Abstract:
The disclosure is directed to a battery assembly that includes a protective cover. The protective cover is positioned over a side plate that includes connections, such as a bus bar and a fixing member, that allow for battery operation. One or more flexible openings within the protective cover open to accept the fixing member, such as a screw or bolt, and close once the fixing member has passed. In this manner, the flexible opening allows for easy assembly and maintenance of the battery assembly while providing a mechanism of protecting the battery components from environmental elements. In addition, the flexible opening may be made by one or more cuts in the protective cover, wherein material elasticity enables the flexible opening to open and close.

Description:
This application claims priority from Japanese Patent Application No. 2005-010949, filed Jan. 18, 2005, and Japanese Patent Application No. JP 2005-329193, filed Nov. 14, 2005, the entire content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The invention relates to energy storage device and, more particularly, battery assemblies. 
     BACKGROUND 
     Batteries may be produced to include multiple battery modules. Each battery module contains a type of chemical that is used to produce an electric current. In some cases, the battery modules are serially connected using a bus bar, which enables the output of high voltage to be produced from the battery. The bus bar is a metallic conductor, which is held by an electrically insulated side-plate, or end plate, and fixed to an output terminal placed on the side of the battery modules. Batteries constructed in this manner may be capable of operating large machinery or other equipment that necessitates a large voltage or current. 
     An assembled battery having multiple battery modules may be used within the transportation industry. For example, such as assembled battery may be mounted on vehicles such as automobiles, buses, or trains. In these cases, one or more batteries of various sizes may be needed. The battery may be used in conjunction with an internal combustion engine, hydrogen fuel cell, or other power source. In some cases, the battery may be used exclusively in an electric vehicle as cleaner fuel sources are used in transportation vehicles. In either case, the battery may be used to power electronic equipment. 
     SUMMARY 
     The disclosure is directed to a battery assembly that includes a protective cover. The protective cover is positioned over a side plate that includes electrical connections, such as a bus bar that allow for battery operation. One or more flexible openings within the protective cover open to accept a fixing member, such as a screw or bolt, and close once the fixing member has passed. In this manner, the flexible opening allows for easy assembly and maintenance of the battery assembly while the protective cover provides a mechanism for protecting the battery components from environmental elements. As one example, the flexible opening may be made by one or more cuts in the protective cover, wherein material elasticity enables the flexible opening to open and close. 
     Due to the assembled battery including several bus bars and fixing operations, such as fixing action and insulation, in conventional assembled batteries there is a risk of causing a short-circuit of the fixed bus bars during these operations. Therefore, it is often necessary to be cautious and attentive when performing these operations. Accordingly, it may be difficult to assemble or perform maintenance on these types of batteries. In addition, assembled batteries in transportation vehicles are commonly used in corrosive environments where fluids or solids can be detrimental to the structure or operation of the battery. 
     The protective cover of the battery assembly described herein covers the side-plate of the battery assembly to reduce short-circuits and protect the battery assembly from corrosive environments. In other words, the flexible openings in the protective cover may improve handling, installation, and maintenance of such a battery assembly. 
     In one embodiment, a battery assembly includes a plurality of battery modules, a side-plate that holds at least one bus bar that connects adjacent battery modules, a fixing member that fixes the bus bar to an output terminal on a side of each of the plurality of battery modules, and a protective cover that covers the side-plate, wherein the protective cover comprises a flexible opening. 
     In another embodiment, a method includes assembling a plurality of battery modules, attaching at least one bus bar to a side-plate, wherein the bus bar connects adjacent battery modules, fixing the bus bar to an output terminal on a side of each of the plurality of battery modules with a fixing member, covering the side-plate with a protective cover, and cutting the protective cover to form a plurality of flexible parts of a flexible opening. 
     In an additional embodiment, a battery assembly comprises a plurality of battery modules, means for holding at least one bus bar, wherein the bus bar connects adjacent ones of the plurality of battery modules, means for fixing the bus bar to output terminals on the side of the plurality of battery modules, and means for protecting holding means, wherein the protecting means comprises a means for accepting the fixing means by opening to receive the fixing means and closing as the fixing means is accepted. 
     In another additional embodiment, a battery assembly comprising a plurality of battery modules, a side-plate that holds at least one bus bar that connects adjacent battery modules, a fixing member that fixes the bus bar to an output terminal on a side of each of the plurality of battery modules, and a flexible opening that opens to accept the fixing member and closes once the fixing member passes through the flexible opening. 
     The embodiments of the disclosure may provide some advantages. For example, the protective cover may reduce the need for further insulation when installing the battery assembly or performing battery maintenance. The protective cover may also help to reduce corrosion or degradation of the battery when the assembly is exposed to corrosive environments such as the ones encountered by automobiles. In addition, the protective cover may prevent injury to a user coming in contact with the battery assembly. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an exemplary battery assembly with a protective cover. 
         FIG. 2  is a side view of an exemplary battery module of the battery assembly of  FIG. 1 . 
         FIG. 3  is a cross-section view of the battery module of  FIG. 2 . 
         FIG. 4  is a perspective view showing an exemplary secondary cell of a battery module shown in  FIG. 1 . 
         FIG. 5  is a plan view of an exemplary protection cover and a side plate. 
         FIG. 6  is a plan view of a bus bar held by a side plate. 
         FIG. 7  is a plan view showing an example of the bus bar housing. 
         FIG. 8  is a cross-section view illustrating a hole in the bus bar of  FIG. 7 . 
         FIG. 9  is a cross-section view illustrating the solid portion of the bus bar of  FIG. 7 . 
         FIG. 10  is a cross-section of an exemplary flexible opening in the protective cover. 
         FIG. 11  is a cross-section of an exemplary concave part of the protective cover. 
         FIG. 12  is a cross-section of an exemplary convex part of the side plate. 
         FIG. 13  is a cross-section view illustrating an exemplary fixing member inserted through a bus bar. 
         FIG. 14  is a cross-section illustrating the flexible opening accepting the fixing member. 
         FIG. 15  is a cross-section illustrating the fixing member fixing the bus bar to the side-plate. 
         FIG. 16  is a cross-section view illustrating an exemplary protective cover. 
         FIG. 17  is a cross-section view illustrating an exemplary side plate. 
         FIG. 18  is a cross-section view illustrating a first fastening position of the protective cover and the side-plate. 
         FIG. 19  is a cross-section view illustrating a second fastening position of the protective cover and the side-plate. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an exemplary battery assembly with a protective cover.  FIG. 2  is a side view of a battery module of the battery assembly of  FIG. 1 .  FIG. 3  is a cross-section view of a battery module of  FIG. 2 .  FIG. 4  is a perspective view showing an exemplary secondary cell of a battery module shown in  FIG. 1 . 
     The assembled battery according to the example of  FIG. 1  is an in-vehicle cell mounted on vehicles, such as automobiles and trains, having twelve battery modules  10 . In this example, the battery modules  10  are piled in three layers to form a module group  30 . The assembled battery comprises four module groups  30 . The module groups  30  are arranged in parallel. The number of battery modules  10  included in the assembled battery, the structure of the module group  30 , or the connecting configuration are not limited to the number or structure shown in  FIG. 1 . Therefore, other embodiments may include more or less battery modules or other assembly configurations, possibly based upon the required performance of the assembled battery. 
     A constraining plate  45  is mounted on battery modules  10 , which is located above battery modules  10  or module groups  30 . Constraining plate  45  holds and fixes module groups  30  with the lower case  40  to create the assembled battery case. 
     U-shape notch holes of each battery module  10  are arranged, and the output terminal (positive and negative electrode)  12  is exposed on the same surface of the side of battery modules  10 . Output terminal  12  has a terminal surface  13  in which a hole  16  is located. Hole  16  has an internal circumference in which a thread is formed. An insulation member  18  is sheathed around output terminal  12 . 
     Battery modules  10  combine to form the illustrated type of assembled cells, having several secondary batteries  20  which are electrically and serially connected. This configuration may be favorable because high voltage is easily achievable. In addition, it is also possible to create batteries  20  with electric cells. The modulation of current or voltage is favorable in accordance with the handling properties and assembling properties during the manufacturing process, as well as the adaptability of the battery assembly to the change the layout of batteries  20  or battery modules  10  depending on the vehicle on which the module is mounted. 
     A secondary battery  20  is a flat lithium ion secondary battery, having an electric power generation component formed by laminating a positive electrode plate, a negative electrode plate, and a separator, in that sequence. The electric power generation component is sealed with an armoring material  22 , such as a laminated film. Secondary battery  20  has a plate-like electrode tab  24  and  26  derived from armoring material  22 . Electrode tab  24  is positive in polarity and electrode tab  26  is negative in polarity. For example, a nickel-hydrogen battery and a nickel-cadmium battery are applicable as secondary battery  20  of battery modules  10 . 
       FIG. 5  is a plan view of an exemplary protection cover  80  and an exemplary side plate  60 .  FIG. 6  is a plan view of a bus bar  50  held by a side plate.  FIG. 7  is a plan view showing an example of a bus bar within a housing.  FIG. 8  is a cross-section view illustrating a hole in the bus bar of  FIG. 7 , where the cross-section is taken at the plan indicated by bold numbers  8  in  FIG. 7 .  FIG. 9  is a cross-section view illustrating the solid portion of the bus bar of  FIG. 7 , wherein the cross-section is taken at the plane indicated by bold numbers  9  in  FIG. 7 . 
     As illustrated in  FIGS. 5-9 , one embodiment of the assembled battery according to the example of  FIG. 1  further comprises bus bar  50  (shown in  FIG. 6 ) for the electrical connection of adjacent battery modules. In addition, the assembled battery may further include a side-plate  60  (means for holding at least one bus bar shown in  FIG. 5 ) for holding bus bar  50 , protective cover  80  (means for protecting the holding means), and fixing member  92  (means for fixing the bus bar shown in  FIG. 13 ) for fixing bus bar  50  to side-plate  60 . Bus bar  50  is used to connect several battery modules  10  serially and achieve a high voltage output. Bus bar  50  is a flat rectangular metallic conductor, having a through-hole  52 . Fixing member  92  is inserted in through-hole  52 , and through-hole  52  is used for fixing the bus bar  50  to the output terminal  12  placed on the side of battery module  10 . 
     Side-plate  60  and protective cover  80  are coupled by a bendable hinge member  70 . Bendable hinge member  70  may be beneficial due to the fact that it is not a complicated mechanical part, which may facilitate reducing the size of the assembled battery and protective cover  80 . 
     Side-plate  60 , protective cover  80 , and hinge member  70  are composed of electrical insulation resin by integral molding. Therefore, it is possible to reduce the cost of components through this construction. For example, the electrical insulation resin includes, but is not limited to, polypropylene or some other polymer or flexible composite. The thickness of the hinge member  70  is smaller than that of side-plate  60  and protective cover  80 , and hinge member  70  is bendable in a shape of a relatively big circular arc. In other embodiments, hinge member  70  may comprise a crease or sharp angle and retain structural properties necessary for proper operation. Side-plate  60  has a housing  62  for storing bus bar  50  and a convex part  66  for fixing the protective cover  80  to the side-plate. 
     Seven housings  62  are arranged in a lateral direction and three housings  62  are arranged in a parallel direction. Opening  63  contains a bridge  64  and a gripper  65 . Opening  63  is used to position through-hole  52  of bus bar  50  and insert fixing member  92 . The size of opening  63  is bigger than terminal surface  13  of output terminal  12  and the bus bar terminal where through-hole  52  is placed. Bridge  64  is arranged in opening  63  where gripper  65  is placed. The side of the center part of bus bar  50  is removably attached to gripper  65  in order to prevent unwanted detaching of bus bar  50 . Hole  61  is a through-hole used for fixing strong and light electric cables and bolts. 
     In one embodiment, protective cover  80  includes opening  82  and concave part  86  and is installed to cover side-plate  60  through the use of bending hinge member  70 . Accordingly, it is possible to prevent bus bar  50  held by side-plate  60  from contacting foreign matters without separate insulation or causing a short-circuit. The foreign matters are, for example, electrically conductive parts and tools. 
     Not requiring separate insulation may be particularly favorable to the application to the assembled battery. For example, the assembled battery has many output terminals which requires a long time to complete the total assembly. Without protective cover  80 , it may be necessary to utilize insulation (for example, attachment of an insulation tape) with each fixation operation in order to prevent a short-circuit. Accordingly, omitting separate insulation enables to significantly shorten the total time of the attaching and assembly of the battery. 
       FIG. 10  is a cross-section of an exemplary flexible opening in the protective cover.  FIG. 11  is a cross-section of an exemplary concave part of the protective cover.  FIG. 12  is a cross-section of an exemplary convex part of the side plate. 
     Opening  82  is used for inserting fixing member  92 , where the opening includes flexible part  84 . The flexible part  84  features bendable elasticity. When pressed, the flexible part is bent to open opening  82  with a bias force in the direction the arrows. On the other hand, when no bias force is present, the flexible part  84  is restored by its elasticity to close opening  82 . Briefly, flexible part  84  allows easy construction of the battery through the use of opening  82 . 
     Several flexible parts  84  are arranged radially toward the center of the opening  82  to facilitate the insertion of the fixing member  92 . It may be favorable to form flexible part  84  from several cuts placed in protective cover  80 . Alternatively, one cut may include multiple angles to create opening  84 . 
     Concave part  86  of protective cover  80  corresponds, or mates, to convex part  66  of side-plate  60  and is coupled by the interface fit (see  FIG. 12 ). The taper-shaped convex part  66  of side-plate  60  is joined to concave part  86  by the elastic interface fit, where the parts are removable from each other. Concave part  86  of protective cover  80  and convex part  66  of side-plate  60  function as a fixing structure for fixing protective cover  80  and side-plate  60  together. Accordingly, a separate part for fixing protective cover  80  and side-plate  60  is not required, which may lead to a simplified structure. In addition, the structure of convex part  66  and concave part  86  may be easily formed during the manufacturing process. 
     The concave part  86  is placed on the top surface  87  of the protruding part which projects from the nearly flat base. Accordingly, it is possible to easily form gap D corresponding to the height of protruding part  88  between protective cover  80  and side-plate  60 , when concave part  86  and convex part  66  are joined by the interface fit. The space created by gap D is utilized for deforming flexible part  84  of opening  82  accepting fixing member  92 . It is also possible to place convex part  66  on protective cover  80  and concave part  86  on side-plate  60 . 
       FIG. 13  is a plan view illustrating an exemplary fixing member inserted through a bus bar. Fixing member  92  is a bolt with axis  93  and head  94 . The axis  93  has a communicable diameter for the through-hole  52  of the bus bar  50 , and the thread is formed on the outer circumference. The head  94  can be inserted through opening  82  of protective cover  80 , where the diameter of the head is bigger than that of through-hole  52  of bus bar  50 . Accordingly, bus bar  50  can be easily and electrically connected due to head  94  of fixing member  92  by simply inserting the axis of fixing member  92  in through-hole  52  of bus bar  50 . 
     Axis  93  corresponds to hole  16  arranged on terminal surface  13  of output terminal  12  placed on the side of battery modules  10 . The thread on the outer circumference of axis  93  is screwed together with the a thread on the inner circumference of the hole  16 . Accordingly, it is possible to join the stick-like rotor of the torque wrench with head  94  of fixing member  92  by the interface fit and to screw axis  93  of fixing member  92  together with hole  16  by rotating fixing member  92 . The tool for rotating the fixing member  92  includes, but is not limited to, a torque wrench or screwdriver. 
     When axis  93  is inserted in opening  82  of protective cover  80 , opening  82  can be opened by pressing and bending flexible part  84  of opening  82 . On the other hand, when the entire fixing member  82  passes through opening  82 , flexible part  84  is restored by its elasticity due to the loss of the bias force to deform flexible part  84 , and opening  82  of the protective cover  80  is closed. 
     Briefly, opening  82  of protective cover  80  is closed when axis  93  of fixing member  92  is screwed together with hole  16  of output terminal  12  by the rotor of the torque wrench inserted in the opening  82 , the bus bar  50  is fixed with output terminal  12 , and then the rotor of the torque wrench is withdrawn from the opening  82 . Protective cover  80  does not interfere with the fixation by fixing member  92 , on the other hand, it retains the insulation of bus bar  50  from fixing member  92 . Therefore, separate insulation is not necessary. 
       FIG. 14  is a cross-section illustrating the flexible opening accepting the fixing member.  FIG. 15  is a cross-section illustrating the fixing member fixing the bus bar to the side-plate. In  FIG. 15 , the torque wrench  98  is omitted. 
     Side-plate  60  holding bus bar  50  is placed on the side of battery modules  10 . The center of through-hole  52  of bus bar  50  is positioned so as to correspond with the center of the hole  16  of battery modules  10 . Protective cover  80  is installed so as to cover side-plate  60  by bending hinge member  70 . Bus bar  50  held by side-plate  60  prevents contact with foreign matters, which prevents a short-circuit of the battery. 
     When convex part  66  of side-plate  60  is joined to concave part  86  of protective cover  80  by the interface fit, side-plate  60  and protective cover  80  are fixed. At this time, the center of opening  82  of protective cover  80  is positioned so as to correspond with the center of through-hole  52  of bus bar  50 . Protruding part  88  of protective cover  80  forms gap D between the protective cover  80  and side-plate  60  in order to allow for the deformation of the flexible part  84  and the fixation by the fixing member  92  (see  FIG. 12 ). Thereafter, fixing member  92  is inserted in opening  82  of protective cover  80 . Opening  82  of axis  93  of fixing member  92  is opened by pressing, or applying a bias force, and bending flexible part  84  of opening  82  (see  FIG. 14 ). 
     Axis  93  of fixing member  92  passes through-hole  52  of bus bar  50  and is inserted in hole  16  formed on the terminal surface  13  of the output terminal  12  of battery modules  10 . On the other hand, the rotor of torque wrench  98  is inserted in opening  82  and joined to head  94  of fixing member  92  by the interface fitted to rotate fixing member  92 . 
     Axis  93  of fixing member  92  moves forward while being screwed together with hole  16 . When bus bar  50  held by side-plate  60  is pressed by head  94  of fixing member  92  and bus bar  50  and output terminal  12  of the battery modules  10  are fixed, or connected, the insertion of fixing member  92  is complete (see  FIG. 15 ). 
     Removing the interface fit between the rotor of torque wrench  98  and head  94  of fixing member  92  and withdrawing the rotor of torque wrench  98  from opening  82  by raising torque wrench  98 , flexible part  84  is restored by its elasticity and opening  82  of protective cover  80  is closed. Briefly, opening  82  is closed when bus bar  50  held by side-plate  60  is fixed to output terminal  12  located on the side of battery modules  10  by fixing member  92 . 
     When all securing of multiple bus bars  50  with output terminals  12  is complete, the assembled battery is mounted on vehicles by holding protective cover  80 . As protective cover  80  functions to prevent bus bar  50  from exposure, the protective cover facilitates battery attachment, accessibility, and removal during maintenance tasks. 
     As mentioned above, short-circuiting of the fixed bus bar can be prevented without separate insulation because the side-plate for holding the bus bar is covered by the protective cover. On the other hand, the protective cover does not interfere with the fixation because the fixing member can be inserted via the opening in the protective cover to fix the bus bar with the output terminal placed on the side of the battery module. Accordingly, the fixation is easily conducted, which results in the improvement of battery installation, use, and maintenance. In other words, the assembled battery may provide improved battery handling and maintenance because of the protection provided by the protective cover. 
     In other embodiments, it may be favorable to form a slit at the lower end of side-plate  60  and a receptor joined to the slit by the interface fit at the upper end of the lower case  40  to facilitate the positioning of the side-plate  60 . 
     The fixing structure is not limited to a mode that uses the interface fit of concave part  86  and convex part  66 . For example, two-sided tapes, clips, and adhesives are also applicable. Fixing member  92  is not limited to bolts. For example, rivets can be used. Hinge member  70  may be constructed by forming separately and joined to side-plate  60  and protective cover  80 . 
     Side-plate  60  and protective cover  80  may be coupled by appropriate members other than hinge member  80 . It is also possible to install protective cover  80  on the side of the lower case without using hinge member  70 . In addition, after completing the fixation, if necessary, protective cover  80  may be removed and separated. 
       FIG. 16  is a cross-section view illustrating an exemplary protective cover.  FIG. 17  is a cross-section view illustrating an exemplary side plate.  FIGS. 16 and 17  differ from  FIG. 12  due to reducing the space (dead space) occupied between the side-plate  60  and the protective cover  80 . 
     More specifically, the fixing structure of  FIGS. 16 and 17  include first and second fixing mechanisms in order to change the gap between the protective cover and the side-plate before and after completion of fixing the bus bars. When fixed by the second fixing mechanism, the gap is smaller than that in the case of being fixed by the first fixing mechanism. Therefore, the case for the assembled battery may be downsized. The description to follow will highlight differences when providing for a first and second fixing mechanism. 
     Protective cover  180 , similar to protective cover  80 , contains protruding parts  188  and  198  that project from the nearly flat base. Protruding part  188  has a top surface  187  on which concave parts  186  and  189  are arranged. Protruding part  198  has a top surface  197  on which concave part  196  is arranged. Protruding parts  188  and  198  have a similar height, and concave parts  186 ,  189 , and  196  have a similar depth. 
     Side-plate  160  contains protruding parts  168  and  178  which project from the taper-like convex parts  172  and  174  arranged on the nearly flat base and from the base. Protruding part  168  has top surface  167  where the taper-like convex part  166  is arranged. Convex part  166  is joined to concave part  186  of protruding part  188  of protective cover  180  by an elastic interface fit and is removable. Convex part  166  and concave part  186  compose the first fixing mechanism. Thus, since the structure of convex part  166  and concave part  186  may be easily manufactured due to easy formation of the first fixing mechanism. 
     Convex part  172  (the second convex part) is joined to concave part  189  of protruding part  188  of protective cover  180  by an elastic interface fit and is removable. Convex part  174  is joined to concave part  196  by an elastic interface fit and is removable. Briefly, because the structure of convex parts  172  and  174  and concave parts  189   196  are not complicated, the second fixing mechanism may be easily formed during the manufacturing process. 
     Protruding part  178  has a top surface  177  on which convex part  176  is arranged. The taper-like convex part  176  may join concave part  196  of protruding part  198  of protective cover  180 . Protruding parts  168  and  178  have similar heights. The height from the base of side-plate  160  to the top of convex parts  166  and  176  is set so as to be lower than that of protruding parts  188  and  198  of protective cover  180 . 
     Side-plate  160  and protective cover  180  are coupled by the hinge member (not shown). Side-plate  160 , protective cover  180 , and the hinge member comprise of the electrical insulation resin by integral molding. The thickness of the hinge member is thinner than that of side-plate  160  and protective cover  180 , where the hinge member is bendable to the shape of relatively large circular arc. In other embodiments, the hinge member may fold or form a crease. In other embodiments, it may be possible to place convex parts  166 ,  172 , and  174  on protective cover  180  and concave parts  186 ,  189 , and  196  on side-plate  160 . 
       FIG. 18  is a cross-section view illustrating a first fastening position of the protective cover and the side-plate.  FIG. 19  is a cross-section view illustrating a second fastening position of the protective cover and the side-plate. The first and second fixed locations refer to those with protective cover  180  and side-plate  160  before and after completing the securing of the bus bar. 
     Before beginning to securing the bus bar, protective cover  180  and side-plate  160  are positioned in the first fixed location. At this point, the opening (not shown) of protective cover  180  is positioned in the opening (not shown) located in the housing to store the bus bar (not shown) on side-plate  160 . 
     At the first fixed location, protective cover  180  and side-plate  160  are removably fixed by the elastic interface fit of concave part  186  located on the top surface  187  of protruding part  188  of protective cover  180  with top surface  167  of protruding part  168  of side-plate  160 . Concave part  196  located on top surface  197  of protruding part  198  of protective cover  180  joins convex part  176  located on top surface  177  of protruding part  178  of side-plate  160 . 
     When top surfaces  187  and  197  of protruding parts  188  and  198  of protective cover  180  joins top surfaces  167  and  177  of protruding parts  168  and  178  of side-plate  160 , gap D 1  is formed between protective cover  180  and side-plate  160 . Gap D 1  is a total of the height of protruding parts  188  and  198  of protective cover  180  and the height of protruding parts  168  and  178  of side-plate  160 . Gap D 1  is set to the appropriate value for the securing of the bus bar. 
     Similar to  FIGS. 1-15 , the bus bar held by side-plate  160  is fixed to the output terminal (not shown) placed on the side of the battery module by the fixing member (not shown) inserted through the flexible opening of protective cover  180 . 
     After completing the securing of the bus bar, the interface fit of concave part  186  and convex part  166  is separated. Protective cover  180  and side-plate  160  are positioned in the second fixed location by transferring protective cover  180  to side-plate  160  at another location. At this time, the curvature of the hinge member connecting side-plate  160  with protective cover  180  varies. 
     At the second fixed location, protective cover  180  and side-plate  160  are removably fixed by the elastic interface fit of concave parts  189  and  196  located on top surfaces  187  and  197  of protruding parts  188  and  198  of protective cover  180  with convex parts  172  and  174  of side-plate  160 . Concave parts  166  and  176  of side-plate  160  do not join protective cover  180 , so they do not interfere with the interface fit of concave parts  189  and  196  with convex parts  172  and  174 . 
     Gap D 2  is formed when top surfaces  187  and  197  of protruding parts  188  and  198  of protective cover  180  join the base of side-plate  160 . Gap D 2  corresponds to the height of protruding parts  188  and  198  of protective cover  180 . 
     Because gap D 1  is a total of the height of protruding parts  188  and  198  of protective cover  180  and the height of protruding parts  168  and  178  of side-plate  160 , gap D 2  is smaller than gap D 1 . 
     As mentioned above, the case for the assembled battery can be downsized by reducing the space (dead space) occupied by side-plate  160  and protective cover  180 . In addition, this smaller gap does not affect the securing of the bus bar because the gap between side-plate  160  and protective cover  180  is reduced after completing the securing of the bus bar. 
     The present invention is not limited to the abovementioned embodiments and can be appropriately modified within the scope of the claims. For example, when constructing the opening of the protective cover with a separate member having favorable rubber-like elasticity, the flexible part can be formed by a single cut. 
     Various implementations and embodiments of the invention have been described. Nevertheless, it is understood that various modifications can be made without departing form the invention. These and other embodiments are within the scope of the following claims.