Patent Publication Number: US-2019189997-A1

Title: Lead Acid Battery Cell Connecting Assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of co-pending U.S. patent application Ser. No. 15/214,959, filed on Jul. 20, 2016. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to a lead acid battery and, in particular, to a cell connecting assembly for a lead acid battery. 
     BACKGROUND 
     Conventionally, a lead-acid battery has a housing with a plurality of cells, each generating approximately 2.1 volts, connected in series to provide a desired battery voltage. For example, six cells generally form a 12 V battery. In an even cell number battery wherein cells are connected in series, the battery has two terminal posts positioned near the same edge. The arrangement results in terminals arranged near the same edge of the battery because of the series connection locations alternating from front to back for each series connected cell. To explain in more detail, each cell includes a number of positive and negative plates, each plate having a tab rising from its top and positioned off-center. The plates are stacked in an alternating fashion, so that all the tabs for plates of the same polarity are lined up with each other, but not with the tabs of the opposite polarity plates. Separators are provided between each plate in order to prevent direct physical contact between plates of opposite polarity. Both the positive and negative plates are connected at the top by separate cast-on-straps that are welded to the tabs. One strap connects the plates of one polarity near the front of the housing and another strap connects the plates of opposite polarity near the back of the housing. Adjacent cells are connected in series to each other by vertical extensions connected to the straps, known as flags or tombstones, that are welded to each other though openings in the housing. 
     When an odd number of cells is required for the desired voltage, connecting the cells in the customary manner described above results in the terminal posts being positioned near opposite corners of the battery. This creates problems in manufacturing and presents problems with existing venting and valve systems. 
     SUMMARY 
     A lead acid battery comprises a plurality of cells provided in an odd number arrangement greater than one in only a single row, a plurality of outer cell connectors connecting the plurality of cells to provide a single series electrical current path, and a pair of inner cell connectors. Each cell has a plurality of plates of differing polarity. Each of the outer cell connectors is positioned in an alternating manner on opposite sides of a longitudinal centerline of the plurality of cells. The plurality of outer cell connectors include a plurality of flags positioned on opposite sides of the longitudinal centerline of the plurality of cells. The inner cell connectors are connected to each other along the longitudinal centerline of the plurality of cells. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying figures, of which: 
         FIG. 1  is a perspective of a lead acid battery having a cell connecting assembly according to the invention; 
         FIG. 2  is a top view of the lead acid battery of  FIG. 1 ; 
         FIG. 3  is a sectional view of the lead acid battery of  FIG. 2 , taken along line  3 - 3 . 
         FIG. 4  is a perspective view of the cell connecting assembly according to the invention; and 
         FIG. 5  is a top view of the cell connecting assembly shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     As shown in  FIGS. 1-3 , a lead acid battery  1  according to the invention is shown. The lead acid battery  1  includes the following major components: a housing  10 , a plurality of cells  20 , a cover  30 , and a cell connecting assembly  50 . 
     As shown in  FIG. 1 , the housing  10  is a container having a front wall  12 , a rear wall  14 , a first and second side wall  16   a , 16   b , and a base wall  18 . In an embodiment, the length and height of the front wall  12  and the rear wall  14  are approximately equal. In another embodiment, the length and height of the first side wall  16   a  and the second side wall  16   b  are approximately equal. The width of the base wall  18  is approximately equal to the length of the side walls  16   a ,  16   b . The length of the base wall  18  is approximately equal to the length of the front wall  12  and the rear wall  14 . The height of the side walls  16   a ,  16   b  is approximately equal to the height of the front wall  12  and the height of the rear wall  14 . The four substantially rectangular walls of substantially equal height and the substantially rectangular floor together form a box. 
     An interior of the housing  10  is divided into N substantially equal cell cavities by a plurality of N−1 partitions  19  substantially parallel to the end walls  12 ,  14 . The height of the partitions  19  is substantially equal to the height of the four outer walls  12 ,  14 ,  16   a ,  16   b . As shown, the housing  10  includes a plurality of cells  20  and of partitions  19  and, in particular, seven cells  20  and six partitions  19 . However, one skilled in the art should appreciate that for the implementation of this invention the number of cells  20 , N, can be any odd integer greater than one. 
     The housing  10  can be made from a heat moldable plastic resin or any suitable non-conductive material resistant to sulfuric acid and known to those of ordinary skill in the art. 
     As shown in  FIGS. 1-3 , each cell cavity  20  receives a plurality of battery plates, including a plurality of positive plates  22   a  and plurality of negative plates  22   b , and a plurality of separators  24 . Each plate  22  has a tab  23 , which is positioned off-center in the embodiment shown, and disposed on the top end thereof. Suitable rotation of the plates allows all the tabs of the plates of one polarity to be lined up with each other forward of the battery center line while all the tabs of the plates of the opposite polarity are lined up with each other to the rear of the battery center line. 
     Each plate  22  is formed as a grid with perforations extending from one planar surface to an opposite planar surface thereof. Each surface on the positive plate  22   a  is coated with a positive active material which also fills the grid perforations. Each surface of the negative plate  22   b  is coated with a negative active material which fills the grid perforations. The grid forms a framework and current collector for the plates and is typically made substantially of lead. However, one skilled in the art should appreciate that any compatible arrangement of materials suitable for this framework and collecting of the current to a tab may be employed. 
     Each separator  24  is a porous electrical insulator substantially impervious to the electrolyte and resistant to electrochemical oxidation. The electrolyte is commonly a solution of water (H 2 O), sulfuric acid (H 2 SO 4 ) and possibly various additives. When interposed between two adjacent positive and negative plates  22   a ,  22   b , the separator  24  prevents electrical contact between adjacent plates  22   a ,  22   b  while providing minimal restriction to movement of ions (H 3 O + , HSO 4   − ) and water molecules (H 2 O). Separators can be made from various materials including micro-porous polyethylene, matted substantially glass fibers, phenolic sheet, certain rubber materials, expanded PTFE or any suitable non-conductive porous material known in the art. 
     The positive and negative active materials generally begin as a paste of lead oxide (PbO or lead (II) oxide), lead, water and sulfuric acid. Other ingredients in may include fibers or red lead (Pb 3 O 4 ) in positive plates. Negative recipes may include fibers, barium sulfate (BaSO 4 ), lignins, or various forms of carbon. Through processes of curing and electrical formation, the materials are converted substantially to lead dioxide (PbO 2  or lead (IV) oxide) in the case of positive plates or lead sponge (Pb) in the case of negative electrodes. However, one skilled in the art should appreciate that other known starting ingredients or conversion methods may be used. 
     In the shown embodiment, the plurality of partitions  19  are used to separate each cell cavity  20  from adjacent cell cavities  20 . The partition  19  is generally made from the same material as the housing and is often molded with the housing as a single piece. Any suitable material capable of substantially blocking ion flow between cells and allowing a series electrical connection to be made through it may be used by those skilled in the art. 
     As shown in  FIGS. 1-3 , the cover  30  is provided for the housing  10 . Exemplary embodiments of the cover  30  include a plurality of mold well receiving openings, cutouts, and at least two terminal bushings (not shown). The cover  30  is generally rectangular in shape, with a length greater than the length of the base wall  18  of the housing  10  and with a width greater than the width of the base wall  18 . The cover  30  may include a wall receiving groove (not shown) that extends around the periphery of a bottom surface of the cover  30 , proximate to an outer circumferential edge of the cover  30 . Further embodiments may include an electrolyte filling hole that extends through the cover  30 . The cover  30  can be made from a heat moldable resin or any suitable plastic material known to those of ordinary skill in the art. 
     As shown in  FIGS. 4 and 5 , the cell connecting assembly  50  according to the invention includes a pair of terminal posts  52 , a plurality of cell connectors  60 , and a single pair of cell connectors  70  that are centrally positioned along a longitudinal axis of the housing  10 . 
     In the shown embodiment, the pair of terminal posts  52  include a positive terminal post  52   a  and a negative terminal post  52   b  positioned at opposite ends of the lead acid battery  1 . In particular, the positive terminal post  52   a  is positioned at a first end along a first side of the housing  10 , while the negative terminal post  52   b  is positioned a second end, opposite the first end, along the same edge of the housing  10 . 
     Each terminal post  52  includes a post section  54  and a cell connecting body  56 . The post section  54  in the shown embodiment is an elongated tubular body having a blunt end  54   a  opposite the cell connecting body  54   b ,  56 . The post section  54  extends substantially orthogonal with respect to the cell connecting body  56 . In particular, in the shown embodiment, the post section  54  is positioned adjacent and connects to the cell connecting body  56 . However, in other embodiments the post section  54  may extend from the cell connecting body  56 . The cell connecting body  56  is a flat planar body having a cell connecting surface  57  disposed on a lower surface thereof. In the shown embodiment, all the tips of the plate tabs  23  that are aligned with the cell connecting body  56  penetrate the cell connecting surface  57  and are at least partially fused together (see  FIG. 3 ). The terminal posts  52  are made from lead, copper, or any other common electrically conductive material known to those of ordinary skill in the art. 
     As shown in the  FIGS. 4 and 5 , each off-center cell connector  60  includes a strap  62  and a flag  64 . The strap  62  is an elongated body extending along horizontal plane along a longitudinal length of lead acid battery  1 . The strap  62  includes a cell connecting surface  63  disposed on a lower surface thereof. In the shown embodiment, all the tips of the plate tabs  23  that are aligned with the strap  62  penetrate the cell connecting surface  63  and are at least partially fused together (see  FIG. 3 ). The flag  64  is a tabular body in the embodiment shown, which extend substantially orthogonal to the strap  62 . As shown, the flag  64  is positioned adjacent and connects to the strap  62 . However, in other embodiments, the flag  64  may extend from the strap  62 . As shown, the strap  62  and the flag  64  are integrally formed. However, one skilled in the art should appreciate that other designs are possible, including a multi-piece assembly, with the strap  62  and flag  64  connected through a mechanical connection, such as a weld or fastener. 
     Now, with reference to  FIGS. 4 and 5 , the pair of inner cell connectors  70  will be discussed. In particular, each inner cell connector  70  includes a strap  72 , a flag  74  and a link  76 . 
     The strap  72  is an elongated body extending along horizontal plane along a longitudinal length of lead acid battery  1 . The strap  72  includes a cell connecting surface  73  disposed on a lower surface thereof. In the shown embodiment, all the tips of the plate tabs  23  that are aligned with the strap  72  penetrate the cell connecting surface  73  and are at least partially fused together (see  FIG. 3 ). The flag  74  is a tabular body in the embodiment shown and extends substantially orthogonal with respect to the strap  72 . As shown, the flag  74  is offset from the elongated body of the strap  72 . The link  76  is an elongated body connecting the flag  74  and the strap  72 . As shown, the strap  72 , the flag  74 , and the link  76  are integrally formed. However, one skilled in the art should appreciate that other designs are possible, including a multi-piece assembly, with the strap  72 , the flag  74 , and the link  76  connected through a mechanical connection, such as a weld or fastener. 
     Now, positioning of various components of the cell connecting assembly  50  will be described in detail with reference to  FIGS. 4 and 5 . 
     A first pair of outer cell connectors  60  are aligned with each other, such that each strap  62  is linearly aligned with the other and the pair of flags  64  face each other. Next a second pair of outer cell connectors  60  positioned opposite the first pair of outer cell connectors  60  and aligned with each other. Each strap  62  of the second pair of outer cell connectors  60  is linearly aligned with the other, and the pair of flags  64  face each other. Next, the pair of inner cell connectors  70  are positioned between the first pair of outer cell connectors  60  and the second pair of outer cell connectors  60 . The straps  72  are offset from each other, with one strap  72  aligned with the strap  62  from the first pair of outer cell connectors  60 , and another strap  72  aligned with the strap  62  of the second pair of outer cell connectors  60 . The pair of flags  64  face each other in a substantial center between the pair of straps  72 . 
     A first terminal post  52  is disposed on one side of the pair of inner cell connectors  70 , while a second terminal post  52  is positioned on an opposite side of the pair of inner cell connectors  70 . The first terminal post is positioned opposite the first pair of the outer cell connectors  60  and aligned with the second pair of outer cell connectors  60 . The second terminal is positioned adjacent to and aligned with the second pair of outer cell connectors  60 . 
     Now, assembly of the lead acid battery  1  will now be describe in detail with reference to  FIGS. 1-3 . 
     As for positioning, the plurality of positive plates  22   a  and plurality of negative plates  22   b  are positioned in the housing  10 . Each positive plate  22   a  and negative plate  22   b  is separated from each other by the separator  24 , and an electrolyte is disposed with an electrolyte receiving space  26 . Each cell  20  is separated from each other by the divider  19 . 
     Next, the cell connecting assembly  50  is positioned in the housing  10  on top of the cell  20 , with the terminal posts  52  connect with cells  20  at opposite ends of the lead acid battery  1 . The plurality of outer cell connectors  60  and pair of inner cell connectors  70  also connecting with cells  20 . 
     The assembly consisting of the straps  72 , flags  74 , links  76  and posts  52  is cast and simultaneously welded to the proper plate tabs  23 . Proper plate polarity must be maintained throughout the final series circuit. In the diagrammed embodiment the straps  72  with notched ends are intended to be welded to positive plates  22   a  and the opposite straps to negative plates  22   b . It should be clear to those skilled in the art that other methods of polarity marking are acceptable. It should be clear to those skilled in the art that visible polarity markings are for the benefit of human observers and not strictly necessary for the workings of the battery. Holes are punched through the container partitions so that every opposed pair of flags will be centered over a hole after the assembly is stuffed into the housing. Electrical connections between opposing flags are made through the holes by a welding or similar process. 
     Next, the cover  30  connects with the housing  10  and encloses the cells  20 . 
     Electrolyte is added. The battery is electrically formed. The electrolyte levels or strength may be adjusted and the battery is closed up. It should be understood by those skilled in the art that several variations are possible. Formation of the plates could occur prior to assembly. Formation of the assembled elements could occur prior to stuffing them into the housing. In these manufacturing variations, the responsibility of filling the battery with electrolyte could shift to the end user after sale. 
     The terms and expressions which are employed in this specification are used as terms of description and not of limitation. Mirrored or rotated configurations are equally functional. There is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. It is recognized that various modifications are possible within the invention described and claimed herein.