Abstract:
Disclosed herein an adhesive substrate having a peelable backing for use with battery packs. The adhesive substrate can include an integral tab, and perforations can be formed between a main body of the substrate and the tab. To peel the backing from the main body, the tab can be detached from the main body while remaining bonded to the peelable backing. The tab can be pulled to peel the backing from the main body of the substrate. The substrate is then applied to the battery pack.

Description:
RELATED APPLICATION 
     This application is a non-provisional application claiming priority on U.S. Provisional Patent Application Ser. No. 61/237,447 filed Aug. 27, 2009, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates to protective substrates applied to batteries and methods for making and applying same. 
     BACKGROUND 
     Battery packs are used in many environments including medical equipment, environmental monitoring equipment and power tools, to name a few. Each battery pack can include, for example, one or more battery cells, connectors that are welded to the cells to electrically connect the cells, one or more sheets of vulcanized paper adhered to a top and/or bottom of the cells, and shrink wrap that encloses the cells, connectors and vulcanized paper. 
     The vulcanized paper, which is also known as “fish paper”, can serve to serve to insulate the cells and otherwise protect the cells from damage, such as damage that may result from an impact to the battery pack. Vulcanized paper can be adhered to the top or bottom of the cells in various manners. In one example, a worker can bond vulcanized paper to the cells by applying a layer of adhesive to the vulcanized paper and then quickly pressing the vulcanized paper against the cells and allowing the adhesive to set. In another example, the vulcanized paper can be manufactured to include an adhesive layer on one of its sides, and the adhesive layer can be covered with backing paper to protect the adhesive layer until the vulcanized paper is ready to be applied to the cells. At the time of applying the vulcanized paper to the cells, a worker can peel the backing paper from the vulcanized paper and then press the vulcanized paper against the cells to bond the vulcanized paper to the cells. 
     Bonding vulcanized paper to battery cells is problematic. Having a worker bond vulcanized paper to the cells by applying a layer of adhesive to the vulcanized paper and then quickly pressing the vulcanized paper against the cells and allowing the adhesive to set is an inefficient and time consuming operation. For example, the worker must manually apply the layer of adhesive to each piece of vulcanized paper and evenly distribute the adhesive on a surface of the vulcanized paper before bonding the vulcanized paper to the cells. Additionally, manufacturing vulcanized paper to include an adhesive layer on one of its sides and covering the adhesive layer with backing paper until the vulcanized paper is ready to be applied to the cells is also inefficient. Workers often struggle to remove the backing paper from the vulcanized paper. Since different patterns of vulcanized paper are often cut from stock sheets of adhesive-backed vulcanized paper using an automated die, laser or water cutting tool, it is impractical to use backing paper that is pre-scored (i.e., scored prior to cutting patterns into the stock sheet) because the scores may not line up with the cut patterns of vulcanized paper. 
     SUMMARY 
     Examples of a protective layer for positioning on adjacent battery cells in a battery pack are shown. In one such example, the protective layer includes a substrate including a main section having a shape substantially corresponding to at least one surface of the battery cells and having a tab extending from an edge of the main section. The tab is frangibly coupled to the main section. A backing material overlays the substrate in a region corresponding to at least a portion of the main section and the tab. A layer of adhesive material between the backing material and the substrate to releasably bond the backing material to the substrate. The backing material is selectively removable in response to breaking the tab from the main section and peeling the backing material from the main section to expose the layer of adhesive on the main section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  is an exploded perspective view of a plurality of battery cells and a protective layer; 
         FIG. 2  is a perspective view of a stock sheet of vulcanized paper having an adhesive layer and backing paper that is partially peeled away from the vulcanized paper; 
         FIG. 3  is a top elevation of the stock sheet of vulcanized paper having the adhesive layer and backing paper illustrating a cutting template for forming a plurality of protective layers, the stock sheet oriented such that the vulcanized paper side faces upward; 
         FIG. 4  is a cross section view along line A-A in  FIG. 3  at a junction between a main section and a tab of one of the protective layers; 
         FIG. 5  is another example of a cross section view along the junction between the main section and the tab of one of the protective layers; 
         FIG. 6  is a perspective view of one of the protective layers oriented such that its backing paper faces upward; and 
         FIG. 7  is a perspective view of the protective layer of  FIG. 6  with the tab separated from the main section and the backing paper partially peeled from the main section. 
     
    
    
     DETAILED DESCRIPTION 
     A protective layer for positioning adjacent at least one of a first end and a second end of one or more battery cells in a battery back is disclosed and the protective layer can be easily applied to the battery cells. In one embodiment, the protective layer includes a brittle substrate having a main section having a shape substantially corresponding to a perimeter of the first or second end of the one or more battery cells and having a tab extending from an edge of the main section. The substrate defines one or more perforations along a junction between the main section and the tab. A layer of adhesive overlays a surface of the substrate, and backing paper having a shape corresponding to the main section and the tab of the substrate is attached to the layer of adhesive. The backing paper is selectively removable in response to breaking the tab from the main section and peeling the backing paper from the main section to expose the layer of adhesive on the main section. 
     As shown in  FIG. 1 , an example of a battery pack  10  can include one or more battery cells  12 , with the illustrated battery pack  10  including three cells  12 . Alternatively, a different number of cells  12  can be included. The cells  12  can be lead-acid cells, lithium-ion cells, nickel-cadmium cells or another type of cells. Each cell  12  can have a top or first end  12   a  and a second or bottom end  12   b  opposite the top end  12   a . Each end  12   a  and  12   b  can be electrically conductive. For example, the top end  12   a  can define a positive terminal and the bottom end  12   b  can define a negative terminal. The cells  12  can be oriented in alternating fashion with a first cell having its top end  12   a  oriented upward, a second cell having its bottom end  12   b  oriented upward, a third cell having its top end  12   a  oriented upward, etc. 
     The cells  12  can be electrically connected to one another using connectors  14 . The connectors  14  can be formed of a highly electrically conductive material, such as nickel, brass or silver. Each connector  14  can extend between respective terminals of a pair of adjacent cells  12  and can be electrically connected thereto. For example, a first end of one of the connectors  14  can be connected to a positive terminal of one cell  12  and an opposing end of the connector  14  can be connected to a negative terminal of an adjacent cell  12  for electrical communication between the two cells  12 . Each connector  14  can be connected to cells  12  by, as an example, soldering the connector  14  to the cells  12 . While the cells  12  are shown as being serially connected, some or all of the cells  12  can alternatively be connected in parallel. 
     Still referring to  FIG. 1 , a protective substrate  16  can be positioned against an end  10   a  of the battery pack  10 . While not shown, another substrate can be positioned against an opposing end  10   b  of the battery pack  10 . The substrate  16  can have shape substantially corresponding to a perimeter of the group of cells  12 . For example, the substrate  16  can be shaped to overlay the conductive portions at the ends  12   a  and  12   b  of the cells  12  on the end  10   a  of the battery pack  10 . As another example, the substrate  16  can be shaped to corresponding to a perimeter shape defined by the ends  12   a  and  12   b  of the cells  12  in aggregate. As yet another example, the substrate  16  can be shaped to overlay the terminals of the cells  12   a  and  12   b  without extending to the perimeters of the ends  12   a  and  12   b  of the cells  12 . 
     The substrate  16  can be formed of a brittle material such as vulcanized paper, also known as “fish paper”, of the type available from S &amp; S Electronics of Oceanside, Calif. or Composite Components of Carlsbad, Calif., among others. When made of vulcanized paper, the substrate  16  can have a thickness of 0.010 inches to 0.062 inches, though the substrate  16  can have a thickness outside that range. Instead of being constructed from vulcanized paper, the substrate  16  can be formed of another material such as cardboard, PVC, thermoplastic such as sold under the trademark Plexiglas or another material. The substrate  16  can be highly electrically insulating, and the substrate  16  can additionally have other properties such as a high impact resistance and/or an aversion to chemical reactions. The substrate  16  can protect the battery  10  from damage if the battery  10  is impacted, and the substrate  16  can also provide insulation to avoid unintended paths of electrical flow. Alternatively, the substrate need not be brittle. 
     Referring now to  FIG. 2 , a stock sheet of material  18 , e.g., vulcanized paper, from which the substrate  16  is formed is shown. The stock sheet of material  18  can have a standard size, such as 18″ by 24″, or the material  18  can come in rolled form. The material  18  can have a first side  18   a  and a second side  18   b . A layer of adhesive  20  can be applied to the second side  18   b  of the material  18 , and backing paper  22  can overlay the layer of adhesive  20  to form a composite as best seen in  FIGS. 4 and 5 . The backing paper  22  can be peelable from the adhesive  20 . For example, the backing paper  22  can be made of a material that is not strongly bonded to the adhesive  20 . 
     As shown in  FIG. 3 , a plurality of patterns  24 , each corresponding to one of the substrates  16  and a tab  26  conjoined therewith (see  FIG. 6 ) once cut from the material  18 , can be arranged on the material  18  to maximize the number of substrates  16  produced from the material  18 . The patterns  24  can be programmed in an automated cutting machine and need not actually be transcribed onto the material  18 . The substrates  16  and tabs  26  can be die cut, laser cut, water cut, or otherwise cut from the material  18 . Cuts can extend through the material  18  and the backing paper  22  in order to separate each substrate  16  and its tab  26  from the remainder of the material  18 . 
     In addition to cutting the substrates  16  from the material  18 , perforations  28  can be formed between the substrate  16  (also referred to as a main section) and its tab  26  as shown in  FIG. 4 . The perforations  28  can be at a junction between each substrate  16  and its tab  26 , such as along an edge or perimeter of the substrate  16 . In the example shown in  FIG. 4 , the perforations include alternating through perforations  28   a  that extend from one side of the substrate  16  to the other side of the substrate  16  without penetrating the backing paper  22  and shallow perforations  28   b  that do not extend all the way to the backing paper  22 . The perforations  28  thus result in the tab  26  being frangibly connected to the substrate  16  by only spaced apart portions of the tab  26  having a thickness less than the thickness of the substrate  16 , while the backing paper  22  covering the tab  26  is fully intact with the remainder of the backing paper  22 . The perforations  28  can be formed by configuring the power of a cutting tool and/or timing during which the cutting tool performs a cutting operations between the substrate  16  and tab  26  to achieve a desired perforation  28  depth, such as operating the cutting tool for a longer time and/or at a higher power while forming perforations  28   a  compared to perforations  28   b.    
     The perforations  28  can have an alternative form than shown in  FIG. 4 . For example,  FIG. 5  shows another example of perforations that include only perforations  28   a , which extend from one side of the substrate  16  to the other side of the substrate  16  without penetrating the backing paper  22 . The perforations  28  shown in  FIG. 5  may be necessary, for example, when variable cutting tool power is not available. 
     After cutting each substrate  16  and its tab  26  from the material  18  and forming perforations  28  that facilitate separation of the tab  26  from the substrate  16 , the substrate  16 , tab  26  and backing paper  22  assembly shown in  FIG. 6  is ready to be distributed to a worker for applying the substrate  16  to cells  12 . The backing paper  22  can easily be separated from the substrate  16 , thereby exposing the adhesive layer  20 , by breaking the tab  26  from the substrate  16  along the perforations  28  and then peeling the backing paper  22  from the substrate  16 . The tab  26  thus facilitates removal of the backing paper  22  from the substrate  16  by allowing a worker to grasp the tab  26  and backing paper  22  while peeling the paper  22  from the substrate  16 . After removing the backing paper  22  from the substrate  16 , the worker can apply the substrate  16  to the cells. At the time of applying the substrate  16  to the cells, the worker can press the substrate  16  against the cells so that the adhesive layer  20  bonds the substrate  16  to the cells. 
     The above-described examples have been described in order to allow easy understanding of the protective layer and do not limit the protective layer. On the contrary, the attached claim is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law.