Abstract:
A solderless battery pack. The pack has a generally thin wall cell body portion with two tubular segments each adapted to hold a plurality of batteries. An upper end cap and a lower end cap are provided for fitting tightly over the upper and lower ends of the cell body portion, respectively. The end caps are compressingly engaged to make electrical connection with the terminals of the uppermost and the lowermost batteries by use of opposing all-thread fasteners. The all thread fasteners each extend through the upper and lower end caps and and along side of the cell body portion in a spaced apart relationship. The all thread fasteners are removably affixed by nuts below and above the end caps. In this manner, batteries are provided a complete electrical circuit without current draining soldered or welded contacts.

Description:
The priority of this application is based on prior pending U.S. Provisional Patent Application Ser. No. 60/049,413, filed Jun. 10, 1997, the disclosure of which is incorporated herein by this reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates to novel battery holders, especially for holding a plurality of battery cells, and to methods of using the same, particularly for small electric powered vehicles such as model trucks and model aircraft. 
     BACKGROUND OF THE INVENTION 
     In the use of batteries to power electrical toys and tools, such as small electrically powered model airplanes, or for other purposes, it is often desirable to gang seven to ten rechargeable cells together to provide the desired amount of power. At this time, it is popular to use rechargeable cells of about 1.2 volts each, arranged in groups ranging from about 4 cells to about 12 cells per battery pack. At present, for use in model cars, the use of 6 cells per battery pack is preferred. In small aircraft, the use of 8 to 10 cells per battery pack is presently preferred. 
     In spite of the various schemes which have so far been offered to the marketplace for holding multiple batteries together in a pack, a continuing and growing demand exists for a simple, inexpensive method which can be used to maximize battery output, to preserve and enhance the reliability of the batteries in the pack, and to enhance the service life of batteries between recharge cycles. A particular problem often seen in various prior art battery holders is the presence of spot welded or soldered junctions which are somewhat resistant to electrical conduction, resulting in heating of the junction, sometimes to unacceptably high levels, and in any event needlessly dissipating power. 
     As will be evident to those familiar with model cars, trucks, and aircraft, and to whom this specification is particularly addressed, a battery holder which effectively eliminates the loss of energy in soldered, welded, or other inefficient joints would be of great benefit in increasing the operating life of such types of apparatus, when compared with battery holders which are currently in widespread use. Moreover, a battery pack which increases the output power and/or battery discharge cycle time to the apparatus using the battery pack is always a welcome addition to the model competitor&#39;s arsenal. 
     OBJECTS, ADVANTAGES, AND FEATURES OF THE INVENTION 
     From the foregoing, it will be apparent to the reader that one important and primary object of the present invention resides in the provision of a novel battery pack for ganging together a plurality of cells in a manner that maximizes the efficiency of extracting power from the battery cells in the pack. 
     Another important objective of the invention is to eliminate battery power loss due to resistive heating in spot welds or soldered joints, by providing a battery pack which avoids using such means for forming electrical connections. 
     Yet another object of the invention is to provide a battery pack with a phantom battery cell, to enable a battery pack to provide power output from an uneven number of battery cells. 
     Other important but more specific objects of the invention reside in the provision of novel battery packs which: 
     are highly efficient in supplying electrical power from rechargeable battery cells; 
     can easily withstand repeated opening and closing cycles for replacement of discharged or weak battery cells in the battery pack; 
     are, in one embodiment, available in a configuration that allows the testing and/or recharge of individual battery cells; 
     provide various marking indicia to allow easy verification of the correct individual battery cell orientation, to assist the user in avoiding incorrect polarity during battery cell loading into a battery pack; 
     are preferably configured with non-identical tightening stays to help assure that correct polarity orientation is achieved when securing battery cells in the pack; 
     are easily worked on to achieve quick installation or removal of battery cells. 
     Other important objects, features, and additional advantages of our invention will become apparent to the reader from the foregoing and from the appended claims, and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a front elevation view of a battery pack, with a transparent cell holder sleeve body, end caps, and contacts, shown holding ten battery cells. 
     FIG. 2 is an exploded perspective view of the battery pack just illustrated in FIG. 1, now showing the top and bottom end caps, the cell holder sleeve body, an insulating insert strip running axially in the cell holder sleeve body to separate first and second rows of battery cells, and importantly, a first and a second stay with retaining nuts for securing the battery pack together. 
     FIG. 3 is front elevation view of one embodiment of a transparent cell holder sleeve body portion of the battery pack. 
     FIG. 4 is a plan view of the reference indicia utilized to enable the user to properly orient battery cells in the battery pack; the reference indica are preferably applied externally by affixing a label near the middle of the transparent cell holder sleeve body, normally between the broken lines provided for label location as noted in FIG.  3 . 
     FIG. 5 is a cross-sectional view of the cell holder sleeve body as just illustrated in FIG. 3 above, as taken across section  5 — 5  of FIG.  3 . 
     FIG. 6 is a cross-sectional view of a top end cap of my battery pack, showing the electrical connection to positive terminals of battery cells on one side and to negative terminals of battery cells on the other side. 
     FIG. 7 is a cross-sectional view of a bottom end cap of my battery pack, showing the electrical connector bar used in the bottom end cap to connect a first battery stack with a second battery stack. 
     FIG. 8 is a reflected plan view of the interior of the end cap just illustrated in FIG. 6 above, taken as if looking from line  8 — 8  of FIG.  2 . 
     FIG. 9 is a full size schematic of and electrical lead line and the electrical contacts used, showing the preferred hollow copper contacts and the heavy flexible wire utilized. 
     FIG. 10 is a top plan view of the electrical connector bar used in the bottom end cap to connect the bottom battery in one battery cell holder sleeve with the bottom battery in an second battery cell holder sleeve. 
     FIG. 11 is a side elevation view of the electrical connector bar first illustrated in FIG.  10 . 
     FIG. 12 is a side elevational view, with partial cutaway in the upper left to show, in cross-section, a phantom cell useful for battery pack operation with an odd number of battery cells. 
     FIG. 13 is a top plan view of the phantom cell just illustrated in FIG. 12 above, showing the use of six flutes or ribs as provided in my preferred phantom cell arrangement. 
     FIG. 14 is a side elevation view of the phantom cell illustrated in FIGS. 12 and 13, with the electrical lead line moved downward, now showing the moveable spacer sleeve used to seat the electrical contact below the phantom cell. 
     FIG. 15 is a vertical cross-sectional view, showing a single cell battery holder with electrical lead wires and contacts as taught herein, for manual use in testing battery cells. 
     FIG. 16 is a vertical cross-sectional view, showing the single cell battery holder just illustrated in FIG. 15, but now showing a spacer for use in conjunction with testing smaller size battery cells than optimally fit in the battery holder lengthwise. 
     FIG. 17 is a perspective view of a spacer for use in conjunction with the single cell battery holder first shown in FIG.  16 . 
     FIG. 18 is a top plan view of the spacer first shown in FIGS. 16 and 17. 
     FIG. 19 is a reflected plan view, taken looking upward into the single cell battery holder first shown in FIG. 15 above. 
     FIG. 20 illustrates an electric drive vehicle, here an electrically driven propeller airplane, driven by my novel battery pack. 
    
    
     DESCRIPTION 
     I have now invented, and disclose herein, a novel, improved battery pack for holding battery cells. I have also developed a method for changing battery cells in such battery packs. Importantly, I have developed a method for operating electrically powered vehicles, especially model aircraft and automobiles, with my novel battery packs. 
     As seen in the embodiment depicted in FIG. 1, my battery packs  20  have in the central portion thereof an elongated cell holder sleeve (or body)  22 . This cell holder sleeve  22  is preferably provided in a thin-wall and “see-through” material (e.g., {fraction ( 1 / 32 )}″ thick wall that allows the user to see through the cell holder sleeve  22  to check the polarity orientation of each of the battery cells  24  that are confined and contained by the cell holder sleeve  22 . More specifically, each of typical battery cells  24  has a positive terminal  26  and a negative terminal  28  at opposing ends of an elongate and usually cylindrical body portion  30 , and it is important that the positive and negative terminals in adjacent battery cells be properly oriented to avoid creating an electrical short circuit at any pair of battery cells  24  in the battery pack  20 . 
     As better seen in FIGS. 2 and 5, the cell holding sleeve  22 , when provided in a configuration to hold two columns of battery cells  24 , is generally “figure-eight” in shape, substantially resembling two extended cylinders joined at their circumference and extended along a common axis in a nip-roll type configuration. In this configuration, a pair of side-by-side battery cell sleeve holding tubes  22   a  and  22   b , each adapted for close fitting engagement around and securely holding (at least transversely) a plurality of battery cells  24  in first and second battery cell columns is provided. Ideally, a central dividing insulator strip  32  is provided at gap G (typically about ¼ inch width when provided for sub-C type Ni-Cad batteries) located between the otherwise substantially cylindrical portions of the side-by-side battery cell holding sleeve tubes  22   a  and  22   b . At the first  34  and second  36  ends of the battery cell holder sleeve  22 , a high strength bottom end cap  40  and a top end cap  42  are affixed, respectively. Inside the bottom end cap  40  is placed an elongate copper connector bar  44 , for connecting the lowermost battery cell  24   1(L)  in a first column with the lowermost battery cell  24   2(L)  in a second column. In this manner, the first column of battery cells is a series of longitudinally co-axially oriented battery cells from lowermost cell  24   1(L)  to uppermost cell  24   1(L+N) , where an integer X of quantity N+1 (where N is a an integer equal to or greater than zero and representing the number of cells N above the lowermost cell in the column) equals the number of cells in the first column of battery cells. Similarly, a second column of battery cells is a series of longitudinally co-axially oriented battery cells from lower most cell  24   2(L)  to upper most cell  24   2(L+M) , where an integer Y of quantity M+1 (where M is a an integer equal to or greater than zero and representing the number of cells M above the lowermost cell in the column) equals the number of cells in the second column. Importantly, as further explained in connection with FIGS. 12,  13 , and  14  below, when using my novel battery pack  20  and a phantom cell  50 , the number of battery cells X in a first column does not have to equal the number of battery cells Y in a second column. In other words, an odd number of battery cells can be included in a battery pack to meet the unique needs of a particular service situation. Also, it should be understood that while I have shown and explained my battery pack by use of the most commonly encountered two column configuration for battery cells, it is to be understood that any convenient integral number C of columns, from a single column (where C=1) up to any desired quantity of battery cell columns, could be accomplished by use of the techniques taught and claimed herein, by simply changing the shape of the battery holder sleeve body  22  (and number of tubes provided in the sleeve to match the desired number of columns), the shape of the bottom end cap  40  and of the top end cap  42 , as well as providing a the connector bar  44  in the appropriate electrical contacting configuration. 
     Referring now to FIGS. 1,  2 ,  6 , and  7 , it can be seen that top end cap  42  has an interior end wall portion  53 , an exterior end wall portion  54 , and first and second electrical lead line passageways defined by sidewalls  56  and  58 . The interior wall  60  (, with wall thickness of {fraction ( 3 / 64 )}″) of peripheral wall flange  62  extends outward from interior end wall portion  53  to cover and confiningly contain, at least that portion of the outer sidewall S of battery cell holder sleeve  22  which is adjacent first end  34  of the battery holder sleeve  22 . Similarly, bottom end cap  40  has an interior end wall portion  63 , an exterior end wall portion  64 , and, for minimization of parts requirements, may further include unused first and second electrical lead line passageways defined by sidewalls  66  and  68 . In the bottom end cap  40 , the interior wall  70  of peripheral wall flange  72  extends outward from interior end wall portion  63  to cover and confiningly contain at least that portion of the outer sidewall S of battery cell holder sleeve  22  which is adjacent the second end  36  of the battery holder sleeve  22 . In other words, to minimize costs, the top  42  and bottom  40  end caps may be molded identically, and then a connector bar  44  may be added to be bottom end cap  40 , in connector bar receiving indentation  45 . Connector bar  44  has a centrally located pocket or land portion  47  sized and shaped complementary to the indentation  45 , for secure engagement of the connector bar  45  in its operating location. Usually, I prefer a thin connector bar  44 , such as about {fraction (1/32)}″ in thickness. 
     To help the user assure that polarity of batteries is correctly maintained, the battery pack  20  preferably uses a first stay-bolt  80  and a second stay-bolt  82  which are not interchangeable, i.e., they are of different in configuration, so that they are not reversible. To assure this arrangement is achieved, one ideal configuration is to use stay-bolts of different diameter. I prefer to use a first stay-bolt  80  of “all-thread” configuration in a rather small diameter, such as a 4-40 size, and a different small diameter “all-thread” second stay-bolt  82 , preferably in the 2-56 size. Each of first  80  and second  82  stay-bolts are provided in a length A and A′ respectively which is suitable to accommodate the length B of the battery cell sleeve  22  used to contain battery cell columns of a pre-selected size (i.e., desired number of cells). Sometimes, it may be desirable that one of the nuts on each stay-bolt, normally the bottom nut  84  on the first stay-bolt  80 , and the bottom nut  86  on the second stay-bolt  82 , can be permanently secured, to their respective stay-bolts, to simplify removal and reattachment of the stay-bolts. 
     As can be seen from comparing FIGS. 1 and 2, all of an even number of battery cells in the battery pack  20  are securely compressed for tight fitting engagement of their respective positive and negative terminals, in a properly configured polarity fashion, by: 
     (a) inserting a first column of X battery cells  24  in a battery cell holder sleeve  22   a , carefully and properly aligning the polarity to avoid a short circuit; 
     (b) inserting a second column of Y battery cells in a battery cell holder sleeve  22   b , carefully and properly aligning the polarity to avoid a short circuit; 
     (c) inserting the insulator strip  32  between columns of cells, in order to prevent adjacent columns of battery cells from touching each other and possibly rubbing off insulation on the cells; 
     (d) inserting the first stay-bolt  80  through the first stay passage  90 , defined by sidewall  92  in bottom end cap  40 , 
     (e) inserting second stay-bolt  82  through the second stay passage  94 , defined by sidewall  96  in bottom end cap  40 ; 
     (f) inserting battery cell holder sleeve  22 , containing sleeve tubes  22   a  and  22   b  into a confined relationship with interior  70  of the peripheral flanged wall  72  of the bottom end cap  40 , carefully observing the polarity markings “−” and “+” on the bottom end cap  40 , and insuring that such polarity markings “−” and “+” agree with the orientation of the battery cells in the cell holder sleeves  22   a  and  22   b ; 
     (g) running first and second stay-bolts longitudinally along the main axis of battery cell holder sleeves  22   a  and  22   b , preferably adjacent but outside the outer surface S of the battery cell holder sleeves  22   a  and  22   b ; 
     (h) inserting the first stay-bolt  80  through the first stay passage  110  defined by sidewall  112  in top end cap  42 , carefully observing the polarity markings on the top end cap  42 , and insuring that such polarity markings agree with the orientation of the battery cells in the cell holder sleeves  22   a  and  22   b , and that each of the first stay-bolt and second stay-bolt is inserted into the stay passageway of proper size; 
     (i) inserting the second stay-bolt  82  through the second stay passage  114 , defined by sidewall  116  in top end cap  42 ; 
     (j) affixing top nut  120  to first stay-bolt and initially tightening the nut  120  finger tight; 
     (k) affixing top nut  122  to second stay-bolt  82  and initially tightening the nut  122  finger tight; 
     (1) tightening both top nut  120  and  122  in a balanced fashion to bring substantially uniform pressure to both the first stay-bolt side and the second staybolt side of both the top end cap  42  and the bottom end cap  40 , so as to evenly and firmly apply compressive force on a cell-to-cell basis, and from the uppermost cell  24   1(L+N)  in the first column, and the upper most cell  24   2(L+M)  in the second column, to the respective positive electrical lead line contactor and negative electrical lead line contactor. 
     After the battery pack has been prepared, connectors K +  and K −  are used to connect the positive and negative lead lines (discussed below) to the apparatus being driven. 
     In FIG. 5, a cross-sectional view of the cell holder sleeve body  22  is shown, further illustrating the provision of multiple columns for sets of battery cells, while providing a thin-wall battery cell holder sleeve  22 . As noted in FIG. 4, to assist the user in keeping polarity of batteries correct, I have found it useful to provide a label  95  with reference indicia  97  and  99  thereon (as well as “−” and “+” terminal markings) so that both end caps and the batteries can be properly assembled into a finished battery pack  20 . The reference indica are preferably applied externally by affixing the label  95  near the middle of the transparent cell holder sleeve body  22 , normally between the broken lines  101  and  103  provided for label location as noted in FIG.  3 . 
     Battery cells  24  must be properly prepared prior to inserting the same into the battery cell holding sleeves  22  of my Solderless Power Tube (tm) battery pack  20 . For example, Sanyo brand 2000 mah, Sub-C cells have two shrink wrappings, and the top layer must be removed in order that the positive and negative parts of the cells can touch each other when such cells are stacked into a column. For removing the top layer, the Sanyo brand cell should be held with the bottom or negative side up, and the top layer is slit and peeled from the cell. However, care must be taken to prevent damage to the second or bottom shrink wrap layer, as it is the only protection against a short circuit. On the other hand, Panasonic brand 1700 mah cells have only one shrink wrap layer, and require no preparation. After the wrapping is properly configured, then I recommend that the terminals on each battery cell be properly cleaned by rubbing both the positive and the negative terminals of each cell with “Scotch-Brite” (tm) brand scouring pads, made by 3-M Corporation of Minneapolis, Minn. Steel wool should not be used, as it may have deleterious effects, including the creation of short circuits. Also, if damaged insulation is found on any cells, it must be repaired before the cell is placed into the battery pack  20 . 
     The Solderless Power Tube (tm) battery pack  20  allows high current flow, because the unique design provides the smallest possible number of connections, and the connections present are designed to carry high current with the smallest possible resistance. The battery cells  24  touch each other, under compression, in series in columns, with absolutely nothing in between adjacent cells in the same column. Also, the cross-over connection bar  44  between columns is preferably made of silver plated copper, and is designed to carry a high current load. The positive electrical contact  130  (affixed to the positive electrical lead  132 ) and the negative electrical contact  134  (affixed to the negative electrical lead  136 ) of the battery pack  20  are preferably made of copper, also. Also, the positive and negative lead lines  132  and  136 , respectively, are preferably provided in  14  gauge insulated copper wire, over which a hollow cylindrical portion  140  and  142  of the positive  130  and negative contacts  134  are crimped. Further, a “wave washer” W is provided between each of the positive and negative contacts and the interior wall  53  of the top end cap  42 , to keep the copper positive  130  and negative  132  contacts flat on their respective positive and negative contacts on cells  24   1(L+N)  and  24   2 (L+M) , to assure that the most efficient electrical connection possible is attained. 
     As described, the opposing top and bottom end caps and the thin walled battery cell sleeve are secured together in a single battery pack  20  assembly, with batteries within the cell holding sleeve body  20 . Compression and security of the package is achieved by use of adjustably tightenable fasteners, preferably in the form of stays, such as the all thread bolts above described. Also, it is important to emphasize that ideally the all-thread bolts are each of different size, to aid in keeping the polarity of the batteries correct. As noted above, I prefer to use a 4-40 all-thread bolt on one side, and a 2-56 all thread bolt on the other side. Nuts of appropriate size are provided on either end of the all thread bolts, above the upper end and below the lower end, respectively, of the top and bottom end caps. The nuts are tightened until the cells in the pack are adequately compressed together and against the contacts provided. As described, no solder joints are used, and the battery power is efficiently provided to the apparatus using the battery pack. 
     For model cars, it is common to utilize six (6) cells in a battery pack. For model aircraft, it is more common to utilize ten (10) or twelve (12) cells. In the later case, amperage may range from ten (10) to eighty (80), depending upon the amount of instantaneous work being done by the electric motor. 
     When using Ni-Cad type batteries, it is common to have a requirement to test individual cells. This is easily accomplished with my single cell unit  200  shown in FIGS. 15,  16 , and  19 . In such units, and upper housing  201  and a lower housing  202  are shaped for complementary close fitting mating engagement, with a male flange  204  fitting inside the lip  206  in the upper housing  201 , and slipping inside the upper housing  200  in close fitting fashion until stop  210  is encountered. When using cylindrical batteries, the upper  201  and lower  202  housings are shaped in complementary cylindrical fashion. 
     Sometimes, testing of short batteries is desired, and in such cases, a spacer  220  is required, as depicted in FIGS. 16,  17 , and  18 . Ideally, spacer  200  is configured as a cylindrical disc of any desired diameter D and thickness T, and with an elongated slot  224  for passage of positive or negative leads therethrough, as defined by substantially rectangular type sidewalls  226 . 
     After testing Ni-Cad batteries, it is sometimes found that it is desirable to place an odd number of batteries in a battery pack  20 . In such cases, a phantom cell  50  as shown in FIGS. 12,  13 , and  14  can be utilized. Ideally, the phantom cell approximates in size one of the cells being removed from the battery pack  20 . For heat dissipation, I prefer the use of a fluted design, having multiple flutes F spaced about a central passageway P that allows an extended length lead line  136 ′, for example, to pass therethrough. For increased cooling, a base  300  can be provided to space the phantom cell  50  upward from the battery on which it sets. Also, tubular flanged bushing  302  can be provided for locating electrical contacts, such as contacts  132 ′, below the phantom cell. 
     It is to be appreciated that the novel battery pack provided by the present invention is a significant improvement in the state of the art of battery packs for use in model aircraft and autos. My novel battery pack, and the method of employing the same in operation of model aircraft and the like, is relatively simple, and it substantially improves the cost effectiveness of the battery operations in apparatus which utilize the same. It will be readily apparent to the reader that my novel, recyclable battery pack device and the method of using the same may be easily adapted to other embodiments incorporating the concepts taught herein. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the embodiments presented herein are to be considered in all respects as illustrative and not restrictive. All changes and devices which are described within the meaning and range of equivalents of the claims set forth herein are therefore intended to be embraced therein.