SUMMARY

This disclosure relates to automotive battery packs and, in particular, to directing and allowing fluids to exit the battery pack.

A typical automotive battery pack may be designed to withstand a wide range of environmental conditions, such as a wide range of temperatures (e.g., environmental temperatures from −40° C. to 60° C.), humidity, air pressure, etc. For example, if a particular defined volume is held constant, the pressure within that area may have a large spread variation, such as approximately 40% to accommodate a full range of conditions. In other instances the volume available to accommodate the molecules of air within the battery enclosure could also vary in accordance with changed conditions (e.g., approximately 40% volume change). If a pressure change such as a 40% pressure change were to occur based on an original pressure of 1 atmosphere, the change could be as much as 400 mbar, which may be enough of a pressure change to damage or otherwise impact seals or lids that encompass the volume.

In an exemplary battery pack, an interior air volume (e.g., 40-90 L) that experiences a very large change in volume may exert severe forces on any sealing components. Attempts to alleviate a large pressure change by removing a portion of air (e.g., using a bellows-type volume exchange system) may not be feasible in a vehicle, where space for operational components and rider comfort is paramount. For example, given an exemplary battery pack with an interior air volume of 70 L, any bellows-type volume exchange system would need to be able to hold on the order of 30 L of air to accommodate a 40% change in volume. Accordingly, a gas-exchange system of some sort may be utilized, e.g., to exchange air with the environment outside of the vehicle.

A water molecule (approximately 2.75 angstroms in length) is smaller than a nitrogen molecule (approximately 3.7 angstroms in length). As such, any membrane designed to equalize pressure by air transfer must let gaseous water molecules through. As the battery pack thermally cycles, this exchange will enable condensation if the dew point is exceeded. In this manner, a battery pack that is operating in a cold or high-humidity environment may exceed the dew point, which may cause water to form on the battery pack and drain to adjacent surfaces. If the water level increases too much, debris and corrosion may cause isolation failures over time. As such, a fluid exchange system may be utilized to drain water from the battery pack or the environment of the battery pack (e.g., a frame for accommodating multiple water packs). To allow fluid to drain from the battery pack, a plurality of valves may be located on one or more of a plurality of retaining members which comprise the frame of the battery pack, wherein the plurality of valves allow liquid to exit the battery frame.

In some embodiments, a battery frame intended for a vehicle should be able to withstand forces encountered during driving as well as blunt forces, such as those caused by a ground strike (e.g., from rebar, trailer hitches, antlers, rocks, etc.). Vehicles may also be utilized off road, which means that a battery frame must be able to withstand ground strike at full vehicle weight on very sharp rocks, trees, etc.

In some embodiments, the battery frame comprises a base plate, a plurality of retaining members fixedly connected from the base plate, wherein the plurality of retaining members extend from the base plate in a vertical direction, and a plurality of cross members coupled to at least one of the base plate or one or more of the plurality of retaining members. In some embodiments, one or more of the plurality of cross members may be coupled only to the base plate or only to the plurality of retaining members. In some embodiments, one or more of the plurality of cross members is may be coupled to a plurality of the retaining members. The configuration of the base plate, retaining members, and cross members defines a plurality of at least partial cavities for a plurality of battery modules.

In some embodiments, the base plate is coupled to each of the retaining members at an angle. The angle formed between a level surface and the base plate when coupled to the retaining members may be at least three degrees in a direction from front to rear of the battery frame, though in some embodiments the angle comprises a high region at the front of the battery frame and a low region at the rear of the battery frame.

In some embodiments, the base plate may not include any through holes, while in other embodiments the base play may include any number of through holes. Substantially all through holes in the base plate may be filled or covered. For example, each through hole may be covered or filled by a weld or a bolt.

The retaining members which form the battery frame may include two side retaining members, a front retaining member, and a rear retaining member. The plurality of valves may be located on the side retaining members only. In some embodiments, however, the plurality of valves may be located on the rear retaining member only. In yet other embodiments, at least one valve may be located on the side retaining members and at least one valve may be located on the rear retaining member. The valves may be located on a rear lower portion of at least one of the side retaining members. The valves may also be located on a lower portion of the rear retaining member. The valves may be one-way valves, only allowing fluid to exit the battery frame.

The base plate may further include one or more channels. The channels may direct the flow of liquid to one or more of the plurality of valves. One or more of the plurality of cross members may include one or more fluid passages at an end thereof nearest to the base plate.

Battery modules may be attached to the base plate, the retaining members, and/or the cross members. The battery modules may also include one or more fluid passages at an end of thereof closest to the base plate.

In some embodiments, the battery frame comprises a base plate, a retaining structure fixedly connected to the base plate, wherein the retaining structure extends from the base plate tin a vertical direction, a battery attachment structure coupled to at least one of the base plate or retaining structure, wherein the base plate, the retaining structure, and the battery attachment structure define a plurality of at least partial cavities for a plurality of battery modules, and a plurality of valves located on the retaining structure, wherein the plurality of valves allow liquid to exit the battery frame. The valves may be located to facilitate exit of the liquid during forward acceleration of a vehicle, deceleration of a vehicle, and/or turning of a vehicle.

