Patent Publication Number: US-2023141568-A1

Title: Door assembly with rechargeable electrical power supply for integrated electric devices and methods thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 63/276,060, filed Nov. 5, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present technology is directed to exterior or interior doors for residential or commercial buildings, such as for a home, apartment, condominium, hotel room or business, and more particularly to a door assembly provided with a rechargeable source of electrical power to provide power to operate electric devices mounted to the door assembly. 
     BACKGROUND 
     Typical existing exterior or interior doors for residential or commercial buildings may have a number of electric devices (or components) mounted to the doors in order to provide desired functions, such as electronic access control, door state feedback, an entry camera and audio communication, an electric powered door latch, an electric powered door lock, etc. Also, the market for exterior and interior doors has seen an increasing adoption of additional electric devices including video doorbells, smart locks, LED lighting, smart glass, electromechanical door closers, wireless connectivity electronics, etc. Each of these discrete electric devices typically is an add-on to or near an existing door, functions with the existing door construction, and is powered separately with at least one battery that requires periodic replacement or charging. Should the battery not be replaced or recharged, then the electric device will not operate. 
     Current electric devices are mounted to exterior or interior doors in a manner that can be unattractive and unpleasant to look at. The electric devices typically each have either one or more rechargeable battery packs or at least one non-rechargeable battery that must periodically be recharged or changed and have some type of weatherable housing that may not match the appearance of the door. The need for multiple different battery packs and different kinds of batteries, each for a different electrical device renders the power management for those different batteries difficult and cumbersome to manage. 
     It has been proposed that AC line current be supplied to power a door in order to enhance electric operating capability of a door, such as to power accessories, such as electric door locks, electric cameras, electric latches and the lock. While providing AC power for new construction projects is possible, providing AC power in after market, rehabilitation, or remodeling projects can create scheduling issues, increase component costs, including costs for building in and connecting AC power to existing walls and outer door frames and other issues due to the various crafts that are required. 
     Therefore, there exists a need for a door and methods of operation designed for integration of electric devices into the door, with electrical power provided from a single battery source without adversely impacting structural integrity, insulation and/or acoustic performance, energy efficiency, and aesthetics of the door, and without the need to retrofit existing walls and exterior door frames with AC power. 
     SUMMARY 
     The present disclosure generally relates to exterior or interior doors for residential or commercial buildings, such as for a home, apartment, condominium, hotel room or business, and more particularly to a door assembly provided with a rechargeable source of electrical power to provide power to operate electric devices mounted to the door assembly. Exemplary embodiments provide a door that includes: a door slab, including a rectangular inner door frame; a first facing or skin secured to or formed on a first rectangular side of the inner door frame; a second facing or skin secured to or formed on a second, opposite rectangular side of the inner door frame; at least one hinge portion or point of attachment configured to affix to a corresponding hinge portion or point of attachment on or within a separate outer door frame; wherein the rectangular inner door frame includes at least one hollow cavity housing a plurality of at least partially internal components, the components including plural direct current (DC) electrical devices, including: at least one internal rechargeable battery; and at least one device selected from the group comprising: an electronic access control; a door state sensor; an entry camera with video; an audio communication unit; an audio or video doorbell; a digital camera; a light; a motion detector or sensor; a proximity sensor; a door opener; heating and cooling thermostat controls; alarm sensor or controls; lighting; household or automobile batteries; or automotive controls; wherein the at least one internal rechargeable battery is configured to power the at least one device, and wherein the at least one internal rechargeable battery is configured to be recharged by at least one further rechargeable battery that is placed in wired or wireless proximity to the at least one rechargeable battery. 
     In exemplary aspects described herein, such a door may advantageously retrofit to existing door construction without the need to replace components or otherwise provision AC power supply to the door itself. 
     In further exemplary embodiments, the door components further include a charging circuit interposed between the at least one internal rechargeable battery and the at least one further rechargeable battery. 
     In further exemplary embodiments, the door slab includes at least one user interface or low battery notification module. 
     In further exemplary embodiments, the at least one further rechargeable battery is configured to recharge the at least one internal rechargeable battery via magnetically mounted locations, with at least one magnet positioned in the door and at least one corresponding magnet mounted in the at least one further rechargeable battery. In the event that such magnetically mounted location utilizes magnetic connections for power transfer/charging/recharging, then plural magnetic connections may be provided, e.g., at least one for a positive (+) and one for a ground (−) connection to provide for that power transfer. 
     In further exemplary embodiments, plural magnets are provided within the door slab proximate a wireless recharging module in the door slab. 
     In further exemplary embodiments, the at least one further rechargeable battery is configured to recharge the at least one internal rechargeable battery via a physical connection. 
     In further exemplary embodiments, the physical connection includes plural pogo pins or spring contacts. 
     In further exemplary embodiments, the physical connection that is configured to recharge the at least one internal rechargeable battery is also a magnetic connection configured to mount the at least one further rechargeable battery. 
     In further exemplary embodiments, the at least one further rechargeable battery is configured to wireless recharge the at least one internal rechargeable battery via an inductive or resonance charge system. 
     In further exemplary embodiments, the inductive or resonance charge system includes at least one power receiver configured to receive power from an inductive or resonant power transmitter, within a minimal proximity between the receiver and the transmitter. 
     In further exemplary embodiments, the at least one rechargeable battery is configured to fit in a pre-configured recess in the door slab corresponding to the shape of at least one other door or facing shape. 
     In further exemplary embodiments, the at least one further rechargeable battery is configured to recharge the at least one internal rechargeable battery via a mounted location, with at least one physical connector in the door and at least one slot or interference fit mount on the at least one further rechargeable battery. 
     In further exemplary embodiments, the at least one further rechargeable battery is configured to recharge the at least one internal rechargeable battery via a door slab mounted recharge connector, with at least one physical connector in the door configured within at least one slot or on an interference fit mount on or within the door slab. 
     Additional exemplary embodiments relate to door systems and methods of charging a door in accordance with the above and additional exemplary embodiments described herein. 
     The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an elevational exterior view of a door system; 
         FIG.  2    is an elevational interior view of the door system; 
         FIG.  3    is an elevational view of the door system according to an embodiment of the present invention without an exterior door skin in order to allow observation of the interior of the door; 
         FIG.  4    is a block diagram showing a first embodiment of the rechargeable power supply; 
         FIG.  5    is a perspective view of the door having a battery pack inserted therein; 
         FIG.  6    is an enlarged view of the battery pack shown in  FIG.  5   ; 
         FIG.  7    is an enlarged view of the battery pack having a cylindrical shape; 
         FIG.  8    is a block diagram showing a second embodiment of the rechargeable power supply; 
         FIG.  9    is a perspective view of the door having a rectangular battery pack attached to its door skin; 
         FIG.  10    is the same view as  FIG.  9    showing the hidden internal battery inside the door; 
         FIG.  11    is an enlarged view of the circled portion of  FIG.  10   ; 
         FIG.  12    is a perspective view of the door having a circular puck battery pack attached to its door skin; and 
         FIG.  13    is a flow chart of an exemplary method in accordance with the present disclosure 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the exemplary embodiments and exemplary methods as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and exemplary methods. 
     This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “horizontal,” “vertical,” “front,” “rear,” “upper”, “lower”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “vertically,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion and to the orientation relative to a vehicle body. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. The term “integral” (or “unitary”) relates to a part made as a single part, or a part made of separate components fixed (i.e., non-moveable) and connected together. Additionally, the word “a” and “an” as used in the claims means “at least one” and the word “two” as used in the claims means “at least two.” 
       FIGS.  1  and  2    illustrate a door system ten according to an exemplary embodiment of the present invention, such as a pre-hung door. The illustrated, exemplary door system  10  includes a conventional hinged residential exterior door assembly  11 , but it should be understood that the door assembly  11  may be a pivotally mounted exterior or interior door assembly provided for a residential or commercial building, such as a home, apartment, garage, condominium, hotel, office building, or the like, or a door with alternate door to exterior frame connections, such as a door hanging on a rail, etc. The door assembly  11  may be made of any appropriate material, such as wood, metal, wood composite material, fiberglass reinforced polymer composite or the like. The illustrated, exemplary door assembly  11  includes a substantially rectangular door frame  12  and a door  14  pivotally attached thereto by at least one hinge  16   1 , such as a “butt hinge” that includes two leaves. 
     The illustrated door frame  12  includes first and second parallel, spaced apart vertically extending jamb members  12   1 ,  12   2  and a horizontally extending upper jamb rail member or header  12   c  that connects upper ends of the first and second jamb members  12   1 ,  12   2 . Those skilled in the art recognize that lower ends of the jamb members  12   1 ,  12   2  may be interconnected through a threshold  12   t . The at least one hinge  16   1  pivotally attaches the door  14  to the first jamb member  12   1 . Typically, at least two hinges  16   1  and  16   2  are provided to secure the door  14  to the first jamb member  12   1 . Preferably, as best shown in  FIG.  2   , three hinges  16   1 ,  16   2 ,  16   3  are used to secure the door  14  to the door frame  12 . In the interest of simplicity, the following discussion will sometimes use a reference numeral  16  without a subscript numeral to designate an entire group of the hinges. For example, the reference numeral  16  will be sometimes used when generically referring to the hinges  16   1 ,  16   2  and  16   3 . The same is also true from the door frame  12  which comprises the jambs  12   1 ,  12   2 , and the header  12   c  (some frame  12  may also include a threshold  12   t . 
     The illustrated door  14  includes a rectangular inner door frame  20 , an exterior door skin (or facing)  23 , and an interior door skin (or facing)  24  secured to opposite sides of the inner door frame  20 , as best shown in  FIGS.  1 - 3   . The exterior and interior door skins  23  and  24  are formed separately from one another, and typically are identical in appearance, though it should be noted that the present disclosure contemplates door facings or skins that are more generally secured to or integral with the door  14 . The door skins  23  and  24  are secured, e.g., typically adhesively, to a suitable core and/or to opposite sides of the inner door frame  20  so that the inner door frame  20  is sandwiched between the exterior and interior door skins  23  and  24 . In exemplary embodiments, the exterior and interior door skins  23  and  24  are made of a polymer-based composite, such as sheet molding compound (“SMC”) or medium-density fiberboard (MDF), other wood composite materials, fiber-reinforced polymer, such as fiberglass, hardboard, fiberboard, steel, and other thermoplastic materials. The door  14  has a hinge side  14 H mounted to the inner door frame  20  by the hinges  16 , and a horizontally opposite latch side  14 L. 
     The inner door frame  20  includes a pair of parallel, spaced apart horizontally extending top and bottom rails  21   1 and  21   2 , respectively, and a pair of parallel, spaced apart vertically extending first (lock side) and second (hinge side) stiles  22   1  and  22   2 , respectively, typically manufactured from wood or an engineered wood, such as a laminated veneer lumber (LVL). The top and bottom rails  21   1  and  21   2  horizontally extend between the first and second stiles  22   1  and  22   2 . Moreover, the top and bottom rails  21   1  and  21   2  may be fixedly secured to the first and second stiles  22   1  and  22   2 , such as through adhesive or mechanical fasteners. The inner door frame  20  further may include a mid-rail (not shown). The mid-rail extends horizontally and is spaced apart from the top and bottom rails  21   1  and  21   2 , respectively, and is typically also manufactured from wood or an engineered wood, such as a laminated veneer lumber (LVL). Moreover, the mid-rail may be fixedly secured to the first and second stiles  22   1  and  22   2 . The hinges  16  are secured to the first stile  22   1 , which define a hinge stile of the inner door frame  20 . 
     The inner door frame  20  and the exterior and interior door skins  23 ,  24  of a typical door  14  surround an interior cavity, which may be hollow or may be filled with, for example, corrugated pads, foam insulation, or other core materials, if desired. Thus, the door  14  may include a core  15  disposed within the inner door frame  20  between the exterior and interior door skins  23  and  24 . The core  15  may be formed from foam insulation, such as polyurethane foam material, cellulosic material and binder resin, corrugated pads, etc. While a door  14  is described in exemplary embodiments as having a frame  20  with skins  23 ,  24  and an interior cavity, exemplary embodiments of the present disclosure contemplate any door construction that includes at least one hollow interior space, as will be described in more detail below, at least partially housing plural interior DC components, including an internal rechargeable battery and at least one additional of a plurality of possible DC components described herein. 
     As shown in  FIGS.  3 - 4   , in the illustrated exemplary embodiment, the door system  10  includes at least one of a number of possible direct current (DC) electrical devices  30  mounted to or at least partially housed within the door  14  of the door system  10  to provide functions, such as electronic access control, door state feedback, entry camera and audio/video communication, etc. Specifically, the electrical devices  30  that may be mounted to the door system  10  include, but are not limited to, an electric powered door latch  30   1 , a doorbell  30   2 , a digital camera  30   3 , a light  30   4 , a motion detector  30   5  (or motion sensor), a proximity sensor  30   6 , as best illustrated in  FIG.  3   . Specifically, the electric powered door latch  30   1  may be mounted to the inner door frame  20  of the door  14 , while the doorbell  30   2 , the digital camera  30   3  and the light  30   4  may be mounted to the door  14  of the door system  10 , as best illustrated in  FIG.  3   . Although  FIG.  3    shows the electrical devices  30 , their positions on the drawings are representative and are not intended to be fixed. The position of the electrical devices  30  on the door  14  may vary significantly from the positions shown in  FIGS.  3 - 4   . It should be understood that the door system  10  may include electric devices other than the electric powered door latch  30   1 , the doorbell  30   2 , the digital camera  30   3 , the light  30   4 , the motion detector  30   5 , the proximity sensor  30   6 , as there are a number of electric devices marketed to be mounted to doors and provide functions such as electronic access control, door state feedback, entry camera and communication, etc. In the interest of simplicity, the following discussion will sometimes use a reference numeral without a subscript numeral to designate an entire group of the electric devices. Herein, the reference numeral  36  used when generically referring to the electrical devices  30   1 - 30   6  and/or other electrical devices. 
     In exemplary embodiments, the electrical devices  30  typically are low-voltage DC electric devices operated by low-voltage DC electrical power. Low voltage direct current (DC) is known in the art as 50 volts (V) or less. Common low voltages are 1.8 V, 3.3 V, 5 V, 12 V, 24 V, and 48 V. Low voltage is normally used for doorbells, video doorbells, garage door opener controls, heating and cooling thermostats, alarm system sensors and controls, outdoor ground lighting, household and automobile batteries. Many DC electric devices operate at 5 V DC. Low voltage (when the source is operating properly), such as 5 V DC, will not provide a shock from contact. However, a high current, low voltage short circuit (automobile battery) can cause an arc flash and possibly burns. 
     As illustrated in  FIGS.  3 - 4   , the illustrated, exemplary door  14  further includes a rechargeable power source  40  to provide electrical power to the electrical devices  30 . In exemplary embodiments, the rechargeable power source  40  is a rechargeable battery pack that is mounted inside or at least partially housed within an interior space of the door  14 , such as attached to a hinge side stile  22   2 , and is electrically connected through an electrical distribution system to the electrical devices  30 . In certain embodiments, one or more of the electrical devices  30  may be connected to the rechargeable power source  40  via a controller  42  to provide the proper operating voltage to the particular electrical device  30 . For example, as illustrated in  FIG.  3   , the light  30   4  and the motion detector  30   5  are connected to the rechargeable power source  40  via the controller  42 , while the door latch  30   1 , the doorbell  30   2 , are connected directly with the source  40 . It should be understood that  FIG.  3    illustrates an exemplary embodiment and that the electrical connection between the individual electrical devices  30  and the rechargeable power source  40  correspond with the power requirement of that electrical device  30 . 
     In exemplary embodiments, the rechargeable power source  40  includes a rechargeable battery pack  120  and a removable rechargeable battery pack  100 . In a first exemplary embodiment, as illustrated in  FIG.  4   , the door system  10  is provided with multiple removable rechargeable battery packs  100 , for example at least two (shown in  FIGS.  4    as  100   a  and  100   b ). The rechargeable battery pack  100  may be removeable from the door  14 , e.g., via an opening in the door  14 , to be recharged at a remote charging station  102 . 
       FIG.  4    shows an exemplary configuration for the charging station  102  and the rechargeable power source  40 . The charging station  102  is electrically connected to an alternating current (AC) power source  104 . The AC power source  104  may be a standard 120 (or 110) volts general-purpose AC electrical power supply known in the USA as grid power, wall power, or domestic power. Other voltages, such as 220 volts, may also be used. The AC power source  104  provides electrical power to the charging station  102  for charging the removable battery pack  100 . The charging station  102  preferably includes an AC to direct current (DC) converter  112  which rectifies the AC to provide DC for charging the battery pack  100 . The charging station  102 , in exemplary embodiments, also includes a user interface  106  which contains an input power indicator  108  and charging status indicator  110 . The input power indicator  108  may be, e.g., a light or LED showing whether the charging station  102  is electrically connected to the AC power source  104 ; and the charge status indicator  110  is preferably one or more lights or LEDs showing the charging status of the battery  100  (whether the battery is fully charged or still being charged). In certain embodiments, the user interface  106  and/or the charging circuit  118  may be located on the rechargeable battery pack  100  (e.g., as shown in  FIG.  8   ), instead of the charging station  102 . The DC from the AC to DC converter  112  (note that while  FIGS.  4  and  8    show exemplary 120 VAC to 12 VDC converter, any conversion is contemplated (e.g., to 5 V DC, etc. or otherwise) as is further described in the descriptions of the various embodiments herein) is routed to the power interface  114  to charge the battery  100 . The battery  100  may be connected to the power interface  114  to make electrical connection with electrical terminals  116  on the power interface  114 . The exemplary illustrated power interface  114  also include a charging circuit  118  to control and regulate the charging of the battery pack  100 . 
     In exemplary methods, the charged battery pack  100  may be inserted into the door to provide additional power to the power source  40 . The exemplary power source  40 , as shown in  FIG.  4   , includes an internal battery  120  that is built into or at least partially housed within the door  14  and, in exemplary embodiments, is not easily removable. The internal battery  120  receives power from and is kept charged by the battery pack  100  via a charging circuit  122 . The internal battery  120  allows the door to operate when the removable battery  100  is removed from the system to be recharged. 
     In exemplary embodiments, the power source  40  also includes a low battery indicator  124  to monitor the power status of the battery pack  100  to warn the user that the battery pack  100  is low on power and needs to be replaced and recharged. When the battery pack  100  is indicated as being low, the user removes the battery pack  100  from the door  14  and replaces it with a freshly charged battery pack  100 . The removed battery pack  100  is then recharged at the charging station  102  to be used at a later time to replace the battery pack  100  that is then being used in the door  14 . 
     In exemplary embodiments where only one removable battery pack  100  is available, the exemplary door system  10  and associated electrical components  30  can be configured to be fully operational due to the presence of the internal battery  120 , even in the absence of the removable battery pack  100  (e.g., while it is recharging). 
     As shown in  FIGS.  5  and  6   , in exemplary embodiments, the battery pack  100  is inserted into an edge  42  of the door  14 , for example via a lock side edge to allow for easy access to the battery pack  100 . The illustrated edge  42  of the door  14 , which may be formed in the frame  12 , includes an opening  44  for insertion of housing  126  for the battery pack  100 . The housing  126  fits into the opening  44  and is secured therein, such as with mechanical fasteners, such as screws, or adhesively. The housing  126  may also be wired to the power source  40  to allow the battery pack  100  to be electrically connected thereto. In exemplary embodiments, the battery pack  100  slides into the housing  126  and is retained therein, e.g., by one or more latches  128 . To remove the battery pack  100 , the user unlatches the battery pack  100  and slides it out of the housing  126 . Although  FIGS.  5 - 6    show the battery pack  100  having a rectangular shape, it may also be of different shapes, such as cylindrical as shown  FIG.  7   . 
     As shown in  FIG.  9   , in an additional exemplary embodiment, the rechargeable battery pack  100  may be attached to the interior door skin  24 . In this embodiment, the battery pack may be shaped and configured to compliment the design features on the interior door skin  24 . For example, as shown the  FIG.  9   , the door skin  24  has rectangular shaped designs  200  on its exterior surface. The illustrated rechargeable battery pack  100  also has the same rectangular shape as the designs  200  so that it blends in with the over aesthetic design of the door. Although rectangular shaped designs  200  are shown in  FIG.  9   , the present invention also contemplates other designs, such as a circular puck, as shown in  FIG.  12   . 
     In exemplary embodiments, the battery pack  100  may charge the internal battery  120  wirelessly or by hard wired connection. For hard wired charging, the battery pack  100  may include electrical connectors that mate to corresponding connectors on the interior door skin  24 . The battery pack  100  may be attached to the exterior of the door skin  24  magnetically (using on or plural possible sets of magnets) or by one or more latches, such as a push latch, magnetically touch latch, traditional latch, or combinations thereof, and positioned proximate to the internal battery  120 . Magnetic attachment provides further advantage with regard to ease of attachment and detachment of the battery pack  100  to and from the door skin  24  without requiring any tools or mechanical interfaces. In exemplary embodiments, magnetic contacts used to attach the battery pack  100  both hold the battery pack (e.g., configured as a puck) in place and act as charge terminal(s) for the battery. Battery pack  100  may be used for wireless charging, e.g., using magnetic induction or magnetic resonance, or for charging via physical connections, including wired or non-wired connections (e.g., without limitation, pogo pins or spring contacts). Additional advantages of a magnetic connection include water and dust resistance for the door and associated door system, as well as providing an overall fast mechanism for charging the internal battery. 
       FIG.  8    illustrates a further exemplary embodiment, which includes a charging station  102  that is similar to the charging station  102  shown in the  FIG.  4    and described above. The battery pack  100  includes an input interface  300  and output power interface  302  to respectively interface with the charging station  102  and the power source  40  of the door  14 . The battery pack  100  also includes a charging circuit  304  to control and regulate the charging to the battery pack  100 . Alternatively, the charging circuit  304  may be located on the charging station  102  instead, as shown in  FIG.  4   . The battery pack  100  also includes a user interface  306  which has a low battery power indicator  308 , an input power indicator  310 , an output power indicator  312 , and an output power button  314 . The indicators  308 ,  310 ,  312 , respectively indicate whether the battery pack  100  is low in power, connected to the charging station  102 , and delivering charge to the internal battery  120 . In certain embodiments, the user interface  306  may also include an indicator showing any fault status (not shown) for the battery pack  100 . The output power button  314  allows the user to turn on/off the charging of the internal battery  120  from the battery pack  100 . The output power button  314  may serve as a safety feature, e.g., when the user wishes to turn off the system when he/she leaves the premise or when there is a fault in the system. Additionally, while charging circuit  122  in the exemplary embodiment of  FIG.  8    is illustrated as being within the door slab, we note that such circuit could be provided within the portable recharging puck. 
     As has been noted with regard to various exemplary embodiments, the battery pack  100  may be used to charge the internal battery  120  by wired connection or wirelessly. When connected by wired connection, the battery pack  100  and the internal battery  120  perform as described above for the first embodiment, except for the difference in how the battery pack  100  is connected to the door  14 . The charged battery pack  100  may be inserted into the door  14  to provide DC power to the power source  40 . The preferred power source  40  of the second embodiment, as shown in  FIG.  8   , includes an internal battery  120  that is built into the door  14  and is not easily removable. In exemplary embodiments, the battery pack  100  is attached to the door skin  24  (as aforementioned), which preferably is the door skin facing the interior of the home, building, etc. The output power interface  302  of the battery pack  100  mates (wire or wireless) with an input power interface  316  of the power source  40 . In exemplary embodiments, the battery pack  100  may be attached on the interior side of the door for security reasons so that it may not be removed without approval of the user. When the battery pack  100  is low on power, the low power indicator  308  is turned on to warn the user of the low power status. The user may then remove the battery pack  100  from the door  14  and recharges it at the charging station  102 . While the battery pack is being recharged, the internal battery  120  contains sufficient energy to power the door while the battery pack  100  is being recharged. 
     As noted above, the battery pack  100  of the second embodiment may charge the internal battery  120  wirelessly. Wireless charging is known in the art, e.g., in U.S. Pat. Nos. 9,143,000 and 8,193,764, the disclosures of which are incorporated by reference herein. Wireless charging for the present invention may be accomplished, e.g., using near field techniques, such as by inductive coupling. Wireless charging preferably involves a power transmitter (preferably in the battery pack  100 ) and a power receiver (preferably in the power source  40 ). The battery pack  100  may charge the internal battery  120  with inductive charge systems, such as through use of Qi Standard, Apple MagSafe, Magne Charge, SAE J2954 Standard, PMA Stadard, Rezence (A4WP), or the like. The power transmitter includes at least one transmitter coil and a controller for controlling the charging of the power receiver. The power receiver and the power transmitter (and thus, the battery pack  100  and the power source  40 ) are mounted within proximity of one another to provide effective power transmission. The proximity is generally provided by the charging standard used by the system. In exemplary embodiments, materials separating the power transmitter and the power receiver are made of electrically insulating material to minimize energy loss during wireless charging. The battery pack  100  and/or the power source  40  may also include hardware and/or software to monitor the status, to optimize/control the charge/discharging cycle, or to optimize/control the operation of the internal battery  120  and/or the battery pack  100 . In exemplary embodiments, such magnetic induction is configured along with modulating data over the charging coils for a smart door system. 
     In other exemplary embodiments, wireless charging may be performed via magnetic resonance, which relies on the resonant frequency of the charging coils in order to create the electrical current. In exemplary embodiments, this advantageously permits multiple devices to be in the same resonant field, without relying on exact coil alignment. In further exemplary embodiments, such differing devices can have varying power requirements and varying placements along the transmission field. Further, such magnetic resonance can have longer range relative to induction, e.g., up to about 50 centimeters (cm) (versus, e.g., 15 cm for magnetic induction) and power transmission up to, e.g., 100 watts (W). 
       FIG.  13    provides a flowchart, generally at  400 , for an exemplary methods of charging a door (in accordance with any of the various embodiments described herein) that houses a plurality of at least partially internal components, the components including plural direct current (DC) electrical devices, including at least one internal rechargeable battery and at least one device selected from the group including: an electronic access control; a door state sensor; an entry camera with video; an audio communication unit; an audio or video doorbell; a digital camera; a light; a motion detector or sensor; a proximity sensor; a door opener; heating and cooling thermostat controls; alarm sensor or controls; lighting; household or automobile batteries; or automotive controls. The method includes: at step  410 , powering the at least one device via the at least one internal rechargeable battery; at step  420 , attaching to the door at least one further rechargeable battery that is placed at a recharging location on the door; and at step  430 , charging the at least one internal rechargeable battery using the at least one further rechargeable battery that is positioned at the recharging location. Additional steps may include at  440 , detaching the at least one further rechargeable battery from the door while continuing to power the at least one device via the at least one internal rechargeable battery; at  450 , recharging the at least one further rechargeable battery (e.g., externally via a wall wart or other device); and at  460 , reattaching the at least one further rechargeable battery to the recharging location. 
     It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a smart door.