Abstract:
Streetlights along streets and in parking lots are often suitably located for a vehicle to park in immediate proximity. An electric vehicle charging system and method allows the power supply previously dedicated to the streetlight to be used for electric vehicle recharging whenever the streetlight is not lit. In some embodiments, if the total of the current drawn by the electric vehicle charging and the lit streetlight is less than the rating of the streetlight power supply, then charging may continue even while the streetlight is lit. Further, if an electric vehicle so charging offers a utility-interactive inverter, then upon demand the electric vehicle may be available to supply power back to the electric grid.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a system and method for charging electric vehicles by using the electric service provided for streetlights. More specifically, the present invention relates to a system and method for allowing the charging of electric vehicles when it does not otherwise threaten the operation of a streetlight whose power source has been tapped. 
       CROSS REFERENCE TO RELATED APPLICATIONS 
       [0002]    Not Applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0003]    Not Applicable 
       REFERENCE TO COMPUTER PROGRAM LISTING APPENDICES 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    A drawback that inhibits wide adoption of electric vehicles is the lack of infrastructure for conveniently charging them; and while hybrid electric vehicles are increasingly popular, plug-in versions that operate to maximize use of their battery and minimize use of their gasoline-fueled generator are rare, in part due to the same lack of infrastructure. 
         [0006]    Provision of a vehicle charging infrastructure is inhibited primarily by cost: Such infrastructure has been expensive, typically requiring allocation of a physical location that vehicles can access and providing new electric service to that location. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0007]    The present invention relates generally to a system and method for charging electric vehicles by using the electric service provided to streetlights. More specifically, the present invention relates to a system and method for allowing the charging of electric vehicles when it does not otherwise threaten the operation of a streetlight whose power source has been tapped. 
         [0008]    Presently, facility owners wishing to provide electrical vehicle charging stations need to identify a location to be reserved for vehicle recharging, provide electric service to that location (typically by providing additional, independent electric service from their electrical panel and through a new underground power conduit running to the location), connecting a vehicle charging station to that electric service, and protecting the vehicle charging station from being overrun by a vehicle. There is a need for a charging infrastructure for electric vehicles that substantially reduces the amount of new construction and new electrical service required to provide electrical service for charging at locations that vehicles can access. 
         [0009]    There is a further need to provide such charging infrastructure in a manner that can minimize labor and materials costs, is arbitrarily scalable. 
         [0010]    Additionally, there is a need to provide such charging infrastructure in easily accessed locations, but in a manner that is also aesthetic. 
         [0011]    Further, there is a need for such charging infrastructure to fail safe, that is, to have no adverse affect on the operation of the streetlight. 
         [0012]    The present invention satisfies these and other needs and provides further related advantages. 
         [0013]    Herein, the term “streetlight” includes electrolier streetlights (on steel or concrete poles), utilitarian lights (on wooden power poles), whether found along streets, alleys, or in parking lots. 
         [0014]    Herein, the term “circuit breaker” refers to a reusable circuit protection device. 
         [0015]    The term “fuse” is usually a single-use circuit protection, however, where used herein, it may be acceptably substituted with a circuit breaker. 
         [0016]    The terms “relay”, “coil”, and “contact” usually describe an electromechanical device (the “relay”) which provides an electromagnetic “coil” in a first circuit to magnetically operate a switching “contact” in series with a second circuit when the “coil” is energized by a voltage or current; however, where used herein, “relay” may be acceptably substituted with a “solid-state relay” or other semiconductor circuit, for example employing such components as a triac, or opto-isolators. When such substitution is made, the term “contact” refers to that portion of the substitute (e.g., the two anodes of a triac) in series with the second circuit; and the term “coil” refers to that portion of the substitute which can be operated by a voltage or current to control the second circuit (e.g., the LED of an opto-isolator, or the gate of a triac). Such a substitute need not be a direct replacement for a relay, and may include analog and/or digital logic elements, including a microprocessor. 
         [0017]    It is an object of the present invention to provide a charging infrastructure for electric vehicles that substantially reduces the amount of new construction and new electrical service required to provide electrical service for charging at locations that vehicles can access by using the electrical service already provided for use by streetlights. 
         [0018]    It is an object of the present invention to provide such charging infrastructure in a manner that can minimize labor and materials costs by providing a charging station that may be mounted in or on a streetlight. 
         [0019]    It is a further object of the present invention to provide such charging infrastructure in easily accessed locations, that is in or on streetlights along streets or in parking lots. 
         [0020]    It is an object of the present invention to provide such charging infrastructure in a manner that is unobtrusive and aesthetic, yet easy to find for those looking for a charging station. 
         [0021]    It is a still further object of the present invention for such charging infrastructure to fail safe such that operation of the streetlight is not affected. 
         [0022]    Another object of the present invention is to allow electric vehicles with a utility-interactive inverter to be made available to the electric grid in cases of extreme demand. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The aspects of the present invention will be apparent upon consideration of the following detailed description taken in conjunction with the accompanying drawings, in which like referenced characters refer to like parts throughout, and in which: 
           [0024]      FIG. 1  is a street scene showing electric vehicles connected to charging stations of the present invention; 
           [0025]      FIG. 2  is a wiring diagram for a block of typical municipal streetlights of the prior art; 
           [0026]      FIG. 3  shows a charging station using an electrolier streetlight; 
           [0027]      FIG. 4  shows a charging station using a utilitarian streetlight; 
           [0028]      FIG. 5  is an example schematic for a charging station monitoring a streetlight; 
           [0029]      FIG. 6  is an example schematic of a charging station monitoring combined streetlight and charging current; 
           [0030]      FIG. 7  is an example schematic of a charging station separately monitoring a streetlight and a charging current; 
           [0031]      FIG. 8  is an example state transition diagram for controlling the operation of a charging station. 
       
    
    
       [0032]    While the invention will be described and disclosed in connection with certain preferred embodiments and procedures, it is not intended to limit the invention to those specific embodiments. Rather it is intended to cover all such alternative embodiments and modifications as fall within the spirit and scope of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    Referring to  FIG. 1 , sidewalk  20  parallels street  10 , and is separated by curb  30 . Charging stations  100  of the present invention comprise streetlights  102  having light fixture  104  for illuminating street  10 . Cars  110  and  120  are parked along street  10 , next to curb  30 , where cars  110  are electric vehicles, or hybrid vehicles, and are connected by charging cord  112  terminated by plug  114  to outlet  108  in base  106  of charging station  100 . 
         [0034]    Signage  130 , curb markings  132 , and in-street markers  134  can designate streetlights  102  as being charging stations  100 , since outlet  108  might not be easily seen by a driver looking for a parking or charging location. Designations  130 ,  132 , and  134  may be used individually, or in combination. 
         [0035]    Non-electric vehicles  120  are preferably prohibited from parking in the locations designated by signage  130  or curb markings  132  while connectors  108  may be used for charging; however, if outlet  108  is not available for charging, for example when a lamp in light fixture  104  is lit causing streetlight  102  to use much of its electricity supply, then such a prohibition from parking may not apply. 
         [0036]    In an alternative embodiment, outlet  108  may be replaced by another form of coupler to which electric vehicles may standardize. For instance, rather than charging cable  112  with plug  114  inserted into outlet  108 , another cable (not shown) may be attached in place of outlet  108  and have its own connector (not shown) that is inserted into electric vehicle  110  for charging. Herein, the term “outlet” should be considered include to such alternative embodiments. 
         [0037]    In  FIG. 2 , a schematic of one prior art power supply  200  is shown to illustrate how power is supplied to streetlights  102 . In this example, most of power supply  200  is located beneath street  10  and sidewalk  20 . In other implementations, power for streetlights  102  may come from overhead wiring on power poles (described in conjunction with  FIG. 4  below). 
         [0038]    The power mains  202  are energized by a municipal supply (not shown) and may run for many miles. Periodically, for example every block, an electrical vault  204  is located below street  10 . Access is typically a manhole cover (not shown). Within vault  204 , power lines  206  are connect to mains  202  and run to one or both sides of the street  10  (only one side shown in  FIG. 2 ), as needed to supply streetlights  102 . Power lines  206  comprise multiple conductors that carry, typically, two or three phase alternating current. Lines  206  pass through a conduit, under curb  30 , and into pull box  210  where main fuses  212  are located to limit the current draw of this interval of streetlights  102 . 
         [0039]    From main fuse pull box  210 , power is distributed under sidewalk  20  by power lines  214  to each streetlight pull box  220 , typically located in immediate proximity to corresponding streetlight  102 . In each streetlight pull box  220 , streetlight fuse  222  is provided to limit the current provided to streetlight  102  by power supply  200 . The last leg is delivered by power lines  224 , which pass under sidewalk  20 , through conduit, into the base  106  (shown in  FIG. 1 ) of streetlight  102 . 
         [0040]    Within streetlight  102  (under the prior art), power supply  200 , delivered on power lines  224  was connected to internal wires  234  at connection  232 , accessed through hand access port  230 . Connection  232  is normally made after steetlight  102  has been erected. Internal wires  234  deliver power to control  240  to drive lamp  242  in light fixture  104  (shown in  FIG. 1 ). Control  240  may comprise a starter and/or ballast or other circuit as needed to start and run lamp  242 . Control  240  may further comprise a photoelectric sensor or a timer (neither shown) to turn on streetlight  102  as it gets dark and turn off as it gets light. Most municipalities require control  240  to fail-safe, so if something goes wrong with the sensor or timer of control  240 , corresponding streetlight  102  is on all of the time, rather than being off all of the time. 
         [0041]    The importance of  FIG. 2  is not only to describe an example of power supply  200  and its protective elements, fuses  212  and  222 , but also to illustrate how much infrastructure, often below ground, is already in place to provide street lighting. Those skilled in the art already appreciate the difficulty of increasing the amount of power that supply  200  can deliver: All of cables  202 ,  206 ,  214 , and  224  may need to be replaced with larger gauges. The underground conduits carrying the present cables may be inadequate for larger conductors. Likewise, fuses  212  and  222  would need replacement. 
         [0042]    Referring to  FIG. 3 , The conversion of streetlight  102  into charging station  100  of the present invention is shown. Power lines  224  enter base  106  of streetlight  102  from beneath sidewalk  20 . Preferably, charging station panel  330  is a modification of or substitution for the cover panel for hand access port  230 . Rather than internal wiring  234  connecting directly to power lines  224  at connection  232 , both connect separately to charging control module  332 . Internal wiring  234  still runs up to light fixture  104 , containing control  240  and lamp  242  (shown in  FIG. 2 ). 
         [0043]    Charging control module  332  is preferably located inside of streetlight  102  when hand access port  230  is covered by charging station panel  330 , exposing only outlet  108 , reset switch  334 , and input  336 . Outlet  108 , as described above, connects with plug  114  of charging cable  112  of electric vehicle  110  for charging. Reset switch  334  and input  336 , when provided, are described below, in conjunction with  FIGS. 5-8 . 
         [0044]    In some embodiments of charging cable  112  and plug  114 , an integral ground-fault circuit interrupt may be provided (not shown), in which case ground-fault circuit interrupt functions need not be supplied by charging station  100 . 
         [0045]    An alternative embodiment of the present invention, shown in  FIG. 4 , is charging station  400 , comprising utilitarian streetlight  402  mounted to power pole  401 . Streetlight  402  has light fixture  104  which in the prior art would typically be connected directly to power supply lines  424 , but in the present invention is connected to charging control module  332  by lamp wiring  434 . Power supply lines  424  should provide one or more phases of alternating current suitable for powering light fixture  104 , and should be protected by a fuse (not shown in  FIG. 4 ). Power supply lines  424  feeds charging control module  332 . Extension cable  438  allows outlet  108 , reset switch  334  and input  336  to be located in box  430  at a convenient, accessible height. 
         [0046]    The details of one implementation of charging control module  332  are shown in  FIG. 5 . Power supply lines  214  are protected by fuse  222  and delivered to input terminals  510  by power lines  224 . 
         [0047]    Lighting circuit  501  is completed by passing the power supply through charging control module  332  to output terminals  512 , to streetlight internal wiring  234  to control  240 , which in turn provides power to lamp  242  when lit. The power to control  240  and lamp  242  and their operation is unaffected by the insertion of charging control module  332 , which has merely elongated connection  232  by the insertion of terminals  510  and  512  and conductors  524 . 
         [0048]    Charging circuit  502  comprises conductors  530  which tap into conductors  524  at or near input terminals  510 . Charging circuit  502  further comprises, in series, a circuit breaker  532  to limit the current drawn through outlet  108  (i.e., by the vehicle  110  charging); a relay contact  534  (discussed below in conjunction with detector circuit  503 ); a ground-fault circuit interrupt  536  (if required); and, outlet  108 . While circuit breaker  532 , contact  534 , and ground-fault interrupt circuit  536  are closed, outlet  108  is available to charge vehicle  110 . 
         [0049]    Where charging cable  112  or plug  114  contains integral ground-fault protection, ground-fault circuit interrupt  536  may be omitted. 
         [0050]    Charger outlet  108  may contain an interlock (not shown) whereby no electric potential is delivered to the contacts of outlet  108  until plug  114  is seated. 
         [0051]    In the case where circuit breaker  532  or ground-fault circuit interrupt  536  are tripped, they can be reset with switch  334  (not shown in  FIG. 5 ). 
         [0052]    Preferably, ground-fault circuit interrupt  536  is provided with a test button (not shown) that simulates a current leak to ground, e.g., through a resistor (not shown). Alternatively, such a test may be performed by an external tester (not shown) plugged into outlet  108 , which shunts a small amount of current to ground. 
         [0053]    In particular, circuit breaker  532  must be of a lower current rating and/or faster break response time than fuse  222  so that a inadvertent draw of excess current through charging circuit  502  trips breaker  532  (which can be reset by the operator of vehicle  110 ) rather than blowing fuse  222 , which requires a maintenance service call. 
         [0054]    Control circuit  503  comprises detector  540  for detecting current flow in lighting circuit  501  and a driver  542  for operating relay  543  when the current in circuit  501  indicates that lamp  242  is lighting or lit. 
         [0055]    The response time of control circuit  503  must be sufficiently fast that the steady state maximum draw on charging circuit  502  plus any in-rush current as control  240  begins to light lamp  242  does not damage fuse  222  before contact  534  opens circuit  502 . Response time under 100 mS should be adequate in most cases, with response time of one-half cycle of the alternating current being preferred. 
         [0056]    As previously defined, relay  543  comprising coil  544  and contact  534  may be an electromechanical device, or an analogous solid-state device (an example of which is Model A2425 manufactured by Crydom, Inc. of San Diego, Calif.). Contact  534  of relay  543  may be normally-open, with coil  543  energized when the current sensed by detector  540  indicates lamp  242  is not lit. Alternatively, contact  534  may be normally-closed, with coil  543  energized when detector  540  indicates lamp  242  is lit or lighting. Still another alternative would be for breaker  534  to have a shunt-trip input such that the contacts of breaker  532  would also serve as contact  534  and let coil  544  be the shunt-trip mechanism internal to the breaker (an example of such a device is the ED21B015 circuit breaker with the S01ED60 shunt trip accessory manufactured by Siemens Energy &amp; Automation Inc. of Alpharetta, Ga.). 
         [0057]    In still another embodiment, relay  543  may be a latching device which can be opened or closed by a corresponding pulse from driver  542 . Following the pulse, relay  543  would remain in the same state (opened or closed) until commanded to switch. 
         [0058]    Detector  540  may be an inductive coil (as shown), a hall effect device, or may require a sense resistor or current shunt inline with conductor  524  across which a voltage drop is developed to which driver  542  responds. 
         [0059]    Driver  542  requires a power source (not shown), which may be tapped from input terminals  510 , or developed inductively by detector  540  when current is flowing in conductors  524 . In an alternative embodiment, a battery and/or a solar-powered photovoltaic (neither shown) may be used. 
         [0060]    An example of a suitable, integrated detector  540 , driver  542 , and relay  543  is the AS3-NCAC-FF-15 Current Operated Switch by NK Technologies of Campbell, Calif., which integrates an inductive pickup for both current detection and power collection, drive electronics, and solid state relay. A similar product is the ECSJ407SC by Eaton Corporation, Moon Township, Pa. 
         [0061]    In still another embodiment, control  240  may directly signal driver  542  (interconnection not shown) when lamp  242  is lit or lighting. 
         [0062]    In yet another embodiment, detector  540  may be a photodetector that optically senses the strike and illumination from lamp  242 . 
         [0063]    Another embodiment of charging control module  332  is shown in  FIG. 6 . This embodiment also consists of lighting circuit  601 , charging circuit  602 , and control circuit  603 . Here, the primary difference is that control circuit  603  responds to the sum of the currents drawn by lighting circuit  601  and charging circuit  602 , whereas control circuit  503  responds to just the status of lighting circuit  501  as determined by detector  540 . 
         [0064]    Here, the power supply is provided at input terminals  610  and passed by conductors  624  to output terminals  612  to the streetlight control  240  and lamp  242 , forming lighting circuit  601 . Charging circuit  602  is powered by conductors  624 , but the pickoff conductor  630  is at or near output terminals  612  so that current detector  640  will read the sum of currents drawn by lighting circuit  601  and charging circuit  602 . 
         [0065]    The driver  642  shown in  FIG. 6  is an example of a more integrated control circuit  603 , where the ground-fault detection coil  636 , current detector  640 , and coil  644  of relay  643  implement the functions of control circuit  503 , but without separate ground fault circuit interrupt  536  and circuit breaker  532 . 
         [0066]    In this arrangement, reset switch  334  may be electrical, as shown, and cause driver  642  to close contact  634 , provided the current in conductor  624  is not already too high (i.e., using enough current that allowing a vehicle to charge would likely exceed the rating of fuse  222 ). Alternatively, reset switch  334  may be mechanical (not shown), allowing manual, latching closure of contact  634 , again provided the current in conductor  624  is not already too high. Care should be taken that a mechanical reset switch  634  does not permit an operator to directly and continuously hold contact  634  closed, as this would override the control of driver  642  and could permit currents in conductor  624  to threaten fuse  222 . 
         [0067]    Having driver  642  responsive to the total of the currents drawn by lighting and charging circuits  601  and  602  is desirable, since a retrofit of streetlight  102  in which lamp  242  is replaced with an LED-based illuminator (not shown) would likely reduce the current draw of circuit  601  well below the rating of fuse  222 , and this may be sufficient to allow simultaneous operation of lighting and charging circuits  601  and  602 . 
         [0068]    That same advantage can be obtained using another embodiment, shown in  FIG. 7  in which the streetlight circuit  701  passes through charging control module  332  at input terminals  710 , through conductors  724 , and output terminals  712 . Conductor  730  of charging circuit  702  taps off of conductors  724  near input terminals  710 . Charging circuit  702  can be interrupted by contact  734  of relay  743 . In this embodiment, charging control circuit  703  uses current sensor  740  to monitor the current in lighting circuit  701 , while current sensor  746  is used to monitor the current in charging circuit  702 . Driver  742  computes the total current drawn by lighting and charging circuits  701  and  702  (whether through an analog sum or through separate analog to digital conversions which are then summed). If the total current drawn is above a value determined to threaten fuse  222 , then coil  744  is appropriately driven to cause contact  734  to open. 
         [0069]    Ground-fault sensor  736  may be monitored by driver  742  to interrupt circuit  702  with relay  743  when a ground-fault is detected. 
         [0070]    Switch  334  may be an electrical or mechanical switch to reset contact  734  following an over-current or a ground-fault detection which resulted in contact  734  being opened. 
         [0071]    To measure power usage, driver  742  also comprises voltage monitor connection  748 . The instantaneous product of the measured voltage (e.g., in volts) at connection  748  and the current measured with current detector  746  (e.g., in amps) represents the instantaneous power drawn through circuit  702  (in watts). By measuring this instantaneous power periodically (e.g., 1000 times per second) and multiplying that reading by the period (i.e., 1 mS), and accumulating the result as the measure of energy transferred (i.e., watt-seconds, or with the appropriate conversion factors, kilowatt-hours). A similar measure of energy delivered to lighting circuit  701  may also be made and recorded, if desired. 
         [0072]    In a case where electric vehicle  110  comprises a utility-interactive inverter and power is being fed from electric vehicle  110  to power supply  214 , then such instantaneous power measurements would register a supply of power by vehicle  110 , rather than a draw, and may be credited in accordance with the utility&#39;s policy. 
         [0073]    A similar measurement could be made with current detector  640  of charging control circuit  603  (which would, of course, require the additional of a voltage measurement connection like  748 , not shown in  FIG. 6 ), so that a power measurement would represent the total power being delivered to both lighting circuit  601  and charging circuit  602 . Power measurements accumulated only when contact  634  was closed, or only during certain hours of the day, could be presumed to be substantially or exclusively due to energy delivered through charging circuit  602 , if such a separation was desired. 
         [0074]      FIG. 7  also shows monitoring and communication subsystem  750 , which also may be connected to charge control circuit  503 ,  603 . 
         [0075]    Monitoring and communication subsystem  750  preferably comprises a control  752  having access to memory  754  for storing the software program of control  752 . Memory  754  may also store data, for example, data representative of the accumulated power (i.e., energy, as in watt-hours) delivered through charger circuit  702  as measured and communicated by driver  742  to control  752 . Such record of energy delivered is preferably stored in non-volatile memory. (Note that while this is a preferred implementation for an energy meter, other implementations are well known.) 
         [0076]    Memory  754  may also contain a unique identifier for identifying charging control module  332 , and by association, streetlight  102 , which is useful for reporting and management. Alternatively, a unique identifier may be provided in control  752  (e.g., a unique CPU serial number) or in communications module  756  (e.g., a Media Access Control address, or MAC address). 
         [0077]    Monitoring and communication subsystem  750  may comprise a human readable display (not shown) and/or a short range wireless reporting system (not shown) such as those commonly used for utility meter reading to allow efficient readout of the record of energy delivered and the unique identifier of the charge control module  332 . 
         [0078]    Preferably, monitoring and communication subsystem  750  further comprises communication module  756  which is able to connect through communication channel  762  with management server  760  located at a remote site, for status monitoring, meter reading, and billing (discussed below in conjunction with input  336 ). Communication channel  762  preferably comprises a wireless leg and may further comprise other communications legs, including the Internet. The wireless leg(s) may be based on any of a number of wireless network technologies, for example, cellular telephone, IEEE 802.11 (i.e., WiFi), or IEEE 802.15.4 (i.e., ZigBee). In some wireless network topologies, for example those using ZigBee, communications from charging control module  332  in one streetlight  102  may be routed and relayed through other such modules  332  in other streetlights  102  until a gateway is reached. 
         [0079]    Management server  760  may receive reports from charging control modules  332 , or may interrogate them, or both. Whether communication is initiated by management server  760 , or by communication module  756 , management server  760  is able to access status, energy meter records, and other information. 
         [0080]    Monitoring and communication subsystem  750  preferably comprises input  336 , which accepts an authorization code (which may be an identification) supplied by a user before enabling charging circuit  702  and outlet  108 . Preferably, input  336  is an RFID (radio-frequency identification) reader that is able to read authorization token  770 , comprising an RFID tag. Alternatively, authorization token  770  may be a magnetic card (for instance, a credit card or drivers license) and input  336  comprises a magnetic card reader, in which case the authentication code comprises the credit card number or drivers license number contained on the magnetic stripe of the card). In still another embodiment, input  336  may comprise a keyboard and a user enters an authentication code (i.e., an identification number, personal identification number, or passcode) manually, rather than using a token that is read. 
         [0081]    If, as a matter of policy, only validated users are permitted to make use of charger outlet  108 , then an RFID tag or other authorization token, identification code, or passcode would be provided to the authorized users in advance. The authorization code would be accepted by input  336 . The authorization code so received is used by control  752  to query management server  760  (through communication channel  762 ) to verify the authorization code. If server  760  responds that the authorization code represents a currently authorized user, then the user is validated and charging circuit  702  may be energized. 
         [0082]    Also, if as a matter of policy, use of the charging outlet  108  is billed, either by time or by energy consumed, then the authentication code would be used by management server  760  to charge the user&#39;s corresponding account. In this case, management server  760  may accumulate the monthly usage by each user and bill periodically (e.g., adding the energy consumed from each of a user&#39;s chargings to the user&#39;s utility bill, and in the case of an electric vehicle with a utility-interactive inverter, crediting a user for energy supplied by the vehicle), or may handle each transaction independently (e.g., placing a charge or credit to the credit card used as authorization token  770 ). 
         [0083]    Thus, a simple example use case would be that, during daylight hours, while the streetlights  102  are not lit, a user (not shown) pulls up to streetlight  102  in electric vehicle  110  and parks. User connects vehicle  110  to charging station  100  by plugging charging cable  112  into charging outlet  108 . If necessary, user presses reset switch  334  to clear a previous ground-fault circuit interrupt or current overload condition. If needed, the user presents an authorization code through input  336 , for example by passing a key fob containing an RFID authorization token  770  in proximity to input  336 . Charging circuit  502 ,  602 , or  702  is active, and electric vehicle  110  is charging. As the sun sets, streetlight control  240  begins to light lamp  242 . The increased current drawn by lighting circuit  501 ,  601 , or  701  is detected, and relay  543 ,  643 , or  743  actuates to open lighting circuit  502 ,  602 , or  702 , all respectively, without threatening fuse  222 . 
         [0084]    In implementations that can determine that the total current of both the lighting and charging circuits ( 601 ,  701  and  602 ,  702 , respectively in  FIGS. 6 and 7 ), it may be the case that the charging of electric vehicle  110  has slowed to the point where the addition of the operating current of lamp  242 , when lighting or when lit, does not exceed the rating of fuse  222 , in which case, relay  643  or  743  may remain closed. This will be especially true if lamp  242  is a retrofit LED-based illuminator that consumes substantially less power than streetlight  102  was originally designed to draw. 
         [0085]    While the schematics of  FIGS. 5-7  have shown a single-phase power supply to facilitate explanation, the principles presented here can be adapted for a two- or three-phase power system to provide more power and correspondingly shorter vehicle charge times. 
         [0086]    A state transition diagram  800  for the charging station  100  of the present invention is shown in  FIG. 8 . 
         [0087]    Unpowered, faulted state  810  is the initial state, occurring when charging control module  332  is unpowered with a fault recorded. Preferably, module  332  is delivered from the factory in this state. The only transition from this state occurs when power is applied  811 , where module  332  transitions to a faulted state  820 . 
         [0088]    In faulted state  820 , charging circuit  502 ,  602 ,  702  is off. If power is removed  821  while in faulted state  820 , the module  332  transitions back to unpowered, faulted state  810 . If reset switch  334  is thrown  822 , module  332  transitions to check state  830 . 
         [0089]    In check state  830 , charging circuit  502 ,  602 ,  702  remains off. Upon entry to check state  830 , and if capable, driver  542  first tests for a wiring fault (e.g., a reversal of hot and neutral lines feeding the charging circuit) and if detected  831 , module  332  transitions back to faulted state  820 . This prevents module  332  from operating while miswired. Otherwise, if power is removed  832  (or fails), module  332  transitions to unpowered, unfaulted state  840 . If substantial current is detected  833  in lighting circuit  501 ,  601 ,  701 , indicative of lamp  242  lighting or being lit, or lamp  242  is otherwise detected as being lit, then module  332  transitions to lamp on state  860 . Otherwise, lamp  242  is considered off  834 , and module  332  transitions to ready state  850 . 
         [0090]    From unpowered, unfaulted state  840 , the only transition is when power is reapplied  841 , to check state  830 . In an alternative embodiment, unpowered, unfaulted state  840  may be folded together with unpowered, faulted state  810 , and when power is restored, the successor state is faulted state  820 . 
         [0091]    On entry to ready state  850 , charging circuit  502 ,  602 ,  702  is enabled, unless required by policy to be enabled by an authorization or activation through input  334  (not explicitly shown in state transition diagram  800 ). If power is removed  851 , the system transitions to unpowered, unfaulted state  840 . If a ground-fault is detected  852 , or a ground-fault is induced by test  853 , the state transitions to faulted state  820 , and charging circuit  502 ,  602 ,  702  is disabled. If the charging circuit  502 ,  602 ,  702  current draw exceeds a predetermined value  854 , a value selected to protect fuse  222 , then the system transitions to faulted state  820 : In the case of example charging circuit  502 , this would correspond to tripping the circuit breaker  532 , whereas in example charging circuit  602 ,  702 , the corresponding driver  642 ,  742  would open the corresponding relay  643 ,  743 . If the aggregate current draw of charging circuit  602 ,  702  and lighting circuit  601 ,  701  exceeds a predetermined value  855  (or if lamp  242  is detected as being lit in lighting circuit  501 ), a value selected to protect fuse  222 , then the system transitions to lamp on state  860 , where charging circuit  502 ,  602 ,  702  will be disabled, thereby relieving the over-current situation before fuse  222  is damaged. 
         [0092]    Upon entry into lamp on state  860 , charging circuit  502 ,  602 ,  702  is disabled, and the streetlight  102  operates normally. Note that charging control module  332 , as shown, does not protect fuse  222  from excessive currents drawn solely by lighting circuit  501 ,  601 ,  701 . From lamp on state  860 , if power is removed  861 , the state transitions to unpowered, unfaulted state  840 . When the current in lighting circuit  501 ,  601 ,  701  is detected as being below a predetermined value  862  indicating that lamp  242  is no longer lit, charging control module  332  transitions to ready state  850 . Preferably, the predetermined value that indicates that lamp  242  is no longer lit is different than the predetermined value indicative of lamp  242  lighting used to trigger transition  855 , as some degree of hysteresis is desirable to prevent unwanted, rapid oscillations between ready state  850  and lamp on state  860 . A time delay of several seconds or minutes may further be included in conjunction with transition  862  during which a re-lighting of lamp  242  would cause the system to return to lamp on state  860  without having energized charging circuit  502 ,  602 ,  702 . 
         [0093]    Embodiments of the present invention should comply with Article  625  of the National Electrical Code, and if used to support an electric vehicle feeding energy back into the electric grid, then embodiments should further comply with Article  705 . 
         [0094]    Various additional modifications of the described embodiments of the invention specifically illustrated and described herein will be apparent to those skilled in the art, particularly in light of the teachings of this invention. It is intended that the invention cover all modifications and embodiments, which fall within the spirit and scope of the invention. Thus, while preferred embodiments of the present invention have been disclosed, it will be appreciated that it is not limited thereto but may be otherwise embodied within the scope of the following claims.