# Patent

## Title
Powered surfboard for preserving energy of a surfer during paddling

## Abstract

An improvement to a conventional surfboard includes an impeller and an electric motor contained primarily within the body of the surfboard, whereby performance of the surfboard is substantially unaffected by the presence of the impeller and the electric motor. The electric motor is operatively connected to the impeller for providing a forward thrust of the surfboard. The improvement to the conventional surfboard also includes a throttle for selective control of the electric motor for operating the impeller to provide a forward thrust of the surfboard, the throttle being configured for use by a surfer lying in a prone position on the smooth top surface of the body of the surfboard. An extent of the surfer's energy that otherwise would be expended during paddling can be preserved for riding waves by using the impeller to provide the forward thrust during paddling.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a U.S. continuation patent application of, and claims priority under 35 U.S.C. §120 to, U.S. nonprovisional patent application Ser. No. 11/929,931, filed Oct. 30, 2007, now U.S. Pat. No. 7,731,555, which nonprovisional patent application is incorporated by reference herein, which application is a U.S. continuation patent application of, and claims priority under 35 U.S.C. §120 to, U.S. nonprovisional patent application Ser. No. 11/757,375, filed Jun. 3, 2007, which nonprovisional patent application is incorporated by reference herein, and which nonprovisional patent application is a U.S. continuation-in-part patent application of, and claims priority under 35 U.S.C. §120 to, U.S. nonprovisional patent application Ser. No. 11/263,505, filed Oct. 31, 2005, now U.S. Pat. No. 7,226,329, which nonprovisional patent application and patent are incorporated by reference herein, and which is a nonprovisional patent application of, and claims priority under 35 U.S.C. §119(e) to, U.S. provisional patent application Ser. No. 60/624,455, filed Nov. 1, 2004, now expired, which provisional patent application is incorporated herein by reference.


COPYRIGHT STATEMENT
All of the material in this patent document is subject to copyright protection under the copyright laws of the United States and other countries. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in official governmental records but, otherwise, all other copyright rights whatsoever are reserved.
BACKGROUND OF THE INVENTION
The present invention generally relates to a motor driven surfboard.
Surfing is the sport of riding a surfboard (heavy timber “plank”, fiberglass, light wood or foam board) on the face of an ocean wave towards the shoreline. Jet powered surfboards have been devised and utilized for the purpose of surfing without waves such as in lakes or other calm waters. Several types of motorized water boards in the prior art include U.S. Pat. No. 6,702,634 to Jung; U.S. Pat. No. 6,409,560 to Austin; U.S. Pat. No. 6,142,840 to Efthymiou; U.S. Pat. No. 5,017,166 to Chang; and U.S. Pat. No. 4,020,782 to Gleason.
SUMMARY OF THE INVENTION
The present invention includes many aspects and features.
In one aspect of the invention, a conventional surfboard has a body with substantially flat and smooth top and bottom surfaces, wherein the body of the surfboard is configured to support a surfer lying in a prone position on the smooth top surface while paddling. This aspect of the invention is an improvement to such a conventional surfboard, wherein the improvement includes an impeller and an electric motor contained primarily within the body of the surfboard, whereby performance of the surfboard is substantially unaffected by the presence of the impeller and the electric motor. The electric motor is operatively connected to the impeller for providing a forward thrust of the surfboard. The improvement to the conventional surfboard also includes a throttle for selective control of the electric motor for operating the impeller to provide a forward thrust of the surfboard, the throttle being configured for use by the surfer lying in the prone position on the smooth top surface of the body of the surfboard. As a result of the improvement, an extent of the surfer's energy that otherwise would be expended during paddling is preserved for riding waves, thereby providing an more enjoyable surfing experience.
In features of this aspect, the body of the surfboard is made from wood, fiberglass, or foam board.
In another feature, the impeller and the electric motor both are contained within a thickness of the surfboard body such that neither protrudes beyond either top and bottom surfaces of the body of the surfboard.
In another aspect of the invention, a conventional surfboard has a body configured to support a surfer lying in a prone position while paddling. This aspect of the invention is an improvement to such a conventional surfboard, wherein the improvement includes a radio frequency (RF) receiver contained primarily within the body of the surfboard; an impeller contained primarily within the body of the surfboard; and a remote controlled electric motor contained primarily within the body of the surfboard. The electric motor is operatively connected to the impeller for providing a forward thrust of the surfboard and, in turn, the RF receiver is operatively connected to the remote controlled electric motor for selective operation of the impeller through RF communications with the receiver for providing the forward thrust of the surfboard.
In a feature of this aspect, the improvement further includes a RF transmitter in the surfboard that is configured to communicate with the RF receiver for selective operation of the impeller for providing forward thrust of the surfboard. The RF transmitter preferably is disposed proximate one end of the surfboard and the impeller is disposed proximate an opposite end of the surfboard.
In still yet another aspect of the invention, a method for preserving an extent of a surfer's energy that otherwise would be expended during paddling, comprising the steps of: paddling while lying in a prone position on a surfboard, and actuating an impeller such that a forward thrust of the surfboard is provided during paddling by the surfer.
In a feature of this aspect, actuating the impeller includes controlling an electric motor that is the electric motor being operatively connected to the impeller. The electric motor may be controlled by transmitting radio frequency (RF) signals to a RF receiver. The RF signals are transmitted from an RF transmitter.
In other features of this aspect, the impeller, the electric motor, the RF receiver, and/or the RF transmitter are contained primarily within the body of the surfboard.
In addition to the aforementioned aspects and features of the present invention, it should be noted that the present invention further encompasses the various possible combinations of such aspects and features



BRIEF DESCRIPTION OF THE DRAWINGS
One or more preferred embodiments of the present invention now will be described in detail with reference to the accompanying drawings, wherein the same elements are referred to with the same reference numerals, and wherein,
FIG. 1 is a top view of one embodiment of the motorized surfboard.
FIG. 2 is a bottom view of one embodiment of the motorized surfboard.
FIG. 3 is a bottom view of the tail portion of one embodiment of the motorized surfboard.
FIG. 4 shows an upside-down view of the tail end of one embodiment of the motorized surfboard.
FIG. 5 is a block drawing showing a configuration of one embodiment of the drive system, which may be placed within the motorized surfboard.
FIG. 6 is a drawing of the interior portions of one embodiment of the motorized surfboard.



DETAILED DESCRIPTION
As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art (“Ordinary Artisan”) that the present invention has broad utility and application. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the present invention. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure of the present invention. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present invention.
Accordingly, while the present invention is described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present invention, and is made merely for the purposes of providing a full and enabling disclosure of the present invention. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded the present invention, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection afforded the present invention be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself.
Thus, for example, any sequence(s) and/or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular sequence or order, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present invention. Accordingly, it is intended that the scope of patent protection afforded the present invention is to be defined by the appended claims rather than the description set forth herein.
Additionally, it is important to note that each term used herein refers to that which the Ordinary Artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of a term used herein—as understood by the Ordinary Artisan based on the contextual use of such term—differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the Ordinary Artisan should prevail.
Furthermore, it is important to note that, as used herein, “a” and “an” each generally denotes “at least one,” but does not exclude a plurality unless the contextual use dictates otherwise. Thus, reference to “a picnic basket having an apple” describes “a picnic basket having at least one apple” as well as “a picnic basket having apples.” In contrast, reference to “a picnic basket having a single apple” describes “a picnic basket having only one apple.”
When used herein to join a list of items, “or” denotes “at least one of the items,” but does not exclude a plurality of items of the list. Thus, reference to “a picnic basket having cheese or crackers” describes “a picnic basket having cheese without crackers”, “a picnic basket having crackers without cheese”, and “a picnic basket having both cheese and crackers.” Finally, when used herein to join a list of items, “and” denotes “all of the items of the list.” Thus, reference to “a picnic basket having cheese and crackers” describes “a picnic basket having cheese, wherein the picnic basket further has crackers,” as well as describes “a picnic basket having crackers, wherein the picnic basket further has cheese.”
Referring now to the drawings, one or more preferred embodiments of the present invention are next described. The following description of one or more preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its implementations, or uses.
Traditionally, the sport of surfing comprises a rider (“surfer”) “paddling out” by lying prone on the surfboard and paddling away from the shoreline towards a point at which waves are cresting; turning to face the shoreline; paddling quickly towards the shoreline when a wave begins to crest so as to “catch the wave”; and “riding the wave” on the surfboard propelled by the wave towards the shoreline in a prone, sitting or standing position. When riding a wave, a surfer may turn the surfboard towards or away from different parts of the cresting wave depending on the preference and skill of the surfer. Subsequently, the surfer must paddle out and repeat the process of catching and riding waves. After catching and riding waves for a period of time, the surfer must “paddle in” by lying prone on the surfboard and paddling towards the shoreline to end the sport of the surfing for the day. Paddling out, turning, paddling quickly to catch waves and paddling in can be tiring and time consuming to the surfer and can thus limit the surfer's energy and time for riding waves. Advantageous embodiments of the present invention preserve a surfer's maximum energy for riding waves rather than exhausting the surfer's energy on paddling.
Jet powered motorized surfboards have been used for the purpose of surfing without the need for waves, such as in lakes or other calm waters. The general purpose of the present invention, which will be described in greater detail below, is to provide a motorized surfboard which has the advantages of traditional surfboard design, with increased performance and function without many of the disadvantages of the motor driven surfboards, wakeboards, boogie boards, belly boards, personal watercraft, etc. in the prior art.
In advantageous embodiments, a motorized surfboard body 101 has substantially flat and smooth top 102 and bottom 201 surfaces, a maximum thickness of approximately three inches and no substantial protruding parts other than fins 202 extending from the bottom of the tail portion of the body of the surfboard 101. The body of the surfboard 101 may be elongated, rounded or square shaped. In advantageous embodiments the body of the surfboard 101 is an oblong, traditional surfboard shape and comprises a nose, a tail and left and right rails. Generally, the body of the surfboard 101 will be made from wood, fiberglass or foam board, although other types of strong, low density materials may also be used. FIG. 1 shows the body of the surfboard 101 with a top surface 102 and essentially no protruding parts from the top surface 102. FIG. 1 shows the tail of the surfboard in this embodiment with a stomp pad 103 where a surfer may stand on the board when riding waves. FIG. 2 shows the body of the surfboard 101 with a bottom surface 201 and no substantial protruding parts other than fins 202. FIG. 3 shows the body of the surfboard 101 with a bottom surface 201 with no substantial protruding parts other than fins 202. FIG. 4 shows the body of the surfboard 101 as well as the top surface 102 and the bottom surface 201 with no substantial protruding parts other than fins 202. The drawing of this embodiment also shows a gentle curvature of the generally flat and smooth top surface 102 towards the sides of the surfboard.
Some embodiments of the present invention use at least one impeller 501. Advantageously, an impeller 501 comprises rotating blades attached to a hub contained within a tube. The impeller 501 is attached to an electric motor or motors 502 via a motor shaft or a coupler 508. The motor shaft or a coupler 508 allows the electric motor or motors 502 to rotate the blades of the impeller 501 so that when the surfboard is floating in water, water will enter into impeller tube entrance holes 203 and exit out of impeller tube exit holes 104. In some advantageous embodiments, an impeller or plurality of impellers 501 is encased within the body of the surfboard in such a way that water will have access to enter the impeller tube entrance hole 203 and exit the impeller tube exit hole 104. When in combination with an electric motor or motors 502, the impeller or plurality of impellers 501 will force water out of impeller exit holes 104 and propel the surfboard and/or a surfboard and rider combination generally in a forward direction when the surfboard body 101 is floating in water.
FIGS. 1-4 show various physical features of advantageous embodiments of the impeller tubes of the motorized surfboard. FIG. 1 shows the tail of the surfboard where impeller tube exit holes 104 in this particular embodiment allow water to be expelled and thus propel the surfboard in a forward direction when the surfboard is floating in water. FIG. 2 shows the impeller tube entrance holes 203 as recessed openings in the bottom of the tail portion of this particular embodiment. The impeller tube entrance holes 203 allow water to enter the impellers 501 when the surfboard is floating in water. FIG. 3 shows impeller tube entrance holes 203 as recessed openings in the bottom portion of the tail of the surfboard body 101 in this particular embodiment. FIG. 4 shows one embodiment of the motorized surfboard that positions impeller tube exit holes 104 in the tail of the surfboard. FIG. 4 also shows one way in which the impellers 501 may be embedded within the body of the surfboard 101 without significantly interfering with the relatively flat and smooth top surface 102 of the surfboard.
In some embodiments, impellers 501 may be advantageously placed in the front, side or rear portion of the surfboard body 101 depending on the type of control desired by the surfboard rider when riding a motorized surfboard. In some embodiments an impeller 501 connected to a motor 502 may be partly contained within some portion of one or more fins 202 protruding from the body of the surfboard 101. In some advantageous embodiments the impeller-electric motor combination is contained primarily within the body of the surfboard 101; thus, the body of the surfboard 101 will encase 105 the impeller 501 and the electric motor 502 such that a protrusion or disturbance of the flat surface of the board will be minimal—e.g. not greater than the radius of an impeller 501 or of an electric motor 502. In the case of a protrusion or disturbance in the otherwise flat surface of the board 102, that protrusion or disturbance will not affect the performance of the surfboard when engaged in a traditional form of surfing. An impeller-motor combination may be configured to propel an otherwise stationary surfboard in a reverse direction, such as for purposes of braking, if desired. Types of impellers 501 may include water jets with reverse bucket and excess reinforcement fins removed. Jet drives or impellers such as those types used in and adopted for use in toy model boats are also appropriate.
In some advantageous embodiments of the present invention a motorized surfboard may be propelled by at least one lightweight electric motor 502. In some embodiments the electric motor has adequate power to propel a surfboard and rider combination in water when paddling out, turning, catching waves, riding waves or paddling in. An acceptable electric motor may have power and performance characteristics similar to those used in toy model boats and/or model airplanes. Acceptable electric motors 502 include those of a brushless DC type or types comprising components originally designed for radio controlled hobby vehicles. In some advantageous embodiments, the electric motor(s) 502 is rated at approximately 150 to 450 watts.
Advantageously, the electric motor or motors 502 are embedded in the surfboard body 101. In some embodiments the electric motor 502 is completely enclosed within the surfboard body. Within the surfboard body 101 the electric motor 502 is coupled to an impeller or plurality of impellers 501 as described above. The electric motor or motors 502 in combination with the impeller or impellers 501 are configured to propel the surfboard when the surfboard is floating in water as described above.
In advantageous embodiments the electric motor or motors 502 receive power from a power source 506. Acceptable sources of power include a lithium battery or plurality of lithium batteries capable of generating approximately 70 amps of current embedded in the body of the surfboard. A power source 506 including LiPo batteries may provide sufficient electrical current to power to the electric motor 502 coupled to an impeller 501. Types of batteries used as a power source 506 might include a 3 cell 860 mAh, 11.1 V LiPoly Pack with a JST connector, a 3 cell 2100 mAh, 11.1 V High Discharge LiPoly Pack with 16 gauge wire, or one or more 3S2P 4200 mAh, 11.1 V LiPoly Pack with 16 gauge wire. A series connector module 505 may be used to connect multiple lithium battery packs and maximize voltage output to the motor or motors 502.
In some advantageous embodiments the electric motor or motors 502 connect to a motor controller 503. The motor controller 503 is embedded into either the nose or tail portion of the body of the surfboard such that the motor controller 503 does not protrude from the body of the surfboard 101 in such as way as to interfere with the performance of the surfboard during traditional surfing. Advantageously, the motor controller 503 connects to a receiver 504, such as a radio receiver, using a splitter. A basic splitter is a transformer-like device comprising a ferrite core and windings of fine wire, which accepts a single signal stream and splits it into identical parts that are each diminished in strength. The radio receiver 504 and splitter are embedded in the body of the surfboard 101 so that neither interferes with the generally flat and even top 102 and bottom 201 surfaces of the motorized surfboard.
In another advantageous embodiment, a motorized surfboard is configured so that the motor controller 503 connected to the receiver 504 may receive radio signals from a radio transmitter circuit board 601 connected to a throttle 602. Acceptable radio control circuit boards 601 and throttles 602 may be obtained from dismantling a pistol grip radio. The radio transmitter circuit board 601 may be of the type found in RC remote controllers. FIG. 5 shows impellers 501 connected to electric motors 502 controlled by motor controllers 503. FIG. 5 also shows motor controllers 503 connected to a connector module 505 that receives power from a power source 506. Motor controllers 503 in FIG. 5 are additionally connected to a radio receiver 504 that receives radio signals from a radio circuit board 601, which is connected to a throttle 602.
In some embodiments the radio circuit board 601 is embedded within the body of the surfboard 101 such that it does not protrude or significantly disturb the otherwise even surface of either the top 102 or bottom 201 surfaces of the motorized surfboard. In some embodiments the throttle 602 is embedded in the body of the surfboard 101, but is not completely encased within the body of the surfboard 101. In those embodiments, the throttle 602 protrudes sufficiently from the top 102 or bottom 201 surface of the surfboard body 101 to allow hand operation of the throttle 602 by a surfer when the surfer is riding the surfboard in a sitting or prone position. In some advantageous embodiments the throttle 602 may be customized with a dowel and a dimmer switch to allow for throttle control via twisting of the dowel. In some advantageous embodiments the throttle 602 may be a customized throttle embedded so as to be flush with or slightly protrude from the body of the surfboard 101, and which may still allow for throttle control by a surfer.
FIG. 6 shows the surfboard with one arrangement of the motorized components within the body of the surfboard 101 that would power this embodiment of a motorized surfboard. In FIG. 6 impeller tube exit holes 104 are built into the body of the surfboard 101. FIG. 6 shows impellers 501 are connected to electric motors 502 controlled by motor controllers 503. Within a dry box area 507 a connector module 505 is connected to a power source 506. Additionally in FIG. 6 the connector module 505 is connected to a radio receiver 504, which receives signals transmitted from a radio circuit board 601 connected to a throttle 602. In some embodiments the throttle 602 is located in the nose of the surfboard and protrudes slightly from the top surface of the board 102. The radio circuit board 601 in FIG. 6 is connected to a power source via wires 604 embedded within the surfboard body 101. In other embodiments, the throttle 602 is connected directly to the motor controller 503 without the use of the radio circuit board 601 or the radio receiver 504.
In some advantageous embodiments a throttle 602 may also be connected directly to a motor controller 503 via a regulator and switch combination. The motor controller 503 may be thus configured to receive signals from the throttle 602 via the regulator and switch. In those embodiments, neither a radio receiver 504, nor a radio circuit board 601 is present. At least one electric motor is connected to a motor controller, which is connected to a receiver.
In some embodiments a radio control circuit board 601 in combination with a throttle 602 may also be hand held. In such an embodiment, the hand held radio controlled circuit board 601 and throttle 602 may allow hand operation of the throttle either by a surfer riding in a sitting or prone position on the surfboard or by a surfer or other person not riding on the surfboard. In such an embodiment, a throttle 602 may be customized with a dowel and a dimmer switch to allow for power control of the electric motor or motors via twisting the dowel.
In some advantageous embodiments the throttle 602 is configured to control the electric motor or motors 502 connected to the impeller or plurality of impellers 501. In those embodiments, the impellers will propel the surfboard body 101 when the surfboard body 101 is floating in water. Thus, in those embodiments, the throttle control 602 will control the propulsion of the surfboard.
In some advantageous embodiments, holes are cut or otherwise formed into the body of the surfboard 101 to accommodate each impeller 501, electric motor 502, motor controller 503, power source 506, receiver 504, circuit board 601, and throttle 602 combination. A dry box area 507 may house the power source 506 and/or a combination of other components. In embodiments in which a battery power source 506 is located within the dry box 507, the dry box 507 may allow for easy access to the battery or batteries for recharging purposes. In some embodiments a watertight recharge nipple may be embedded in the body of the surfboard to allow for recharging of the battery or batteries without opening the dry box 507 or removing the battery or batteries embedded within the body of the surfboard 101. After placing each impeller 501, electric motor 502, motor controller 503, power source 506, receiver 504, circuit board 601, and throttle 602 into the holes cut into the surfboard body 101, the holes may be foamed where there are no moving parts then sealed with wood, resin foam etc. The exterior of the surfboard body 101 may then be glassed and finned.
In one advantageous embodiment a motorized surfboard is designed as and configured to perform as a traditional surfboard. It will be appreciated that the present invention does not have a heavy bulky design or the presence of an outboard motor that might inhibit the safety and performance of the motorized surfboard in the manner of traditional surfing. In advantageous embodiments, the motorized surfboard will nevertheless have all of the capabilities and characteristics of a traditional surfboard; advantageous embodiments will improve the surfer's ability to catch and ride waves by the extra forward thrust provided, and will act and ride like a traditional surfboard. Advantageous embodiments will also avoid significant drag from protruding parts or significant deviation from a traditionally flat, smooth surfboard design.
Based on the foregoing description, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those specifically described herein, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing descriptions thereof, without departing from the substance or scope of the present invention.
Accordingly, while the present invention has been described herein in detail in relation to one or more preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended to be construed to limit the present invention or otherwise exclude any such other embodiments, adaptations, variations, modifications or equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.

## Claims

1. A surfboard having a body with top and bottom surfaces, wherein the body of the surfboard is configured to support a surfer lying in a prone position on the top surface while paddling, the surfboard defining a longitudinal axis and having substantially no protruding parts other than fins;
at least one impeller contained within the body of surfboard;
at least one brushless DC electric motor contained within the body of the surfboard, the electric motor being operatively connected to the impeller for providing a forward thrust to the surfboard;
a radio circuit board contained within the body of the surfboard and configured to receive throttle commands for selective control of the electric motor for operating the impeller to provide a forward thrust of the surfboard; and
one or more lithium batteries within the body of the surfboard configured to provide power to said electric motor;
wherein performance of the surfboard when riding waves is not significantly adversely affected by the presence of the weight and bulk of the motor and lithium batteries contained within the body of the surfboard, and wherein the performance of the surfboard when paddling and catching waves is significantly enhanced by the thrust provided by the impeller powered by the motor and lithium batteries.

2. The surfboard of claim 1, wherein the body of the surfboard is made from wood.

3. The surfboard of claim 1, wherein the body of the surfboard is made from fiberglass.

4. The surfboard of claim 1, wherein the body of the surfboard is made from foam board.

5. The surfboard of claim 1, wherein the motor is rated at approximately 150 to 450 watts.

6. The surfboard of claim 1, wherein an input for the impeller is provided in a bottom surface of the surfboard.

7. The surfboard of claim 1, wherein an output for the impeller is provided on a rear surface of the surfboard.

8. The surfboard of claim 1, wherein a diameter of the impeller is less than a thickness of the surfboard.

9. The surfboard of claim 1, wherein the body of the surfboard comprises a cavity and the motor and lithium batteries are positioned within the cavity.

10. The surfboard of claim 9, further comprising a recharge nipple embedded in the body of the surfboard and positioned to allow for recharging of the lithium batteries without direct access to the cavity.