Patent Publication Number: US-2023139302-A1

Title: Thermal management for a conformal wearable battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 17/491,117 filed on Sep. 30, 2021 and is also a continuation of co-pending International Application No. PCT/US22/77264 entitled “Thermal Management for a Conformal Wearable Battery,” filed on Sep. 29, 2022, which claims priority to U.S. patent application Ser. No. 17/491,117 filed on Sep. 30, 2021 and also claims priority to U.S. Provisional Patent Application No. 63/360,404 filed on Sep. 30, 2021. All of the above referenced applications are herein incorporated by reference in their entirety. 
     This application is also related to U.S. patent application Ser. No. 17/038,287 filed on Sep. 30, 2020, now U.S. Pat. No. 11,064,604 issued on Jul. 13, 2021, U.S. application Ser. No. 17/085,873 filed on Oct. 30, 2020, now U.S. Pat. No. 11,081,755 issued on Aug. 3, 2021, U.S. application Ser. No. 17/086,132 filed on Oct. 30, 2020, now U.S. Pat. No. 10,950,913 issued on Mar. 16, 2021, U.S. application Ser. No. 17/085,864 filed on Oct. 30, 2020, now U.S. Pat. No. 10,980,116 issued on Apr. 13, 2021, U.S. application Ser. No. 17/085,928 filed on Oct. 30, 2020, now U.S. Pat. No. 11,349,174 issued on May 31, 2022, and U.S. application Ser. No. 17/202,109 filed on Mar. 15, 2021, now U.S. Pat. No. 11,251,497 issued on Feb. 15, 2022. All of the above referenced applications are herein incorporated by reference in their entirety. 
    
    
     FIELD 
     Aspects described herein generally relate to portable electrical power storage systems. More specifically, aspects of this disclosure relate to thermal management for a portable electrical power storage system. 
     BACKGROUND 
     Portable battery systems may be utilized to provide mobile and/or remote location electrical power. Integrated communications equipment and/or weapons gear utilized, for example, by law enforcement and/or military personnel requires increasingly high levels of power storage carried proximate the user&#39;s body. Methods of increasing power storage capability in a device, such as a conformal wearable battery (CWB) are to include additional battery cells and/or use higher capacity battery cells. However, these solutions may unacceptably increase the size and/or weight of the resulting systems, reducing mobility. 
     In addition, batteries may come in different shapes and sizes depending on their intended usage. In some instances, the batteries may be desired to flex or bend and may be exposed to harsh environments. Some batteries may be arranged as packages of battery cells that are assembled together to provide a predetermined power output, while maintaining a portable size and weight. These battery cells may be arranged in a durable and sealed housing to protect the battery cells from damage. As these battery cells discharge, heat may be produced, and in some cases due to internal and/or external factors, one or more of the battery cells may become damaged or unstable that can cause the cell to go into an exothermic reaction called thermal runaway, which may cause a fire. A thermal management system may allow the mobile electrical power storage package to operate safely. 
     BRIEF SUMMARY 
     Aspects of the disclosure provide solutions that address and overcome technical problems associated with minimizing size of a portable battery system (e.g. a conformal wearable battery system). 
     Some aspects of this disclosure may relate to a conformal wearable battery (CWB) that includes: a flexible printed circuit board assembly (PCBA) comprising: (a) a flexible printed circuit board (PCB) and (b) a plurality of battery cells connected to the flexible PCB in a grid-like pattern, each battery cell of the plurality of battery cells comprising a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side and where each battery cell of the plurality of battery cells is a lithium-ion pouch cell comprising a seal on the first side of each battery cell. The CWB may also include a plurality of fire-blocking foam members, where a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of a first battery cell of the plurality of battery cells and a flame-suppressant grease located between the first battery cell of the plurality of battery cells and an adjacent second battery cell of the plurality of battery cells. A first battery terminal and a second battery terminal may extend from the first side of each battery cell. The first fire-blocking foam member may have a generally cuboid shape. In addition, the first fire-blocking foam member may have a surface area, on an inward facing side of the first fire-blocking foam member, that is at least 90 percent of a surface area of the first side of the first battery cell. The first fire-blocking foam member may be one or both of thermally insulating and electrically insulating. The first fire-blocking foam member may be formed from a silicone based material. The first fire-blocking foam member may have an inward facing surface that faces the first side of the first battery cell and an outward facing surface opposite the inward facing surface, where a second battery cell spacing between the outward facing surface of the first fire-blocking foam member and the second side of an adjacent third battery cell is within a range of 7 percent and 14 percent of a length of the first battery cell. In some examples, a fuse may be arranged on the flexible PCB for each battery cell connected to the flexible PCB, such that when a first battery cell of the plurality of battery cells has a current flow greater than a predetermined current flow limit, a first fuse corresponding to the first battery cell opens to shut off an electrical connection between the first battery cell and the flexible PCB. An outward facing surface of the first fire-blocking foam member and the second side, the third side, and the fourth side of the first battery cell define a perimeter of a first battery cell module, and where the flame-suppressant grease is arranged along the perimeter of the first battery cell module. The flame-suppressant grease may be chemically inert and non-flammable. In some examples, the flame-suppressant grease may include a Teflon based material. The plurality of battery cells may include a first battery cell spacing from the fourth side of the first battery cell to the third side of the adjacent second battery cell adjacent to the first battery cell is within a range of 6 percent and 11 percent of a width of the first battery cell. The CWB may include a housing that receives the PCBA, where the housing is formed from a polymeric material comprising a flame retardant additive. 
     Other aspects of this disclosure may disclose a conformal wearable battery comprising: a flexible printed circuit board assembly (PCBA) comprising: a flexible printed circuit board (PCB) with a plurality of battery cells connected to the flexible PCB in a grid-like pattern, where each battery cell of the plurality of battery cells has a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side. Each battery cell of the plurality of battery cells may comprise a lithium-ion pouch cell that comprises a seal on the first side of each battery cell. A fuse may be arranged on the flexible PCB for each battery cell of the plurality of battery cells on the flexible PCBA. When a first battery cell of the plurality of battery cells has a current flow greater than a predetermined current flow limit, a first fuse corresponding to the first battery cell may open to shut off an electrical connection between the first battery cell and the flexible PCB. The CWB may include a plurality of fire-blocking foam members, where a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of the first battery cell (e.g., forming a battery cell) and a flame-suppressant grease located along a perimeter of a first battery cell module, where the perimeter of the first battery cell module may be defined by a boundary that extends along an outward facing surface of the first fire-blocking foam member and the second side, the third side, and the fourth side of the first battery cell. The CWB may include a housing that includes a housing member and an interior cavity that receives the PCBA, where a wall of the housing member includes a first channel and a second channel oriented parallel to each other, and a third channel and a fourth channel that intersect the first and second channels. The first channel, the second channel, the third channel, and the fourth channel may have interior surfaces that form a perimeter wall around an internal receiver in the housing member that receives the first battery cell of the plurality of battery cells. The flame-suppressant grease may be located between the first battery cell and the perimeter wall. The perimeter wall may help retain the flame-suppressant grease around the first battery cell module. In addition, the housing member is formed from a polymeric material comprising a flame retardant additive. 
     Additional aspects of this disclosure may relate to an electronic system comprising: (a) an upper housing member; (b) a lower housing member that connects to the upper housing member forming an interior cavity; and (c) a printed circuit board assembly (PCBA) received within the interior cavity comprising: (1) a printed circuit board (PCB) and (2) a plurality of battery cells connected to the PCB in a grid-like pattern, where each battery cell of the plurality of battery cells has a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side. Each battery cell of the plurality of battery cells may comprise a lithium-ion pouch cell comprising a seal on the first side of each battery cell. Additionally, the rear side of each battery cell of the plurality of battery cells may be physically affixed to the PCB. A plurality of fire-blocking foam members, wherein a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of a first battery cell of the plurality of battery cells. A flame-suppressant grease may be located along a perimeter of a first battery cell module comprising the first battery cell and the first fire-blocking foam member, where the perimeter of the first battery cell module is defined by a boundary that extends along an outward facing surface of the first fire-blocking foam member and the second side, the third side, and the fourth side of the first battery cell. The CWB may also include a fuse arranged on the PCB for each battery cell of the plurality of battery cells on the PCBA, where when a first battery cell of the plurality of battery cells has a current flow greater than a predetermined current flow limit, a first fuse corresponding to the first battery cell may open to shut off an electrical connection between the first battery cell and the PCB. The first fire-blocking foam member may have an inward facing surface that faces the first side of the first battery cell and an outward facing surface opposite the inward facing surface defining a foam thickness, where the foam thickness is within a range of 25 percent and 75 percent of the second battery cell spacing. The second battery cell spacing may be defined as a shortest distance between the first side of the first battery cell to a second side of a second adjacent battery cell. 
     Other aspects of this disclosure may relate to an electronic system comprising: (a) an upper housing member; (b) a lower housing member that connects to the upper housing member forming an interior cavity; and (c) a printed circuit board assembly (PCBA) received within the interior cavity comprising: (1) a printed circuit board (PCB) and (2) a plurality of battery cells connected to the PCB in a grid-like pattern, where each battery cell of the plurality of battery cells has a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side. Each battery cell of the plurality of battery cells may comprise a lithium-ion pouch cell comprising a seal on the first side of each battery cell. Additionally, the rear side of each battery cell of the plurality of battery cells may be physically affixed to the PCB. A plurality of fire-blocking foam members, wherein a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of a first battery cell of the plurality of battery cells. A flame-suppressant grease may be located along a perimeter of a first battery cell module comprising the first battery cell and the first fire-blocking foam member, where the perimeter of the first battery cell module is defined by a boundary that extends along an outward facing surface of the first fire-blocking foam member and the second side, the third side, and the fourth side of the first battery cell. The CWB may also include a fuse arranged on the PCB for each battery cell of the plurality of battery cells on the PCBA, where when a first battery cell of the plurality of battery cells has a current flow greater than a predetermined current flow limit, a first fuse corresponding to the first battery cell may open to shut off an electrical connection between the first battery cell and the PCB. The first fire-blocking foam member may have an inward facing surface that faces the first side of the first battery cell and an outward facing surface opposite the inward facing surface defining a foam thickness, where the foam thickness is within a range of 25 percent and 75 percent of the second battery cell spacing. The second battery cell spacing may be defined as a shortest distance between the first side of the first battery cell to a second side of a second adjacent battery cell. 
     Another aspects of this disclosure may relate to an electronic system comprising: (a) an upper housing member; (b) a lower housing member that connects to the upper housing member forming an interior cavity; and (c) a printed circuit board assembly (PCBA) received within the interior cavity comprising: (1) a printed circuit board (PCB) and (2) a plurality of battery cells connected to the PCB in a grid-like pattern, where each battery cell of the plurality of battery cells has a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side. Each battery cell of the plurality of battery cells may comprise a lithium-ion pouch cell comprising a seal on the first side of each battery cell. Additionally, the rear side of each battery cell of the plurality of battery cells may be physically affixed to the PCB. A first group of battery cells of the plurality of battery cells electrically may be connected in parallel forming a first battery cell string and a second group of battery cells of the plurality of battery cells electrically connected in parallel forming a second battery cell string, where the first group of battery cells and the second group of battery cells are connected in series. In addition, a plurality of fuses may be arranged on the PCB, where each battery cell may be connected to an individual fuse of the plurality of fuses. When a first battery cell of the first battery cell string has a current flow greater than a first predetermined current flow limit, a first fuse of the plurality of fuses corresponding to the first battery cell of the first battery cell string may open to shut off an electrical connection between the first battery cell of the first battery cell string and the PCB. The electronic system may also include a plurality of fire-blocking foam members, where a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of a first battery cell of the plurality of battery cells. And when a second battery cell of the second battery cell string has a current flow greater than a second predetermined current flow limit, a second fuse corresponding to the second battery cell of the second battery cell string may open to shut off an electrical connection between the second battery cell and the PCB. In some cases, the first predetermined current flow limit may be equal to the second predetermined current flow limit. The first fire-blocking foam member has an inward facing surface that faces the first side of the first battery cell and an outward facing surface opposite the inward facing surface defining a foam thickness, where a second battery cell spacing defined as a shortest distance between the first side of the first battery cell to a second side of a second adjacent battery cell, and the foam thickness is within a range of 25 percent and 75 percent of the second battery cell spacing. The upper housing member and the lower housing member may be formed from a polymeric material comprising a flame retardant additive. A first battery cell spacing from the fourth side of the first battery cell to the third side of a second battery cell adjacent to the first battery cell is within a range of 6 percent and 11 percent of a width of the first battery cell. A wall of the upper housing member includes a first channel and a second channel oriented parallel to each other, and a third channel and a fourth channel that intersect the first and second channels, wherein the first channel, the second channel, the third channel, and the fourth channel have interior surfaces that form a perimeter wall around an internal receiver in the upper housing member that receives the first battery cell of the plurality of battery cells, where a perimeter wall height may be within a range of 35 percent and 65 percent of a height of the first battery cell. 
     Yet more aspects of this disclosure may relate to a conformal wearable battery that includes a flexible printed circuit board assembly (PCBA) comprising: (a) a flexible printed circuit board (PCB); (b) a plurality of battery cells connected to the flexible PCB in a grid-like pattern; (c) a first group of battery cells of the plurality of battery cells electrically connected in parallel forming a first battery cell string; (d) a second group of battery cells of the plurality of battery cells electrically connected in parallel forming a second battery cell string, where the first group of battery cells and the second group of battery cells are connected in series; and (e) a plurality of fuses arranged on the PCB, wherein each battery cell is connected to an individual fuse of the plurality of fuses. The PCBA may be arranged such that when a first battery cell of the first battery cell string has a current flow greater than a first predetermined current flow limit, a first fuse of the plurality of fuses corresponding to the first battery cell of the first battery cell string may open to shut off an electrical connection between the first battery cell of the first battery cell string and the PCB. And when a second battery cell of the second battery cell string has a current flow greater than a second predetermined current flow limit, a second fuse corresponding to the second battery cell of the second battery cell string opens to shut off an electrical connection between the second battery cell of the second battery cell string and the PCB. In some examples, the first predetermined current flow limit may be equal to the second predetermined current flow limit. Each battery cell of the plurality of battery cells may have a front side, a rear side opposite the front side, a first side extending between the front side and the rear side, a second side opposite the first side, a third side extending between the first side and the second side, and a fourth side opposite the third side and wherein each battery cell of the plurality of battery cells comprises a lithium-ion pouch cell comprising a seal on the first side of each battery cell. The PCBA may also include: (a) a plurality of fire-blocking foam members, where a first fire-blocking foam member of the plurality of fire-blocking foam members is located adjacent to the first side of the first battery cell forming a first battery cell module, and (b) a flame-suppressant grease located along a perimeter of a first battery cell module, where the perimeter of the first battery cell module is defined by a boundary that extends along an outward facing surface of the first fire-blocking foam member and the second side, the third side, and the fourth side of the first battery cell. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements and in which: 
         FIG.  1    illustrates a front perspective view of a portable battery system according to aspects described herein; 
         FIG.  2    illustrates a rear perspective view of the portable battery system of  FIG.  1    according to aspects described herein; 
         FIG.  3    illustrates a front exploded perspective view of the portable battery system of  FIG.  1    according to aspects described herein; 
         FIG.  4    illustrates a front view of the portable battery system of  FIG.  1    with an upper housing member removed according to aspects described herein; 
         FIG.  5    illustrates a rear view of the portable battery system of  FIG.  1    with a lower housing member removed according to aspects described herein; 
         FIG.  6    illustrates a side cross-sectional view of the portable battery system of  FIG.  1    along line  6 - 6  according to aspects described herein; 
         FIG.  7    illustrates a side cross-sectional view of the portable battery system of  FIG.  1    along line  7 - 7  according to aspects described herein; 
         FIG.  8    illustrates a partially exploded perspective view of a printed circuit board assembly of the portable battery system of  FIG.  1    according to aspects described herein; 
         FIG.  9    illustrates an exploded perspective view of a battery cell module of the printed circuit board assembly of  FIG.  8    according to aspects described herein; 
         FIG.  10    illustrates an exploded perspective view of the battery cell module of  FIG.  9    according to aspects described herein; 
         FIG.  11    illustrates a schematic of a battery cell string of a printed circuit board assembly of the portable battery system of  FIG.  1    according to aspects described herein; and 
         FIG.  12    illustrates a schematic of a plurality of battery cell strings of a printed circuit board assembly of the portable battery system of  FIG.  1    according to aspects described herein. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of various illustrative arrangements, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, various arrangements in which aspects of the disclosure may be practiced. It is to be understood that other arrangements may be utilized, and structural and functional modifications may be made, without departing from the scope of the present disclosure. It is noted that the accompanying drawings may not be drawn to scale. 
     It is noted that various connections between elements are discussed in the following description. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect, and that the specification is not intended to be limiting in this respect. 
     A portable battery system or a rechargeable conformal wearable battery (CWB) may be worn by a user to power electronic devices that the user carries. The CWB may be subjected to a multitude of environmental conditions such as harsh shock and vibration, moisture exposure, and extreme temperatures. To provide a desired power output, the CWB may include a plurality of battery cells, each with a rated power capacity and when electrically connected, may allow the CWB to provide a desired power output. The battery cells of the CWB may be received in a housing that is sealed to facilitate longer battery life and utility for the user regardless of environmental conditions it may encounter. 
     A CWB may include an array of a first quantity of battery cells disposed adjacent to one another in a horizontal direction and a second quantity of battery cells disposed adjacent to one another in a vertical direction. The array of battery cells may be arranged in a grid-like pattern. Each of the battery cells may be encased or housed in a battery cell housing (e.g., a pouch, a metal enclosure, etc.) separate from other battery cells. A battery cell as described herein may include a plurality of individual battery cell elements that are electrically connected together to form a compound battery cell that electrically performs as a single unit. Each of the battery cells may be physically connected to adjacent battery cells by flexible elements (e.g., a flexible printed circuit board (PCB)). The array of battery cells may be attached to the flexible PCB to form a flexible printed circuit board assembly (PCBA) that is secured in a housing, where the housing may be able to flex, to form the CWB. The CWB may then be able to flex to generally conform to a surface outline or shape of a user wearing the CWB. For example, the housing of the CWB may include one or more grooves or flex lines along which the CWB may flexibly conform to a shape of an object adjacent to the CWB, such as a portion of a user&#39;s body. The CWB may be required to meet one or more of the requirements of MIL-PRF-32383. 
     One or more of the battery cells may include a positive-charge electrical terminal (a cathode) and a negative-charge electrical terminal (an anode) that are electrically connected with the flexible PCB, which also connects a first battery cell to a second battery cell within the array of battery cells to provide electrical power to electrical devices that are connected to the CWB. The CWB may include a set of positive-charge electrical terminals and negative-charge electrical terminals that are shared among the array of battery cells. The array of battery cells may be connected together to route electrical current through the flexible PCB to the set of positive-charge electrical terminals and negative-charge electrical terminals that are shared among the plurality of the battery cells. The positive-charge electrical terminal and the negative-charge electrical terminal may provide an electrical current that passes through an electrically conductive path, for example, through an electronic device, via transfer of electrons through the electrically conductive path between a positive-charge electrical terminal and a negative-charge electrical terminal on the exterior of the CWB. The array of battery cells may be electrically coupled together, for example, in series or in parallel. 
     In some cases, each battery cell may be provided in a package, such as a button cell, a prismatic cell, a pouch cell, and a cylindrical cell. For example, a pouch cell type battery, which may be formed of electrodes and a liquid, gel, or solid electrolyte that are stacked in layers or laminations and enclosed in a foil envelope housing, which is then sealed. The positive-charge terminal and the negative-charge terminal may each include a conductive region that passes between the interior of the foil envelope housing and the exterior of the foil envelope battery cell housing. 
     The CWB housing may secure a plurality of the battery cells within an interior region, which may be formed from a molding process such as injection molding. The CWB housing may be formed of a polymeric material, for example. The CWB housing may be sealed to prevent ingress of solid material and/or liquid material, for example, according to an IP67 rating, IP68 rating, or other ingress protection rating. The CWB housing may include a plurality of electrically conductive contacts and/or connectors that may pass between the interior region of the CWB housing and the exterior of the CWB housing. The IP67 rating is specified by the Ingress Protection Code (IP Code) IEC standard 60529. The equivalent European standard is EN 60529. The IP Code also may be referred to as the International Protection Code. The IP Code classifies and rates a degree of ingress protection provided by mechanical casings and electrical enclosures for electronic equipment against intrusion, dust, accidental contact, and liquid (e.g., water). In the IP67 rating, the first digit (i.e., ‘6’) specifies a level of protection offered against ingress of solid objects, while the second digit (i.e., ‘7’) specifies a level of protection offered against ingress of liquids. The larger the value of the digit specifying the level of protection, the greater the amount of protection offered. For example, an IP67 rating specifies total protection against dust ingress and protection against short periods of immersion in water. An IP68 rating specifies dust resistance and immersion in 1.5 meters of freshwater for up to 30 minutes duration. 
       FIGS.  1 - 3    illustrate an exemplary portable battery system as a conformal wearable battery (CWB)  10 . In some examples, the CWB  10  may be provided in a form factor easily carried by a person, such as within a pocket or other means of securing the CWB  10  to a person&#39;s clothing, uniform, or the like. The CWB  10  may have an external housing  12 . The housing  12  may include an upper housing member  14  and a lower housing member  16  that may be connected together to form an interior cavity  18 . As shown in  FIG.  3   , the CWB  10  may include a flexible printed circuit board assembly (PCBA)  100  that is received into the interior cavity  18  of housing  12 , where the flexible PCBA  100  includes a flexible printed circuit board (PCB)  110  with a plurality of battery cells  130  connected both electrically and physically to the flexible PCB  110 . The upper housing member  14  and the lower housing member  16  may be sealed together along the perimeter to protect the flexible PCBA  100  by preventing ingress of solid material and/or liquid material as well as protecting the flexible PCBA  100  and its battery cells  130  from impacts, since a damaged battery cell  130  may be a fire hazard and/or could render the CWB  10  inoperable. 
     As shown in  FIG.  3   , the flexible PCBA  100  may include a flexible printed circuit board (PCB)  110  with a plurality of battery cells  130  connected both electrically and physically to the flexible PCB  110 . To provide the specified power output, while also providing flexibility for conforming to a shape of person&#39;s body or equipment when carried, a matrix of battery cells  130  may be arranged on, and affixed to, the flexible PCB  110 . To fit within the housing  12  of the CWB  10 , the flexible printed circuit board  110  may have a bend axis  112  (e.g. a centerline) that facilitates folding of the flexible PCB  110  to form an upper portion  114  of the flexible PCB  110  and a lower portion  116  of the flexible PCB  110 . Each portion  114 ,  116  may be substantially the same size (i.e., same surface area). Each battery cell  130  may be mounted on an outward facing surface  118 A,  118 B of each respective portion  114 ,  116  of the flexible printed circuit board  110  while the electrical connections may be made on an inward facing surface  120 A,  120 B of the respective upper and lower portions  114 ,  116  of the folded flexible PCB  110 . A central shock-attenuating or shock-absorbing member  190  may be positioned between the upper portion  114  of the flexible PCB  110  and the lower portion  116  of the flexible PCB  110  to prevent the upper portion  114  from contacting the lower portion  116 . The central shock-attenuating member  190  may absorb or dampen any shock and/or vibrational loading the CWB  10  may receive while also providing electrical insulation for the electrical contacts. 
     As an illustrative example, each battery cell  130  of the plurality of battery cells may be a pouch cell type battery (i.e., a packaged polymer lithium-ion battery or similar type battery). For instance, each battery cell  130  may include a pouch cell portion and a foil portion that wraps around at least three sides of the pouch cell portion. The foil portion may have a length that is greater than a length of the pouch cell portion. In addition, the foil portion may contact the sides of the pouch cell portion across the width of the battery cell  130 . Each battery cell  130  (e.g., polymer battery cell) may have a non-cylindrical shape and may have a generally rectangular cuboid shape or a substantially parallelepiped shape. In addition, each battery cell  130  of the plurality of battery cells may have has a front side or outward facing surface  132 , a rear side  134  opposite the front side  132 , a first side  136  extending between the front side  132  and the rear side  134 , a second side  138  opposite the first side  136 , a third side  140  extending between the first side  136  and the second side  138 , and a fourth side  142  opposite the third side  140 . In some examples, each battery cell  130  may be a lithium-ion pouch cell, where the lithium-ion pouch cell is sealed on the first side  136  of the battery cell  130 . The positive-charge electrical terminal and the negative-charge electrical terminal may exit from or near the first side  136  of the battery cell  130  in a direction such that the terminals extend away from the first side  136  of the battery cell  130 . In some examples, the terminals of each battery cell  130  may electrically connect to the flexible PCB  110  on an inward facing surface  120 A,  120 B of the respective upper and lower portions  114 ,  116  of the folded PCB  110 . In some cases, one or more of the battery cells  130  may have a different packaging format, such as a prismatic cell, a cylindrical cell, and/or the like. 
     In an illustrative example, the dimensions of the battery cell  130  may be about 43 mm in length (BL), about 34 mm in width (BW), and about 6 mm in height (BH), but battery cells of other dimensions may be used within the scope of this disclosure. Additionally, each battery cell  130  may weigh between 22.5 grams and 24.5 grams (i.e., 23.5 grams) and may have an energy storage capacity between 1400 mAh and 1500 mAh (i.e., about 1,435 mAh). The size, weight, and energy storage capacity of each battery cell  130  of the CWB  10  may be designed such that the overall size, weight, and energy storage capacity of the flexible PCBA  100  for the CWB  10  meets an energy storage capacity specification, weight specification, and/or size specification for a CWB  10 . For example, the height, width, and length of each battery cell  130  may be designed, at least in part, to meet a flexibility requirement of the CWB  10 . Additionally, the size, and/or shape of the battery cells  130  may allow for a specified number of battery cells (e.g., about 36 battery cells) and/or configuration of the battery grid such that the energy capacity for the CWB  10  may be at least 148 Watt-hours (Wh) (e.g., about 150 Wh, about 170 Wh, about 190 Wh, about 200 Wh, etc.) and/or where the maximum weight of the CWB  10  is less than a specified maximum weight (e.g., about 2.6 pounds). In some cases, a configuration of the battery cells  130  of the CWB  10  may allow the CWB  10  to output a voltage between about 10 and about 20 V, (e.g., about 14.8V) within a specified size and/or shape of the CWB  10 . For example, an illustrative CWB  10  may have overall dimensions of between about 8.5 in. and 9.0 inches (i.e., about 8.7 in.)×between about 7.5 in and 8 in. (i.e., about 7.66 in.)×between about 0.5 in. and 0.8 in. (i.e., 0.70 in.). 
     As the battery cells  130  go through cycles of discharging and recharging, the chemical reaction inside the battery cells  130  may cause the battery cells  130  to swell or increase in volume. A chemical system of battery cell  130  may include one of a lithium cobalt oxide, nickel cobalt manganese, nickel cobalt aluminum, or other such chemical systems. In some examples, each battery cell  130  may also go through cycles of swelling and then shrinking (e.g., increasing and decreasing in volume) as it goes through the discharging and recharging cycles. If a battery cell  130  has an internal short circuit due to a defect or due to damage to the battery cell  130 , the battery cell  130  may begin to heat, which in some cases may cause evaporation of the electrolyte. In some cases, damage to the battery cell  130  may result from physical penetration of the CWB  10 . The electrolyte evaporation may, in turn, cause pressure to build up within the pouch cell portion. In some cases, if the pressure inside the pouch cell portion gets too high, the internal pressure of the battery cell  130  may cause a failure in the pouch cell portion (e.g., a thermal runaway condition) causing a flammable mixture that can include hot gases, molten materials, and in some cases a flame to escape through the seal of the battery cell  130 . This flammable mixture coming from a failing battery cell  130  may propagate to an adjacent battery cell, which could cause the adjacent battery cell to also fail and possibly cascade to additional battery cells  130  causing them to fail. This failure of multiple battery cells  130  may cause the battery system (the CWB  10 ) to fail with a thermal runaway situation, and possibly cause a fire that could injure the user. In some cases, a thermal runaway situation may be caused by failure of a single battery cell  130 . 
     To mitigate the risk of this flammable mixture of gases and flames escaping from a damaged battery cell  130  from causing thermal runaway propagation to other (e.g., adjacent) battery cells  130  via a fire, a fire-blocking foam member  150  may be installed adjacent to the first side  136  of each battery cell  130 . By locating each fire-blocking foam member  150  adjacent the first side  136  of each battery cell  130 , the fire-blocking foam member  150  may be adjacent the seal of the pouch cell portion to prevent any flammable gases or flames that escape through the seal of the pouch cell portion from affecting any adjacent battery cells  130 . Accordingly, each battery cell  130  of the plurality of battery cells  130  on the flexible PCBA  100  may have a fire-blocking foam member  150  located adjacent the seal of the pouch cell portion. In the illustrated example, the battery cell  130  and the adjacent fire-blocking foam member  150  adjacent the first side  136  of the battery cell may define a battery cell module  144  as shown in  FIGS.  9  and  10   . In some cases, a fire-blocking foam member  150  may be arranged adjacent one or more of the first side,  136 , the second side  138 , the third side  140 , or the fourth side  142  of a battery cell  130 . The fire-blocking foam members  150  may be formed from a silicone based material that is thermally insulating to help prevent the heat of any escaping gases or other material to affect another battery cell  130  in the CWB  10 . Additionally, the fire-blocking foam members  150  may act as a flame resistant barrier by preventing any escaping flames from burning through it and affecting other battery cells  130  in the CWB  10 . The fire-blocking foam members  150  may also be electrically insulating to prevent the fire-blocking foam members  150  from shorting any electrical connections between the battery terminals or any other connections on the PCB  110 . In some examples, the fire-blocking foam member may be able to operate in temperatures ranging from −55° C. to 200° C. and may also be able to resist flames burning at over 1000° C. for short periods of time. 
     Each fire-blocking foam member  150  may have a generally cuboid shape, such as a rectangular cuboid shape or a substantially parallelepiped shape, although the fire-blocking foam member  150  could have a different shape in other examples. Each fire-blocking foam member  150  may cover most of a face of the seal or may cover substantially all of the entire face of the seal of the pouch cell portion on the first side  136  of its respective battery cell  130 . For example, each fire-blocking foam member  150  may cover at least 95 percent of a surface area of the first side  136  of its respective battery cell  130 , or may cover at least 90 percent of a surface area of the first side  136  of its respective battery cell  130 . In addition, the fire-blocking foam member  150  may have a foam length  152  that is approximately equal (within +/−5 percent) to a battery width (BW) or within 80 percent of the battery width (BW), where the first battery width is the length of the first side  136  of its respective battery cell  130 . Each fire-blocking foam member  150  may have a foam thickness of approximately 3 mm, or within a range of 1.5 mm and 5 mm. The foam thickness may be defined as the distance from a front side or inward facing surface  154  of the fire-blocking foam member  150  that faces the first side  136  of the battery cell  130  to a rear side or outward facing surface  156  opposite the inward facing surface  154 . The foam thickness may also be expressed as a percentage of the spacing between adjacent battery cells. For instance, the foam thickness may be approximately 25 percent and 75 percent of the spacing between the first side  136  of a battery cell to the second side  138  of an adjacent battery cell  130  (the second battery cell spacing  160  described below). Furthermore, the fire-blocking foam member  150  may have a foam thickness that is less than the distance from the first side  136  of its respective battery cell  130  to a midpoint of the protrusion  28  located nearest the first side  136  the respective battery cell  130  to prevent the fire-blocking foam member  150  from encroaching the groove regions  20 ,  22 . This arrangement may prevent the fire-blocking foam members  150  from impinging or resisting any flexing of the CWB  10 . 
     In addition, the spacing of the battery cells  130  within the CWB  10  may assist in preventing a thermal runaway condition, a fire, or possible flammable gases from spreading from a first battery cell  130  that has been damaged to an adjacent battery cell  130  that could cause the adjacent battery cell to fail. For instance, as shown in  FIG.  6   , a first battery cell spacing  158 , in a generally horizontal direction, of a first battery cell  130 A to a second battery cell  130 B that may be defined as a distance from between the fourth side  142  of the first battery cell  130 A to the third side  140  of a second adjacent battery cell  130 B. The first battery cell spacing  158  may be a distance that is defined as a function of one or more variables, such as the battery cell width (BW), a bend radius of the CWB  10 , a distance the edges of the CWB  10  move when the CWB  10  is in a deformed state, and a predetermined clearance around each battery cell  130 . As an example, the first battery cell spacing  158  may be within a range of 2.0 mm and 3.5 mm. In some cases, the first battery cell spacing  158  may also be expressed as a percentage of the battery cell width (BW), a percentage of a bend radius of the CWB  10 , a percentages of the distance the edges of the CWB  10  move when the CWB  10  is in a deformed state, a percentage of a predetermined clearance around each battery cell  130 , or a percentage of a combination of one or more of variables identified above. For instance, the first battery cell spacing  158  may be approximately 9 percent of the width, BW, of a battery cell  130 , or within a range of 6 percent and 11 percent of the width, BW, of a battery cell  130 . 
     Additionally, as shown in  FIG.  7   , a second battery cell spacing  160 , in a generally vertical direction, from a first battery cell  130 A to a third adjacent battery cell  130 C may have be defined as the shortest distance between the two adjacent battery cells  130 A and  130 C in a vertical direction (a direction parallel to a first side  136  to a second side  138  of a battery cell  130 ). The second battery cell spacing  160  may be distance that is defined as a function of one or more variables, such as the battery cell length (BL), a bend radius of the CWB  10 , a distance the edges of the CWB  10  move when the CWB  10  is in a deformed state, and a predetermined clearance around each battery cell  130 . As an example, the second battery cell spacing  160  may be a distance within a range of 5.0 mm and 8.5 mm. In some examples, the second battery cell spacing  160  may also be expressed as a percentage of the battery cell length (BL), a percentage of a bend radius of the CWB  10 , a percentage of the distance the edges of the CWB  10  move when the CWB  10  is in a deformed state, a percentage of a predetermined clearance around each battery cell  130 , or a percentage of a combination of one or more of variables identified above. For instance, the second battery cell spacing  160  may be approximately 16 percent of the battery cell length, BL, or within a range of 10 percent and 20 percent of the battery cell length, BL. 
     Battery cell spacing  158 ,  160  may help to prevent the flammable mixture escaping from the first battery cell  130 A if it begins to fail from negatively affecting any of the adjacent battery cells  130 B,  130 C, while also allowing the CWB  10  to flex and bend to the desired amount and desired direction. In addition, the battery cells  130  arranged along the outer regions of the flexible PCBA  100  (i.e. the battery cells  130  with at least one side adjacent the edges of one of the housing members  14 ,  16 ) may also have similar spacing  158 ,  160  between the adjacent side and the corresponding edge of the respective housing member  14 ,  16 . 
     The spacing  158 ,  160  between the battery cells  130  creates gaps or spaces  162  around the battery cells  130  within the CWB  10 . These gaps  162  are needed to allow the CWB  10  to flex and move the desired amount. In the illustrated examples, these gaps  162  may be at least partially filled with a flame-suppressant grease  170  that is arranged along the perimeter  164  of each battery cell module  144 . In some cases, the gaps  162  may be fully filled with a flame-suppressant grease  170  as shown in  FIGS.  6  and  7   , however, the flame-suppressant grease  170  may have a viscosity that does not inhibit any bending of flexing of the housing  12  or of the CWB  10 . The perimeter  164  of each battery cell module  144  for the arrangement of the flame-suppressant grease  170  may be defined as the boundary along the second side  138 , the third side  140 , and the fourth side  142  of the battery cell  130  in conjunction with the outward facing surface  156  of the fire-blocking foam member  150  adjacent the battery cell  130  as shown in  FIG.  5   . For example, the flame-suppressant grease  170  may be located between a first battery cell  130 A and the second battery cell  130 B. The flame-suppressant grease  170  may act to inhibit any flames or flammable gases that may escape from a failing battery cell  130  from contacting any oxygen, thus, preventing the flammable gases from causing a fire that could disable or damage neighboring battery cells  130  or render the CWB  10  inoperable. In different examples, the flame-suppressant grease  170  may be one of the properties listed below or may have a combination of one or more of the properties listed below, such as (a) being formed from a thermally stable polymeric material, such as perfluoropolyether (PFPE), polytetrafluoroethylene (PTFE) (i.e., Teflon®), or other similar polymer; (b) being non-flammable, (c) being operable over a wide temperature range, such as within a range of −55° C. to 200° C., within a range of −36° C. to 260° C., or within a range −55° C. to 260° C.; (d) being an intumescent material that can expand when heated to take up the oxygen within the space; (e) having a density within a range of 1.0 g/cc and 2.0 g/cc; (f) being biologically inert; (g) being free of volatile organic compounds (VOCs); (h) being non-corrosive to metals; (i) being electrically insulating or electrically conductive; and (j) having a base oil viscosity at 40° C. within a range of 100 cSt and 260 cSt. 
     Each housing member  14 ,  16  may be flexible and may be formed from a polymeric material using an injection molding process or other technique known to one skilled in the art. Accordingly, each housing member  14 ,  16  may be flexible or bendable to be able to withstand repeated bending or flexing cycles to allow CWB  10  to meet the requirements of MIL-PRF-32383 CWB  10  may be required to flex at least 800 times under load to a 7 inch radius curved surface, such that an edge of the CWB  10  may be capable of deflecting, in each direction, at least a specified distance (i.e., 1 inch) from a centerline of the CWB  10  without sustaining physical or electrical damage. The housing members  14 ,  16  may be injection molded from a polymeric material that has elastomeric properties to allow the housing members  14 ,  16  that form the housing  12  to flex and bend. For example, the housing members  14 ,  16  may be formed from a thermoplastic elastomer (TPE), a thermoplastic urethane (TPU), thermoplastic vulcanizates (TPV), or other similar material. In addition, the polymeric material forming the housing  12  may contain flame retardant additives to help prevent the housing  12  and/or the CWB  10  from catching on fire. In some examples, the housing may have a UL94 V-0 rating. These flame retardant additives may include: (a) phosphorus based compounds; (b) chlorinated or brominated compounds; (c) aluminum or magnesium hydroxides; (d) carbon based compounds; or (e) other flame retardant compounds. 
     In addition, the upper housing member  14  and the lower housing member  16  may include a plurality of vertically oriented grooves  20  and a plurality of horizontally oriented grooves  22  that are arranged on the front walls  24 ,  26 , of the respective upper housing member  14  and the lower housing member  16 . The vertically oriented grooves  20  and horizontally oriented grooves  22  may be substantially perpendicular to each other and may also intersect each other. For instance, as shown in  FIGS.  1 - 3   , the front wall  24  of the upper housing member  14  and the front wall  26  of the lower housing member  16  may both include a pair of vertically oriented grooves  20  that are oriented parallel to each other, and a pair of horizontally oriented grooves  22  that are also oriented parallel to each other, such that the pair of vertically oriented grooves  20  intersect the pair of horizontally oriented grooves  22 . Each of the grooves  20 ,  22  may form protrusions  28  on the interior of its respective housing member  14 ,  16 . The protrusions  28  of the intersecting pairs of grooves  20 ,  22  may form a perimeter wall  30  along the interior of its respective housing member  14 ,  16  around an internal receiver  32  receives and/or at least partially surrounds a battery cell module  144 . The protrusions  28  may have an angled surface that slopes away from the battery cell module  144  received in the internal receiver  32  formed by the perimeter wall  30 . The perimeter wall  30  may have a perimeter wall height that is approximately 50 percent of a height, BH, of a battery cell  130 , where the perimeter wall height is defined a distance from an outer surface of the corresponding front wall  24 ,  26  of the respective housing member  14 ,  16  to an uppermost edge of the protrusion  28  formed by its respective groove  20 ,  22 . In some examples, the perimeter wall height may be within a range of 35 percent and 65 percent of the height, BH, of a battery cell  130 . The perimeter wall  30  may help to retain the flame-suppressant grease  170  around the battery cell module  144 . For instance, the flame-suppressant grease  170  may be located between one of the sides,  138 ,  140 ,  142  of a battery cell  130  or an outward facing surface  156  of a fire-blocking foam member that comprise a battery cell module  144  and one of the sides of the perimeter wall  30  as shown in  FIGS.  6  and  7   . 
     In some cases, the battery cells  130  may have a plurality of battery cell shock-attenuating members  180  individually attached to the front side  132  of each battery cell  130 . Each battery cell shock-attenuating member  180  may have an opening  182  extending through the thickness of the battery cell shock-attenuating member  180 . In some examples, the battery cell shock-attenuating member  180  may also have thermal insulating properties that may help prevent heat from a failing battery cell  130  from affecting an adjacent battery cell  130 . Each opening  182  may create a cavity  184  between the respective front side  132  of the battery cell  130  and one of the interior surfaces of the housing members  14 ,  16 . The cavity  184  may provide room for a battery cell  130  to expand into the cavity  184  to prevent any swelling induced stress on the battery cell  130  as it expands. In some examples, the opening  182  may not extend through the entire thickness of the battery cell shock-attenuating member  180  creating cavity  184  within the battery cell shock-attenuating member  180 . As shown in the illustrated example, the opening  182  may have an oval shape or may have a different shape such as a rectangular shape, circular shape, or other geometric shape. The rear surface of each battery cell shock-attenuating member  180  may be affixed the front side  132  of each respective battery cell  130  with an adhesive, such as a glue, an epoxy, an acrylic, or a tape. 
     In addition, a central shock-attenuating member  190  may be positioned between the upper and lower portions  114 ,  116  of the folded PCB  110  and may also contact the inward facing surfaces of the PCB  110 . The central shock-attenuating member  190  may compress to absorb any impacts or forces that are received by the CWB  10 . The central shock-attenuating member  190  may be a continuous layer free of openings or holes that extend through the central shock-attenuating member  190  in the region that corresponds to the PCB  110 . The central shock-attenuating member  190  may also serve to electrically insulate the upper and lower portions  114 ,  116  from each other. In some examples, the central shock-attenuating member  190  may also have thermal insulating properties to help prevent heat from a failing battery cell  130  transferring to a battery cell  130  on an opposite side of the PCB  110  from the failing battery cell  130 . The central shock-attenuating member  190  may be affixed to one or both of the inward facing surfaces of the folded PCB  110  with an adhesive, such as with a glue, an epoxy, an acrylic, or a tape. In some examples, the central shock-attenuating member  190  may be free floating between the inward facing surfaces or only attached along its perimeter. 
     The central shock-attenuating member  190  and the battery cell shock-attenuating members  180  may be formed from a visco-elastic material that can attenuate shock and vibration while also having electrically insulating properties. In addition, the shock-attenuating members  180 ,  190  may be compressible to assist in absorbing any swelling from the battery cells  130 . The visco-elastic material may be formed from a polymeric material such as a polyurethane based material such as Poron®, Sorbothane® or similar material. In some cases, the visco-elastic material may comprise glass-reinforced epoxy laminate material, such as FR4 or similar material, or may comprise an acrylic foam tape, such as VHB™ or similar material. In some cases, the visco-elastic material may be thermally insulating to prevent heat from a first battery cell  130  affecting another battery cell  130  within the CWB  10 . The central shock-attenuating member  190  and/or the battery cell shock-attenuating members  180  may be formed from the same material or, in some examples, formed from different materials. The material forming the central shock-attenuating members and/or the battery cell shock-attenuating members  180  may be a polymeric foam (i.e., porous) or a solid polymeric material. The central shock-attenuating members and/or the battery cell shock-attenuating members  180  may be formed from a sheet of material and then cut to the final shape using a die cutting, laser cutting, water-jet cutting process, or other cutting process known to one skilled in the art. The central shock-attenuating members  190  and/or the battery cell shock-attenuating members  180  may have a constant thickness, where the thickness of the central shock-attenuating member  190  may substantially the same thickness (i.e., within 10 percent) as a thickness of at least one of the plurality of battery cell shock-attenuating members  180 . 
     The flexible PCB  110  for the CWB  10  according to aspects of the present disclosure may be configured to provide power and/or electrical signals from a plurality of battery cells  130  and/or other components of a CWB  10 . The flexible PCB  110  may be formed of one or more of a flexible polymer or plastic material, such as a polyimide or other such flexible substrate. In some cases, markings showing locations of placement of battery cells may be formed through a silk screening process or other like method. Electrical conductors may be included in one or more layers of the flexible PCB  110 . In some cases, electrical conductors may be configured as a conductive pattern (e.g., a copper overlay, a conductive ink, etc.) on the surface of the substrate of the flexible PCB  110 . In some cases, exposed conductive features (e.g., conductors, a bare copper surface, a bare aluminum surface, etc.) may be coated with a coverlay substance, such as an electrical insulator. For conductive portions of the flexible PCB not covered with a coverlay, the surface may be plated, such as with an electroless nickel immersion gold (ENIG) finish, a lead-free immersion silver finish or other substances with improved conductive properties. The flexible PCB  110  may have a plurality of physical connection sections disposed in a grid like pattern, where each of the plurality of battery cells  130  is physically affixed to the flexible PCB  110  at a corresponding physical connection section of the plurality of physical connection sections. In an illustrative example, the rear side  134  of each battery cell  130  of the plurality of battery cells may be physically affixed to the flexible PCB  110  at a corresponding physical connection section. 
     In addition, the flexible PCB  110  may also include a plurality of fuses  122 , where each fuse  122  may be arranged on the PCB  110  to be connected electrically with a particular battery cell  130 . Thus, each battery cell  130  of the plurality of battery cells  130  may have an individual fuse  122  that corresponds with a particular battery cell  130 . As such, the number of fuses  122  may be the same as the number of battery cells  130 . In some cases, excessive current flow to or from a battery cell  130  may be symptomatic of a failure condition and/or may be a cause of a failure condition. For example, if a battery cell  130  overheats or begins to fail, the battery cell  130  may have a current flow either entering to or exiting from the failing battery cell  130  that is greater than a predetermined current flow limit for the battery cell  130 . Accordingly, when the current flow is greater than the predetermined current limit, the fuse corresponding to the failing battery cell  130  opens to shut off an electrical connection between the failing battery cell  130  and the flexible PCB  110 . For instance, the fuse  122  may be a surface mount fuse, a trace fuse, or another fuse package type. In an illustrative example, the fuse  122  may be a trace fuse made of a conductive material (e.g., copper) having a cross-sectional area (e.g., thickness and width) designed to open (i.e. blow, or fail) when conducting current approximately at a predetermined current flow value. In some examples, the fuse  122  may be formed in a 2 ounce copper layer and having a width of approximately 0.127 mm+/−0.025 mm. As the electrical connection is shut off to the overheated battery cell  130 , the risk of a fire being caused the overheated or venting battery cell  130  is reduced. As shown in  FIG.  8   , a fuse  122  may be physically located anywhere on the PCB  110  and adjacent to a point of an electrical connection of a particular battery cell  130  to establish the electrical connection of the particular battery cell  130  to a power bus of the flexible PCBA  100 . 
     As discussed above, the flexible PCBA  100  may have a plurality of battery cells  130  attached to the PCB  110 . The battery cells  130  may be arranged such that a predetermined number of battery cells  130  (e.g., two or more) are electrically connected in parallel to define a battery cell string  200  as shown in  FIG.  11   . The flexible PCBA  100  (e.g., the battery system or CWB  10 ) may have a plurality of battery cell strings  200  (e.g., two or more) that are electrically connected in series as shown in  FIG.  12   . By arranging the battery cells  130  in this manner, the flexible PCBA  100  and the CWB  10  may be able to provide an operational voltage and current level as designed. In some cases, each battery cell  130  may be individually fused with one or more fuses  122  such that the operational voltage may be provided even during conditions when a battery cell  130  fails, such as from either damage or an internal defect. 
     For example, each battery cell string  200  may comprise a plurality of battery cells  130  arranged in a parallel circuit such that if a single battery cell  130  fails, such as with a catastrophic failure as described above, the fuse  122  connected to the anode or the cathode (or fuses  122  connected to each of the anode and the cathode) of the failing battery cell  130  may open to electrically isolate the failing battery cell  130  from the other battery cells  130  within the battery cell string  200  such that a thermal runaway condition of the failed battery cell  130  does not propagate to other adjacent or electrically connected battery cells. In some cases, when the failing battery cell  130  is electrically disconnected from the string, electrical current may flow through remaining battery cells  130  of the string that are arranged in parallel to ensure power flow continues from the remaining battery cells of the battery cell string  200 . By electrically isolating the failing battery cell  130 , the remaining battery cells  130  within the battery cell string  200  remain active and intact. Without the fuse  122  to electrically isolate the failing battery cell  130 , the entire battery cell string  200  may drain quickly through the failing battery cell  130 , where heat generated via the electrical current may facilitate a thermal runaway condition. This draining of the entire battery cell string  200  may destroy multiple battery cells of the battery cell string  200 , which would cause the battery system (CWB)  10  to fail or the battery system (CWB)  10  to operate at a voltage lower than the desired operational level. The individual fusing of each battery cell  130  may allow the plurality of battery cell strings  200  to function and may allow the battery system (CWB)  10  to remain operational after a battery cell  130  fails either from an internal defector physical damage caused by an impact or penetration of housing  12  or of the battery system  10 . In some cases, a failed battery cell  130  may cause the battery system  10  to lose some capacity, while the battery system  10  maintains an operational current and voltage level within specified levels. 
     In an example, each battery cell string  200  may be comprised of a number of battery cells (e.g., 9 battery cells) and the battery system  10  may comprise one or more battery strings (e.g., 4 battery cell strings  200 ). As shown in the illustrated example of  FIGS.  4  and  5   , the PCBA  100  may include 36 battery cells  130  that are arranged as four battery cell strings  200 . Each battery cell string  200  has nine battery cells  130  arranged in parallel. The four battery cell strings  200  may be connected in series to provide a defined output. If a fuse  122  connected to a first battery cell in one of the four battery cell strings  200  opens, then the current to the first battery cell is shut off. The current through the string  200  may continue to flow through the remaining eight parallel-connected battery cells in the battery cell string. Thus, the PCBA  100  (and the CWB  10 ) is still able to operate with 35 battery cells  130 . In other examples, each battery cell string  200  may comprise any number of battery cells  130 , such as 4 battery cells, 5 battery cells, 6 battery cells, 7 battery cells, 8 battery cells, 10 battery cells, or more than 10 battery cells. Similarly, the battery system  10  may comprise any number of battery cell strings  200 , such as 2 battery strings, 3 battery strings, 5 battery strings, 6 battery strings or more than 6 battery strings. The electrical connection of the battery cells  130  and the fuses  122  may work in conjunction with the fire-blocking foam members  150 , the flame-suppressant grease  170 , and the battery cell spacing  158 ,  160  to create a robust passive thermal management system for a CWB  10 . 
     Aspects of the disclosure have been described in terms of illustrative examples thereof. Numerous other examples, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one or more of the steps depicted in the illustrative figures may be performed in other than the recited order, and one or more depicted steps may be optional in accordance with aspects of the disclosure.