Abstract:
A higher amp-hour capacity battery is formed in a conventional battery package by arranging cylindrical cells in a bundled configuration. A bundle of cylindrical cells, whether nonrechargeable or rechargeable may be less expensive to produce and may offer more desirable charge and discharge characteristics than other arrangements and cell geometries, even though some space in a resulting package is not occupied by cells. A rectangular 9-volt type battery may include seven cells wired in series and bundled horizontally or vertically inside the rectangular case.

Description:
FIELD OF THE INVENTION 
     Embodiments of the present invention relate to electrical batteries formed from multiple cylindrical cells. 
     BACKGROUND OF THE INVENTION 
     A conventional electrical battery may be used to power relatively small, lightweight, portable equipment and may itself consist of a series or parallel connection of cells. The design of particular batteries may conform to standard package dimensions such as the common AAA, AA, C, D, and miniature rectangular 9-volt sizes. In a conventional miniature rectangular 9-volt battery package with snap terminals, tub-shaped cells are typically arranged to occupy the entire volume of the package interior. 
     The useful life of battery operated equipment is primarily affected by the amp-hour capacity of the battery or the single cycle of a rechargeable battery. Further increase in amp-hour capacity is desirable and cannot be achieved without the present invention. 
     SUMMARY OF THE INVENTION 
     A battery according to various aspects of the present invention includes a retainer and a circuit. The circuit includes a plurality of cells retained in position by the retainer. The circuit provides a positive and a negative conductor to which all of the cells are coupled. When a dimension of the retainer must meet a predetermined maximum, a number of cells may be dictated by a desired cell chemistry and circuit arrangement (series, parallel, or combination series and parallel). When a bundle of cells of identical diameter is desired, the diameter of each cell of the bundle may be maximized so that the bundle snuggly fits within the retainer dimension. 
     By constraining all cells of the bundle to be of identical diameter, overall manufacturing costs for the battery may benefit from various economies of scale (e.g., unit costs for materials, subassemblies, and labor operations may decrease). 
     In an exemplary implementation, the retainer may provide an enclosure having a substantially hexahedral interior cavity and a cap through which a first and a second terminal pass current. A series circuit may include the first terminal, a plurality of cylindrical cells, and the second terminal. The cylindrical cells may be arranged in a bundle having all axes of cylindrical symmetry in parallel. All axes of cylindrical symmetry may pass through a plane that includes the terminals. Or, all axes may be substantially parallel to such a plane. By arranging a bundle of cylindrical cells inside a hexahedral cavity, cylindrical cell geometry may provide better discharge or charge characteristics compared to a plurality of close-packed tub-shaped cells as well as lower cost of manufacture, higher reliability, better seal stability, and more uniform unit-to-unit characteristics. 
     In another implementation, the battery includes an enclosure that supports at least one battery terminal and a vent formed in the battery terminal. The terminal may include a hollow rivet that provides an aperture. The vent may include a filter over the aperture, for example, a sheet of porous foam. Filtered ambient air may pass into the enclosure and discharged vapor from any cell may pass out of the enclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Embodiments of the present invention will now be further described with reference to the drawing, wherein like designations denote like elements, and: 
     FIG. 1 is a perspective view of a battery according to various aspects of the present invention; 
     FIG. 2 is an electrical schematic diagram of the battery of FIG. 1; 
     FIG. 3 is a cross-sectional view of the battery of FIG. 2 in a first implementation; 
     FIG. 4 is a cross-sectional view of the battery of FIG. 2 in a second implementation; and 
     FIG. 5 is a perspective view of the rear of the cap of the battery of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A battery, according to various aspects of the present invention, provides an output voltage (or current) that includes a multiple of a cell voltage (or current) when a plurality of identical cells are connected in series (or parallel). The plurality of cells are bundled in close-packed arrangement to snuggly fit against a retainer. The retainer may provide an enclosure, substantially surrounding the bundled cells, with a cap that may be vented to balance air pressure between the interior and the exterior of the enclosure. Any number of cells may be bundled. In a preferred implementation, identical cylindrical cells are bundled. 
     For example, battery  100  of FIG. 1 includes case  102 , cap  104 , positive terminal  106 , and negative terminal  108 . Negative terminal  108  includes vent  110  mounted coaxially in terminal  108 . Battery  100  may conform to industry standard dimensions for length, width, height, and terminal shape and dimensions. For example, battery  100  may conform to the standard dimensions of a conventional nominal 9-volt type battery with snap terminals. In one implementation of a nominal 9-volt type battery, according to various aspects of the present invention, seven cells each having chemistry to provide about 1.2 volts are coupled in a series circuit. An exemplary series circuit (e.g., schematic  200  of FIG. 2) includes seven identical cells  202 ,  204 ,  206 ,  208 ,  210 ,  212 , and  214  coupled in series between terminals  106  and  108 . Cells may be electrically coupled by links  220 ,  222 ,  224 ,  226 ,  228 ,  230 ,  232 , and  234 . Cell chemistry and the series circuit provide an output voltage across terminals  106  and  108  of about 8.4 volts which is considered satisfactory for a nominal 9-volt type battery. 
     Cylindrical cells may be arranged with respective axes of cylindrical symmetry oriented parallel to the longest dimension of the retainer. For example, arrangement  300  of FIG. 3 provides one bundle of seven identical cylindrical cells  202 ,  204 ,  206 ,  208 ,  210 ,  212 , and  214  each having an axis of cylindrical symmetry parallel to dimension L of case  102  and electrically connected according to schematic  200 . A cell diameter approximately one-half of the shortest dimension H of the interior cavity of case  102  is preferred. A cell length approximately the dimension L of the interior cavity of the case  102  is preferred. 
     Cylindrical cells may be arranged with respective axes of cylindrical symmetry oriented parallel to a plane that includes the battery terminals. For example, battery  100  has terminals  106  and  108  located in a plane that includes a surface of cap  104 . Arrangement  400  of FIG. 4 provides one bundle of seven identical cylindrical cells  202 ,  204 ,  206 ,  208 ,  210 ,  212 , and  214  each having an axis of cylindrical symmetry parallel to that plane (e.g., parallel to axis AA of FIG. 1) and electrically connected according to schematic  200 . A cell length approximately equal to the dimension W of the interior cavity of case  102  is preferred. 
     A preferred cell diameter is selected to close pack the desired number of cells into the interior cavity of case  102 . For example, in the arrangement in FIG. 3, a portion of the length of each cell abuts at least two other cells and (except for cell  210 ) abuts a portion of the interior cavity of case  102 . In another implementation, passage of links  220  and  234  along the length of a cell between the cell and the interior side wall is avoided. Cell diameters may then be used so that all cells contact one or more interior surfaces of the cavity except one (e.g., cell  210  in FIG.  3 ). In the arrangement in FIG. 4, each cell of a majority of cells abuts two other cells and abuts an interior surface of the cavity. 
     Cell terminals may be electrically coupled to battery terminals in series. For example, links  222 ,  224 ,  226 ,  228 ,  230 , and  232  are identical in dimensions, formed of plated copper or steel sheet material, and are spot welded at each respective end of the link to a cell terminal. Link  234  may be formed of similar material, spot welded to cell  202 , insulated on one or all sides to avoid electrical contact with other links and cells, and be connected to one of the battery terminals, (e.g., negative terminal  108 ). Connection to a battery terminal may be made in any conventional manner, for example, with a rivet that concomitantly binds terminal  108  to cap  104 . 
     Battery  100  may include conventional snap terminals (e.g., of the type common to 9-volt nominal battery packages). For example, cap  104  of FIG. 5 includes hollow rivets  504  and  506  respectively securing links  220  and  234 , through holes in cap  104 , to male and female snap terminals  106  and  108  (not shown in FIG.  5 ). Each hollow rivet defines an aperture  110  and  112  through which pressure equalization may occur between ambient air external to the enclosure (formed by cap  104  suitably affixed in any conventional manner as an air-tight seal to case  102 ) and air internal to the enclosure. A filter may cover apertures  110  and  112  to limit contamination of the interior of the enclosure by airborne particulates or fluids (e.g., condensation). For example, foam sheet  502  serves as a filter and provides mechanical cushioning between cap  104  and cells of battery  100 . Foam sheet  502  may include any conventional adhesive applied to at least a portion of surface  503  to maintain position of foam sheet  502  over apertures  110  and  112  (e.g., adhering sheet  502  to cap  104 ) without occluding airflow through apertures  110  and  112 . 
     Any suitable internal dimensions, structure, and chemical composition may be used for each cell. For example, any conventional cell structure and composition may be used. A rechargeable chemistry (e.g., nickel-cadmium) is preferred. Cells  202 ,  204 ,  206 ,  208 ,  210 ,  212 , and  214  may be of various types (dissimilar or identical to each other) including cells of the type described in U.S. Pat. No. 4,259,416 to Ikeda; U.S. Pat. No. 4,663,247 to Smilanich; and U.S. Pat. No. 4,929,519 to Catotti, each incorporated herein by this reference. 
     Particular synergies are realized in the present invention by employing high energy density cylindrical cells for batteries. A battery according to various aspects of the present invention may have an overall geometry (established by the retainer or enclosure) that is cylindrical (e.g., bundled parallel 1.2 volt cells in a conventional AAA, AA, C, or D battery package) or noncylindrical (e.g., cubic, prismatic, or hexahedral) and either regular in geometry (having several pairs of equal dimensions) or irregular. 
     For a battery that includes a retainer that encloses one or more cells, the enclosure may include any suitable vent. When supported within an enclosure and exposed to heat, individual cells may release vapor pressure into the enclosure (e.g., case  102  closed with cap  104 ). For example, as discussed above, battery  100  may include one or more vents in cap  104  (preferably coaxial with a terminal). Such a vent may be of the type described in U.S. Pat. No. 5,879,831 to Ovshinsky, incorporated by this reference along with all patents referred to therein. 
     The foregoing description discusses preferred embodiments of the present invention which may be changed or modified without departing from the scope of the present invention as defined in the claims. While for the sake of clarity of description, several specific embodiments of the invention have been described, the scope of the invention is intended to be measured by the claims as set forth below.