as required , detailed embodiments of the present invention are disclosed herein ; however , it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms . the figures are not necessarily to scale ; some features may be exaggerated or minimized to show details of particular components . therefore , specific structural and functional details disclosed herein are not to be interpreted as limiting , but merely as a representative basis for teaching one skilled in the art to variously employ the present invention . as shown in fig1 , a battery pack in accordance with an embodiment of the invention includes a housing made up of a base 10 and a cover 12 that is shown removed to expose the interior of the battery pack . the battery pack interior may be divided into an electronics section 14 and a battery cell section 16 . the battery pack is adapted for use in an automotive vehicle . battery cell section 16 includes two generally parallel arrays 20 a , 20 b each of which comprises a plurality of voltaic cells 22 . the voltaic cells 22 of each array 20 a , 20 b are supported in a linear arrangement by a chassis which may , for example , comprise inner and outer support rails 24 a , 24 b connected at either end to end plates 25 . spacers 26 ( best seen in fig3 ) may be located between adjacent voltaic cells 22 to allow a flow of cooling gas , usually ambient air , to pass . spacers 26 may be integrated with the voltaic cells 22 or may be separate components assembled to the cells when the arrays are built up . spacers 26 may also be utilized as and / or combined with mounting brackets to retain cells 22 in position relative to support rails 24 a , 24 b and to adjacent cells . seals are provided between the upper edges of adjacent pair of cells 22 within each array . in the depicted embodiment , portions of spacers 26 adjacent the upper edges of cells 22 act as seal . when cover 12 is fastened to base 10 to enclose battery cell section 16 , a center portion 12 a of the cover seals against the top surfaces of inner support rails 24 a . in a similar fashion , outboard portions 12 b of the cover seal against the top surfaces of outer support rails 24 b . these four linear seals combine with the seals between the upper edges of adjacent cells 22 to form a sealed cooling chamber below the upper surfaces of the two arrays 20 a , 20 b . clearance is provided between the side walls of cover 12 and the outboard edges of cells 22 ( beneath outer rails 24 b ) so that cooling gas is able to flow generally horizontally between cells . the surfaces of cells 22 that face one another within each array ( the vertical surfaces as viewed in the present figures ) are adapted to enable heat transfer between the cells and the cooling gas , as is well known in the art . in fig1 , flow arrows f indicate a possible direction of the cooling flow . one or more fans or other gas movement devices ( not shown ) may be provided to force cooling gas through the battery pack , and / or ram air from movement of the vehicle may be used to induce the cooling flow . if air is used as the cooling gas , the air may come from exterior to the vehicle and / or from within the interior of the vehicle . some or all of the cooling gas exiting the battery pack may be returned to the vehicle interior for climate control purposes , and / or some may be exhausted exterior of the vehicle . cover 12 further comprises two raised portions 12 c , 12 d located directly above the respective arrays 20 a , 20 b when the cover is attached to base 10 . raised portions 12 c , 12 d sealingly cover the upper surfaces of arrays 20 a , 20 b to define a pair of vent chambers or manifolds 38 a , 38 b ( see fig2 ) extending along and above the length of the respective arrays . since vent holes 32 are located in / on the portions of cells 22 that form the upper surfaces of arrays 20 a , 20 b , any byproduct gasses issuing from the vent holes will be contained by vent manifolds 38 a , 38 b . as best seen in fig2 , each voltaic cell 22 has a positive terminal 28 , a negative terminal 30 , and a vent hole 32 . bus - bars , wires , or other electrically conductive connectors ( not shown ) interconnect the appropriate terminals of adjacent battery cells 22 so that the cells within each array 20 a , 20 b are connected in electrical series , as is well known in the art . in addition to connecting the cells within each array 20 a , 20 b in series , it may be necessary for the two arrays to be connected in series to achieve a desired voltage level for the battery pack . in this case , a terminal of a cell in array 20 a is connected with a terminal of a cell in the other array 20 b having the appropriate ( opposite ) polarity . this connection may be made by a bridge bar 36 extending between the inboard terminal ( closest to the center - line of battery pack dividing the two arrays ) at the extreme end of first array 20 a , and the adjacent inboard terminal of array 20 b . during some abnormal operating conditions , such as overheating , the voltaic cells 22 may generate a gaseous byproduct . to prevent an undesirable pressure buildup within the cells , any such byproduct gases are allowed to escape from the cells through vent holes 32 . it is generally desirable that any byproduct gases be exhausted outside of the vehicle rather than being allowed to enter the interior of the vehicle . if the cooling gas circulating through the battery arrays is returned to the vehicle interior , as is commonly the case , this dictates that the byproduct gases must be kept separate from the cooling gas flow . this may be achieved by providing gas - proof seals at appropriate locations in the vicinity of the tops of the cells 22 so that the cooling gas is kept below the upper surface of battery arrays 20 a , 20 b and a separate manifold is defined above the arrays for collecting any byproduct gases issuing from vent holes 32 . center section 12 a of the cover seals against the top surfaces of inner support rails 24 a when the cover is attached to base 10 . in a similar fashion , outboard portions 12 b of the cover seal against the top surfaces of outer support rails 24 b . raised portions 12 c , 12 d are located directly above the respective arrays 20 a , 20 b and define first and second vent manifolds 38 a , 38 b ( see fig2 ) extending along the length of the respective arrays above the voltaic cells 22 to receive any byproduct gasses issuing from vent holes 32 . a tunnel 50 extends between raised portions 12 c , 12 d and connects the first and second manifolds 38 a , 38 b . seals or gaskets 42 may be provided at appropriate locations between cover 12 , support rails 24 a , 24 b and end plates 25 as necessary to substantially seal the interior of battery pack from its environment . a bridge bar 36 connects terminal 28 of the end - most cell in array 20 a with terminal 30 of the adjacent cell in array 20 b . bridge bar 36 comprises a conductive bar 44 ( preferably made from copper , aluminum , or other material having good electrical conductivity ) and a sealing portion 46 covering the central portion of the conductive bar . sealing portion 46 may completely surround the center section of conductive bar 44 , as shown , or it may be disposed only at locations where sealing contact is required . bridge bar 36 may be secured to terminals 28 , 30 by clips or nuts ( not shown ) which fit over the top of the terminals . when in the bridging position , sealing portion 46 covers any gap that may exist between inner support rails 24 a and may have a rib 46 a projecting downwardly into the gap as shown in fig4 . sealing portion 46 is preferably made of a resilient material that will achieve an effective gas seal when compressed , such as a polymer or synthetic rubber . sealing portion 46 may be efficiently formed around the conductive bar 44 by an over - molding process . tunnel 50 is located on cover 12 so as to be positioned over bridge bar 36 to provide clearance for the bar , and also provides a passage through which any gases collecting in first manifold portion 38 a may flow into the second manifold portion 38 b . tunnel 50 may be formed as a part of ( integrally with ) cover 12 , as a single sheet metal stamping or molded plastic part , for example . alternatively , tunnel 50 may be fabricated as a separate piece and assembled to cover 12 by welding , adhesive , or a joining technique appropriate for the materials used . as best seen in fig4 , bridge bar sealing portion 46 has flanges 46 b extending outward from conductive bar 44 . flanges 46 b span a width greater than the width of tunnel 50 so that the sealing portion effectively seals off the tunnel from the cooling gas chamber below . extra seals may be provided , if necessary , in the vicinity of sealing portion 46 , for example , a bead seal 52 disposed above flange 46 b as shown in fig4 . a vent outlet tube 54 communicates with vent manifold 38 b so that any byproduct gases generated by the cells of either array 20 a , 20 b can escape and prevent an undesirable pressure increase inside battery pack . the gases are preferably vented outside of the vehicle via outlet tube 54 . while exemplary embodiments are described above , it is not intended that these embodiments describe all possible forms of the invention . rather , the words used in the specification are words of description rather than limitation , and it is understood that various changes may be made without departing from the spirit and scope of the invention . additionally , the features of various implementing embodiments may be combined to form further embodiments of the invention .