor housing comprises a first portion that houses the battery pack and a second portion that houses the motor assembly. 
     Example embodiment 3: The assembly of example embodiment 2, wherein the first portion of the housing defines a first interior volume and the second portion of the housing defines a second interior volume, the first interior volume being greater than the second interior volume. 
     Example embodiment 4: The assembly of example embodiment 2, where the outboard motor assembly defines a longitudinal axis extending from the upper unit to the lower unit, wherein a first circumferential measurement of the first portion of the housing at a mid-point of the upper unit along the longitudinal axis is greater than a second circumferential measurement of the second portion of the housing at a mid-point of the middle unit along the longitudinal axis. 
     Example embodiment 5: The assembly of example embodiment 2, wherein the outboard motor housing comprises an inboard end operative for facing inboard of the watercraft and an outboard end operative for facing outboard of the watercraft, the inboard end of the second portion of the housing being indented in relation to the inboard end of the first portion of the housing. 
     Example embodiment 6: The assembly of example embodiment 2, wherein a transom mount is attachable to one of the second portion of the housing and an internal support structure of the outboard motor at a location beneath the upper unit. 
     Example embodiment 7: The assembly of example embodiment 2, where at least a portion of the first portion of the housing and the second portion of the housing are integrally formed together. 
     Example embodiment 8: The assembly of example embodiment 2, where at least part of the first portion of the housing enables access to the battery pack. 
     Example embodiment 9: The assembly of example embodiment 2, where at least part of the second portion of the housing enables access to the motor assembly. 
     Example embodiment 10: The assembly of example embodiment 2, where a seam separates the first portion of the housing from the second portion of the housing. 
     Example embodiment 11: The assembly of example embodiment 1, where the battery pack comprises a plurality of prismatic battery modules. 
     Example embodiment 12: The assembly of example embodiment 1, where the battery pack comprises a plurality of pouch battery cells. 
     Example embodiment 13: The assembly of example embodiment 1, where each battery module includes at least one battery cell. 
     Example embodiment 14: The assembly of example embodiment 1, where the battery pack comprises a first stack of battery modules and a second stack of battery modules, where the first stack is positioned over the second stack. 
     Example embodiment 15: The assembly of example embodiment 13, where the first stack of battery modules are oriented in a first orientation and the second stack of battery modules are oriented in a second orientation different than the first orientation. 
     Example embodiment 16: The assembly of example embodiment 14, where the first orientation is at 90 degrees with respect to the second orientation. 
     Example embodiment 17: The assembly of example embodiment 1, where the motor assembly is an integrated motor assembly with an inverter and an ac motor contained within a common motor assembly housing. 
     Example embodiment 18: The assembly of example embodiment 1, the propeller assembly including a propeller drive shaft, and where a motor drive shaft of the motor assembly is perpendicular to the propeller drive shaft. 
     Example embodiment 19: The assembly of example embodiment 1, comprising a gear mechanism coupled between the motor assembly and the propeller assembly. 
     Example embodiment 20: The assembly of example embodiment 1, comprising a thermal management system in communication with the battery pack and the outboard motor assembly. 
     Example embodiment 21: The assembly of example embodiment 20, wherein the thermal management system comprises a closed loop liquid cooling system. 
     Example embodiment 22: The assembly of example embodiment 1, where the assembly has a center of gravity located between the battery pack and the motor assembly. 
     Example embodiment 23: An electric outboard motor assembly comprising: an outboard motor housing a battery pack including a plurality of prismatic pouch battery modules, the battery pack located within the outboard motor housing; and a motor assembly located within the outboard motor housing. 
     Example embodiment 24: The assembly of example embodiment 23, the outboard motor housing comprising a first housing portion and a second housing portion, where the battery pack is positioned within the first housing portion. 
     Example embodiment 25: The assembly of example embodiment 23, where the battery pack comprises a first stack of battery modules and a second stack of battery modules, where the first stack is positioned over the second stack. 
     Example embodiment 26: The assembly of example embodiment 25, where the first stack of battery modules are oriented in a first position and the second stack of battery modules are oriented in a second position different than the first position. 
     Example embodiment 27: An electric outboard motor assembly comprising: an outboard motor housing; a battery pack; a motor assembly comprising an inverter and outboard motor; and a thermal management system in fluid communication with the battery pack and the motor assembly, where at least two of the battery pack, the motor assembly and the thermal management system are located within the outboard motor housing. 
     Example embodiment 28: The assembly of example embodiment 27, where the battery pack, motor assembly and thermal management system are all at least partially located within the outboard motor housing. 
     Example embodiment 29: The assembly of example embodiment 27, where the thermal management system comprises a closed loop liquid system. 
     Example embodiment 30: The assembly of example embodiment 19, the thermal management system comprising a coolant pump and a reservoir tank, in fluid communication with the battery pack and the motor assembly. 
     Example embodiment 31: The assembly of example embodiment 22, where the reservoir tank is located adjacent the battery pack. 
     Example embodiment 32: The assembly of example embodiment 22, the thermal management system further comprising a heat exchanger. 
     Example embodiment 33: The assembly of example embodiment 24, where the heat exchanger further includes a raw water inlet and outlet to aid in removing rejected heat from coolant moving therethrough.