Patent Publication Number: US-2022216551-A1

Title: Pressure-based battery ejection system

Description:
CROSS REFERENCE TO OTHER APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/809,831 entitled PRESSURE-BASED BATTERY EJECTION SYSTEM filed Nov. 10, 2017 which is incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     In the event of a battery malfunction such as cell thermal runaway, batteries may produce hazardous gases and/or large amounts of heat. Techniques to detect and handle malfunctioning batteries would be desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings. 
         FIG. 1A  is a diagram illustrating an embodiment of a pressure-based battery ejection system prior to battery ejection. 
         FIG. 1B  is a diagram illustrating an embodiment of a pressure-based battery ejection system after battery ejection. 
         FIG. 2A  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising a latch and o-rings prior to battery ejection. 
         FIG. 2B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising a latch and o-rings after battery ejection. 
         FIG. 3A  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising bolts prior to battery ejection. 
         FIG. 3B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising bolts after battery ejection. 
         FIG. 4A  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising magnets prior to battery ejection. 
         FIG. 4B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising magnets after battery ejection. 
         FIG. 5A  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising shear o-rings prior to battery ejection. 
         FIG. 5B  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising shear o-rings after battery ejection. 
         FIG. 6A  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising an orifice in the pressure cavity. 
         FIG. 6B  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising an exhaust monitor. 
         FIG. 7  is a flow diagram illustrating an embodiment of an exhaust monitoring process. 
         FIG. 8A  is a diagram illustrating an embodiment of a spring contact electrical connection. 
         FIG. 8B  is a diagram illustrating an embodiment of a blade and spring electrical connection. 
         FIG. 9  is a diagram illustrating an embodiment of an aircraft comprising a pressure-based battery ejection system. 
         FIG. 10  is a diagram illustrating an embodiment of a barrier between batteries. 
         FIG. 11A  is a diagram illustrating an embodiment of a latch prior to battery ejection. 
         FIG. 11B  is a diagram illustrating an embodiment of a deployed latch that prevents a neighbor battery from ejecting. 
     
    
    
     DETAILED DESCRIPTION 
     The invention can be implemented in numerous ways, including as a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer readable storage medium; and/or a processor, such as a processor configured to execute instructions stored on and/or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Unless stated otherwise, a component such as a processor or a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. As used herein, the term ‘processor’ refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions. 
     A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured. 
     A battery ejection system is disclosed. The battery ejection system comprises a pressure vessel, a battery submodule positioned at least partially in the pressure vessel and configured to release gas into the pressure vessel, and a seal. The seal is configured to seal the pressure vessel in a first mode and is configured to release in a second mode. The second mode is triggered in the event a pressure level in the pressure vessel exceeds a threshold pressure level. The battery is configured to be disconnected from an electrical connection in the second mode. 
     In some embodiments, a pressure vessel includes or is a cavity which is formed by a structure and a battery of the battery ejection system is partially or completely sealed in such a cavity. In some embodiments, an electrical contact of the battery is positioned within the cavity. For example, the battery is connected to a wire or any other appropriate electrical component within the cavity. In the event of battery failure or malfunction, the battery may vent gases. In some embodiments, the battery is positioned in the cavity such that vented gases from the battery release into the cavity. In the event pressure in the cavity exceeds a threshold pressure that a seal of the cavity is designed to handle, the seal will release. In some embodiments, the battery is ejected from its electrical connection in the event the seal releases. For example, the seal holds the battery in the cavity to make electrical contact and the battery falls from the cavity in absence of the seal. In some embodiments, the force of the vented gas pushes the battery out of the cavity and ejects the battery electrically. 
     In some embodiments, a battery ejection system is used in an electric aircraft. An electric aircraft powered by batteries may require a lightweight system of detecting malfunctioning batteries and removing them from the aircraft&#39;s electrical systems. The pressure-based battery ejection system automatically electrically ejects batteries based on an amount of venting gases, which is a measure of battery malfunction. For example, a battery may release gases when it malfunctions whereas a properly functioning battery does not release gases or releases a low volume of gases. Active monitoring and ejection using monitors, gauges, processors, or other heavy equipment is not required. In some embodiments, the battery ejection system provides a reliable, safe, simple, and lightweight way of electrically ejecting malfunctioning batteries. 
       FIG. 1A  is a diagram illustrating an embodiment of a pressure-based battery ejection system prior to battery ejection. In the example shown, battery  100  is positioned inside structure  102 . Structure  102  may comprise part of an electrical load (or electrical connection to such an electrical load) that battery  100  provides power to. For example, structure  102  may comprise an aircraft framework. In the example shown, seal  106  between structure  102  and battery  100  creates cavity or pressure vessel  104 . The seal as shown is positioned near one end of the battery, leaving a small portion of the battery unsealed. In some embodiments, the battery is configured to vent gases from a portion of the battery that is sealed in the cavity. In some embodiments, the battery includes a covering that directs gas released by the battery. For example, the battery may be stored in a can that has venting slots that direct where gas released from the battery may travel; such slots may direct any released gases from battery  100  into pressure vessel  104 . 
     As shown, the battery has an electrical connection at the end of the battery that is pointing into cavity  104 . The electrical connection is positioned at one end of the battery whereas the seal is positioned near the midsection of the battery (at least in this example). Battery  100  has an electrical connection with structure  102 . In some embodiments, the electrical connection comprises wiring that allows the battery to provide or draw power. In some embodiments (not shown here), seal  106  does not wrap around the midsection of the battery but rather surrounds the battery such that all of the battery is within or otherwise enveloped by the cavity or pressure seal (e.g., seal  106  goes below or underneath battery  100 ). In some embodiments, the battery touches or is in contact with structure  102  at some portions of the battery such that there is no need for a seal where they make contact. For example, seal  106  may comprise discrete pieces of material that seal multiple gaps between battery  100  and structure  102 . 
     In the event a battery fails, it may release gases. In some embodiments, vented gases are released into cavity  104 . In some embodiments, seal  106  is designed to withstand up to a threshold level of pressure. The threshold level of pressure may be determined based on a level of battery malfunction that is critical. For example, using a slightly venting battery may be safer than ejecting the slightly venting battery and flying with less power in some cases of electric aircraft flight. A battery venting a large volume of gas and/or a lot of heat may pose a larger risk where it is worthwhile to eject the battery. The threshold level of pressure of the seal may map to an amount of gas corresponds to a high risk battery which cannot be used any longer. In the event pressure inside cavity  104  exceeds a threshold pressure of seal  106 , the seal releases. In some embodiments, the pressure provides a force that ejects the battery from structure  102 . In some embodiments, the release of the seal allows the battery to disconnect from its electrical connection. For example, gravity may cause the battery to fall from structure  102 . 
     In the example shown, battery  100  is positioned under structure  102 . In some embodiments, battery  100  is positioned atop structure  102 . In some embodiments, the battery and structure are positioned on their sides (e.g.  FIG. 1B  is rotated 90 degrees). In all the examples shown, the positioning of the battery and structure may be implemented in a rotated orientation from what is illustrated. Regardless of the orientation, any venting slots (not shown) in a battery&#39;s can may be oriented to be facing upwards. This is because the emitted gases may be hot and rise upwards as a result. Venting slots which are positioned or otherwise oriented to be facing upward will more readily permit the hot gases to exit into the cavity or pressure vessel. 
       FIG. 1B  is a diagram illustrating an embodiment of a pressure-based battery ejection system after battery ejection. In the example shown, seal  106  of  FIG. 1A  has released. In various embodiments, the seal ruptures or is pushed off intact. Release of the seal causes battery  100  to be ejected from its electrical connection with structure  102 . In some embodiments, battery  100  is ejected from a high power electrical connection. 
     In some embodiments, seal  106  is reversible or replaceable. Battery  100  may be replaced with a new battery by removing the seal, placing a new battery in position such that it establishes electrical contact with structure  102 , and replacing the seal or putting a new seal in place. 
       FIG. 2A  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising a latch and o-rings prior to battery ejection. In various embodiments, various configurations and combinations of seals are used in the pressure-based battery ejection system. In some embodiments, various components are used in combination to create the pressure vessel. The various components may perform separate functions. For example, one component may be used to hold the battery in a position wherein it maintains an electrical connection. The component may exert a force on the battery that pushes an electrical contact of the battery against an electrical contact of an electrical load it powers. The component may restrain the battery within a structure. Another component may be used to create an airtight seal around at least a portion of the battery and the structure. 
     In the example shown, battery  200  is positioned within structure  202 . Battery  200  is held in place by latch  208 . In some embodiments, latch  208  keeps battery  200  in electrical contact with structure  202 . The latch may comprise a force-regulating latch that has zero deflection under force until it buckles and completely releases when subjected to a threshold amount of force. The latch may comprise a piece of bowed metal that springs from one stable position to another stable position after subjected to a large amount of force. A bistable spring mechanism may be used. In some embodiments, a latch or spring that has two stable positions and changes from one stable position to a second stable position after a certain amount of pressure is exerted is used, wherein one stable position causes the latch or spring to hold the battery in the cavity and another stable position releases the battery. In some embodiments, the latch or spring comprises a flattened portion that is attached to the structure (e.g. structure  202 ). The rest of the latch or spring may pivot around the flattened portion. 
     In the example shown, o-rings  204  and  210  are positioned between battery  200  and structure  202 . In some embodiments, the o-rings create an airtight barrier but are not strong enough to hold battery  200  in place. For example, the o-rings may comprise a flexible material such as rubber. In the example shown, the o-rings are held in place via indents in structure  202 . As shown, o-rings  204  and  210  create pressure vessel  206 . The o-rings may prevent air from escaping from pressure vessel  206 . The pressure vessel is bounded by structure  202  and the o-rings. In some embodiments, the front face of battery  200  as shown and a back face of battery  200  are flush against structure  202 . O-rings  204  and  210  may block areas where air may escape from pressure vessel  206 . In various embodiments, any number of o-rings are positioned between the battery and structure to provide an airtight seal and create pressure vessel  206 . As shown, about half of battery  200  is sealed inside pressure vessel  206 , including a portion of the battery that comprises an electrical contact. The electrical contact is in contact with an electrical contact of structure  202 , creating an electrical connection. In some embodiments, battery  200  is configured to release gas into pressure vessel  206 , causing a force to build up on latch  208  in the event the battery malfunctions. 
       FIG. 2B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising a latch and o-rings after battery ejection. In the example shown, latch  208  assumes an inverted position compared to its position in  FIG. 2A . In some embodiments, the latch is configured to invert when subjected to a threshold amount of force. As shown, latch  208  no longer holds battery  200  in position and in electrical contact with structure  202 . In some embodiments, battery  200  is ejected such that a pressure vessel no longer exists. In the example shown, battery  200  is ejected past o-rings  204  and  210 . The o-rings are not in contact with the battery and a sealed cavity ceases to exist. The o-rings may be configured to allow the battery to slide past them in the event the battery is not held in position by another element, such as a latch. 
     As shown, battery  200  is no longer electrically connected to structure  202 . In some embodiments, the electrical contact of battery  200  is configured to not reestablish an electrical connection with structure  202  after ejection, even in the event that battery  200  falls back into structure  202 . In some embodiments, battery  200  is positioned underneath structure  202  and gravity causes battery  200  to fall from structure  202  after latch  208  ceases to hold battery  200  in electrical contact with the structure. In some embodiments, battery  200  and structure  202  are positioned on their sides such that battery  200  is ejected to one side rather than ejected down or up from the structure. In some embodiments, pressure from vented gases is sufficient to push battery  200  away from an electrical contact of the structure. For example, the battery may be pushed sufficiently far from an electrical contact of the structure such that it will not regain electrical contact. 
     In some embodiments, latch  208  is a reversible seal. For example, latch  208  may be returned to its original position in  FIG. 2A . In some embodiments, a reversible seal is used to seal battery replacements that are put in place after an original battery is ejected. 
       FIG. 3A  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising bolts prior to battery ejection. In some embodiments, non-reversible seals are utilized. For example, once the seal is broken, it may not be reversed to an original position wherein it creates an airtight cavity surrounding at least a portion of the battery. In the example shown, battery  200  is held in electrical contact with structure  302  via panel  306 . Panel  306  is bolted into structure  302  using bolts  304  and  308 . O-rings  310  and  312  as shown create an airtight seal with battery  300 , creating pressure vessel  314  from which air cannot escape. 
       FIG. 3B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising bolts after battery ejection. In the example shown, panel  306  is fractured into multiple pieces. Panel  306  may be configured to break under a threshold amount of pressure. Bolts  304  and  308  remain intact and hold portions of panel  306  to structure  302 . In some embodiments, bolts  304  and  306  are configured to shear under a threshold amount of force. In the event the bolts shear, panel  306  may be removed from structure  302  in one piece, causing battery  300  to be ejected from its electrical connection. For example, panel  306  and battery  300  may fall away from structure  302  due to gravity in the event battery  300  is positioned below structure  302 . 
       FIG. 4A  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising magnets prior to battery ejection. In the example shown, battery  400  is completely sealed in pressure vessel  414  using panel  406 , magnets  404  and  408 , and o-rings  410  and  412 . Magnets  404  and  408  hold panel  406  against structure  402 , keeping battery  400  in contact with structure  402  at an end of the battery that comprises an electrical contact. In the example shown, panel  404  is held adjacent to structure  402  using magnets  404  and  408 , which are attracted to magnets that are embedded in structure  402 . In some embodiments, the magnets and panel do not create an airtight seal. O-rings  410  and  412  may create an airtight seal with battery  400 , creating pressure vessel  414 . In some embodiments, o-rings or other components are utilized to create a smaller pressure vessel than would otherwise be created by using a seal that encloses the entire battery in the pressure vessel. The positioning of the o-rings or airtight seal component may be determined based on a threshold pressure level of the magnets or restraining component. For example, in the event the magnets are displaced only under a force that is much larger than a force that maps to a dangerous level of gas venting, the o-rings may be positioned to create a small pressure vessel. The battery&#39;s enclosure or covering may ensure that released gas is released into the pressure vessel. The small pressure vessel may cause the magnets to be displaced in the event a dangerous level of gas venting occurs. In some embodiments, the panel and magnets hold battery  400  in a position wherein an airtight seal is created around a portion of the battery using o-rings  410  and  412 . 
       FIG. 4B  is a flow diagram illustrating an embodiment of a pressure-based battery ejection system comprising magnets after battery ejection. In some embodiments, magnets  404  and  408  are configured to separate from magnets embedded in structure  402  when subjected to a threshold force. In the example shown, magnets  404  and  408  have separated from magnets embedded in structure  402 , causing panel  406  to be removed from its prior position. As shown, panel  406  is not in contact with structure  402 , allowing battery  400  to be ejected from its electrical connection. 
     In various embodiments, reversible or irreversible seal components are utilized in various positions around a battery. In some embodiments, seal components are used only between the battery and an electrical load the battery powers. For example, in lieu of o-rings between battery  400  and structure  402 , a magnet may be used that is dislodged from its position with a specified amount of force. A latch may be used between a battery and an electrical load the battery provides power to create an airtight cavity. In some embodiments, seal components are used only externally on the battery and powered electrical load. For example, a battery may be completely enclosed in a pressure vessel constrained by a seal. In some embodiments, a combination of seal components in various positions is used. 
       FIG. 5A  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising shear o-rings prior to battery ejection. In the example shown, shear o-rings  504  and  506  are positioned on either side of battery  500 . The shear o-rings are positioned between the battery and structure  502 . In some embodiments, the shear o-rings each comprise two flexible o-rings connected by a component that shears under a threshold force. In some embodiments, the component consists of a brittle material. In the example shown, structure  502  and battery  500  are shaped to accommodate the shear o-rings. Pressure vessel  508  comprises an airtight cavity bounded by shear o-rings  504  and  506 , battery  500 , and structure  502 . In some embodiments, shear o-rings  504  and  506  hold battery  500  in a position wherein the battery is in electrical contact with structure  502 . 
       FIG. 5B  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising shear o-rings after battery ejection. In the example shown, the component that connects the o-rings of each shear o-ring has broken due to pressure created by vented gases. As shown, o-rings  510  and  512  previously of shear o-rings  504  and  506  respectively remain positioned in a covering of the battery. For example, o-rings  510  and  512  remain positioned lodged in indents of a can battery  500  is stored in. O-rings  514  and  516  previously of shear o-rings  504  and  506  respectively remain positioned lodged in indents of structure  502 . Battery  500  is ejected from its electrical connection with structure  502 . 
       FIG. 6A  is a diagram illustrating an embodiment of a pressure-based battery ejection system which includes an orifice in the pressure cavity. In the example shown, battery  600  is held in position via latch  602  while o-rings  604  and  606  create an airtight seal to pressure vessel  608 . In the example shown, pressure vessel  608  comprises orifice  610 . In various embodiments, pumps or venturis connected to the orifice are used to modify a pressure level inside the pressure vessel or extract vapor samples for battery health monitoring. 
     In some embodiments, pressure inside pressure vessel  608  is regulated to change characteristics of the battery ejection so that system can be used with different types of batteries which vent gases at different rates. For example, a vacuum or pressure-regulating device attached at orifice  610  may be used to calibrate or adjust the pressure inside the pressure vessel so that the battery is ejected at whatever pressure level corresponds to an unsafe and/or undesirable level. Alternatively, in lieu of pressure regulation (e.g., for systems which do not include a vacuum or pressure-regulating device), latch  602  may be released while battery  600  is still safe to use. For example, the latch may be released when battery  600  is venting at low levels if there is no pressure regulation. 
     In an aircraft application, a pressure-regulating device may equalize pressure inside the pressure vessel to match pressure outside the aircraft via the orifice. In some embodiments, the pressure-regulating device ensures that pressure changes due to altitude do not cause the seal of the pressure vessel to release. Over long time scales, the pressure-regulating device may cause pressure to equalize, whereas a sudden venting of gas caused by battery malfunction cannot be equalized quickly enough by the pressure-regulating device and the seal is released. 
     In some embodiments, an interior of the pressure vessel or cavity comprises a thermally resistant coating. Gases released during battery malfunction may be hot. In some embodiments, the coating is ablative and vaporizes when subjected to heat. Vapors created by the coating may be accounted for in calibrating the seal for properly timed battery ejection. 
       FIG. 6B  is a diagram illustrating an embodiment of a pressure-based battery ejection system comprising an exhaust monitor. In some embodiments, an exhaust monitor is used to analyze gas in the pressure vessel. In the example shown, exhaust monitor  612  analyzes gas from pressure vessel  608  via a tube that connects the exhaust monitor to the pressure vessel. The exhaust monitor may determine whether battery  600  is (e.g., abnormally and/or dangerously) venting gas based on the composition of gas in the pressure vessel. For example, malfunctioning batteries release electrolytes of specific compositions. In the event exhaust monitor detects the electrolytes in the pressure vessel, the battery may be determined to be (e.g., abnormally and/or dangerously) venting and responsive actions may be performed. In some embodiments, a warning is automatically delivered to relevant systems or persons in the event the battery is determined to be venting. For example, a pilot or autopilot system of an aircraft is automatically and/or in advance warned via an aircraft application of the system. In some embodiments, the pressure-based battery ejection system is calibrated to eject a venting battery only when a volume of released gases indicates the battery cannot be used any longer, which is designed to occur after the indicative electrolytes have been detected. However, a battery that has started to vent or is venting a low volume of gas may provide an (e.g., early) indication to a pilot or autopilot that the aircraft should be landed soon or power intensive aircraft maneuvers should be avoided. In some embodiments, the exhaust monitor is part of a suite of battery management elements. In some embodiments, a pilot or autopilot forcibly ejects a battery based on information collected by the exhaust monitor. For example, batteries of the pressure-based battery ejection system can be actively ejected in addition to passively ejected due to pressure. 
       FIG. 7  is a flow diagram illustrating an embodiment of an exhaust monitoring process. At  700 , gas in the pressure vessel is analyzed. At  702 , it is determined whether threshold levels of venting gases are detected. In some embodiments, various types of gases have different threshold levels. Multiple gases may be required to be detected above their respective threshold levels. In the event threshold levels of venting gases are not detected, gas in the pressure vessel continues to be analyzed. In the event threshold levels of venting gases are detected, at  704  a warning is provided to a pilot. In some embodiments, a battery corresponding to the pressure vessel is actively ejected in the event a second higher threshold level of venting gases is detected. 
       FIG. 8A  is a diagram illustrating an embodiment of a spring contact electrical connection. In various embodiments, the battery is connected to the rest of the electrical system using various configurations of electrical contacts. In some embodiments, the electrical contacts are designed to establish an electrical connection that is easily disconnected. For example, the electrical contacts will not continue to hold the battery in place after the seal of the pressure vessel is released. In some embodiments, the electrical contact of the battery and the electrical contact of the electrical load are configured to disconnect in the event some pushing or pulling force causes the electrical contacts to electrically and/or physically disconnect. In the event the battery is subjected to a force (e.g. pressure from gas build-up or gravity) that causes it to lose contact with the electrical load, the electrical connection is broken. In some embodiments, the electrical contact of the battery must be subjected to a force that pushes it firmly against the electrical contact of the electrical load, otherwise the electrical connection is broken. 
     In the example shown, battery  800  includes plate  802 . Plate  802  is in electrical contact with spring-loaded contact  804 . In the event the plate and spring are no longer touching, the electrical connection is broken. 
     In some embodiments, a pogo pin is used for spring-loaded contact  804 . In the event a spring of the pogo pin is compressed, the electrical connection is complete. In the event the pogo pin is not compressed, the electrical connection is broken. In some embodiments, the battery is held in a position that compresses the pogo pin in the event the seal is intact. 
     In some embodiments, the electrical contact is designed such that an electrical connection will not reconnect or reform after battery ejection. For example, the spring of the pogo pin may be able to withstand the weight of the battery. In the event the battery is ejected up from the structure and falls back down, the weight of the battery would not be sufficient to reform the electrical connection. In some embodiments, a seal (e.g. a bolt, a latch, or a magnet) must be replaced to reform the electrical connection. 
       FIG. 8B  is a diagram illustrating an embodiment of a blade and spring electrical connection. In the example shown, battery  820  includes blades  822  and  824 . The blades extrude from the battery. The blades are in electrical contact with springs  826  and  828  (sometimes referred to as a clip). Spring  826  comprises two pins that blade  822  slides in between. In some embodiments, the pins of spring  826  are tensioned to hold blade  822  securely and create a secure electrical connection. Blade  824  is situated in between two pins of spring  828 . In the event battery  820  is ejected, blade  822  and  824  may slide out from springs  826  and  828 . As shown here, in various embodiments, various types of electrical contacts are used. 
       FIG. 9  is a diagram illustrating an embodiment of an aircraft which includes a pressure-based battery ejection system. In the example shown, aircraft  900  includes (forward) wing  918  and (rear) wing  936 . Wing  918  includes pylons  908  and  916 , on either side of the fuselage. Pylon  908  includes rotor  902  and rotor engine  904 . Pylon  908  also includes eight batteries, including battery  906 . In various embodiments, 4, 10, 12, or any appropriate number of batteries are stored in a single pylon. Pylon  916  includes rotor  910  and rotor engine  912 . Pylon  916  also includes eight batteries, including battery  914 . Wing  936  includes pylons  926  and  934 , on either side of its fuselage. Pylon  926  includes rotor  920  and rotor engine  922 . Pylon  926  also includes eight batteries, including battery  924 . Pylon  934  includes rotor  928  and rotor engine  930 . Pylon  934  also includes eight batteries, including battery  932 . 
     In this example, the pressure-based battery ejection system is installed on each battery shown. For example, battery  906  is stored at least partially within a sealed cavity, wherein a seal on the cavity is configured to release in the event a threshold level of pressure is reached within the sealed cavity. In some embodiments, the batteries are positioned such that an end of the battery that does not have an electrical contact faces downwards towards the ground in normal flight. For example, a latch or panel may be positioned below the battery and hold the battery in place. In the event the latch or panel releases, the battery is dropped and ejected from its electrical connection. The battery may be ejected from its electrical contact via gravity following the release of the seal. In some embodiments, the battery is ejected from its electrical connection but remains in the aircraft. In some embodiments, the battery is ejected completely from the aircraft. In the event the battery is ejected from the aircraft, the aircraft may comprise safety mechanisms to prevent the battery from becoming a projectile. For example, the battery may be attached to the aircraft via a tether. 
     In some embodiments, the batteries are positioned to be ejected upwards from the aircraft or laterally in parallel with the aircraft&#39;s wings. For example, a battery may be ejected upwards from the aircraft. The battery may comprise an electrical contact that will not establish an electrical connection with the aircraft after ejection. The battery may be ejected out to one side of the aircraft rather than downwards. 
     In some embodiments, the pressure-based battery ejection system is permitted to eject a central or primary battery of an aircraft if/when appropriate. Alternatively, in some embodiments, the system is only permitted to eject batteries that do not have a significant impact on the aircraft&#39;s center of gravity or power levels if/when appropriate. For example, the ejection system is only coupled to smaller or outboard batteries wherein the ejection of the batteries does not have a severe adverse effect on flight. 
     In some embodiments, a battery of the pressure-based battery ejection system is configured to allow vented gases to escape from the battery quickly in the event the battery is disconnected from all electrical connections. 
       FIG. 10  is a diagram illustrating an embodiment of a barrier between batteries. In some embodiments, multiple batteries implementing the pressure-based battery ejection system are positioned next to each other (see, e.g., how multiple batteries are stored in the same pylon in  FIG. 9 ). In some embodiments, a barrier is positioned between batteries. The barrier prevents heat transfer between batteries. For example, barriers  1000 ,  1010 , and  1016  may comprise fire-retardant divisions. The barriers prevent hot gas released from battery  1002  from heating up battery  1012 . Excessive heat from one battery may cause an adjacent battery to catastrophically fail, creating a domino effect of failing batteries and fire-retardant divisions would prevent this from happening. In the example shown, battery  1002  and battery  1012  are positioned in alignment. For example, latches  1004  and  1014  are in parallel. 
       FIG. 11A  is a diagram illustrating an embodiment of a latch prior to battery ejection. Ejecting multiple adjacent batteries may cause an unsafe change to a center of gravity of a vehicle or aircraft. In some embodiments, ejecting two or more adjacent batteries causes that section of the aircraft to be dangerously underpowered. The weight or power changes that occur due to ejecting multiple batteries in close proximity may pose more danger than continuing to use the venting batteries. In some embodiments, mechanical means are used to prevent a battery from ejecting in the event an adjacent battery has already been ejected. In the example shown, battery  1100  is held in position via L-shaped latch  1102 . The latch is used in conjunction with o-rings. Adjacent battery  1104  is sealed partially in a pressure vessel utilizing o-rings and L-shaped latch  1106 . 
       FIG. 11B  is a diagram illustrating an embodiment of a deployed latch that prevents a neighbor battery from ejecting. In the example shown, L-shaped latch  1102  has released, allowing  1100  to be electrically disconnected. L-shaped latch  1102  is now in a position where it restrains battery  1104 . In the event latch  1106  releases, battery  1104  will remain electrically connected to the electrical load it powers due to latch  1102 . 
     Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative and not restrictive.