GB2567467A

GB2567467A - Power distribution unit

Info

Publication number: GB2567467A
Application number: GB1716757.8A
Authority: GB
Inventors: Becerra Daniel
Original assignee: Buffalogrid Ltd
Current assignee: Buffalogrid Ltd
Priority date: 2017-10-12
Filing date: 2017-10-12
Publication date: 2019-04-17
Also published as: GB201716757D0; WO2019073264A1

Abstract

A power distribution unit, suitable for charging battery powered devices, in particular mobile phones, in off-grid environment, such as remote or rural villages or communities without civic utility services. A first device disclosed comprises multiple connection ports, each port providing at least two male electrical connection pins, and a controller configured to selectively enable power to each port. A second device disclosed comprises a housing formed of two mating parts, and a printed circuit board disposed between the two housing parts, mounted to one of them to provide a substantially inaccessible compartment, which contains batteries, the housing further comprising output ports for receiving electrical output connectors, and a controller for selectively enabling power to each port. The connection ports may be housed within recesses 510, which may be open at one end, in order to allow the egress of liquids and contaminants, to prevent clogging of the port or contamination using to breakdown, making it suitable for outdoor use. A wireless communication system, such as a modem, may be housed within the unit. Connection leads 610 are also disclosed, with suitable female receiving ports 705, 603 and connections to battery powered units to be recharged 615 and power inputs.

Description

POWER DISTRIBUTION UNIT [0001] This invention relates to a power distribution unit for distributing electrical power in an off-grid environment.

BACKGROUND [0002] Across the world, large populations must function without grid power. Such offgrid environments are typically in remote areas, where infrastructure has not been developed to provide electricity for the local populations. As such, off-grid communities are forced to operate without electricity. To help alleviate this problem, solar panels or diesel generators may be used to provide a temporary source of power to charge a battery, which may subsequently be used to provide electricity.

[0003] Despite off-grid communities having no access to electricity, a growing proportion of the population has mobile network coverage. Mobile phones are one of the main ways off-grid communities communicate. Anyone wishing to operate a business in such an environment is heavily reliant on their mobile phone, as this provides not only the way to communicate to other people, but is increasingly becoming the way to manage finances, as banks are often located in cities and towns far away from the off-grid communities. A power distribution system able to reliably dispense electrical power is essential to being able to operate in the off-grid environment.

[0004] Our international patent application WO2014/114959 describes a power distribution system for distributing electrical power in an off-grid environment. The present disclosure relates to advantageous features of a power distribution unit for use in such a power distribution system.

BRIEF SUMMARY OF THE DISCLOSURE [0005] Viewed from a first aspect, the present invention provides a power distribution unit for distributing electrical power in an off-grid environment to a plurality of battery-powered electrical devices, in particular mobile telephones. The unit comprises: a housing having an external surface; a plurality of electrical output ports provided at the external surface of the housing, each output port being configured to receive a complementary electrical output connector for connection to a respective electrical device to be charged; and a controller within the housing configured to selectively enable the supply of electrical power to each output port. Each output port comprises a first pin for connection to the electrical connector and a second pin for connection to the output connector. The first and second pins are arranged to supply electrical power to an electrical device to be charged when the output port is enabled. The first and second pins project from the external surface of the housing.

[0006] Thus, the invention provides a convenient configuration of the output ports of the power distribution unit in which the power supply pin project from the outer surface of the housing. This is contrary to the usual configuration of power supply connector, in which the live connector is a socket in order to protect the user from the live electrical connections. According to the invention, however, the output ports are selectively enabled by the controller, which reduces the risk of harm to the user. In addition, a detection circuit may be provided to ensure that the output port is only supplied with electrical power when an electrical connector has been attached to the output port. In the context of the invention it has been found highly advantageous to provide exposed, projecting pins rather than sockets, as the pins can be cleaned easily and do not become blocked with debris.

[0007] As mobile phones are often the device most in need of charge, recharging stations typically use USB ports as the interface between the power supply and the portable device requiring charge. However, while this may be adequate in an indoor space or when using a miniature power pack for an individual to charge their device when outside, the off-grid environment provides considerably harsher conditions than USB ports are intended for. Off-grid communities are often located in remote locations where wind, rain and debris may quickly accumulate in a USB port, quickly resulting in the USB port becoming unable to connect to a device for charging. As more of the USB ports on a power distribution system stop functioning, the effectiveness of the unit rapidly decreases until people are no longer able to recharge their mobile phone. The present invention, at least in preferred embodiments, solves this problem.

[0008] The external surface of the housing may define a respective recess for each output port. The recess may be configured to receive the output connector. The first and second pins may be provided within the recess. In this way, the recess assists in locating the output connector on the output port.

[0009] The recess may have a depth. The recess may be open at an end thereof, in particular to the depth of the recess. In this way liquid can drain from the recess.

[0010] Each output port may further comprise at least a third pin configured to connect at least mechanically with the output connector. Such a third pin may be electrically conductive or may be electrically insulating and therefore provide only mechanical engagement with the output connector. Similarly, each output port may further comprise at least a fourth pin configured to connect at least mechanically with the output connector.

[0011] The third pin and/or the fourth pin may be configured to connect electrically with the output connector. In embodiments of the invention the output port may be configured to mimic the electrical characteristics of a USB port.

[0012] The first and second pins may be mutually spaced by a first distance. The third and fourth pins may be mutually spaced by a second distance. The first distance may be different to the second distance. In this way, the orientation of the output port can be defined to prevent misconnection of the output connector.

[0013] The first and second pins may define a first axis. The third and fourth pins may define a second axis substantially parallel to the first axis. The first and second axes may be offset from one another in a direction substantially perpendicular to the first and second axes.

[0014] The housing may comprise a first housing portion and a second housing portion which mates with the first housing portion to provide a complete housing. The power distribution unit may further comprise a printed circuit board. The printed circuit board may be mounted within the housing between the first housing portion and the second housing portion, whereby to define a first compartment between the first housing portion and the printed circuit board and a second compartment between the printed circuit board and the second housing portion. The second compartment may contain batteries and the printed circuit board may be mounted to the second housing portion, whereby the second compartment is substantially inaccessible to the user. In this way, the printed circuit board provides a barrier between the user and the batteries, which should not be accessed by the user, while providing a user-accessible first compartment which can contain userserviceable components, such as a modem.

[0015] This in itself is believed to be novel and thus viewed from a further aspect the invention provides a power distribution unit for distributing electrical power in an off-grid environment to a plurality of battery-powered electrical devices, in particular mobile telephones, comprising: a housing having an external surface; a plurality of electrical output ports provided at the external surface of the housing, each output port being configured to receive a complementary electrical output connector for connection to a respective electrical device to be charged; optionally a controller within the housing configured to selectively enable the supply of electrical power to each output port, wherein the housing comprises a first housing portion and second housing portion which mates with the first housing portion to provide a complete housing, and the power distribution unit further comprises a printed circuit board, wherein the printed circuit board is mounted within the housing between the first housing portion and the second housing portion, whereby to define a first compartment between the first housing portion and the printed circuit board and a second compartment between the printed circuit board and the second housing portion, wherein the second compartment contains batteries and the printed circuit board is mounted to the second housing portion, whereby the second compartment is substantially inaccessible to the user.

[0016] The printed circuit board may comprise a plurality of light emitting diodes (LEDs) for indicating which output port has been enabled by the controller. The first housing portion may be a transparent plastics moulding comprising a plurality of light pipes configured to transmit light from the LEDs to the external surface of the housing.

[0017] The power distribution unit may further comprise a mobile modem. The modem may be located in the first compartment.

[0018] An elastomeric gasket may be provided between the first housing portion and the second housing portion. The gasket may ensure a waterproof, e.g. IP68, sealing of the housing.

[0019] The power distribution unit may comprise a first heat sink provided at a first end of the power distribution unit and a second heat sink provided at a second end of the power distribution unit, the first end being opposite to the second end, each heat sink providing an outer surface of the power distribution unit. The first heat sink may be in thermal contact with an input power management circuit. The second heat sink may be in thermal contact with an output power management circuit.

[0020] The power distribution unit may comprise a fascia releasably mounted to the housing.

[0021] The power distribution unit may further comprise an input power management circuit and at least one electrical input port configured to receive power from an external power supply. The electrical input port may comprise a first power input pin, a second power input pin and a source selection pin. The input power management circuit may be configured to apply a voltage to the source selection pin, whereby to identify a type of the external power supply by reference to the response of the source selection pin to the applied voltage. The invention extends to an electrical input connector comprising a plurality of female connectors configured to receive the power input pins and source selection pin of the power distribution unit.

[0022] The invention further extends to an electrical output connector comprising first and second female connectors configured to receive the first and second pins of the power distribution unit and a further connector configured for connection to a portable electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS [0023] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1A shows a perspective view of a portable power distribution unit;

Figure 1B shows an exploded view of a fascia separated from a housing of the portable power distribution;

Figure 1C & 1D show perspective views of a portable power distribution unit with electrical input and electrical output connectors connected;

Figure 2 shows an exploded view of the housing of the power distribution unit;

Figure 3 shows a perspective view of the inside of the removeable fascia;

Figure 4 shows a perspective view of the inside of a front portion of the housing;

Figure 5 shows an exploded view of a printed circuit board and a rear housing portion;

Figure 6 shows a perspective view of the housing with the rear housing portion detached from a front housing portion;

Figure 7 shows a rear view of the housing;

Figures 8A - 8C show perspective views of a gasket used to connect the front portion of the housing to a rear portion of the housing;

Figures 9A & 9B show views of exemplary electrical output connectors;

Figures 10A - 10C show views of exemplary electrical input connectors;

DETAILED DESCRIPTION [0024] The present portable power distribution unit is intended to provide a safe and reliable way to provide power to communities in an off-grid environment.

[0025] Figure 1A shows a perspective view of a portable power distribution unit 100. As shown in Figure 1B, the recharging unit 100 includes a fascia 110 that can be removed from a housing 105. The housing 105 is designed to prevent debris and liquid reaching the internal region of the housing 105 where the componentry of the power distribution unit 100 are located. Figure 1C shows a perspective view of the portable power distribution unit 100 with electrical input 700 and electrical output 600 connectors connected. The present arrangement of output ports 415 is particularly effective, as it is desirable for a vendor wishing to operate a business using a power distribution unit to have capacity for a large number of charges simultaneously. For example, demand may peak during waiting times for a bus or a train, and so to make a viable business from the power distribution units a large number of charging ports, for example greater than 20, is desirable. To provide an efficient system, the unit 100 may include a locking mechanism configured to enable individual charging ports and to illuminate an LED to indicate which charge port 415 has been enabled for a user. This may be in response to an authorisation message received from a remote server, or may be determined by a controller within the unit 100.

[0026] The rear portion 500 of the housing contains a plurality of electrical output ports 415 formed of a plurality of exposed pins located within a recess in the rear portion 500. The unit may comprise a plurality of electrical input ports 420 formed of a plurality of exposed pins located within a different recess of the rear housing portion 500. Also shown are a plurality of heat sinks 515, an antenna input 428 and a selectively permeable vent 520. The construction of the housing 105 is best shown in Figure 2.

[0027] The housing 105 is formed by connecting a front housing portion 200 to a rear housing portion 500. A liquid-tight seal is created by sandwiching a gasket 300 between the front 200 and rear portions 500. As shown in Figure 2, a PCB 400 is located within the rear portion 500 which is used to mount the componentry needed to operate the hub 100. Components such as a screen 403 or a modem 405, can be secured to the PCB 400 and be used to display information received via a telecommunications network to users of the recharging unit 100 or people in the vicinity. Such information could be advertising, or could be specific to a user’s charge request. The modem 405 may also receive unlocking instructions from a remote server via the telecommunications network so that one of the charge ports 415 is enabled following a request by a user for charge. This may be achieved by sending an SMS text message to a predetermined phone number. Similarly, making an unanswered call to a predetermined phone number may be used to generate a charge request. In either case, following a request by a user for charge, a remote server can transmit an authorisation message to the locking mechanism of the power distribution unit 100 via a telecommunications network.

[0028] Figure 3 shows a perspective view of the inside of the removeable fascia 110. The fascia 110 has a front face 112, side walls 135 and a handle 115 which can be used to handle or move the portable unit 100. The front face 112 may be marked with different indicia to identify functions of the recharging hub 100 or advertising or branding. This allows the underlying componentry within the housing 105 to be used for a variety of vendors or operators by only changing or manufacturing a new fascia 110. As the fascia 110 does not form part of the sealed product, it can be manufactured cheaply and replaced if damaged or swapped if required, for example for advertising reasons. The preferred implementation of the present unit 100 is to mount the fascia 110 to the housing 105 using a series of releasable fixings through attachment holes 145. Releasable fixings include screws or bolts, but it would be understood by the skilled person that other fixings, such as cantilever clips, that can be releasably connected would be equally suitable. As shown, the fascia 110 comprises a camera port 130, indicator ports 140 and a screen port 125. These ports allow visual indicators or screens 403 located within the housing 105 to be displayed through the ports in the fascia 110. These do not affect the liquid-tight seal of the housing 105, as the fascia 110 is used as a form of additional surface protection with no electrical connection to the componentry within the housing 105.

[0029] Figure 4 shows a perspective view of the inside of the front housing portion 200. The front portion 200 is preferably formed as a single moulding to ensure a waterproof surface. A front face 205 and side walls 214 make up the overall structure of the front portion 200 and in combination with the PCB 400 define a user-accessible region 215 of the housing. This region 215 is accessible to a user, because it contains components, such as a modem 405 able to store a sim card 412 so that the recharging unit 100 may communicate via the telecommunications network. Additionally, any repairs, for example to the screen 403 or any wiring connecting any of the components may be performed by local maintenance workers without risk of injury as the electrical hazard posed by the battery pack is located in a user-inaccessible region 530 (see Figure 5). A screen cover portion 210 is formed as part of the front face 205. This ensures information displayed on the screen 403 placed behind the front portion 200 remains visible to customers walking past the unit 100. Similarly, a camera cover portion (not shown) is formed as part of the front housing portion 200 to enable video communication via the power distribution unit 100. Preferably the front portion 200 is manufactured as a single transparent plastics moulding. This avoids the need to include holes in the front face to accommodate screens 403 or cameras which would subsequently require sealing to make the housing 105 water-tight. By using a single solid transparent piece, it is also possible to easily incorporate a series of light pipes 225 to optically connect LEDs located on the PCB 400 or mounted to components attached to the front portion 200, which are not necessarily in close proximity to the front face 205, to the customers by protruding these light pipes 225 through the indicator ports 140 on the fascia 110. The light pipes 225 may be of different lengths depending on the distance between the LED on the PCB and the front face 205. As the front 200 and rear 500 portions are separable, it would be impractical to ensure any LEDs located in the user-inaccessible region 530 remain aligned to a series of holes in the PCB 400, the front portion 200 and the fascia 110 after maintenance of components in the useraccessible region 215, particularly if the number of LEDs is high, as is the case with a unit 100 having many recharging ports. The LEDs used may be any combination of RGB or RG and may be configured to flash or remain solid in a particular colour to indicate to the user or vendor information such as a low internal battery level, a charge is complete, or the hub is connected to a telecommunications network.

[0030] By manufacturing the front portion 200 as a single piece, it is possible to tightly control the dimensions of each light pipe 225 to ensure the information displayed by LEDs within the housing 105 are displayed clearly on the outside of the housing 105 and fascia 110. This is due to the PCB 400 being secured to the rear portion 500 and the front portion 200 also being secured to the rear portion 500. Therefore, the light pipe 225 is always located in very close proximity to the LED and information can be reliably displayed outside the fascia for users and vendors to see. As the LEDs are located in the userinaccessible region 530, holes 435 are cut into the PCB 400 so that light emitted by each LED can be transmitted across the PCB 400 into the user-accessible region 215 and a light pipe 225 located substantially over a corresponding hole 435 can relay this information to a user.

[0031] Figure 5 shows an exploded view of the PCB 400 and the rear housing portion 500. As shown, the PCB 400 has a plurality of mounting holes 440 to provide mounting points for components such as rechargeable batteries (not shown) used as part of the power distribution system. The power source may be a series of rechargeable batteries, such as lithium-ion batteries. Further, the pins for the charging ports 415 and input ports 420 are moulded into the rear portion 500 to ensure a water-tight seal is maintained across the entire rear portion 500. Similarly, the antenna input 428 is moulded into the rear portion 500. The projecting pins 417, 422 are connected to the PCB 400 by a sprung connection which is configured such that contact is maintained between the pins 417, 422 and the PCB 400.

[0032] As shown in Figure 5, the external surface 535 of the rear portion 500 incorporates two recesses 525 that are configured to accommodate two heat sinks 515 used to dissipate heat from the housing 105. Components that pose an electrical hazard or that should not be maintained by local vendors are mounted to the PCB 400 and located in a user-inaccessible region 530 of the housing 105. The rear portion 500 is designed to accommodate these components. The user-inaccessible region 530 is defined by the surface 535 of the rear portion 500 and the substrate of the PCB 400. By securing the PCB to the rear housing using security screws, it is considerably more difficult for a user or maintenance person to injure themselves during maintenance of the housing 105.

[0033] Figure 6 shows a perspective view of the housing 105 with the rear housing portion 500 detached from the front housing portion 200. This view best shows the types of components located in the user-inaccessible region 530. One inductor coil 425 is located at the top of the PCB 400, whereas a further four inductor coils 425 are located at the base of the PCB 400. Also shown is an access port 430 for the antenna (not shown) and a plurality of PCB bus bars 445 arranged along the rows of output ports 415 and inductors 425. As shown in Figure 5, the rear portion 500 is configured to securely mount two heat sinks 515 located at opposite ends of the housing so that the inductor coils 425 and other heat generating components are placed into direct physical contact with the heat sinks 515 when the housing 105 is assembled.

[0034] Figure 7 shows a rear view of the housing 105. When describing the recharging port 415, reference will be made to the recharging connector 600 which is best illustrated in Figures 9A and 9B. The rear portion 500 comprises a plurality of recharging ports 415 having a recess 505 and a plurality of pins 417 projecting from the external surface 535 of the rear portion 500 away from the housing 105. Optionally, the recess may have a slot 510 substantially the depth of the recess to accommodate the electrical cable from the recharging connector 600. As shown, two rows of electrical output ports 415 are arranged along the sides of the PCB 400. Each port 415 comprises first and second pins configured to provide a charging voltage therebetween. One of the first or second pins may be electrically earthed. Optionally, third and fourth pins may be provided which provide additional mechanical stability to a connector 600 connected to the charging port 415. The presence of exposed charging pins 417A, 417B is not common, as this may be considered an electrical hazard. However, the present power distribution unit 100 is configured to detect when a connector 600 is connected to one of the charging ports 415 and unless a charging connector 600 is connected, the charging pins 417A, 417B of the output port 415 are not enabled for charging and do not pose an electrical hazard. Ensuring the output ports 415 are only enabled by the central controller of the unit 100 also prevents vendors from acting unscrupulously and charging customers to recharge their device outside of the authorised economic agreement for the power distribution unit 100. Further, it is also not possible for a person to manually enable a charge port 415, which might pose an electrical risk. By requiring a connector 600 to be connected before a charge port 415 is powered, this electrical risk is virtually eliminated.

[0035] Preferably, the third and fourth pins are used to carry data signals and provide electrical connections and mechanical stability to a connector connected to the output port. However, the third and fourth pins may provide mechanical support only. Pins acting as a mechanical support may be made of a polymer or insulating material, such as plastics. It would be apparent to the skilled person that a single wider pin may be configured to provide sufficient stability to the connector and that it is not essential to use two pins to act as the mechanical support. Where four electrical connections are provided, the recharging port 415 of the power distribution unit 100 is able to mimic the functionality and/or electrical characteristics of a USB port. However, unlike a USB port which will accumulate debris over time and with use in the off-grid environment, the ports 415 of the present charging unit 100 are easy to clean, as the recess 505 and projecting pins 417 are easily accessible and therefore any debris located within the port 415 can be easily removed to keep the port clean and functioning.

[0036] It should be noted that the recharging unit of the present disclosure is intended for off-grid use, and therefore must remain operational in strong wind and rain. The pins 417 of the recharging port 415 are considerably more robust than a USB port which is not suitable for the harsh environmental conditions. The output port 415 comprises pins 417 that are preferably made of steel, in particular stainless steel. Further, using a relatively large gauge pin will ensure the pins 417 are robust compared to standard electrical pins. A larger gauge pin also enables the system to handle larger currents entering and leaving the hub 100. This creates power input 420 and output 415 ports that are considerably more rugged than typical USB ports. The pins 417 of the charging port 415 are arranged such that the first and second pins 417A, 417B are spaced to prevent electrical bridging between the charging pins 417A, 417B when liquid residue may reside in the recess. Having a slot 510 located in the side wall of the recess 505 that is substantially the depth of the recess prevents liquid pooling in the charging port 415 which may cause damage to the electrical components of the housing 105 by short-circuiting the charging pins of the output port 415. To provide additional mechanical stability, the third 417C and fourth 417D pins are arranged offset to the charging pins. The charging pins 417A, 417B and stabilising pins 417C, 417D may be offset laterally to one another, such as shown in Figure 7. The spacing between the charging pins 417A, 417B may be different to the spacing between the stabilising pins 417C, 417D in order to ensure that the charging connector 600 is connected in the correct orientation.

[0037] The recess 505 and corresponding output connector head 605 are configured to form complementary shapes that determine the orientation of the output connector 600. The cross-sections of the recess 505 and output connector head 605 are intended to form a tight fit which will substantially prevent liquid and debris from entering the recess 505 when connected, but not so tight that a user cannot remove the output connector 600 when they have finished charging their device. When the output connector 600 is connected to the charging port 415, a complementary fit between the pins 422 and the corresponding sockets 606 receiving the pins is formed to prevent damage or liquid entering the sockets 606. This is significantly more robust than USB ports typically used for such purposes. Preferably the sockets 606 and pins 415 are made from the same material to prevent oxidation or chemical corrosion of one or both surfaces. Preferably the sockets

606 and pins 415 are made from steel, in particular stainless steel. To aid removal of the output connector 600 the head 605 has a grooved profile 603 at one end to enhance a user’s grip on the connector head 605. The output connector 600 further comprises a sleeve 607 used to reinforce the interface at which the cable 610 enters the connector head 605. The slots 510 in the output port 415 are configured to receive the sleeve 607 and aid the fit of the output connector 600 in addition to preventing a build-up of liquid in the charging port 415. By having a slot 510 as part of the port 415, the rows of output ports 415 have a series of grooves which aids locating a specific port by a user, as the output ports 415 are typically located on the back side of the unit 100 facing away from the user (see also Figures 9A and 9B).

[0038] As shown in Figure 9A and 9B, the connector cable 610 is a four-core cable and can provide connections 615 for each of the charging and data pins should this be required. The output connector 600 may include electronics which identify the output connector as genuine. The charging electronics for the charge port 415 include a microcontroller or control chip configured to recognise different types of devices when connected so that the power output can be optimised for the specific connected device. A further microcontroller located in the output connector head 605 may be configured to enable the higher power domain of the USB-C protocol whilst remaining compatible with older USB protocols. The control electronics of the charge port 415 is configured to detect a connected device if the charge port 415 is activated. Each charge port 415 is controlled by a central locking mechanism within the housing which is configured to receive an authorisation signal or authorisation message from a remote server.

[0039] When describing the electrical input port 420, references will be made to the input connector 700 used to connect the external power supply to the input port 420. The input connector is best illustrated in Figures 10A to 10C. The input port 420 is formed of a recess 502 with a plurality of pins 422 projecting from the recessed surface away from the housing 105. The input port 420 comprises a pair of pins 422A, 422B configured to receive an input charging voltage and a further pin 422C configured to receive an identification signal from an input connector 700. The pair of input pins 422A, 422B are spaced apart and the source selection pin 422C is preferably located between the input pins 422A, 422B. The source selection pin 422C may be offset from a notional line extending between the pair of input pins 422A, 422B. When not in use, the input ports 420 may be covered by a connector cap to prevent debris or egress of liquid into the input port 420.

[0040] The input port 420 of the present unit is particularly effective, as the source selection pin 422C is part of a power management circuit configured to passively detect the presence and type of input source. Passive detection of the presence and type of external power source is important, as active detection would require power to be consumed to detect the presence of an external power supply. This is inefficient use of any power stored within the unit 100, but also requires the unit 100 to always have an on-board power source. For example, the external power source may be a power brick 720 (i.e. an external battery pack), a solar panel or grid power (when available). Knowing what type of external power supply is connected to the power distribution unit 100 is important, as a constant power supply, such as grid power or a power brick, is managed differently to a non-continuous power source, such as a solar panel. Where a non-continuous or varying power source is present, the maximum power point tracking (MPPT) algorithm is used to maximise the power harvested from a solar input in order to optimise the charging of any on-board batteries in the device. If the MPPT algorithm is applied to a power brick, it will rapidly reduce the lifespan of the power brick due to the way the MPPT probes the supply for different power levels. The power management circuit is configured to passively detect the presence and type of external power supply connected to the input port 420 by probing the source selection pin 422C for different identification signals. In a simple arrangement, the source selection pin 706C of the input connector 700 is connected to the earth pin 706B within the input connector head 705 to identify one type of external power supply and the source selection pin 706C of the input connector 700 is left unconnected within the input connector head 705 to identify a different type of external power supply. When a voltage is applied to the source selection pin 422C of the input port 420, there will only be a resultant current drawn by the source selection pin 706C of the input connector 700 for the first type of external power supply where the source selection pin 706C is connected to the earth pin 706B. By having the identifying circuit in the input connector 700, the plurality of input ports 420 can be used to receive a combination of external power supplies. For example, any combination of solar panel, power brick 720 and grid power can be used at the same time to provide power to the unit 100.

[0041] Further, two selectively permeable vents 520 are installed into the rear housing portion 500 to allow air and any build-up of air pressure within the housing to escape, while preventing any liquid from being able to enter the housing 105. The vents are designed to allow gas to pass through at a rate of up to 2L/min while preventing any liquid ingress. While 2L/min is given as an exemplary flow rate, vents capable of allowing greater or lower flow may be used in the present hub. This ensures the housing can maintain a waterproof rating of IP68. The assembled housing 105 illustrates the preferred embodiment of the electrical input 420 and output ports 415. Also shown is a mechanical switch 525 moulded into the rear portion 500. A mechanical switch is preferable to other modalities, such as a capacitance switch, as there is no power consumption with a mechanical switch. Further the mechanical switch 525 may incorporate a deformable seal which spans an access port used to access the mechanical switch 525 in order to maintain a liquid-tight housing 105. A capacitance switch requires a minimum level of power consumption to be able to monitor a sensing surface for contact. This would drain the rechargeable power source without necessarily providing any recharging to connected devices, which would reduce the efficiency of the recharging unit 100. A mechanical switch is able to disconnect the rechargeable power source from the remainder of the power distribution system and substantially eliminate power loss.

[0042] Figures 8A to 8C show perspective views of a gasket used to connect the front portion 200 of the housing to a rear portion 500 of the housing. It should be noted that gaskets are typically designed to be flexible in terms of orientation and not have a particular orientation or handedness to facilitate ease of implementation in systems. However, the present invention requires a particularly robust seal so that the housing 105 can remain sealed in even the most demanding environments. This requires a gasket 300 which can provide optimal sealing. The gasket of the present disclosure achieves this with the keyed design described and shown in the Figures. Figure 8A shows one side of the gasket 300 which has an inner wall portion 305. Sealing surface 310 contacts a section of the side wall 205 of the front housing portion 200 and is held in place by fasteners passing through holes 230 located around the gasket 300. Corresponding holes are located in the front housing portion 200 and rear housing portion 500. Figure 8B shows the other side of the gasket 300 which has part of the inner wall portion 305, sealing surface 315 and an outer wall portion 320. The inner 305 and outer 320 wall portions create a recess within which the side wall 535 of the rear portion 500 is received. When the housing 105 is assembled and secured, the sealing surface 315 and received section of the side wall 535 form a liquid-tight seal. The keyed design of the gasket 300 is best shown in Figure 8C. As can be shown the inner wall 305 extends across the cross section of the gasket 300, whereas only one side of the gasket 300 incorporates an outer wall 320. In addition to providing a liquid-tight seal, this asymmetric design provides the gasket with a handedness to aid local installers who may need to re-assemble the housing 105 following maintenance or repairs. By incorporating an asymmetric arrangement of holes 230 to secure the housing 105, this provides an additional guide to local vendors or technicians assembling the housing 105. The combination of an asymmetric hole arrangement and a keyed gasket ensure the gasket 300 is properly attached to the front 200 and rear 500 housing portions each time which will result in optimal sealing of the housing 105. This is important, as incorrectly assembling the housing 105 will result in a non-liquid-tight seal, which could result in damage to the components within the housing, for example, after any local repairs or maintenance have occurred or even opening the housing to insert a SIM card into the modem 403. Therefore, the housing 105 should be properly assembled each time in order to maximise the life of each power distribution unit 100.

[0043] As there is the potential for large currents to be drawn, the unit 100 may include a high voltage rail to connect the output ports 415 to the source of power. By using inductor coils 425, which are particularly efficient at retaining power, power loss is reduced compared to, for example a diode-based system. However, a switch mode power supply, such as that of the present units, is a four phase power supply able to delivery up to 250W. This level of power generation also causes a large amount of heat to be generated, which needs to be dissipated. This is achieved by the heat sinks 515 located at the two ends of the housing 105. A first heat sink 515 is located at the top of the unit near the input ports 420, and a second heat sink 515 is located at the base of the unit to handle the heat generated by the output power management system. The present units 100 are able to operate up to 60°C without requiring any safety mechanisms to be implemented. Between 60°C - 70°C, the power management system will scale back the outputted power and above 75°C, the system will shut down to prevent power sources within the housing 105 from reaching a critical temperature. The arrangement of heat sinks 515 shown optimises the thermal design of the housing 105.

[0044] The housing 105 may also include a GPS unit. This ensures any units deployed would remain locatable and in the event a unit is stolen, can be recovered. Additionally, a GPS unit is able to provide an accurate source of time. The preferred method of requesting charge is by SMS message. However, the SMS message protocol does not include a timestamp on the messages sent and as up to 25% of charge requests may be dropped by the payment provider, this creates an auditing problem for the remote server. The remote server needs to be able to verify charge requests and be able to link them to transmitted authorisation messages to ensure the system is accountable and fair to customers. By incorporating a GPS unit, the present system can receive data packets which use the Network Time Protocol and will have a time-stamp which will allow auditing of the transactions taking place. Additionally, GPS allows the present unit to diagnose and track system performance as it provides an accurate record of when communications throughout the system. These communications may include receiving the initial charge request, sending authorisation messages and communicating diagnostic information between the hub and the server. This can provide a back-up for the SMS service should time-stamps be necessary to validate a charge request.

[0045] In summary, a power distribution unit 100 for distributing electrical power in an offgrid environment to a plurality of battery-powered electrical devices, in particular mobile telephones, comprises a housing 105 having an external surface and a plurality of electrical output ports 415 provided at the external surface of the housing. Each output port 415 is configured to receive a complementary electrical output connector 605 for connection to a respective electrical device to be charged. The unit further comprises a controller within the housing configured to selectively enable the supply of electrical power to each output port. Each output port 415 comprises a first pin 417A for connection to the electrical connector 600 and a second pin 417B for connection to the output connector 600. The first and second pins are arranged to supply electrical power to an electrical device to be charged when the output port 415 is enabled. The first and second pins 422 project from the external surface of the housing 105, which prevent the output port 415 from becoming clogged with debris.

[0046] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0047] Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A power distribution unit for distributing electrical power in an off-grid environment to a plurality of battery-powered electrical devices, in particular mobile telephones, comprising:

a housing having an external surface;

a plurality of electrical output ports provided at the external surface of the housing, each output port being configured to receive a complementary electrical output connector for connection to a respective electrical device to be charged; and a controller within the housing configured to selectively enable the supply of electrical power to each output port, wherein each output port comprises a first pin for connection to the electrical connector and a second pin for connection to the output connector, the first and second pins being arranged to supply electrical power to an electrical device to be charged when the output port is enabled, and wherein the first and second pins project from the external surface of the housing.

2. A power distribution unit according to claim 1, wherein the external surface of the housing defines a respective recess for each output port, the recess being configured to receive the output connector and the first and second pins are provided within the recess.

3. A power distribution unit according to claim 2, wherein the recess has a depth and the recess is open at an end thereof to the depth of the recess, whereby liquid can drain from the recess.

4. A power distribution unit according to any preceding claim, wherein each output port further comprises at least a third pin configured to connect at least mechanically with the output connector.

5. A power distribution unit according to claim 4, wherein each output port further comprises at least a fourth pin configured to connect at least mechanically with the output connector.

6. A power distribution unit according to claim 4 or 5, wherein the third pin and/or the fourth pin is configured to connect electrically with the output connector.

7. A power distribution unit according to any of claims 5 to 6, wherein the first and second pins are mutually spaced by a first distance and the third and fourth pins are mutually spaced by a second distance and the first distance is different to the second distance.

8. A power distribution unit according to any of claims 5 to 7, wherein the first and second pins define a first axis and the third and fourth pins define a second axis substantially parallel to the first axis, and wherein the first and second axes are offset from one another in a direction substantially perpendicular to the first and second axes.

9. A power distribution unit according to any of claims 5 to 8, wherein the output port is configured to mimic the electrical characteristics of a USB port.

10. A power distribution unit according to any preceding claim, wherein the housing comprises a first housing portion and second housing portion which mates with the first housing portion to provide a complete housing, and the power distribution unit further comprises a printed circuit board, wherein the printed circuit board is mounted within the housing between the first housing portion and the second housing portion, whereby to define a first compartment between the first housing portion and the printed circuit board and a second compartment between the printed circuit board and the second housing portion, wherein the second compartment contains batteries and the printed circuit board is mounted to the second housing portion, whereby the second compartment is substantially inaccessible to the user.

11. A power distribution unit for distributing electrical power in an off-grid environment to a plurality of battery-powered electrical devices, in particular mobile telephones, comprising:

a housing having an external surface;

a plurality of electrical output ports provided at the external surface of the housing, each output port being configured to receive a complementary electrical output connector for connection to a respective electrical device to be charged; and a controller within the housing configured to selectively enable the supply of electrical power to each output port, wherein the housing comprises a first housing portion and second housing portion which mates with the first housing portion to provide a complete housing, and the power distribution unit further comprises a printed circuit board, wherein the printed circuit board is mounted within the housing between the first housing portion and the second housing portion, whereby to define a first compartment between the first housing portion and the printed circuit board and a second compartment between the printed circuit board and the second housing portion, wherein the second compartment contains batteries and the printed circuit board is mounted to the second housing portion, whereby the second compartment is substantially inaccessible to the user.

12. A power distribution unit according to claim 10 or 11, wherein the printed circuit board comprises a plurality of light emitting diodes (LEDs) for indicating which output port has been enabled by the controller, and wherein the first housing portion is a transparent plastics moulding comprising a plurality of light pipes configured to transmit light from the LEDs to the external surface of the housing.

13. A power distribution unit according to any of claims 10 to 12 further comprising a mobile modem, wherein the modem is located in the first compartment.

14. A power distribution unit according to any of claims 10 to 13 further comprising an elastomeric gasket provided between the first housing portion and the second housing portion.

15. A power distribution unit according to any preceding claim further comprising a first heat sink provided at a first end of the power distribution unit and second heat sink provided at a second end of the power distribution unit, the first end being opposite to the second end, each heat sink providing an outer surface of the power distribution unit.

16. A power distribution unit according to claim 15, where in the first heat sink is in thermal contact with an input power management circuit and the second heat sink is in thermal contact with an output power management circuit.

17. A power distribution unit according to any preceding claim comprising a fascia releasably mounted to the housing.

18. A power distribution unit according to any preceding claim further comprising an input power management circuit and at least one electrical input port configured to receive power from an external power supply, wherein the electrical input port comprises a first power input pin, a second power input pin and a source selection pin, wherein the input power management circuit is configured to apply a voltage to the source selection pin, whereby to identify a type of the external power supply by reference to the response of the source selection pin to the applied voltage.

19. An electrical input connector comprising a plurality of female connectors configured to receive the power input pins and source selection pin of the power distribution unit according to claim 18.

20. An electrical output connector comprising first and second female connectors configured to receive the first and second pins of the power distribution unit according to any of claims 1 to 18 and a further connector configured for connection to a portable electronic device.