Patent Publication Number: US-7898212-B2

Title: Portable solar generator

Description:
The present invention relates to solar electric generators, and in particular, to portable solar electric generators. This application is a continuation of Ser. No. 10/116,857, filed Apr. 5, 2002, now U.S. Pat. No. 7,492,120, issue date Feb. 17, 2009; which is a continuation-in-part of Ser. No. 09/828,114, filed Apr. 6, 2001, now U.S. Pat. No. 6,396,239, issue date May 28, 2002; both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     In recent years, the cost of generating electricity has increased dramatically. In California, the monthly electric bill for many consumers has more than doubled in the past year. Rolling blackouts, a condition in which geographical sections of the community are alternately cut-off from receiving electricity during an electrical shortage crisis, are becoming increasingly commonplace. As our planet&#39;s natural resources are depleted and as population increases, the importance of effectively harnessing alternative methods of generating electricity has increased. 
     Solar Energy 
     Photovoltaic panels (also called solar panels) are well known and are used to generate electricity from sunlight. Sunlight is “free” and so the cost of electricity generated by a photovoltaic panel is extremely low. However, solar energy is not widely used to generate electricity for residences because of the expense associated with installing a solar energy system onto a residence. Typically, photovoltaic panels are currently fixedly attached to the roof of a house and wired directly into the home&#39;s electrical system. Some disadvantages include the fact that the roof may not be the optimum location on the home owner&#39;s property to receive the best, most direct sunlight. Also, once the system is installed, it is permanent. In other words, if the homeowner moves to a new home, he cannot take the solar generating system with him. Also, it is extremely expensive to install a roof mounted solar generating system. Current estimates range from $20,000 to $30,000. 
     Prior Art Portable System 
     U.S. Pat. No. 6,201,181, issued to Azzam, discloses a portable modular solar cart. However, the cart disclosed by Azzam is inadequate for effectively supplying enough energy to satisfy the needs of a typical residence. 
     What is needed is a better portable solar generator. 
     SUMMARY OF THE INVENTION 
     The present invention provides a portable PV modular solar generator. A plurality of wheels are attached to the bottom of a rechargeable battery container. At least one rechargeable battery is contained inside the rechargeable battery container. A power conditioning panel is connected to the rechargeable battery container. At least one photovoltaic panel is pivotally connected. In a preferred embodiment, the rechargeable battery container is a waterproof battery enclosure having a knife switch connection. A mast having a rotation bar is supported by the waterproof battery enclosure. At least one solar panel support brace for supporting the photovoltaic panel is attached to the rotation bar. The power conditioning panel is waterproof, is attached to the mast and has a door. When the door is opened, at least one safety switch is opened, breaking an electric circuit. The waterproof power conditioning panel has a charge controller and an inverter. The charge controller is electrically connected to at least one rechargeable battery and at least one photovoltaic panel, and is capable or receiving auxiliary power inputs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a preferred embodiment of the present invention. 
         FIG. 2A  shows a preferred battery enclosure. 
         FIGS. 2B and 2C  show a preferred battery enclosure lid. 
         FIG. 3  shows a preferred embodiment in its non-deployed position 
         FIG. 4  shows a detailed view of the mast shown in  FIG. 3 . 
         FIG. 5  shows details of a ball and socket joint. 
         FIG. 6  shows details of gears shown in  FIG. 4 . 
         FIG. 7  shows a preferred embodiment in its erected position. 
         FIG. 8  shows a simplified drawing of the electrical components of the preferred embodiment. 
         FIGS. 9 and 10  show a preferred solar panel support brace. 
         FIG. 11  shows another preferred embodiment of the present invention. 
         FIGS. 12-14  show another preferred embodiment of the present invention. 
         FIGS. 15-17  show another preferred embodiment of the present invention. 
         FIGS. 18A-18B  show another preferred embodiment of the present invention. 
         FIGS. 19-21  show another preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a perspective view of a preferred embodiment of the present invention. Five wheels  2  are rotatably mounted on wheel supports  3  of photovoltaic modular platform  1 . Wheel supports  3  are pivotally mounted to the bottom of battery enclosure carriage  5 . Battery enclosure  4  is inserted inside battery enclosure carriage  5 . Mast  6  extends upward through the center of battery enclosure  4 . Power conditioning panel  8  is rigidly attached to the side of mast  6 . Rotation bar  9  is rotatably connected to the top of mast  6  and is capable of rotatably positioning solar panels  10  at various angles. It is estimated that in a preferred embodiment, modular platform  1  (having 16 lead acid batteries weighting 60 lbs each and having 4 solar panels  10  weighing 25 lbs each) weighs less than approximately 1200 lbs. 
     Battery Enclosure 
     A top view of the interior of battery enclosure  4  is shown in  FIG. 2A . Battery enclosure  4  contains four fixed walls  20  rigidly attached to battery enclosure  4 . Four moveable walls  22  are slidingly mounted to tracks  24  and are each capable of being locked in position along track  24 . Four lead acid batteries are arranged adjacent to each other in the corners of battery enclosure  4 . Moveable walls  22  are slid along tracks  22  and then locked in place so that batteries  26  are held flush against one another. Battery enclosure  4  also has mast support cutout section  35  to provide support for mast  6  ( FIG. 1 ). 
       FIG. 2B  shows a side view and  FIG. 2C  shows a top view of battery enclosure lid  7 . Lid connector extensions  28  are arranged to properly align lid  7  over battery enclosure  4  when lid connector extensions  28  are inserted into slots  30 . By lifting up on handles  34 , hinged sections  31  and  32  of lid  7  can be opened. When sections  31  and  32  are raised knife switch connections  33  are broken (see also  FIG. 8 ). Wires (not shown) leading to and from batteries  26  are run through battery raceways  37 . In the preferred embodiment, after lid  7  is placed on battery enclosure  4 , battery enclosure  4  is waterproof. 
     Deployment of PV Panels 
       FIG. 3  shows a perspective view of PV modular platform  1  in its non-deployed state. It is preferable to have modular platform  1  in the position shown in  FIG. 1  when deploying it to different locations at a specific site. As stated above, in the preferred embodiment modular platform  1  weighs less than approximately 1200 lbs. At this weight, it is estimated that one adult male of average strength can easily move it on a flat grade fully loaded with batteries by leaning against battery enclosure  4  with both hands and pushing. If modular platform  1  needs to be moved to a position uphill or over a rough grade, the batteries and PV panels  10  can be temporarily removed and modular platform  1  can be easily pushed uphill or over a rough grade. The weight of modular platform  1  without batteries  26  or PV panels  10  is approximately 100 lbs. 
       FIG. 4  shows a cut out view of mast  6 . DC motor  50  is engaged with gear  52 , which is engaged with gear  54 . A detail view of gears  52  and  54  are shown in  FIG. 6 . By switching switch  56  ( FIG. 3 ) to “on”, DC motor  50  is started. This causes gear  52  to turn gear  54 , which turns erector screw  58 . Erector arm support  60  is threaded onto erector screw  58  so that when erector screw  58  is turned, erector arm support  60  is raised. Erector arm  62  is connected to solar panel support brace  64  via ball and socket joint  66 . Erector arm  62  and ball  68  and socket  70  of ball and socket joint  66  is shown in detail in  FIG. 5 . Socket  70  is also shown attached to solar panel support brace  64  in  FIG. 9 . 
     Solar Panel Support Braces 
       FIG. 9  shows a bottom view and  FIG. 10  shows a top view of solar panel support braces  64 . Solar panels  10  are held in place on solar panel support braces  64  by spring loaded clamps  65 . Solar panel support braces  64  ( FIG. 4 ) are connected to support bars  72  at a hinge at connection points  70 . Support bars  72  are rigidly connected to rotation bar  9 . As erector screw  58  raises erector arm support  60 , erector arms  62  push upward on solar panel support braces  64  causing them to raise and pivot about connection points  70 . 
     When erector arm support  60  is fully raised, solar panel support braces  64  will be in the erected position shown in  FIG. 7 . By manually pressing upward on solar panel support braces  64  at a position shown by the arrows in  FIG. 7 , solar panels  10  will easily rotate about the axis of rotation bar  9  to the deployed position shown in  FIG. 1 . 
     Electrical Components 
     The electrical components of the preferred embodiment of the present invention are shown in  FIG. 8 . Preferably, junction box  100 , charge controller  102 , DC volt meter  104 , inverter  106 , and AC multimeter  108  are all contained within power conditioning panel  8 . In the preferred embodiment, power conditioning panel  8  (also shown in  FIG. 1 ) is waterproof. 
     PV panels  10  and batteries  26  are connected to junction box  100 . In a preferred embodiment each PV panel  10  is capable of generating approximately 120 watts of electricity when impacted by direct sunlight. In the preferred embodiment, junction box  100  can also receive DC electrical input from auxiliary power units. PV panels  10  are connected to junction box  100  through switch  114 , batteries  26  are connected to junction box  100  through switch  110  and the auxiliary power units are connected to junction box  100  through switch  112 . As a safety device, the preferred power conditioning panel  8  is configured to automatically open switches  114 ,  112  and  110  whenever the door of power conditioning panel  8  is opened, thereby preventing a potential mishap. 
     When sunlight strikes PV panels  10 , electricity is generated and flows from PV panels  10  to junction box  100 . Charge controller  102  monitors the condition of batteries  26  to ensure that they are not overcharged, or drained too much. If batteries  26  require further charging, electricity will be directed from junction box  100  to batteries  26  for charging. The current flow will pass through knife switch connection  33  (see also  FIG. 2B ) which is usually in the closed position. 
     DC electricity will flow from either PV panels  10  or batteries  26  through charge controller  102  where its level is preferably monitored by DC voltmeter  104 . DC current can be routed to a DC load by closing switch  116 . Electricity then flows through inverter  106  where the current is converted to AC. Preferably multimeter  108  monitors the level of AC current. AC current then flows through switch  118  (normally closed) to AC sub panel  120 . 
     AC sub panel  120  is configured so that electricity coming from power conditioning panel  8  can be routed to specific areas within the AC load. For example, if the AC load is a residence the residence owner may decide that he wants to power his kitchen using electricity generated by PV modular platform  1 . The owner can then close the breaker within AC sub panel  120  representing the kitchen. Electricity will then flow from AC sub panel  120  through safety switch  121  through AC sub panel  122  where it will be directed to the kitchen. To save money spent on purchasing electricity supplied through the utility grid, the owner can then open the breaker in AC main panel  122  from the utility grid for the kitchen. In this instance, the kitchen would be getting its entire electrical needs from PV modular platform  1  and not from the utility grid. 
     In the first preferred embodiment, PV panels  10  are wired in parallel (see  FIG. 8 ). In the first preferred embodiment, PV panels  10  are 12 volt solar panels that can provide approximately 120 watts of power, so when wired in parallel they will provide a total of 480 watts at 12 volts DC. In the first preferred embodiment lead acid batteries  26  are low cost 6 volt lead acid batteries. As shown in  FIG. 8 , these are wired in series, in sets of two, to provide a 12 volt DC output. The sets of two are then wired in parallel. Typical energy stored in these individual sets of batteries is 350 amp-hours per set of two. Therefore, with 8 sets the storage capacity will be approximately 2800 amp-hours. 
     Second Preferred Embodiment 
     In the first preferred embodiment, PV modular platform was shown as a single power generation unit. In the second preferred embodiment, two auxiliary PV modular platforms are added to a main PV modular platform  1 . The auxiliary PV modular platform is similar in design to PV modular platform  1  described above with the exception that the auxiliary PV modular platform preferably does not contain an inverter. The inverter is unnecessary because the DC current from the auxiliary unit will feed directly into the main PV modular platform  1  at via switch  112  ( FIG. 8 ). 
     By connecting two auxiliary PV modular platforms to PV modular platform  1 , the entire system can provide approximately 1.2 kilowatts, this is enough to power a house. It is estimated that the total purchase price for two auxiliary PV modular platforms and a main PV modular platform is approximately $11,000. If the current monthly electric bill for a residential electricity user is $300/month, it will take slightly more than three years before a purchaser of the second preferred embodiment recovers his cost. 
     Third Preferred Embodiment 
     A third preferred embodiment is shown in  FIG. 11 . The third preferred embodiment is similar to the embodiment shown in  FIG. 8 , except that AC sub panel  120  is replaced with programmable circuit selection panel  200 . 
     Programmable Logic Controller (PLC) 
     PLC  203  is programmed to monitor the utility grid. Multi-meter  201  reports the status of the utility grid to PLC  203 . If the utility grid is not energized (i.e., no current is detectable from the utility grid), PLC  203  opens switch  202 . Modular platform  1  ( FIG. 1 ) then becomes disconnected from the utility grid so that it operates as a stand alone power supply system to the load. PLC  203  will continue to monitor the status of the utility grid. Once PLC  203  determines the utility grid is back on line, PLC  203  will close switch  202  so that AC monitor panel  122  is once again receiving inputs from both modular platform  1  and the utility grid. 
     Programmable Circuit Selection Panel 
     Programmable circuit selection panel  200  includes PLC  203 , actuator  204 , and circuit activation switches  205 . PLC  203  includes a programmable time select variable control parameter that is entered by the user as an input to PLC  203 . The time select control parameter allows PLC  203  to automatically select and deselect circuit activation switches  205  based on the time of day. This, in turn, allows programmable circuit selection panel  200  to be programmed for maximum energy efficiency. 
     Based on inputs received from PLC  203 , actuator  204  will open or close circuit activation switches  205 . For example, as shown in  FIG. 11 , circuit activation switches  205  include individual switches for the kitchen, the master bedroom, the second bedroom, the office and the living room. Table 1 shows a typical preferred programmed scheme for PLC  203  to open or close circuit activation switches  205  based on the time of day. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Kitchen 
                 Master Bd. 
                 Second Bd. 
                 Office 
                 Living Room 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 12:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  1:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  2:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  3:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  4:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  5:00 AM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  6:00 AM 
                 Closed 
                 Closed 
                 Closed 
                 Open 
                 Open 
               
               
                  7:00 AM 
                 Closed 
                 Open 
                 Open 
                 Open 
                 Open 
               
               
                  8:00 AM 
                 Closed 
                 Open 
                 Open 
                 Open 
                 Open 
               
               
                  9:00 AM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                 10:00 AM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                 11:00 AM 
                 Closed 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                 12:00 PM 
                 Closed 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  1:00 PM 
                 Closed 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  2:00 PM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  3:00 PM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  4:00 PM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  5:00 PM 
                 Open 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  6:00 PM 
                 Closed 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  7:00 PM 
                 Closed 
                 Open 
                 Open 
                 Closed 
                 Closed 
               
               
                  8:00 PM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                  9:00 PM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
                 Closed 
               
               
                 10:00 PM 
                 Open 
                 Closed 
                 Closed 
                 Closed 
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                 11:00 PM 
                 Open 
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                 Closed 
                 Closed 
                 Closed 
               
               
                   
               
            
           
         
       
     
     Fourth Preferred Embodiment 
     A fourth preferred embodiment of the present invention is shown in  FIGS. 12-14 . In the fourth preferred embodiment battery cables  206  and  207  are connected to each other by utilization of quick release connection device  208 . 
     Attached to the end of cable  206  are female connection prongs  209 . Attached to the end of cable  207  is male connection prong  210 . As shown in  FIG. 12 , male prong  210  is inserted partway between female prongs  209 . Cam clip  211  is in the position shown in  FIG. 12 . Cam tension adjustment nut  212  (which includes spring  213 ) is pivotally connected to cam clip  211 . Spring  213  is relaxed and connects cam tension adjustment nut  212  to cam tension adjustment strap  214 . 
     In  FIG. 13 , male prong  210  has been inserted further into female prongs  209 . Cam clip  211  has been rotated upward. Spring  213  is now under tension causing cam clip  211  and cam tension adjustment strap  214  to exert a compressive force on female prongs  209 . Male prong  210  is now securely squeezed between female prongs  209 . To remove male prong  210  from female prongs  209 , the user rotates cam clip downward so that it is in the position shown in  FIG. 12 . 
       FIG. 14  shows lead acid batteries  26  connected utilizing quick release connection device  208 . 
     Fifth Preferred Embodiment 
     A fifth preferred embodiment is shown in  FIGS. 15-17 , and  FIG. 11 . In the fifth preferred embodiment, drive housing section  302  is rigidly attached to the bottom of battery enclosure carriage  5 .  FIG. 16A  shows a top see-through view of drive housing section  302 . Drive housing section  302  houses drive motor  303 . Drive motor  303  drives wheels  304  and wheels  305 , which are each connected by treads  306  and  307 , respectively. 
     As shown in  FIG. 11 , PV panels  10 A- 10 D are each monitored by multi-meters  501 - 504 , respectively. PLC  308  ( FIG. 11 ) is in electrical contact multi-meters  501 - 504  and actuator  505 . Actuator  505  controls drive motor  303 . In a preferred embodiment, PLC is housed inside power conditioning panel  8  ( FIG. 15 ). 
     In the fifth preferred embodiment, the repositioning of modular platform  300  ( FIG. 15 ) is controlled with remote control unit  301  ( FIG. 17 ) utilizing three preferred options. Remote control unit  301  utilizes a RF transceiver to remotely communicate with drive motor  303 . 
     Manual Repositioning 
     Modular platform  300  can be repositioned manually by hand. To manually reposition modular platform  300 , the operator moves indicator  310  ( FIG. 17 ) so that it is pointed to position “M”. This causes wheels  304  and  305  to become disengaged so that they are in a freewheeling state. Modular platform  300  can then be physically moved by hand. 
     For example,  FIG. 15  shows PV panels  10 A and  10 B partially covered by shaded region  314 . To position modular platform  300  physically by hand so that it is fully in the sun, the operator pushes it in the direction indicated by the arrow. 
     Remote Control 
     Remote control unit  301  can directly control the positioning of modular platform  300 . To remotely control the positioning of modular platform  300 , the operator moves indicator  310  ( FIG. 17 ) so that it is pointed to position “R”. 
     To cause modular platform  300  to pivot in a counterclockwise direction, the operator presses button  311 . This causes wheels  304  to rotate forward and wheels  305  to rotate backward.  FIG. 16B  shows housing section  302  pivoting counterclockwise. 
     To cause modular platform  300  to pivot in a clockwise direction, the operator presses button  312 . This causes wheels  304  to rotate backward and wheels  305  to rotate forward.  FIG. 16   c  shows housing section  302  pivoting clockwise. 
     To cause modular platform  300  to move forward, the operator moves toggle switch  313  downward. This causes wheels  304  and wheels  305  to move forward.  FIG. 16D  shows housing section  302  moving forward. 
     To cause modular platform  300  to move backward, the operator moves toggle switch  313  upward to the position shown in  FIG. 17 . This causes wheels  304  and wheels  305  to move backward.  FIG. 16D  shows housing section  302  moving backward. 
     For example,  FIG. 15  shows PV panels  10 A and  10 B partially covered by shaded region  314 . To position modular platform  300  utilizing remote control unit  301 , the operator moves toggle switch  313  downward. This causes wheels  304  and wheels  305  to move forward so that modular platform  300  moves in the direction indicated by the arrow. 
     Automatic Positioning 
     Modular platform  300  can also be positioned automatically without any operator input. To place modular platform  300  in automatic mode, the operator moves indicator  310  ( FIG. 17 ) so that it is pointed to position “A”. After modular platform  300  is in automatic mode, solar energy generated by PV panels  10 A- 10 D is measured by multi-meters  501 - 504 . Values corresponding to the amount of solar energy generated by each panel is then sent to PLC  308 . PLC  308  then computes the gradient of the energy between each of the panels and controls actuator  505  to activate drive motor  303  to reposition the unit so that it is located at an optimum position to receive sunlight. 
     For example, as shown in  FIG. 15 , PV panels  10 C and  10 D are receiving greater sunlight than panels  10 A and  10 B. PLC  308  computes the gradient of the energy between panels  10 A- 10 D and sends a signal to drive motor  303  ( FIG. 16A ) to position modular platform  300  so that it moves in the direction indicated by the arrow ( FIG. 15 ) until all panels are in direct sunlight. 
     Sixth Preferred Embodiment 
     A sixth preferred embodiment is shown in  FIGS. 18A and 18B .  FIG. 18B  shows a bottom view and  FIG. 18A  shows a top view of solar panel support braces  364 . Solar panels  10  are held in place on solar panel support braces  364  by spring loaded expansion bars  365 . Solar panel support braces  364  are connected to support bars  72  ( FIG. 4 ) via hinges  366 . Ball and socket connector  367  is shown in  FIG. 18B . 
     Seventh Preferred Embodiment 
     A seventh preferred embodiment is shown in  FIGS. 19-21 .  FIG. 19  shows mast cap lid  451  on top of mast cap  450 .  FIG. 20  shows an exploded view of mast cap lid  451  and mast cap  450 .  FIG. 21  shows mast cap lid  451  and mast cap  450  attached to modular platform  400 . 
     Mast  6  serves as a raceway for wiring for modular platform  400 . Consequently, if mast cap lid  451  is removed during operation of modular platform  400 , serious injury could result. Therefore, in the seventh preferred embodiment, mast cap lid  451  has been configured with solenoids  452  to act as electromagnetic locks. When electrical current is generated by the PV panels, a current is sent to solenoids  452 . This activates the cylinders of the solenoids and injects them into mast cap  450  affecting a locked state between mast cap  450  and mast cap lid  451 . 
     Also, in the seventh preferred embodiment, ventilation fan  453  is mounted on the underside of mast cap lid  451 . Ventilation fan  453  provides ventilation for the entire mast when the internal circuitry is energized. 
     Some Advantages of the Present Invention 
     The compact size, flexibility, mobility and modularity of the present invention provides an easy to install and maintain device. The present invention is a significant benefit to the community. It provides an independent distributed power source that can eliminate power blackouts or brownouts for users. 
     Although the above-preferred embodiments have been described with specificity, persons skilled in this art will recognize that many changes to the specific embodiments disclosed above could be made without departing from the spirit of the invention. For example, although the second preferred embodiment discusses connecting the main PV modular platform to two auxiliary PV modular platforms, it is also possible to connect it to just one auxiliary PV modular platforms or more than two auxiliary PV modular platforms. Also, it is possible to have other devices capable of generating electricity connected to a main PV modular platform, such as a windmill or a fuel-burning generator. Also, although  FIG. 8  showed PV panels  10  wired in parallel, they could also be wired in series. Also the batteries  26  could be wired in series or parallel depending on the application of the system. Also, although the above described embodiments showed lead acid batteries  26  charged by the present invention, the present invention could be used to charge fuel cells. Although the above embodiments discuss the utilization of programmable logic controllers, it would be possible to substitute a variety of types of programmed computers in place of the PLCs specifically mentioned. Therefore, the attached claims and their legal equivalents should determine the scope of the invention.