Abstract:
A family of cordless electric tools and devices is adapted to use one or more identical rechargeable battery packs and each pack is adapted to interchangeably fit into a pocket or any one of a plurality of pockets in the tool or device in which the pack is employed. The battery pack is positively but releasably retained in the respective pocket of the tool or device with which it is used. A pair of standard AC prongs extend from a flat sidewall of the battery pack which is of a relatively flat, rectangular box-like shape. The prongs are adapted for insertion into a standard AC receptacle for charging the battery pack through rectifier means contained in the pack thus eliminating the need for a separate charger. When the battery pack is positioned in the respective pocket of the tool or device, a mechanical switch is actuated by mating formations on the pack and pocket and connects the battery pack in a discharge mode so that the particular tool or device can be powered from the pack battery through the same set of AC prongs. Heavy duty tools or devices are provided with multiple pockets for the reception of a corresponding number of identical battery packs. Cordless hedge and shrub trimmers, grass shears, sprayers, screwdrivers and lanterns exemplify tools and devices suited to the invention.

Description:
BACKGROUND OF THE INVENTION 
     The availability of rechargeable batteries has led to a variety of rechargeable battery-operated &#34;cordless&#34; devices including grass shears, hedge trimmers, toothbrushes, shrub trimmers, lawn mowers, flashlights, sprayers, screwdrivers, and the like. In some cases the batteries are housed in a nonremovable pack. The recharging circuitry usually comprises a separare charging unit. In some cases the charging circuitry is incorporated as a part of a rechargeable battery pack. It has also been previously proposed to provide a removable battery pack having its own recharging circuitry, the pack having AC type prongs and arranged so that the pack can be interconnected through the prongs to the device to be powered or through the same prongs to a household receptacle for recharging. It has also been suggested to have a removable rechargeable battery pack that could be connected to any one of several battery power consuming devices. This concept has been proposed both for portable pocket size cordless apparatus as well as heavier portable cordless apparatus such as a cordless hedge trimmer but only for a fixed energy requirement. 
     A representative collection of prior art patents dealing with the foregoing constructions includes U.S. Pat. Nos. 1,506,302; Ser. No. 427,480, Zdansky (A.P.C.), published June 15, 1943; 2,628,339; 2,818,498; 2,876,410; 2,982,881; 2,995,695; 3,013,198; 3,021,468; 3,027,507; 3,067,373; Re. 25,388; 3,109,132; 3,120,632; 3,145,404; 3,183,538; 3,275,819; 3,280,351; 3,281,636; 3,329,881; 3,360,708; 3,447,058; 3,533,119; 3,623,223; 3,742,832; 3,757,194 and 3,883,789. 
     In a more recent development, a system now on the market is directed to a range of cordless devices including grass shears, lanterns, drills, and shrub trimmers. Each device mates with a standardized &#34;power handle&#34; which serves both as a handle and to contain a rechargeable battery. This handle is required to be removed and placed in a stand-type charger for recharging. Such a system points up the advantages of standardizing the power unit portion of a cordless device. However, this system makes no provision for the power handle to be used except singly. There is no provision for varying the amount of available battery power even though one device in the system might require more or less battery power than another. Also, the power handle in such a system does not, itself, contain recharging circuitry and the handle is not adapted to be plugged directly into a household receptacle for recharging. 
     Despite the extensive development of the art, there has not heretofore been provided a family of cordless portable tools or devices characterized in respect to each device in the family having one or a plurality of outwardly opening pockets adapted to receive a corresponding number of identical rechargeable battery packs according to the energy and power requirements of the individual devices and which packs can be recharged from a household receptacle through the same prongs used for discharge. Further, the prior art has not provided a relatively flat, rectangular-shaped battery pack that can be installed and removed from the particular device with the prongs arranged so as not to require guideways for sliding the pack and so as to minimize the hazard of dropping the pack. 
     With all of the foregoing considerations in mind, it thus becomes the object of this invention to provide a type of construction for mass production of a wide range family of portable cordless devices which for each device can be duplicated with respect to incorporating a standardized selected number of battery pack receiving pockets in the device and providing a standard type of rechargeable battery pack unit incorporating recharging circuitry and which can be used singly or in plural groups corresponding to the number of pockets in the particular device and which can be safely placed in an ordinary household receptacle for recharging purposes. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to individual portable cordless devices of the type which use removable rechargeable battery packs as well as to a family of such devices which are adapted to use a selected number of such battery pack units. Each device in the family has a housing which has one or more pockets of unique construction adapted to receive one or more of the interchangeable battery pack units. Thus, the invention is directed, for example, to a portable cordless device whose power requirements are such that only one of the rechargeable battery pack units is required. The invention is also directed to that type of portable cordless device whose power requirements might require two or three or more of such battery packs. Thus, the invention provides a versatile construction suitable to a wide range of types of devices and which may vary widely in the nature of the electrical load and in such matters as torque, peak power demand and speed. 
     In accordance with the present invention, each power consuming device or tool is complete requiring only the installation of one or more battery packs to render it operative. For example, the grass shear of the invention includes a motor properly sized to provide optimum performance for its specific purpose, i.e., grass shearing, and has a housing and handle formation to provide a balance and convenience of operation equal to that afforded by prior conventional grass shears. Similarly, the hedge trimmer of the invention is provided with a larger motor and a different housing and handle formation particularly suited to hedge trimming. 
     The invention devices thus contrast with prior devices of the type utilizing a common power handle which, unlike the present invention, necessarily requires compromise in construction and operation in any tool or device which is in the family of tools or devices using such a handle. 
     With respect to the power consuming device or unit, the invention is directed to forming one or more outwardly opening pockets in the housing of such device, each pocket having its base plane defined in the preferred embodiment by a base plate member which is the same for all members in the family of devices and which plate member includes an electrical receptacle for receiving the electrical prongs or blades of the battery pack. The plate member also co-operates with the remaining pocket structure to facilitate insertion, retention and removal of the battery pack. 
     As to the battery pack unit of the invention, such battery pack is characterized by being in a rather rectangular flat box-like shape and having a pair of AC type prongs projecting from a position intermediate the length and width of one flat sidewall surface of the pack. These prongs are adapted to be received by a corresponding set of receptacle openings provided in the base plate member or, for recharging, to be received by an ordinary household receptacle supply. The weight of the battery, rectifier means and a switch incorporated in the battery pack, is distributed both longitudinally and laterally over the battery pack so as to minimize the moment exerted by the pack whether the household receptacle openings being utilized are oriented vertically or horizontally. 
     Each pack is mechanically latched to its respective pocket and does not depend on its prongs for such mechanical interlocking. 
     The switch in the battery pack unit comprises a double-pole, double-throw, spring-loaded switch which is incorporated as a part of an AC prong assembly which mounts both the AC prongs of the battery pack and the switch. This switch connects the rectifier means to the battery during recharging and is activated and spring-loaded when the pack is installed and latched in its pocket to connect the prongs to the battery for discharge without requiring manual switching. Also, the switch spring causes the pack to tilt, i.e., to pop out, when unlatched. 
     To facilitate insertion, retention and removal of the pack, the pocket in each device in the family of devices is provided with an outwardly opening receptacle formation at one end of the pocket so that the battery is inserted and removed by first assuming a tilted position. When the battery pack is unlatched, it pops out and initially assumes such an outwardly tilted position. It is then withdrawn from the pocket by linear motion. During insertion, one end of the battery pack is first inserted in the receptacle formation in a tilted position and is then rocked about the inserted end of the pack, the receptacle formation insuring insertion of the prongs of the pack into the mentioned housing base plate receptacle of the device after which it is latched. 
     In one form of the invention the housing of the device is provided with oppositely facing pack receiving pockets positioned back to back. 
     The electrical receptacle in the base plates are offset from the base plate centerlines to permit the receptacles to interfit when arranged back to back thus permitting a substantial reduction in the bulk and weight of the tool. 
     The contact blades or prongs of the pack are similarly offset. To assure uniformity of the packs and pockets the offset construction is also used where the tool requires only one battery pack. 
     The invention also includes the use of a pair of spring contacts in the prong receiving receptacle of the device which makes both electrical and mechanical contact with the edges of the prongs being inserted and which insure both positive electrical and mechanical contact with the prongs. The mentioned switch spring in conjunction with these spring contacts causes the pack, when unlatched, to pop out as described. A configuration of internal rib constructions are incorporated within the pack housing which secures the internal components against end as well as side-applied shock. The device housing and the pack lend themselves to use of clam shell type housings which greatly facilitates fabrication of the device and pack on a mass production basis. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a pictorial view of a cordless electric grass shear and battery pack of the present invention; 
     FIG. 2 is a pictorial view of a cordless electric lantern with a battery pack of the invention; 
     FIG. 3 is a pictorial view of a cordless electric screwdriver and battery pack; 
     FIG. 4 is a pictorial view of a cordless electric shurb trimmer with the battery pack of the present invention; 
     FIG. 5 is a pictorial view of a garden sprayer incorporating dual pockets with two battery packs in a vertical orientation; 
     FIG. 6 is a side view of a heavy-duty shrub trimmer adapted to receive three battery packs in a balanced arrangement; 
     FIG. 7 is a perspective view illustrating the battery pack showing the AC prongs and latch feature; 
     FIG. 8 is an inverted perspective view of the battery pack and showing the latch feature; 
     FIG. 9 is an exploded, fragmentary view of the battery pack with a portion of the pack cutaway to show the inner components; 
     FIG. 10 is a vertical central section of the pack showing the latch in its normal position and with the wiring removed for purposes of illustration; 
     FIG. 11 is an enlarged fragmentary section of the latch showing the latch in its depressed position; 
     FIG. 12 is a section through the battery pocket; 
     FIG. 13 is a vertical section of the pocket, along line 13--13 of FIG. 12; 
     FIG. 14 is an end section view of the pocket, along line 14--14 of FIG. 13; 
     FIG. 15 is a schematic diagram of the electrical circuitry of a typical multiple pack tool or device; 
     FIG. 16 is a view of the inner surface of the pocket base plate or liner and shows the slot openings for receiving the AC prongs of the pack; 
     FIG. 17 is a side view of the pocket base plate or liner illustrated in FIG. 16; 
     FIG. 18 is a view of the outer surface of the liner; 
     FIG. 19 is an enlarged, fragmentary view of the spring contact member as it is initially engaged by the AC prong edges of the battery pack during insertion of the pack; 
     FIG. 20 is a view similar to FIG. 19 showing the prongs fully inserted; 
     FIG. 21 is a vertical section of the pocket similar to FIG. 13 with the liner installed; 
     FIG. 22 is a side view of a grass shear of the present invention with a portion of the shear housing broken away to illustrate the pocket and liner and a battery pack in the partially removed position; 
     FIG. 23 is a view similar to FIG. 22 with the battery pack inserted; 
     FIG. 24 is a side section view of a portion of the housing for a battery-operated device with dual pockets to hold two battery packs in a horizontal orientation; 
     FIG. 25 is a section view of the dual pockets of FIG. 24 taken substantially along line 24--25 of FIG. 24; and 
     FIG. 26 is a schematic circuit diagram of the charging and discharging circuitry of the battery pack. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-6 illustrate a system of six cordless, portable devices and tools which utilize one or more of the same interchangeable, rechargeable battery packs 10 as the source of power. Each tool or device is shown with one or more pack receiving pockets which receive the pack or packs and provides electrical connections to the tool or device. FIG. 1 depicts a lightweight grass shear 11 adapted to cut relatively narrow swaths of grass; FIG. 2 shows a lantern 12; FIG. 3, a screwdriver 13; and FIG. 4, a lightweight shrub trimmer 14. The versatility of the system is further illustrated with reference to tools and devices having heavier load requirements, as later explained, and as seen in FIG. 5 and FIG. 6 showing a cordless sprayer 133 having two packs 10 and a heavy duty hedge trimmer 135 having three packs 10 and each with a corresponding number of the standardized pockets. Each tool or device provides a handle formation. 
     Referring to FIGS. 7 and 8, battery pack 10, in the embodiment illustrated, has a generally rectangular, flat boxlike shape, i.e., a rectangular parallelepiped shape, and has rectangular, generally flat, side wall surfaces 16 and 17. Pack sides 21, 22, 23, 24, formed by side components 21a, 21b, 22a, 22b, 23a, 23b, 24a and 24b, provide a groove 25 which encircles the pack. Pack 10 of the present embodiment has its own latch as will be described. However, if the latch is made a part of the tool or device housing groove 25 can be used to receive the latch and retain the pack. 
     A pair of standard rigidly mounted AC blades or prongs 26, 27 extend from surface 16 and are oriented parallel to the central long axis of pack 10 with the prongs being located at a position intermediate the length and width of the wall surface 16. The blades are on opposite sides of, and offset different distances from, the longitudinal centerline of the pack for a purpose to appear. 
     Located between prongs 26, 27 is a switch actuator 28 which is engaged by a post member 113 in tool pocket 91 to switch the pack circuitry from the charging to the discharging mode when pack 10 is installed in a manner to be described later. Side surface 21 is provided with a resilient latch member 20 which is adapted to engage a ledge portion of the tool pocket in order to hold the pack in place. 
     FIG. 9 shows the outer pack body member 40 separated from pack body member 60 to show the internal components of the battery pack 10. Members 40 and 60 are essentially a pair of secured rectangular pan-shaped clam shell members. The internal components illustrated in FIGS. 9, 10 and 26 include rechargeable nickel-cadmium sub-c batteries 31, 32, 33, capacitor 35, printed circuit board 36, switch 37, diode bridge 154 and resistors 157, 158. Such circuitry minimizes weight and heat. 
     Members 40 and 60 are approximately 2 inches by 41/2 inches by 1/2 inch, have a wall thickness of about 1/8 inch and are preferably molded of an impact resistant, flame retardant polycarbonate. The interior wall surfaces of member 40 are provided with upper circuit board locators 57, 58 into which circuit board 36 slides into place during assembly. The interior of the top wall also includes two spike members 48, 49 which are positioned over switch 37 as shown in FIG. 10 to hold the switch in a rattle-proof, shock proof manner. A recessed area is provided in the front wall surface 21a of member 40 to accommodate latch 20. The recessed area and associated structural members will be described in conjunction with the description of latch 20. 
     Body member 60 is provided with battery locating ribs that aid in locating the batteries during assembly and also serve to keep the batteries in position during use and thereby reduce rattling. The interior of member 60 is also provided with lower circuit board locators 77, 78 which are aligned with upper circuit board locators 57, 58 and serve as a means of locating the circuit board during assembly and keeping the circuit board in position during use. A pair of live ribs 80, 81 span the width of member 60 and provide compartments for batteries 31, 32, 33. Live ribs 80, 81 are designed to be resilient and absorb shock from the batteries when the pack is accidentally dropped on either end. Structural ribs 82, 83 also serve to define compartments for batteries 31, 32, 33. The structural ribs 82, 83 are rigid and are designed to lend strength to the overall construction of the pack. The body members are snap fitted together and are then ultrasonically welded together. 
     Member 60 is provided with two slots through which AC prongs 26, 27 protrude. An aperture 90 is aligned over switch actuator 28 to expose the latter to a switch activating post 113 in the tool pocket as described later. The prong slots and aperture 90 are located off the centerline of member 60 to facilitate the construction of a dual pack as illustrated in FIGS. 5 and 6 and described later. 
     Member 60 also has a recess 59 for accommodating latch 20 which will now be described. Latch 20 in one embodiment was molded from an acetal resilient plastic material. Latch 20 provides a front notched surface 164 and a smooth front surface 171. Intermediate the length of the front surface is a latch groove 167 which is positioned so as to align with power pack groove 25 when latch 20 is in its normally non-depressed position in pack 10. Latch 20 also provides latch alignment members 160 and restraining knobs 163. 
     As best shown in FIG. 11, during assembly of pack 10, latch 20 slides into place with alignment members 160 against structural rib 83 on member 60 of pack 10. 
     After latch 20 is positioned in member 60, member 40 is snap-fitted and ultrasonically welded to member 60 so that the upper portion of latch 20 resides within recess 50 of member 40. When latch 20 is in its normally non-depressed position, front surfaces 164 and 171 essentially form a continuation of pack side member 21 as best shown in FIGS. 7 and 8. 
     The installed latch is adapted to hold pack 10 in place within pocket 91 by engagement of latch groove 167 and pocket lip 125 which is co-extensive with the latch. When pack 10 is pivoted or hinged into place in the manner previously described, pocket lip 125 initially engages smooth front surface 171 and causes resilient latch 20 to bend at point P (FIG. 11) to the depressed position shown in FIG. 11. Upon full insertion of pack 10 into pocket 91, lip 125 will fall into groove 167 thereby allowing latch 20 to return to its non-depressed position (FIG. 7). Knobs 163 on latch 20 are adapted to engage cavity wall surfaces 182 in member 40 when the latch is in its non-depressed position thereby preventing the latch from being pulled outwardly from the pack 10 beyond its normal position. 
     The battery pack unit 10 just described is adapted to fit into any one of the pockets, in any of the tools and devices which are part of the family of devices made according to the invention. What is next to be described is the pocket construction which can be employed singly or plurally in the devices and tools made according to the invention, so that any pocket can accept any pack which allows any pack to be used with any tool or device in the family in single and plural groups as required. 
     The receiving pocket 91 for the standardized pack 10 is depicted in FIGS. 12-14 and 21-23. In the embodiment being used for illustration, the standardized pocket 91 is formed as an integral part of the tool clam shell housing 93. Pocket 91 can be formed in the housing of each tool or device at a point where the battery pack 10 can be easily inserted into the pocket and provide overall tool balance. Pocket 91 is also adapted to provide means for locating and holding in place a standardized pocket liner 100 which is illustrated in FIGS. 16-18. In order to receive liner 100, each housing for the particular tool or device includes a plurality of liner locators 95 which extend from the housing interior wall surfaces of pocket 91 and are adapted to engage locator grooves 101 in liner 100. A front housing wall member 92 of pocket 91 is provided with a recess 99 which is adapted to receive a projection 105 on liner 100 as a further means for locating and holding in place liner 100. Pocket 91 is devoid of guideways and the like which enables the pack to be tiltably inserted and removed and to pop out when unlatched as elsewhere discussed. 
     It should be emphasized here that so far as is known, there has not been available in the marketplace a coordinated family of cordless, portable tools and devices having varying power requirements and in which each tool or device in the family has a housing which both forms a handle and mounts battery power consuming apparatus and in which such housing is adapted with one or more standardized outwardly opening pockets to accept a comparable number of identical battery packs with each pack having a battery recharging circuitry, AC type prongs and switching mechanism enabling the pack to be recharged from a household receptacle or to be used to power the device or tool. 
     A part of the present invention resides in providing a variety of portable cordless devices each of which can be powered by one or more removable rechargeable identical battery packs. In what is believed to be a departure from prior art practices, the battery receiving pocket in each housing includes the same base plate or liner member which provides a means for standardizing the location of the base and side peripheral planes of the pocket and for standardizing the positioning and securement of the AC prong receptacle openings in the tool and device. Thus a standardized outwardly opening pocket is achieved which can be used over a wide range of portable cordless tools and devices, e.g., grass shears, lanterns, sprayers, hedge trimmers, and the like. 
     Referring particularly to FIGS. 16-20, the pocket liner 100, which is a common component of each tool or device and serves as a base wall in pocket 91, includes a flat outer surface 107, an inwardly inclined surface 108, a lip portion 109, and an extension 105. Flat surface 107 is adapted to engage the flat inner wall surface of battery pack 10 when pack 10 is inserted into the pocket. Surfaces 108, 109 are adapted to facilitate the pivotal insertion and removal of pack 10 as later described. Surface 107 provides two prong receiving chamfered slots 111, 112. 
     As later explained, the circuitry provides for the internal battery pack to be normally connected to the AC prongs for recharging. However, the battery pack and device housing pocket are also provided with means to switch the internal battery pack circuitry to connect the AC prongs to the battery for discharge and use as a power source whenever the pack is inserted in the pocket. In this regard, it may be noted that switch activation post 113 is located between slots 111 and 112. When pack 10 is fully inserted into pocket 91, post 113 engages switch actuator 28 so as to switch the circuitry of pack 10 into the discharging mode. Contact spring holders 121, 122 provide in a central portion thereof post members 123, 124 which are each adapted to receive a contact spring 115 as best shown in FIGS. 19 and 20. Contact spring 115 is a curved leaf spring of resilient conductive metal having a loop locator portion 110, a retainer member 116, a U-shaped prong engagement portion 126, and a wire lead solder contact 114. Loop 110 is adapted to be press-fitted over one of post member 123, 124. When loop 110 is pressed into place, resilient retainer member 116 locates on post member 123 or 124 in order to hold contact spring 115 in place. Prong engagement portion 126 is normally in the external position shown in FIG. 19. As pack 10 is pivoted into pocket 91, one of prongs 26, 27 contacts spring 115 and bends it until pack 10 is fully inserted (FIG. 20). Spring 115 is thus adapted to provide exceptionally reliable electrical contact with the leading edges of AC prongs 26, 27. Wire lead solder contact 114 of contact spring 115 is adapted to electrically connect spring 115 to the appropriate wire leads of the tool motor or other device apparatus. Screw bosses 119, 120 serve as means to secure together two liners in the dual pocket version which will be described later with reference to FIGS. 24 and 25. 
     The method of insertion and removal of pack 10 into pocket 91 is best illustrated in FIGS. 22 and 23 with respect to a typical grass shear 11 adapted with a single pocket 91 and battery pack 10 according to the invention. The shear 11 is held by one hand with the pocket 91 facing downwardly. With the other hand, the operator picks up pack 10 with prongs 26, 27 facing upwardly. The end 23 of the pack 10 opposite latch 20 is then inserted into pocket 91 with surface 17 of pack 10 resting on pocket ledge 94 and with pack surface 16 residing proximate incline surface 108. Pack 10 is now rocked about ledge 94 until the side surface 16 of pack 10 lies flush against flat surface 107 of liner 100 (FIG. 23). During this rocking movement, prongs 26, 27 enter chamfered slots 111, 112 until prongs 26, 27 engage and bend contact springs 115. Also, during this rocking motion, spring activation post 113 engages switch actuator 28. When pack 10 is fully inserted, pocket lip 125 engages latch groove 167 in order to hold pack 10 in place without requiring guideways or the like. Thus the front receptacle portion of the pocket formed by the portions 108 and 109 of the liner, housing wall 92 and ledge 94 locates the pack for insertion, supports the pack during the rocking movement and holds the forward end of the pack securely in place. 
     It should be noted that the internal spring for switch 37 (FIG. 10) and contact springs 115 (FIG. 19) are both compressed by latching of pack 10. Thus pack 10 tends to tilt and pop out when unlatched. The removal of pack 10 from pocket 91 becomes a two-step operation which provides a degree of protection against accidental unlatching or dropping of pack 10. First, latch 20 is depressed so that latch groove 167 disengages pocket lip 125 and by the mentioned spring action and possible force of gravity, dependent on how the tool or device is positioned, pack 10 moves to and is held in a partially removed position as illustrated by FIG. 22. Thus, if latch 20 is accidentally depressed, pack 10 can move to the partially removed position and remain there until reinserted or removed. 
     FIGS. 5, 24, and 25 illustrate use of dual packs and pockets for tools or devices having high energy demands. The two-pack pocket 130 is adapted to receive two of the battery packs 10 with the packs&#39; inner surfaces and AC prongs facing each other. Since the AC prongs on each battery pack 10 are offset from the longitudinal centerline of the pack, the opposing prongs of the two battery packs when inserted into pocket 130 interfit permitting a much more compact arrangement than would otherwise be possible and substantially reducing the bulk and weight of the tool. 
     The assembly of pocket 130 is facilitated by the mating of male bosses 119, 119&#39; with female bosses 120, 120&#39;. Screws 128, 129 are inserted into countersunk holes 127 (FIG. 18) which are located at the base of female bosses 120, 120&#39;. Screws 128, 129 secure the bosses and, in conjunction with extensions 105, 105&#39;, serve to hold together liners 100, 100&#39; in a parallel spaced relation. An important feature of pocket 130 is the interfitting of contact spring holders 121, 122, 121&#39;, 122&#39;. As best shown in FIG. 16, contact spring holders 121, 122 are located offset from the centerline of liner 100 so that when liners 100, 100&#39; are interconnected by their respective bosses 119, 120, 119&#39;, 120&#39; in the assembly of a two pack pocket 130, the contact spring holders 121, 122, 121&#39;, 122&#39; interfit so that the liners 100, 100&#39; can be closely nested together to form pocket 130. 
     The two-pack pocket 130 accommodates tools or devices with higher energy demands than the single pack tools illustrated in FIGS. 1-4. A representative tool requiring a two pack pocket 130 is the heavy duty garden sprayer 133 illustrated in FIG. 5 and adapted to receive two oppositely disposed vertically end oriented packs 10. 
     A heavy duty hedge trimmer 135 requiring even more energy is illustrated in FIG. 6. Trimmer 135 is adapted to receive three packs 10 with one pack generally horizontal and fitting in a bottom pocket as in the tools of FIGS. 1-4 and two packs generally vertically side oriented fitting in opposite side pockets generally as shown in FIG. 24. Tool balance is achieved in all of the embodiments. 
     The electrical circuitry of a typical multiple pack tool or device illustrated in FIG. 15 and the pack circuitry is illustrated in FIG. 26. In FIG. 15, power consuming device 153 is illustrated as being a heavy duty device adapted to hold up to three battery packs 10 which are connected through manually operable switch 150 to the load unit of device 153 by the electrical contacts 115. Packs 10 are connected in parallel so that only one switch 150 needs to be located on device 153. Although a multiple pack tool or device will normally be operated with a battery pack 10 in each pack pocket, the parallel circuitry enables the operator to run the multiple pack tool or device with one or more of the pockets empty, though series circuitry can be employed. 
     In all the embodiments illustrated, it is recognized that in the typical tool or device the operator trigger or other type on-off switch 150 is suitably placed for operator control as shown in FIGS. 1-6. 
     The charging and discharging circuitry of pack 10 will now be described with reference to the schematic circuit diagram 140 of FIG. 26. A double-pole, double-throw switch 37 is adapted to place the circuitry in either a charging or discharging mode. Switch 37 includes six terminals 141, 142, 143, 144, 145, 146. AC terminals 141, 142 are connected to the charging circuitry. DC terminals 145, 146 are connected to the discharge circuitry. Common terminals 143, 144 are connected directly to the AC prongs 26, 27 and are, in the preferred embodiment, continuations of the prongs themselves. Movable contacts 151, 152 are spring loaded in such a manner that they normally connect AC terminal 141 to terminal 143 and AC terminal 142 to terminal 144 as depicted in FIG. 26. The charging circuitry comprises (1) a capacitor 35 which is adapted to drop the input voltage; (2) a diode bridge full wave rectifier 154; (3) batteries 31, 32, 33 connected in series; (4) a bleed resistor 157 which is selected to quickly bleed by completing a RC circuit with a short time constant; and (5) a surge resistor 158 which prevents the diode bridge 154 from receiving a large surge when capacitor 35 is completely discharged. The discharge circuitry is, of course, a direct connection between AC prongs 26, 27 (terminals 143, 144) and batteries 31, 32, 33. 
     The described pack circuitry has several practical advantages in that such full wave rectification circuitry minimizes both weight and internal heat. Pack 10 can essentially be encapsulated, though aperture 90 is preferably designed to provide sufficient clearance, both for member 28 and to vent pack 10 in the event of extraneous battery gases. In contrast, recharging circuitry of other types, e.g., half-wave rectification, would both increase weight and temperature and require positive venting. 
     As described previously, when battery pack 10 is assembled, switch actuator 28 is disposed between prongs 26, 27 in aperture 90. 
     When pack 10 is fully inserted into a standard tool pocket 91, switch activation post 113 is positioned so as to align with aperture 90 and depress switch actuator 28. The depression of actuator 28 compresses the return spring in switch 37 and places pack 10 in a discharge mode. At all times when pack 10 is not fully inserted into a pocket 91, pack 10 will be in the charging mode. This safety feature aids in preventing accidental discharge of pack 10 as well as preventing accidental shortage. 
     Pack 10 is plugged into a standard AC receptacle during charging, as previously explained, and uniquely complies with all known requirements relating to maximum weight for unsupported devices plugged into AC wall receptacles and maximum moment arms which can be exerted on the prongs when they are plugged into the receptacle. In the preferred embodiment, pack 10, including all of its components, weighs approximately 7.82 ounces. When pack 10 is plugged into a standard vertically aligned AC receptacle, the moment produced is approximately 4.4 inch ounces. When pack 10 is plugged into a horizontally aligned AC receptacle, the moment is approximately 4.9 inch ounces. In the embodiment shown, pack 10 has a width of about 2 inches, a length of about 41/2 inches, and a thickness of about 1 inch. Of particular significance is the fact that the pack is easy to grasp and handle and the particular arrangement of components allows the pack to be safely inserted in a standard receptacle whether the receptacle openings are vertically oriented or horizontally oriented. Thus, it can be seen that pack 10 provides a very useful configuration for multiple use, interchangeability and as a self-contained battery charger and still meets requirements for unsupported household receptacle rechargeable devices. 
     While recharging of the pack from a household receptacle is contemplated in the preferred embodiment, it is also contemplated, while not being shown, that the pack can be recharged in a suitable recharging stand. For example, such a stand may contain a suitable horizontal receptacle to receive and connect the pack prongs for recharging as well as actuate the switch 37 with the stand receptacle being connected to a separate AC supply. Also, such a stand may contain suitable circuitry for reducing the available AC voltage as, for example, in overseas use where higher receptacle voltages are experienced. Additionally, such a stand could employ supplemental fast charging circuitry to reduce the time required for recharging. 
     From the foregoing, it can be seen that the system of the invention thus provides both a unique battery pack as well as a unique battery pack pocket construction suited to economical mass production and which lend themselves to interchangeability of any pack with any pocket, multiple use of any pack with any tool or device, grouping of packs in plural groups for increasing available power, providing for any pack to be recharged simply by plugging into a typical 110-120 volt AC household receptacle and maintaining tool balance. 
     In summary, the invention now provides a unique system especially suited to portable cordless tools for which widespread application is envisioned. While single, two and three pack applications have been illustrated, it is, of course, apparent that a greater number of packs could be employed and that the specific pack and pocket constructions could be otherwise standardized without departing from the invention as hereafter claimed. Also, with other methods of recharging, it is apparent that the pack itself could be both larger and heavier while retaining many advantages of the invention. While the use of a separate standardized pocket liner or base member secured between clam shell housing halves is a preferred construction, it is also envisioned that a standardized pocket base plane could be established by molding the pocket base plate as part of the tool or device housing.