Patent Publication Number: US-2009239137-A1

Title: Battery module and battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2008-076580, filed Mar. 24, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a battery pack, and more particularly, to a battery pack in which a plurality of battery modules, each including a secondary battery (cell) such as a lithium-ion battery, using a non-aqueous electrolyte and contained in a case, are fixedly arranged in a straight line. 
     2. Description of the Related Art 
     In recent years, non-aqueous secondary batteries, especially lithium-ion batteries, have been noted as energy sources for driving vehicles, such as electric vehicles, as well as ones for cordless, portable electronic devices. 
     Disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2005-268004 (Patent Document 1), for example, is an electricity storage device composed of flat laminated batteries for use as electricity storage cells and an armor case that contains the laminated batteries. 
     Disclosed in Japanese Patent No. 3350189 (Patent Document 2), moreover, is a battery box unit for an electric vehicle in which a drive power source composed of a plurality of batteries are contained in a battery box. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of this invention is to provide a battery pack configured so that a plurality of battery modules can be easily fixed and an operator&#39;s load can be reduced. 
     A battery pack according to a first aspect of the invention comprises: a battery module including a projection; a support which holds the respective projections of a plurality of the battery modules disposed so that the projections are arranged in a straight line; and a fixing member for fixing the support to the projections. 
     A battery pack according to a second aspect of the invention comprises: a battery module; a housing which contains a plurality of the battery modules disposed in a straight line between a first fixing plate extending substantially at right angles from a bottom plate and a tapered second fixing plate extending substantially at right angles from the bottom plate and reduced in thickness with distance from the bottom plate; a wedge member interposed between the battery module and the second fixing plate of the housing; and a fixing member for fixing the wedge member to the housing. 
     A battery pack according to a third aspect of the invention comprises: a battery module; a fixing plate; a movable pressure plate opposed to the fixing plate; and an urging member which urges the pressure plate toward the fixing plate so as to hold the battery modules arranged in a straight line between the fixing plate and the pressure plate, thereby fixing the battery modules. 
     A battery pack according to a fourth aspect of the invention comprises: a battery module provided with a case including an open portion and a cell contained in the case; and a lid member fitted to the case of each of a plurality of battery modules arranged in a straight line, thereby closing the open portion and fixing the battery modules. 
     A battery pack according to a fifth aspect of the invention comprises: a battery module provided with a cell, which is composed of an electrode group and a non-aqueous electrolyte contained in an armor case and includes a cell terminal electrically connected to the electrode group and protruding outward from the armor case, and a case including a cell containing portion which contains the cell and a terminal hole through which the cell terminal of the cell projects; a connecting member which is electrically connected to the cell terminal projecting through the terminal hole of the case of each of a plurality of battery modules arranged in a straight line and electrically connects the adjacent battery modules; and a fixing member for fixing the connecting member to the case of each of the battery modules. 
     According to this invention, there may be provided a battery pack configured so that a plurality of battery modules can be easily fixed and an operator&#39;s load can be reduced. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  is a sectional view schematically showing the basic structure of a battery module according to an embodiment of the invention; 
         FIG. 2  is a perspective view schematically showing the basic structure of the battery module shown in  FIG. 1 ; 
         FIG. 3  is a perspective view schematically showing the construction of a battery pack according to a first embodiment; 
         FIG. 4  is a perspective view schematically showing an external appearance of a plurality of battery modules of the battery pack shown in  FIG. 3  arranged in a line; 
         FIG. 5  is a perspective view schematically showing the construction of a support applicable to the battery pack shown in  FIG. 3 ; 
         FIG. 6  is a perspective view schematically showing a state in which the battery pack shown in  FIG. 3  is secured to a housing; 
         FIG. 7  is a perspective view schematically showing the construction of a current lead applicable to each battery module of the battery pack according to the first embodiment; 
         FIG. 8  is a perspective view schematically showing the construction of another support applicable to the battery pack shown in  FIG. 3 ; 
         FIG. 9  is a sectional view schematically showing a state in which the support shown in  FIG. 8  is attached to a case; 
         FIG. 10  is a perspective view schematically showing the construction of a battery pack according to a second embodiment; 
         FIG. 11  is a perspective view schematically showing the construction of a battery pack according to a third embodiment; 
         FIG. 12  is a side view schematically showing the construction of the battery pack according to the third embodiment; 
         FIG. 13  is perspective view schematically showing the constructions of a fixing plate and pressure plate applicable to the battery pack according to the third embodiment; 
         FIG. 14  is a perspective view schematically showing the construction of a battery pack according to a fourth embodiment; 
         FIG. 15  is an exploded perspective view schematically showing the construction of the battery pack according to the fourth embodiment; 
         FIG. 16  is a perspective view schematically showing the construction of a battery pack according to a fifth embodiment; 
         FIG. 17  is a perspective view schematically showing the construction of a connecting member applicable to the battery pack according to the fifth embodiment; and 
         FIG. 18  is a sectional view schematically showing a state in which the connecting member shown in  FIG. 17  is attached to a case. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A battery pack according to an embodiment of this invention will now be described with reference to the accompanying drawings. 
     The basic structure of a battery module incorporated in the battery pack will be described first. 
     As shown in  FIGS. 1 and 2 , a battery module  1  is composed of a cell  10  and case  20  that accommodates the cell  10 . 
     Specifically, the cell  10  is a secondary battery such as a lithium-ion battery, which uses a non-aqueous electrolyte LQ, and is designed so that an electrode group EL and non-aqueous electrolyte LQ are hermetically sealed in an armor case AC. The external shape of the cell  10  (i.e., that of the armor case AC) is substantially rectangular-parallelepipedic. 
     The electrode group EL includes positive and negative electrodes that are coiled with a separator between them and has a radially compressed, flat rectangular shape. A cell terminal  11  is electrically connected to the electrode group EL constructed in this manner. Positive and negative terminals  11 P and  11 N are electrically connected to the positive and negative electrodes, respectively, of the electrode group EL. The positive and negative terminals  11 P and  11 N both protrude outward from one surface (upper surface)  13  of the armor case AC. 
     The case  20  is provided with a case body  21  that includes a cell containing portion  21 X and a projection  22  that protrudes from the case body  21 . The case  20  is formed of a resin, such as polycarbonate (PC) or polyphenylene sulfide (PPS) resin, or ceramic. The projection  22  corresponds to a projection of the battery module  1 . 
     The case body  21  is substantially rectangular-parallelepipedic and includes six wall plates that enclose the cell  10 . The cell containing portion  21 X is equivalent to a substantially rectangular-parallelepipedic hollow portion formed inside the case body  21  and larger than the contour of the cell  10 . These six wall plates may be formed integrally with one another, or alternatively, at least one wall plate may be joined to another one by screwing or by means of a fitting structure. One wall plate  21 A that constitutes the case body  21  is formed with two terminal holes  21 H into which the positive and negative terminals  11 P and  11 N of the cell  10  can be inserted. 
     When the cell  10  is contained in the case body  21 , a small gap for the passage of a coolant (e.g., cold blast) is formed between the cell  10  and case body  21 . Further, the positive and negative terminals  11 P and  11 N that are inserted individually into the terminal holes  21 H project outward from the wall plate  21 A, so that they can be connected to current leads. 
     The projection  22  protrudes outward (i.e., oppositely from the cell containing portion  21 X) from the wall plate  21 A. In this embodiment, the projection  22  is substantially rectangular-parallelepipedic and includes a top wall  22 E and four sidewalls  22 A,  22 B,  22 C and  22 D that rise outward from the wall plate  21 A. The four sidewalls  22 A to  22 D and top wall  22 E are substantially rectangular. The projection  22  is not limited to this illustrated shape but may be of another shape. 
     The sidewalls  22 A and  22 B face each other. The sidewall  22 A extends substantially at right angles to the wall plate  21 A from which the positive terminal  11 P projects. The sidewall  22 B extends substantially at right angles to the wall plate  21 A from which the negative terminal  11 N projects. The sidewalls  22 C and  22 D face each other and both connect with the sidewalls  22 A and  22 B. Further, the sidewalls  22 C and  22 D are formed integrally and flush with wall plates  21 C and  21 D, respectively, of the case body  21 . The top wall  22 E connects with the four sidewalls  22 A to  22 D. 
     Further, the projection  22  is provided with inserts  30 . The inserts  30  extend individually from the sidewalls  22 A and  22 B into the projection  22 . An internal thread is formed on the inner surface of each insert  30 . These inserts  30  are formed of a metal, such as brass. 
     The following is a detailed description of embodiments of a specific construction of a battery pack CP. 
     First Embodiment 
     In a first embodiment, as shown in  FIG. 3 , the battery pack CP is composed of a plurality of battery modules  1 A,  1 B,  1 C . . . , support  70 , and fixing members  80 . 
     The battery modules  1 A,  1 B,  1 C . . . are disposed so that their respective projections  22  are arranged in a straight line in the order named. 
     More specifically, as shown in  FIG. 4 , the battery modules  1 A,  1 B,  1 C . . . are arranged so that their respective cases  20  face one another. The wall plate  21 D of the case body  21  and the sidewall  22 D of the projection  22  of, for example, the battery module  1 A face the wall plate  21 C of the case body  21  and the sidewall  22 C of the projection  22 , respectively, of the battery module  1 B. As in the example shown in  FIG. 4 , the respective cases  20  of each two adjacent ones of the battery modules  1 A,  1 B and  1 C may be in close contact with each other. 
     In this state, the respective cell terminals  11  of the battery modules  1 A,  1 B and  1 C are arranged in a straight line parallel to the direction of arrangement of the projections  22 . Further, the battery modules  1 A,  1 B and  1 C may be electrically connected in series or in parallel. If they are connected in series, for example, the battery modules  1 A,  1 B and  1 C are arranged so that the cell terminals of the adjacent battery modules are different in polarity. 
     The support  70  holds the respective projections  22  of the battery modules  1  arranged in a straight line. 
     More specifically, as shown in  FIG. 5 , the support  70  can be formed by, for example, bending one plate material. This support  70  is substantially U-shaped and integrally includes an intermediate portion  71  and a pair of clamping portions  72 . 
     The intermediate portion  71  is substantially rectangular and is situated between the pair of clamping portions  72 . The intermediate portion  71  faces the respective top walls  22 E of the held projections  22 . Further, the width of the intermediate portion  71  is equal to a width W 1  of each projection  22 . 
     The clamping portions  72  include first and second clamping portions  72 A and  72 B. The first and second clamping portions  72 A and  72 B are connected individually to the opposite ends of the intermediate portion  71 . Each of the clamping portions  72 A and  72 B is substantially rectangular. Further, the clamping portions  72 A and  72 B face each other at a distance equal to the width W 1  of each projection  22 . Thus, the first and second clamping portions  72 A and  72 B clamp the projections  22  between them. The first clamping portion  72 A faces the respective sidewalls  22 A of the held projections  22 . The second clamping portion  72 B faces the respective sidewalls  22 B of the held projections  22 . 
     Like the sidewalls  22 A and  22 B of the projection  22  that extend substantially at right angles to the top wall  22 E, the first and second clamping portions  72 A and  72 B extend substantially at right angles to the intermediate portion  71 . Thus, the clamping portions  72 A and  72 B face each other in substantially a parallel relationship. 
     Further, each of the first and second clamping portions  72 A and  72 B has an opening  72 H into which each screw  80  as an example of a fixing member can be inserted. A plurality of openings  72 H formed in the first clamping portion  72 A communicate individually with the inserts  30  on the respective sidewalls  22 A of the battery modules when the first clamping portion  72 A faces the sidewalls  22 A. Further, a plurality of openings  72 H formed in the second clamping portion  72 B communicate individually with the inserts  30  on the respective sidewalls  22 B of the battery modules when the second clamping portion  72 B faces the sidewalls  22 B. 
     Each screw  80  is inserted into the opening  72 H in each of the first and second clamping portions  72 A and  72 B with the aid of, for example, a spring washer  81  and flat washer  82  and is tightened to each corresponding insert  30 . Thus, the support  70  is secured to the respective projections  22  of the battery modules  1 A,  1 B,  1 C . . . . At the same time, the battery modules  1 A,  1 B,  1 C . . . can be integrally held and fixed on one another. 
     According to the first embodiment arranged in this manner, the battery modules  1 A,  1 B,  1 C . . . are disposed so that their respective projections  22  are arranged in a straight line. Therefore, the projections  22  can be easily held by means of the support  70 , and the support  70  can be secured to all the projections  22  by means of the fixing members  80 . In other words, the plurality of battery modules  1 A,  1 B,  1 C . . . can be easily fixed on one another by using the one support  70 . The battery modules  1 A,  1 B,  1 C . . . fixed in this manner can be handled with ease, since they are disposed so as to constitute the battery pack CP. Further, the operating efficiency can be improved, and an operator&#39;s load can be reduced. 
     In the first embodiment described above, the battery pack CP may be constructed further including a housing  90 , which contains the battery modules  1 A,  1 B,  1 C . . . fixed by means of the support  70 , and housing fixing members  100  that secure the support  70  to the housing  90 , as shown in  FIG. 6 . 
     The housing  90  includes a flat bottom plate  91 , flat first fixing plate  92  extending substantially at right angles from the bottom plate  91 , and flat second fixing plate  93  opposed to the first fixing plate  92  and extending at right angles from the bottom plate  91 . In the example shown in  FIG. 6 , the housing  90  is a substantially U-shaped structure formed of the bottom plate  91  and first and second fixing plates  92  and  93 . Alternatively, however, the housing  90  may be, for example, box-like. 
     The first fixing plate  92  faces the wall plate  21 C of the case body  21  of the battery module  1 A that, among the plurality of battery modules  1 A,  1 B,  1 C . . . arranged in a line, is located on one end side. Further, the second fixing plate  93  faces the wall plate  21 D of the case body  21  of a battery module  1 Z that, among the battery modules  1 A,  1 B,  1 C . . . arranged in a line, is located on the other end side. The first and second fixing plates  92  and  93  face each other in substantially a parallel relationship at a distance equal to the total thickness of the battery modules  1 A,  1 B,  1 C . . . between them. 
     A screw  100 A as an example of the housing fixing member  100  is tightened to the first fixing plate  92  through the support  70 , thereby securing the support  70  to the first fixing plate  92 . A screw  100 B as another example of the housing fixing member  100  is tightened to the second fixing plate  93  through the support  70 , thereby securing the support  70  to the second fixing plate  93 . 
     Thus, the battery modules  1 A,  1 B,  1 C . . . fixed by means of the support  70  are united with the housing  90  in such a manner that their respective bottom surfaces are pressed against the bottom plate  91  of the housing  90 . Accordingly, the battery modules  1 A,  1 B,  1 C . . . can be firmly fixed to the housing  90 . Further, the battery modules  1 A,  1 B,  1 C . . . are supported by the support  70  and housing  90 . Since the battery modules  1 A,  1 B,  1 C . . . are sandwiched between the first and second fixing plates  92  and  93 , in particular, the cell can be kept from bulging along its thickness (or in the direction of arrangement of the battery modules). 
     Furthermore, an elastic member  110  may be interposed between the housing  90  and battery modules  1 A,  1 B,  1 C . . . . The elastic member  110  is, for example, a rubber sheet. Specifically, the elastic member  110  should be located between the bottom plate  91  of the housing  90  and the respective bottom surfaces of the battery modules  1 A,  1 B,  1 C . . . . 
     Thus, dimensional errors of the battery modules  1 A,  1 B,  1 C . . . can be absorbed, so that the individual battery modules can be fixed to the housing  90  with uniform force. If any external force, such as vibration or impact, is applied to the battery modules  1 A,  1 B,  1 C . . . , moreover, a load acting on the battery modules, especially on the cell  10 , can be reduced. 
     In the first embodiment described above, the battery pack CP may be constructed further including current leads  40  and connecting members  60  embedded in the support  70 , as shown in  FIGS. 7 to 9 . 
     Specifically, each current lead  40  is bent along the contour of each projection  22 . The current lead  40  can be formed by, for example, bending a plate of an electrically conductive material. For example, the lead  40  is a substantially L-shaped structure integrally including a junction  41  and an extending portion  42 . 
     More specifically, the junction  41  is substantially rectangular and faces the wall plate  21 A of the case body  21 . The junction  41  has an opening  41 H into which the cell terminal  11  projecting from the wall plate  21 A can be inserted. The junction  41  is electrically connected to the cell terminal  11  in the opening  41 H by welding or the like. Although only the region where the negative terminal  11 N as a cell terminal and the current lead  40  are connected is illustrated in  FIG. 9 , it is to be understood that the lead  40  is also connected to the positive terminal  11 P. 
     One end of the extending portion  42  is connected to that of the junction  41 . The extending portion  42  is substantially rectangular and faces the sidewall  22 A of the projection  22 . Like the sidewall  22 A that extends substantially at right angles to the wall plate  21 A, the extending portion  42  extends substantially at right angles to the junction  41 . Further, the extending portion  42  has an opening  42 H into which each screw  80  to be tightened to each insert  30  can be inserted. When the projection  22  is held in the support  70 , the extending portion  42  extends between the projection  22  and support  70 . 
     Although the junction  41  is provided, on its other end, with a voltage terminal  50  extending substantially at right angles to it, the terminal  50  is not essential. 
     On the other hand, the body  21  of the case  20  includes a bag-like fitting portion BC to which the junction  41  is fitted. The fitting portion BC protrudes from the wall plate  21 A and includes a gap SP on the side where it faces the projection  22 . The gap SP has a height greater than a thickness D of the junction  41 . Thus, the other end of the junction  41  can be fitted and held in the gap SP of the fitting portion BC. If the voltage terminal  50  is disposed on the other end of the junction  41 , it extends without being fitted to the fitting portion BC. 
     The connecting members  60  are embedded in that surface of the support  70  which faces the current leads  40 . Specifically, the connecting members  60  are embedded in that surface of each of the first and second clamping portions  72 A and  72 B which faces the projections  22 . Each connecting member  60  is a plate that extends in the direction of arrangement of the battery modules  1 A,  1 B,  1 C . . . and is in contact with each two or more adjacent current leads  40 . 
     Further, each connecting member  60  has an opening  60 H into which each screw  80  can be inserted. The opening  60 H communicates with its corresponding one of the openings  72 H in the first and second clamping portions  72 A and  72 B. 
     In this arrangement, the screws  80  are inserted individually into the respective openings  42 H of the current leads  40  through the openings  72 H of the first and second clamping portions  72 A and  72 B and the openings  60 H of the connecting members  60  with the aid of, for example, the spring washers  81  and flat washers  82 , and are tightened to their corresponding inserts  30 . 
     Accordingly, the battery modules  1 A,  1 B,  1 C . . . can be integrally held and fixed on one another, and each two adjacent battery modules can be electrically connected to each other. The example shown in  FIG. 8  corresponds to the case where the battery modules  1 A,  1 B,  1 C . . . are connected in series. Specifically, the current lead  40  connected to the cell terminal  11 N of the battery module  1 A and the lead  40  connected to the cell terminal  11 P of the adjacent battery module  1 B are electrically connected to each other by the corresponding connecting member  60 . 
     Thus, the battery modules can be electrically connected to one another as they are fixed together, so that the number of assembly processes can be reduced, the operating efficiency can be improved, and the operator&#39;s load can be reduced. 
     Second Embodiment 
     In a second embodiment, as shown in  FIG. 10 , the battery pack CP is composed of a plurality of battery modules  1 A,  1 B,  1 C . . . , housing  90 , and fixing member  201 . 
     The battery modules  1 A,  1 B,  1 C . . . are arranged in a straight line in the order named. 
     The housing  90 , which contains the battery modules arranged in a straight line, includes a flat bottom plate  91 , flat first fixing plate  92  extending substantially at right angles from the bottom plate  91 , and tapered second fixing plate  93  opposed to the first fixing plate  92  and extending at right angles from the bottom plate  91 . The second fixing plate  93  is tapered so that its thickness is reduced with distance from the bottom plate  91 . In the example shown in  FIG. 10 , the housing  90  is a substantially U-shaped structure formed of the bottom plate  91  and first and second fixing plates  92  and  93 . Alternatively, however, the housing  90  may be, for example, box-like, provided that the second fixing plate  93  is tapered. 
     The first fixing plate  92  faces a wall plate  21 C of a case body  21  of the battery module  1 A located on one end side. Further, the second fixing plate  93  faces a wall plate  21 D of the case body  21  of a battery module  1 Z located on the other end side so that a wedge-shaped space SPA is formed between the plates  93  and  21 D. 
     The length of the bottom plate  91  between the first and second fixing plates  92  and  93  is equal to the total thickness of the battery modules  1 A,  1 B,  1 C . . . between them. The fixing plates  92  and  93  face each other in substantially a parallel relationship at this distance. 
     A wedge member  200  is shaped corresponding to the space SPA between the second fixing plate  93  and the wall plate  21 D of the battery module  1 Z. The wedge member  200  is inserted between the second fixing plate  93  and battery module  1 Z. 
     A screw  201  as an example of the fixing member is tightened to the wedge member  200  through the second fixing plate  93 , thereby fixing the wedge member  200  and second fixing plate  93  to each other. 
     Thus, force can be applied to bring the battery modules  1 A,  1 B,  1 C . . . into close contact with one another as they are secured to the housing  90 . Since the battery modules  1 A,  1 B,  1 C . . . are sandwiched between the first and second fixing plates  92  and  93  and wedge member  200 , moreover, the cell can be kept from bulging along its thickness. 
     As in the example shown in  FIG. 6 , furthermore, an elastic member  110  may be interposed between the housing  90  and the battery modules  1 A,  1 B,  1 C . . . . In this case, the elastic member  110  should be located between the bottom plate  91  of the housing  90  and the respective bottom surfaces of the battery modules  1 . Thus, the same effect as in the example shown in  FIG. 6  can be obtained. 
     Also in this second embodiment, the support  70  shown in  FIG. 3  may be used so that the support  70  and housing  90  are fixed together. Further, the battery modules may be electrically connected to one another by using current leads  40 , such as the one shown in  FIG. 7 , and a support  70  with connecting members  60  embedded therein, such as the one shown in  FIG. 8 . 
     Third Embodiment 
     In a third embodiment, as shown in  FIGS. 11 and 12 , the battery pack CP is composed of a plurality of battery modules  1 A,  1 B,  1 C . . . , fixing plate  210 , pressure plate  220 , and urging member  230 . 
     The battery modules  1 A,  1 B,  1 C . . . are arranged in a straight line in the order named. 
     The fixing plate  210  and pressure plate  220  are substantially uniform in thickness. The pressure plate  220  is opposed to the fixing plate  210  in substantially a parallel relationship at a predetermined distance and is configured for movement. The fixing plate  210  faces a battery module  1 Z located on the other end side. Further, the pressure plate  220  faces the battery module  1 A on one end side. 
     As shown in  FIGS. 13 , for example, the fixing plate  210  and pressure plate  220  should each be provided with a recess C that is shaped corresponding to the contour of the battery module  1 A or  1 Z so that a part of the battery module can be fitted therein. 
     The urging member  230  is composed of, for example, bands  231  spanning between the fixing plate  210  and pressure plate  220  and band tightening screws  232  for tensioning the bands  231 . By tightening the screws  232 , according to this arrangement, the pressure plate  220  can be urged toward the fixing plate  210  so as to hold the battery modules  1 A,  1 B,  1 C . . . in a straight line between the plates  210  and  220 , thereby fixing the battery modules. Since the battery modules  1 A,  1 B,  1 C . . . are sandwiched between the fixing plate  210  and pressure plate  220 , moreover, the cell can be kept from bulging along its thickness. 
     Since the fixing plate  210  and pressure plate  220  are each provided with the recess C that is shaped corresponding to the contour of the battery module  1 , furthermore, the connected battery modules can be kept from moving at right angles to their thickness. Thus, the battery modules can be fixed more firmly. 
     Also in this third embodiment, the support  70  shown in  FIG. 3  may be used so that the support  70  and a housing  90  are fixed together. Further, the battery modules may be electrically connected to one another by using current leads  40 , such as the one shown in  FIG. 7 , and support  70  with connecting members  60  embedded therein, such as the one shown in  FIG. 8 . 
     Fourth Embodiment 
     As shown in  FIG. 14 , each battery module  1  according to a fourth embodiment is provided with a cell  10  and case  20  that contains the cell  10 . 
     The case  20  includes an open portion  20 H. In this embodiment, the open portion  20 H is formed at the bottom of the case  20 , that is, on the side opposite a wall plate  21 A from which cell terminals  11  project. Further, the case  20  has fitting holes  20 AP in the vicinity of the open portion  20 H. 
     The battery module  1  is further provided with a lid member  300  that is fitted to the case  20  and closes the open portion  20 H. The lid member  300  includes lugs  300 C that engage with the fitting holes  20 AP, individually. 
     In this arrangement, the cell  10  is inserted into the case  20  through the open portion  20 H. When the lugs  300 C of the lid member  300  engage individually with the fitting holes  20 AP of the case  20 , the open portion  20 H of the case  20  is closed so that the cell  10  is contained in the case  20 . Thus, the number of assembly processes for the battery modules can be reduced. 
     The following is a description of a battery pack CP provided with a plurality of battery modules  1  that each include the cell  10  and case  20  connected in the aforementioned manner. 
     As shown in  FIG. 15 , the battery pack CP is composed of a plurality of battery modules  1 A,  1 B,  1 C . . . and lid member  310 . 
     The lid member  310  engages with the case  20  of each of the battery modules  1 A,  1 B,  1 C . . . arranged on a straight line so as to close the open portion  20 H and fixes the battery modules together. Specifically, the lid member  310  includes lugs  310 C that engage individually with the fitting holes  20 AP in the respective cases  20  of the battery modules. 
     After the cell  10  is inserted into each case  20  through the open portion  20 H, according to this arrangement, the lugs  310 C of the lid member  310  engage individually with the fitting holes  20 AP of the cases  20 . Thereupon, the open portion  20 H of each case  20  is closed so that the cell  10  is contained in the case  20 , and the battery modules  1 A,  1 B,  1 C . . . are connected together by the lid member  310 . 
     Thus, the number of assembly processes for the battery modules can be reduced. 
     Further, the aforementioned lid member  310  may be used in place of the bottom plate  91  of the housing  90  described in connection with the first and second embodiments. Thus, the battery modules  1 A,  1 B,  1 C . . . can be easily secured to the housing  90 . 
     As in the example shown in  FIG. 6 , moreover, an elastic member  110  may be interposed between the lid member  310  and battery modules  1 A,  1 B,  1 C . . . . It is effective, in particular, to locate the elastic member  110  between the lid member  310  of the housing  90  and the respective bottom surfaces of the battery modules  1 A,  1 B,  1 C . . . . Thus, the same effect as in the example shown in  FIG. 6  can be obtained. 
     Also in this fourth embodiment, the support  70  shown in  FIG. 3  may be used so that the support  70  and housing  90  are fixed together. Further, the battery modules may be electrically connected to one another by using current leads  40 , such as the one shown in  FIG. 7 , and a support  70  with connecting members  60  embedded therein, such as the one shown in  FIG. 8 . 
     Fifth Embodiment 
     In a fifth embodiment, as shown in  FIG. 16 , the battery pack CP is composed of a plurality of battery modules  1 A,  1 B,  1 C . . . , connecting members  400 , and fixing members  80 . 
     The battery modules  1 A,  1 B,  1 C . . . are disposed so that their respective projections  22  are arranged in a straight line in the order named. The individual battery modules  1 A,  1 B,  1 C . . . are constructed in the same manner as the ones described above. 
     For each of the battery modules  1 A,  1 B,  1 C . . . arranged in a straight line, each connecting member  400  is electrically connected to a cell terminal  11  that projects from a terminal hole  21 H of a case  20  and electrically connects each two adjacent battery modules. 
     Specifically, the connecting member  400  includes a first current lead  410  electrically connected to the cell terminal  11  of the one battery module  1 A, second current lead  420  electrically connected to the cell terminal  11  of the battery module  1 B that adjoins the battery module  1 A, and coupling portion  430  that connects the first and second current leads  410  and  420 . 
     The first and second current leads  410  and  420  and coupling portion  430  are formed of an electrically conductive material, and the coupling portion  430  electrically connects the current leads  410  and  420 . 
     The first current lead  410  integrally includes a junction  411 , intermediate portion  412 , and extending portion  413  and is substantially Z-shaped. Likewise, the second current lead  420  integrally includes a junction  421 , intermediate portion  422 , and extending portion  423  and is substantially Z-shaped. The first and second current leads  410  and  420  have substantially the same construction. The first current lead  410  will now be described further in detail. 
     The junction  411  is substantially rectangular and faces a wall plate  21 A of a case body  21 . The junction  411  has an opening  411 H into which a cell terminal projecting from the wall plate  21 A can be inserted. The junction  411  is electrically connected to the cell terminal in the opening  411 H by welding or the like. 
     One end of the intermediate portion  412  is connected to that of the junction  411 . The intermediate portion  412  is substantially rectangular and faces a sidewall  22 A of the projection  22 . Like the sidewall  22 A that extends substantially at right angles to the wall plate  21 A, the intermediate portion  412  extends substantially at right angles to the junction  411 . Further, the intermediate portion  412  has an opening  412 H into which a screw  80  as an example of a fixing member to be tightened to an insert  30  can be inserted. 
     The one end of the extending portion  413  is connected to the other end of the intermediate portion  412 . The extending portion  413  is substantially rectangular and faces a top wall  22 E of the projection  22 . Like the top wall  22 E that extends substantially at right angles to the sidewall  22 A, the extending portion  413  extends substantially at right angles to the intermediate portion  412 . 
     Although the junction  411  is provided, on its other end, with a voltage terminal  50  extending substantially at right angles to it, the terminal  50  is not essential. 
     The coupling portion  430  is substantially U-shaped and is connected to the intermediate portion  422  of the second current lead  420  as well as to the intermediate portion  412  of the first current lead  410 . 
     In this arrangement, the screws  80  are tightened to their corresponding inserts  30  through the respective openings  412 H and  422 H of the first and second current leads  410  and  420  with the aid of, for example, spring washers  81  and flat washers  82 . 
     Accordingly, the battery modules  1 A,  1 B,  1 C . . . can be integrally held and fixed on one another, and each two adjacent battery modules can be electrically connected to each other. The example shown in  FIGS. 16 to 18  corresponds to the case where the battery modules  1 A,  1 B,  1 C . . . are connected in series. The first current lead  410  connected to a cell terminal  11 N of the battery module  1 A and the second current lead  420  connected to a cell terminal  11 P of the adjacent battery module  1 B are electrically connected to each other by the corresponding coupling portion  430 . 
     Thus, the battery modules can be electrically connected to one another as they are fixed together, so that the number of assembly processes can be reduced, the operating efficiency can be improved, and the operator&#39;s load can be reduced. 
     By fixing the connecting members  400  by means of the fixing members  80 , moreover, the connecting members  400  and cell terminals  11  can be positioned with respect to one another as they are secured to one another. After the battery modules  1 A,  1 B,  1 C . . . are connected to one another, therefore, the cell terminals  11  and connecting members  400  can be easily laser-welded together without requiring a jig for clamping the connecting members  400  on the cell terminals  11 . 
     The housing  90  described in connection with the first and second embodiments may also be used in this fifth embodiment. Further, the support  70  shown in  FIG. 3  may be used so that the support  70  and housing  90  are fixed together. 
     This invention is not limited directly to the embodiment described above, and in carrying out the invention, its components may be embodied in modified forms without departing from the scope or spirit of the invention. Further, various inventions may be made by suitably combining a plurality of components described in connection with the foregoing embodiment. For example, some of the components according to the foregoing embodiment may be omitted. Furthermore, components according to different embodiments may be combined as required.