Abstract:
A battery pack may supply power to a device such as a PDA, a hand-held scanner, or a laptop computer, when inserted and rotatably locked therein. The battery pack is adapted to maintain electrical connectivity with the device, once unlocked, during counter-rotation and before removal. Electrical connectivity is provided by discrete electrical contact pads on the battery pack, each of which may form various annular shapes at different radii. The electrical contact pads are detected by spring-loaded pogo pins on the device. Electrical connectivity is maintained for a battery detect pin for only approximately fifteen degrees of counter-rotation, where its disengagement warns of impending power loss, and triggers a proper shut-down sequence to save data. One contact pad is electrically coupled to a negative terminal within the battery pack, and another is electrically coupled to a positive terminal. The battery pack houses one or more rechargeable batteries, preferably lithium-ion.

Description:
[0001]    This application claims priority on U.S. Provisional Application Ser. No. 61/203,539 filed on Dec. 22, 2008, the disclosures of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to improvements in batteries, and more particularly to batteries which are capable of providing a warning to provide adequate shut-down time of an electronic device&#39;s operating system. 
       BACKGROUND OF THE INVENTION 
       [0003]    An electrical battery generally consists of one or more electrochemical cells that provide for the conversion of stored chemical energy into electrical energy. Electrical batteries have taken many different forms since the first voltaic pile was invented and used by Alessandro Volta in 1800, and today they are utilized to power both household items and industrial equipment. Batteries range in size from the small cells used in hearing aids, watches, and even newer miniature batteries for medical implantation to treat neurological disorders, to large battery packs for hybrid cars. A hybrid car battery today may comprise up to 28 nickel metal hydride modules connected in series to produce a nominal voltage exceeding 200 volts. 
         [0004]    Batteries had for many years been designed for one-time use, only to be discarded after they were unable to support continuous functioning of the unit. Early rechargeable batteries were not very robust, as they suffered from memory effect where, in nickel cadmium batteries, repeated recharging would reduce the batteries ability to be recharged to its maximum energy capacity. But today&#39;s lithium-ion cells may be recharged multiple times and last for years, which is particularly useful for units whose operations normally require standby power, such as for cell phones, personal digital assistants (PDAs), hand-held scanners, and laptop computers. 
         [0005]    Due to the power requirements involved in wireless communications, and particularly for mobile computing, a battery pack is often utilized, where the battery pack interconnects the electrical conductivity between any number of batteries, which are preferably identical. Many units will have a custom-designed battery and battery compartment. An example of this is shown by U.S. Pat. No. 6,421,233 to Hong for “Pocket Personal Computer with Improved Battery Compartment Enclosing Structure.” Some units will merely be designed to accept ordinary rechargeable batteries, such as the “Dual Orientation Display Handheld Computer Devices” in U.S. Pat. No. 5,949,408 to Kang. The detailed disclosure in the Kang patent merely states, as to battery power and battery configuration, that “A main battery receiving area is provided by a chamber defined by a portion the hinge mechanism  25  to receive a pair of replaceable batteries” and that “A back-up battery is held by a tray  29  which is slidably received inside a chamber defined by the clamshell lid  22 .” 
         [0006]    However, none of the battery pack and battery compartment designs have thus far addressed a concern of many users and manager&#39;s of those users, which is that removal of the battery out of a unit with a Microsoft operating system, particularly Windows mobile, doesn&#39;t give the operating system enough time to shut down in an “orderly” fashion. Although axial connectors may be spring loaded in compression to provide a longer contact period, such as that shown by U.S. Pat. No. 7,626,357 to Hoffman, they insufficient to adequately address the problem. 
         [0007]    This invention solves the problem of insufficient system shut-down time during intentional or inadvertent battery disconnection, by provides a means of giving the device enough of warning about impending shut down to close down, so as to save data and keep the unit stable for when it is turned back on. The invention disclosed herein also addresses the need for an easily removable battery pack that nonetheless remains securely attached to the product after accidental dropping, and which also resists inadvertent removal and electrical disconnection. 
       OBJECTS OF THE INVENTION 
       [0008]    It is an object of the invention to provide a battery pack which is capable of powering a device such as a PDA, a hand-held scanner, or a lap-top computer. 
         [0009]    It is another object of the invention to provide a battery pack having electrical connections and circuits grouped to one end of the battery pack. 
         [0010]    It is a further object of the invention to provide a battery pack which is received within a device to engage electrically once inserted, and throughout relative rotation. 
         [0011]    It is another object of the invention to provide a battery pack with electrical connections that provide a warning to the device of impending battery removal and power loss to permit shutdown. 
         [0012]    It is also an object of the invention to provide a rotatable battery pack installation with a quick-release catch that provides feedback to the user of positive locking. 
         [0013]    It is another object of the invention to provide a battery pack with which resists unintentional removal following impact after being accidental dropped. 
       SUMMARY OF THE INVENTION 
       [0014]    A battery pack may supply power to a device such as a PDA, a hand-held scanner, or a laptop computer, when inserted and rotatably locked therein. Rotational movement is advantageous in providing the capability of warning of impending battery power loss, and thus favors a cylindrical battery housing or body. The battery pack is adapted to maintain electrical connectivity with the device, once unlocked, during counter-rotation and before removal. 
         [0015]    Electrical connectivity is provided by discrete electrical contact pads on one end of the cylindrical battery pack, each of which may form various annular shapes at different radii. Two of the electrical contact pads may serve as the positive and negative terminal respectively, and thus may be desirably located far apart. These pads may thus be the annular pad at the outer extreme of the circular end cap of the battery pack, and one annular pad at the center of the circular end cap, which is preferably an annulus with a radius of zero to form a solid filled circular contact pad. The contact pads may be insert-molded into the end cap, and may be gold-plated stainless steel. A second and third annular contact pad may each be connected to a thermistor for temperature measurements, and to a fuel gauge, where each may have electrical components mounted to a printed circuit board, which may be electrically coupled to the contact pads using soldering legs. 
         [0016]    The battery pack preferably holds two or more rechargeable batteries, which may be lithium-ion. The two batteries may be connected in series via spot-welded sheet metal connectors. One end of the battery assembly may be directly coupled to either the printed circuit board or the appropriate electrical contact pad, and the other end of the battery assembly may be electrically coupled using a flexible printed circuit board. 
         [0017]    The electrical contact pads are detected by spring-loaded pogo pins on the device. Electrical connectivity is maintained by a battery detect pin engaging a contact pad comprising a small annulus-segment, for only approximately fifteen degrees of counter-rotation, where its disengagement warns of impending power loss, and triggers a proper shut-down sequence to save data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of the battery pack of the current invention. 
           [0019]      FIG. 2  is a front view of the battery pack of the current invention. 
           [0020]      FIG. 3  is a side view of the battery pack of the current invention. 
           [0021]      FIG. 4  is a bottom view of the battery pack of the current invention. 
           [0022]      FIG. 5  is a cross-sectional view of the battery pack of the current invention. 
           [0023]      FIG. 6  is an enlarged cross-sectional view of the battery pack of the current invention. 
           [0024]      FIG. 6A  is an enlarged bottom view of the second end cap of the battery pack of the current invention. 
           [0025]      FIG. 6B  is an enlarged bottom view of the battery pack of the current invention. 
           [0026]      FIG. 7  is a perspective view of a gun-shaped mobile computer to be illustrative of the types of devices which may receive the battery pack of the current invention. 
           [0027]      FIG. 8  is a view of the pogo-pins and support, as utilized in the device of  FIG. 7 . 
           [0028]      FIG. 8A  is a top view of the pogo-pin arrangement of  FIG. 8 . 
           [0029]      FIG. 8B  is a side view of the pogo-pin arrangement of  FIG. 8 . 
           [0030]      FIG. 9  is an upward looking perspective view of the battery pack of the current invention, as installed and locked in the device of  FIG. 8 . 
           [0031]      FIG. 10  is a perspective view of the battery pack of the current invention, shown in the rotated position, and locked by the catch of the device of  FIG. 8 . 
           [0032]      FIG. 11  is a side view of the battery pack of the current invention engaging corresponding pogo-pins of the device. 
           [0033]      FIG. 12  is an enlarged side view of the battery pack of the current invention engaging corresponding pogo-pins of the device. 
           [0034]      FIG. 13  is a view of the contact pads on the bottom of the battery pack of the current invention. 
           [0035]      FIG. 14  is a perspective view of the battery pack of the current invention engaging corresponding pogo-pins of the device. 
           [0036]      FIG. 14A  is an enlarged view of the contact pads on the bottom of the battery pack of the current invention. 
           [0037]      FIG. 14B  is an enlarged view of an alternate embodiment of the contact pads on the bottom of the battery pack of the current invention. 
           [0038]      FIG. 15  is a reverse perspective view of the battery pack of the current invention engaging corresponding pogo-pins of the device. 
           [0039]      FIG. 16  is an exploded view of the parts comprising the battery pack of the current invention. 
           [0040]      FIG. 17  is an exploded view of the end cap, circular printed circuit board, and body of the battery pack of the current invention. 
           [0041]      FIG. 18  is a reverse exploded view of the end cap, circular printed circuit board, and body of the battery pack of the current invention. 
           [0042]      FIG. 19  is an exploded view of the parts comprising the battery opening of the device of  FIG. 7 . 
           [0043]      FIG. 20  is a perspective view of the opening into the battery compartment of the device of  FIG. 7 . 
           [0044]      FIG. 21  is a perspective view showing insertion of the battery pack of the current invention being inserted into the device of  FIG. 7 . 
           [0045]      FIG. 22  is a reverse perspective view showing insertion of the battery pack of the current invention being inserted into the device of  FIG. 7 . 
           [0046]      FIG. 23  is a perspective view of the battery completely inserted into the battery compartment of the device of  FIG. 7 . 
           [0047]      FIG. 24  is a perspective view of the battery rotated into the locked position. 
           [0048]      FIG. 25  is a perspective view showing the electrical contacts of the battery pack of the current invention and the corresponding spring-loaded pogo-pins of a battery charger. 
           [0049]      FIG. 26  is a perspective view of the battery pack of the current invention being recharged by a battery charger. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0050]      FIG. 1  shows a perspective view of a first embodiment of the battery pack  10  of the present invention. The battery pack is designed to preferably retain 2 or more rechargeable batteries. Since technological advances occur frequently in the area of electrochemistry, it must be emphasized that the battery pack of the present invention need not be limited to a particular type or size of battery or batteries. But currently, lithium-ion batteries demonstrate the most favorable battery chemistry for several reasons, including the fact that they do not suffer from memory effect. One of the most economical lithium-ion batteries, based upon a cost-to-energy ratio, is the 18650 battery. The 18650 lithium-ion battery is cylindrical in shape, having a diameter of 18 mm (0.7 inches) and a length of 65 mm (2.6 inches), and may have a nominal voltage of 3.7 volts 
         [0051]    Although the 18650 battery is favored for use in mobile computing and other electronic applications, it must be emphasized that the battery pack of the present invention is not limited to having a circular body or casing to encompass the battery. In fact, regardless of whether the battery is cylindrical or not, the body may be formed to have, for example, an octagonal cross-section, or even a square or other cross-section. Also, regardless of the particular cross-sectional shape utilized, it should be noted that it would likely be formed to be symmetric about an axis, to leverage as much as possible, the rotational capabilities offered herein. However, even where a battery pack body is formed by a square, octagonal, or other cross-section, it could nonetheless be formed to be eccentric to the rotational axis that is discussed hereinafter. But such an arrangement would naturally impact the envelope and support required, when housing internally within a computing device, which furthermore need not be the only application for the invention. 
         [0052]    Since a cylindrically-shaped casing may be preferable to support use of the cylindrical lithium-ion 18650 battery, the following discussions will focus on use of one embodiment having a cylindrical tube for a casing, notwithstanding the other possible forms available for use with the invention. 
         [0053]    As seen in  FIGS. 2-6 , the battery pack assembly  10  may have a hollow tubular body  15  symmetrically formed about axis  201 , and which has a first end  16  and a second end  17  ( FIG. 2 ), as well as an inside surface  18  and an outside surface  19  ( FIG. 5 ). The body  15  and many of the other parts of the battery pack assembly  10  may preferably be formed of molded plastic, but are not limited solely to such material. Protruding radially outward from the outside surface  19  of the body  15  may be one or more flanges, and in a preferred embodiment, there may be a first flange  21  and a second flange  24 , having a width W 21  and W 24  respectively ( FIG. 6B ) First flange  21  and second flange  24  are preferably clocked to be on opposite sides of tube  15 , and are both also located near the first end  16  of the tube. The proximity of first and second flanges  21  and  24  to the first tube end  16  will be determined from the length of the tube  15 , and its retention in a tubular opening in a device, which may have corresponding flanges (not shown) to assure appropriate electrical connectivity between the battery pack contacts and those of the device. The battery pack assembly  10  may preferably have electrical contact pads, as discussed hereinafter, disposed on one end of tubular body  15 . 
         [0054]    The first and second flanges  21  and  24  may preferable each have respective tapered surfaces  22  and  25 , which terminate on respective engagement surfaces  24  and  26 . The engagement surfaces  24  and  26  may engage the corresponding flanges in the device, as follows. The battery pack assembly  10  may be inserted into a cylindrical opening in a device ( FIG. 20-23 ), after which rotation of the battery pack assembly  10 , with motion of flanges  21  and  24  relative to the corresponding flanges in the device, would result in the tapered surfaces  23  and  25  driving the battery pack further into the opening and oppose any spring biasing therein to firmly seat the battery pack assembly  10  ( FIG. 24 ). The battery pack assembly may be firmly located within the opening, once the respective engagement surfaces  24  and  26  of the battery pack assembly  10  contact the corresponding flanges in the device. 
         [0055]    The battery pack may also include an O-ring seal  70  to prevent fluid from entering the tubular opening of the device and corrupting the electrical contact between the battery pack assembly  10  and the device. A gun-shaped mobile computing device  100  is shown in  FIG. 7  merely to be illustrative, in later discussions, of the installation features of the present invention. The battery pack of the current invention may be used in a conventional laptop, a PDA, or other mobile computing and telecommunication products. 
         [0056]    The battery pack assembly  10  may further comprise a first end cap  27  and a second end cap  30 , to respectively enclose the first and second ends  16  and  17  of body  15 . Either or both of the end caps  27  and  30  may be integrally formed with the body  15 , or may be separately formed and configured, along with body  15 , to be removable through use of mechanical features, including, but not limited to, use of internal and external threading on the respective parts. In  FIG. 5 , it may be seen that first end cap  27  is formed as part of body  15  and only partially encloses the first end  16  of body  15 , but still serves to properly retain the batteries  50  and  51  within the body  15 . 
         [0057]    The second end cap  30  may incorporate a subassembly of parts, and therefore may be more conducive to being formed as a separate part. In one embodiment, the end cap  30  is formed and has those parts installed therein, after which it is attached to the second end  17  of body  15 . Where the battery pack assembly  10  is not expected to provide access for replacement of the batteries, should they eventually degrade in performance, meaning the entire battery pack assembly  10  would be replaceable, the second end cap  30  may be permanently affixed to body  15  using any suitable means, including, but not limited to, ultrasonic welding. 
         [0058]    The second end cap  30  may have an outside surface  36  and an inside surface  37 . The outside surface  36  is clearly shown in the bottom view of the battery pack assembly  10  in  FIG. 4 , and may comprise a plurality of discrete electrical contact pads. The pads may be insert-molded into a plurality of shallow recesses ( FIG. 16 ) in the outside surface  36  of second end cap  30 , and may be formed of a appropriate electrically conductive materials, including, but not limited to gold-plated stainless steel. The number of contact pads may be determined from the electrical functionality that may be desirably incorporated into the battery pack assembly  10 . In a preferred embodiment there may be five distinct electrical contact pads, pads  31 ,  32 ,  33 ,  34 , and  35 , each of which may have a uniquely formed shape. 
         [0059]    The contact pads  31 - 35  may be electrically coupled to a circular printed circuit board (PCB)  40  located within the second end cap  30  using soldering legs  41 . The printed circuit board  40  may connect, using a flexible printed circuit  45 , to a second printed circuit board  42 , which may contain the components for a fuel gauge; and a thermistor for temperature sensing. Battery terminals  52  and  53  may provide electrical coupling between batteries  50  and  51 , and the printed circuit board  42 . 
         [0060]    To take advantage of the rotational capabilities offered by the invention herein, each of the electrical contact pads  31 - 35  may be formed into a full annulus or an annulus-segment. An annulus, simply described without use of a formula, is a circular area that has a smaller concentric circular area removed from within, to leave a ring-shape, which in geometric or mathematical terms, is referred to as an annulus. The formula for the area of an annulus mathematically depicts the literal description, being that the area, A=Π (R 2 -r 2 ), where “R” is the outside radius of the outer periphery of the annulus, and “r” is the inside radius of the inner periphery of the annulus. In the present invention, each of the five electrical contact pads may be a distinct annulus or annulus segment, with each having a respective beginning radius location for the inner periphery, and respective outer radius location for the outer periphery. 
         [0061]    In a first embodiment, the electrical contact pads  31 - 35  may be formed as shown in  FIG. 6A , where contact pad  31  is a full annulus having an outer radius, R 31  and an inner radius r 31 . For the embodiment illustrated, contact pad  32  is a full circle, having an outer radius R 32  and an inner radius r 35 , where r 35  equals zero. In this first embodiment, electrical contact pads  31  and  32  may be used for electrical power connectivity, serving as the negative and positive terminals respectively, and are thus herein desirably located far apart. These contact pads  31  and  32  may also be utilized when the battery pack is inserted into recharging unit to recharge the lithium-ion batteries  50  and  51 . With the use of those shapes (full annulus and solid circle) for power transmission, there may always be power supplied to the device  100  while the battery pack is undergoing rotation. The power connection will only cease when the battery pack assembly  10  is removed from the device, and furthermore, with the use of spring-loaded pogo-pins within the device, as will be discussed later, the contact will not even be immediately be broken at the start of withdrawal of the battery pack assembly  10 . 
         [0062]    In the first embodiment, the electrical contact pad  33  may also be formed to be a full annulus, having an outer radius, R 33  and an inner radius r 33 , where the pad  33  may provide connectivity to a thermistor, which serves as a temperature sensor. The electrical contact pad  34  may be formed to be a full annulus, but depending on the size of the batteries utilized, which affects the radius of the body  15 , and depending on the optimum width of the annulus, shown by (R-r), there may not be sufficient surface area on the bottom of the second end cap  30  for a full annulus, and a part-annulus may be utilized, wherein two part-annuli at approximately the same radial location may be utilized for different functionality. 
         [0063]    Therefore, in the first embodiment, contact pad  34  may be a part annulus having an outer radius R 34  and an inner radius r 34 , with ends that are terminated at a clocking angle or position, θ, about the axis  201  relative to a datum  202 , so that the annulus pad  34  may begin at θ 34b  and end at θ 34e . As shown in  FIG. 6A , electrical contact pad  34  may be roughly one-third of an annulus. Lastly, electrical contact pad  35 , in the first embodiment, may also be formed to be a part-annulus having the same radial dimensions as pad  34  (R 35 =R 34 , and r 35 =r 34 ), but having different beginning and end clocking positions of θ 35b  and θ 35e . The contact pad  35  may serve to provide battery detection to the device. 
         [0064]    As shown in  FIG. 6B , the engagement surfaces  23  and  26  of flanges  21  and  24  may also preferably need to be approximately clocked to correspond relatively with the orientation of datum  202 , which represents the locked position of the battery pack assembly  10 , and therefore assures a proper connection between the device  100  and the electrical contact pads  31 - 35 . The flanges  21  and  24  may have radial clocking positions for its beginning and end, or alternatively, they may be defined to have respective widths W 21  and W 24 , which may be symmetrically located about the datum  202 . 
         [0065]    Similarly, the battery pack assembly  10  may have a lever  60  with a pair of graspable recesses  61 , and be located atop of first end cap  27 . The lever  60  may also have a nose  62 , and a top surface  64 . The entire lever  60  or just top surface  64  may be formed of a shock-resistant material, including, but not limited to, rubber, to improve the durability of the battery pack assembly  10  in resisting damage to itself, as well as damage to the computing device  100  as a result of impact loading from being accidentally dropped. The lever  60  may be over-molded onto the first end cap  27 . First end cap  27  may simply be a circular-shaped, or it may, as in  FIG. 16 , extend outward to provide support for the rubber lever  60 . The lever  60  may also have a nose engagement surface  63 , which may preferably require the lever  60  to also be clocked with respect to the datum  202  at an angle θ 60 , to assure proper engagement of flanges  21  and  24  with the corresponding flanges in the device, when the catch  101  engages the lever  60  of the battery pack assembly  10 . As may be seen from the Figures and the following discussion, the lever  60  may alternatively have both ends formed into a nose  62  (not shown), so that the battery pack may have two possible installation orientations being 180 degree apart. 
         [0066]    Therefore, this coordinated orientation may preferably also exist with respect to the spring loaded mechanical catch  101  ( FIGS. 7 ,  9 - 10 ), and at least some of the pogo-pins within the device. When the battery pack assembly  10  is inserted into the device  100 , and is being rotated, which may provide proper engagement of the flanges  21  and  24  with the corresponding flanges on the device, the mechanical catch  101  may be depressed to allow the nose to pass over the catch, after which the catch  101  would spring back to its extended position, and the vertical retention surface  103  of the catch  100  would serve to prevent unintentional counter-rotation of battery pack assembly  10 . In addition, the spring loaded mechanical catch  100  may have a sloping engagement surface  102 , which, when contacted by the nose engagement surface  63  of the lever  60 , would be automatically deflected downward—not requiring manual deflection—and would pop up or “click” back into its extended position after the lever has finished rotating into the final locked position. Additionally, the flanges  21  and  24  and the corresponding flanges on the device may have protrusions (not shown) to serve as a stop, and prevent over-rotation of the battery pack assembly  10  during its installation to assure proper engagement of the electrical contact pads  31 - 35 . 
         [0067]    The nature of the electrical connections described herein form an essential part of the current invention. As shown in FIGS.  7  and  8 A- 8 B, the device that seeks to properly utilize the battery pack assembly  10  of the current invention may preferably have a battery compartment (not shown) with a plurality of spring-loaded pogo-pins arranged therein. There are a number of different arrangements which may work successfully, as will be elaborated on later, but in a preferred arrangement in  FIG. 8 , there may be a base plate  108  to which is attached a pogo-pin support  109 . Pogo-pin support  109  may preferably house a plurality of spring loaded pogo-pins  111 - 118 . The pogo-pins  111 - 118  may preferably be arranged in a line.  FIGS. 11-13  show the battery pack assembly  10  contacting and depressing the spring-loaded pogo-pins  111 - 118 , and the perspective views in  FIGS. 14 and 15  illustrate the advantageous nature of the battery pack assembly  10  of the current invention. 
         [0068]    In  FIG. 14 , pogo-pin  117  is in contact with electrical contact pad  35  to provide battery sensing, which is integral to a proper shut-down. The annulus-segment comprising the electrical contact pad  35  may be small, but only need sweep out a smaller annulus-segment than the contact pads  31  and  32  which are supplying power to the device. Since contact pads  31  and  32  each comprise a full annulus, contact pad may theoretically be an annulus-segment of any sweep being less than 360 degrees. In practice, disengagement of the battery detect pin from the fifth contact pad  35  preferably occurs for counter-rotation of the battery pack relative to the pogo-pin of the device in the range of approximately 2 degrees to 40 degrees. Disengagement more preferably occurs for counter-rotation in the range of approximately 5 degrees to 30 degrees, and most preferably occurs for counter-rotation in the range of approximately 10 degrees to 20 degrees. However, in a preferred embodiment, electrical contact pad  35  may provide contact with the pogo-pin  117  for approximately 15 degrees of battery pack assembly  10  counter-rotation (for removal) before disconnecting. 
         [0069]    While the pogo-pin  117  contacts the pad  35 , the device  100  senses the presence of the battery. Once counter-rotation has caused pogo-pin  117  to no longer contact the pad  35 , the system may acknowledge the impending loss of power, and begin a proper shut-down sequence to save data before power is completely lost. Utilizing annulus-segments that permit substantially greater than fifteen degrees of rotation before disconnection, for the positive and negative terminals (contact pads  31  and  32 ), allows time for the device  100  to remain supplied with power to complete the shutdown. Utilizing a full annulus for the positive and negative terminals simplifies the design and allows the battery to be inserted into the device in one of two different orientations, those being 180 degrees apart. 
         [0070]    As seen in  FIG. 14 , pogo-pins  111  and  118  are both in contact with the electrical contact pad  31  (the negative terminal), which provides redundancy, and therefore a more robust design, so that where there may be skewing of the battery pack assembly  10  relative to the device  100  ( FIG. 15 ), due to misalignment from loose manufacturing tolerances, or manufacturing defects, or other reasons, at least one of the pogo pins will still contact the pad  31 . The same arrangement may be provided with respect to the electrical contact pad  32  (the positive terminal), whereby it may have two pogo-pins-pins  111  and  118 —both in contact with the solid circular electrical contact pad  32 . The same may also be true of electrical contact pad  33 , which is coupled with the thermistor, so that there is redundant pin contact with pogo-pins  113  and  116 . Lastly, the contact pad  34  may be an annulus-segment of a certain length and be located 180 degrees opposite to the battery detection, and therein contact pogo-pin  112 . Alternatively, if a non-linear arrangement of pogo-pins is utilized, two contact pads  34 A may be utilized in two separate radial positions, and be disposed approximately 90 degrees relative to the battery detection contact pad  35 A, which itself may be redundantly positioned 180 degrees about datum  202  ( FIG. 14B ). 
         [0071]    The examples and descriptions provided merely illustrate a preferred embodiment of the present invention. Those skilled in the art and having the benefit of the present disclosure will appreciate that further embodiments may be implemented with various changes within the scope of the present invention. Other modifications, substitutions, omissions and changes may be made in the design, size, materials used or proportions, operating conditions, assembly sequence, or arrangement or positioning of elements and members of the preferred embodiment without departing from the spirit of this invention.