GB2527805A

GB2527805A - A generator set

Info

Publication number: GB2527805A
Application number: GB1411845.9A
Authority: GB
Inventors: David Hardwick; Jonathan Garnham
Original assignee: JC Bamford Excavators Ltd
Current assignee: JC Bamford Excavators Ltd
Priority date: 2014-07-02
Filing date: 2014-07-02
Publication date: 2016-01-06
Also published as: GB201411845D0

Abstract

A generator set (genset) 10 for supplying power to an outlet for electrical energy comprises a first portion 14 and second portion 30. The first portion 14 comprises a generator driven by a prime mover and the second portion 30 comprises a battery pack connected to, and charged by, the generator, wherein the second portion 30 is located underneath the first portion 14. In addition, the prime mover and generator of the first portion is enclosed by a housing 12 having inlets 38 and outlets 42 defining an airflow path in which a charger for converting AC power from the generator to DC power for charging the battery pack is located. The second portion 30 may comprise an enclosure for the battery pack having inlets 38 and outlets to allow air flow and may also comprise a fan (44, figure 4). The second portion 30 may comprise an opening in an upper surface to allow cabling to pass through. The first portion 14 may comprise a fan (19, figure 2A) to provide forced air flow. A connection may be provided for mounting an external battery pack. The first portion 14 may be releasably secured to the second portion 30.

Description

A generator set

FIELD OF THE INVENTION

[01] The present invention relates to a generator set.

BACKGROUND OF THE INVENTION

[02] Mobile generator sets, often referred to as "gensets", typically include a diesel engine arranged to drive an alternator or other form of generator in order to convert the mechanical output from the diesel engine into electrical energy. Such devices are typically used in locations where mains electricity is unavailable ("off-grid" locations), or as a back-up to mains electricity where supplies are unreliable.

Examples of such locations include construction sites, mines, oil and gas installations, open air cultural and sporting events, temporary camps and the like, [03] The generator sets may vary in electrical power output from approx. 5kVA up to around I000kVA, but continue to be portable, e.g. by providing wheels so as to be towable or lifting points for pallet forks or chains.

[04] Different sites have different demands for electricity. Some may have a relatively constant demand throughout a day and/or from day-to-day, whereas other sites may have demands that are variable. Further certain sites may have noise or emissions rules that preclude the use of diesel generators at certain times of day.

[05] Whereas a known diesel powered generator set may operate efficiently if the power demand is constant and its power output is well matched thereto, in other usage scenarios the present applicants have recognised that efficiency may be less than optimal, resulting in excess usage of fuel and more frequent maintenance requirements.

[06] It is known to provide a diesel powered generator set in combination with a battery pack, in which the battery pack is periodically charged by the generator set, and in which devices draw their electrical power from the battery pack. This enables the diesel engine to be turned off for certain periods of time, and only mn when the battery requires topping up". However, the present applicant has recognised that this approach continues to have limitations in terms of its ability to power electrical equipment that has a high power demand, but which may only be used intermittently, in conjunction with other electrical equipment that has a lower demand over a longer period of time.

[07] Further, known generator sets that include batteries locate the batteries arid associated components in locations that are not optimal from inter alia a cooling and servicing point of view.

[08] The present invention seeks to overcome or at least mitigate the problems of the

prior art.

SUMIvIARY OF THE INVENTION [09] A first aspect of the invention provides a generator set for supplying power to an outlet for electrical energy, the generator set comprising a first portion and a second portion, the first portion comprising a prime mover and a generator, wherein the generator is driven by the prime mover, the second portion comprising a battery pack, wherein the battery pack is connected to the generator to receive power from the generator to charge the battery pack, and wherein the second portion is located substantially underneath the first portion.

[10] Providing a generator set comprising a first portion including the prime mover and generator and a second portion including a battery pack is advantageous as it allows for the easy removal/exchange of the portion containing the battery pack. This would advantageously allow for the exchange of a fully battery pack for an empty one. This arrangement would also advantageously allow for the generator set to be switched between having a battery pack and not having a battery pack when one was not required. Furthermore, providing the battery pack substantially underneath the first portion advantageously improves the weight distribution of the generator set. n j

[11] In one embodiment, the second portion comprises a second portion housing to enclose the battery pack, the second portion housing having at least one inlet and at least one outlet to allow air to flow therethrough.

[12] Providing the second portion housing with at least one air inlet and outlet enables air to flow over the batteries independent of any heat generated in the first portion.

This air flow reduces the risk of the battery pack overheating.

[13] In one embodiment, the second portion further comprises a fan to increase the rate of air flow and therefore cooling.

[14] In one embodiment, one of the inlet and outlet are located on an end face and the other of the inlet and outlet are located on a side face of the battery housing.

[15] Providing the inlet and outlet in this configuration ensures that the air flow passes over the battery pack, thus keeping the battery pack cool, In one embodiment the battery pack is split into two sections with a divider therebetween, and each section has a separate inlet and outlet in this arrangement.

[16] In one embodiment, the second portion housing comprises an opening in an upper surface thereof to allow cabling to pass therethrough.

[17] In one embodiment, the first portion further comprises a bund located at a bottom thereof, the bund comprising a duct located substantially over the opening to enable the electrical cables to pass therethrough and the bund to remain liquid tight.

[18] Providing the bund with a passage through it which is impervious to liquid advantageously enables an easy pathway for the electrical cables to pass in order to connect the first portion to the second portion.

[19] In one embodiment, the first portion comprises a first portion housing to enclose the prime mover and the generator, the first portion housing comprising a first portion inlet and a first portion outlet defining an air flow path to allow air to pass therethrough past the generator and prime mover.

[20] Providing the first portion with an inlet and an outlet is advantageous as this will enable air to flow over the generator and prime mover and so reducing the risk of overheating.

[21] In one embodiment, the first portion housing comprises a fan to provide forced air flow on the air flow path, so as to increase the rate of cooling.

[22] In one embodiment, the first portion comprises a charger to convert AC power from the generator to DC power to charge the battery pack.

[23] In one embodiment, the charger is located in the air flow path.

[24] Locating the charger in the air flow path advantageously allows air to flow over the charger to prevent, reducing the risk of overheating.

[25] In one embodiment, the charger is located upstream of the prime mover in the air flow path.

[26] Locating charger upstream of the prime mover is advantageous as it allows air to flow over the charger before it has been heated by the prime mover, thus providing better cooling of the charger.

[27] In one embodiment, the generator produces three phase AC power.

[28] Three phase AC power allows for quicker charging of the batteries and enables large plant and equipment to be efficiently powered.

[29] In one embodiment, the first portion housing further comprises three chargers to convert the three phase AC power from the generator into DC power so as to charge the battery.

[30] In one embodiment, the generator is an alternator.

[31] In one embodiment, the generator set comprises a power outlet powered directly from the generator.

[32] In one embodiment, the generator set comprises a power outlet powered from the battery pack [33] In one embodiment, the generator set comprises a connection for mounting an external battery pack thereto.

[34] In one embodiment, the prime mover is a diesel engine.

[35] In one embodiment, the prime mover and generator are capable of producing a S greater amount of electricity than can be supplied to the battery pack for charging.

[36] In one embodiment, the first portion is releasably securable to the second portion, [37] A second aspect of the present invention provides a generator set for supplying power to an outlet for electrical energy, the generator set comprising a first portion and a second portion, the first portion comprising a prime mover and a generator, wherein the generator is driven by the prime mover, the second portion comprising a battery pack, wherein the battery pack is connected to the generator to receive power from the generator to charge the battery pack, wherein the first portion comprises a first portion housing to enclose the prime mover and the generator, the first housing comprising a first portion inlet and a first portion outlet defining an air flow path to allow air to pass therethrough past the generator and prime mover, and the first portion comprises a charger to convert AC power from the generator to DC power to charge the battery pack, and the charger is located in the air flow path.

BRIEF DESCRIPTION OF THE DRAWiNGS

[38] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [39] Figures 1 and 2 are isometric and side views of a generator set according to an embodiment of the present invention; [40] Figure 2A is a cutaway side view of an upper portion of the generator set; [41] Figures 3 and 4 are isometric and side views of a lower portion on the generator set of Figures 1 and 2 [42] Figure 5 is a schematic diagram of the maj or components of the generator set of Figures 1 and 2; [43] Figure 6 is a flowchart illustrating operation of the generator set of Figures 1 and 2; and [44] Figure 7 is a schematic diagram of a generator set according to a different embodiment of the present invention,

DETAiLED DESCRIPTION OF EMBODIIMENT()

Physical layout [45] With reference to the Figures the generator set 10 (hereinafter "genset") comprises a canopy U having a largely conventional upper portion 14 including a prime mover (a diesel internal combustion engine 15 in this embodiment) mounted fore-aft and having an output drive coupled to a generator in the form of a three phase alternator 16. The upper portion further includes a fuel tank 18, a cooling system comprising a fan 19 driven by the engine, and at the bottom of thereof, a bund 28 is provided so as to capture any fluid leaks.

[46] The upper portion also includes part of a control system 20, including a control panel with control inputs 22 and a display 24. Additionally, in this embodiment, the upper portion 14 includes an AC/DC converter in the form of three chargers 26a, 26b, 26c. The bund 28 has a passage through it with a liquid impervious side wall around it to route cables (not shown) down to a lower portion 30 beneath the bund, but without compromising its capacity to capture fluid.

[47] The canopy further comprises the lower portion 30 shown in more detail in Figures 3 and 4. The lower portion 30 has substantially the same footprint as the upper section 14 and principally houses a battery pack 32. In this embodiment the battery pack comprises 24 2V lead acid batteries 34 (12 visible in Figure 4) with a gel electrolyte to prevent leakage, and arranged on racks 36 in two layers. Individual batteries 34 may be slid from the rack for inspection or replacement. In other embodiments different battery types may be used, such as Nickel Cadmium or Lithium Ion and the capacity and number may be adjusted as required.

[48] Considering the upper portion 14 in more detail in relation to Figures 1 and 2 it can be seen that the canopy is formed from sheet metal in a conventional manner, with various access doors provided therein in order to access the control inputs 22 arid display 24, and for maintenance purposes. In addition, grilles and louvres are provided to allow air to flow through the canopy.

[49] In this embodiment, louvres 38 are provided in a lower portion of side walls of the canopy 12 at the right hand side as viewed in Figures 2 and 2A for air to be drawn in. A baffle (not visible) directs the intake air upwards past the chargers 26a, 26b, 26c so as to cool them. The air is the drawn from right to left past the generator 16 and engine 15 through the fan 19 and a heat exchanger 40 for the engine, before being exhausted through a grille 42 seen most clearly in Figure 1 Dotted arrow A illustrates this air flow path. This arrangement advantageously enables the chargers 26a, 26b, 26c to be cooled by the incoming air before it becomes significantly heated by the engine 15 downstream. The equivalent space occupied by the chargers 26a-26c has hitherto been vacant in known gensets.

[50] The lower portion 30 is also fabricated from sheet metal, with the internal racks 36 also being sheet metal, In this embodiment the end walls comprise louvres 38 and further louvres 38 are provided on each of the side walls. At each end, between the racks 36 and the end walls, four electric fans 44 are provided to draw air in and through the end louvres and out through the side wall louvres. As can be seen in Figure 3, vertical sections of the racks 36 are perforated to assist in the circulation of air, This arrangement provides for good airflow (illustrated by arrows B) to cool the batteries 34 without this being affected by heat generated in the upper portion 14. The use of multiple fans 44 allows for redundancy in case of a fan failure.

[51] As can be seen in Figure 3, an opening 46 is provided in the top of the lower portion 30 for cabling from the battery pack 32 to pass through and into the upper portion 14.

[52] The lower portion 30 further includes through apertures 45 such that the genset may be lifted using pallet forks, Panels 47 on the side walls are removable (e,g, by removing screws) to access the batteries 34 for inspection and maintenance, [53] In this embodiment, the upper and lower portions 14, 30 are provided as separate self-contained sections, attachable using releasable fasteners such as bolts. The upper and lower portions 14, 30 are secured together via a perforated connecting plate 62, which is secured proximate the bottom corners of the side faces of the upper and S lower portions. The upper and lower portions 14, 30 include angled perforated mounting plates 64, 66 which protrude from the side faces of the upper and lower portions at an angle of around 20 degrees to the vertical. The connecting plate 62 is secured to the mounting plate 64 of the lower portion 30 via bolts 68 secured through the perforations, resulting in the connecting plate 62 extending over the top edge of the lower portion 30.

[54] Upon lowering of the upper portion 14 onto the lower portion 30, as in during assembly of the portions, the angled mounting plates 66 assists in aligning the upper portion with the lower portion as the bolts are tightened, thus allowing for an easier assembly.

[55] This enables the lower portion 30 to be exchanged, for example to swap a ifilly charged battery pack 32 for a discharged pack, or to switch a genset 10 between having a battery storage option and no battery storage.

[56] In other embodiments, the upper and lower portions 14, 30 may be formed as a single, non-separable unit, In these embodiments, the battery pack may nevertheless be removed as a whole or via two or more subassemblies/supports to ease the exchange thereof In further embodiments, the genset may be provided with wheels and a tow bar so as to be transported as a trailer.

Functional layout [57] With reference to Figure 5 the fbnctional layout of the genset 10 is illustrated in more detail. In this Figure, solid lines indicate a power supply connection, dotted lines a signal line, and dot-dash lines a Controller Area Network (CAN) bus connection.

[58] In this embodiment, the prime mover is a four cylinder Dieselmax diesel internal combustion engine 15 manufactured by the present applicant, with a power output of 50kW (to provide 6OkVA of power). However similar engines may be rated to output 100kw (to provide approx, I2OkVA of power). This is mechanically coupled to a three phase generator, suitable for providing three phase electrical power to industrial plant equipment via four three phase outlet sockets/terminals.

[59] In addition, the alternator 16 is connected to the three chargers 26a, 26b, 26c.

Each charger is configured to convert one phase of AC into DC to charge the battery pack 32, when required. This arrangement ensures the battery pack may be charged at the maximum rate possible, when required.

[60] In this embodiment, the battery pack 32 is capable of being charged at a rate of 25kW (i.e. approx. half the output of the engine 15) and at this charging rate it will take approximately two and a half hours to reach an 80% battery charge. Above an 80% battery charge, it becomes less efficient to charge the battery pack, such that above this battery level it would not be as efficient to run the engine simply for the purpose of charging the batteries.

[61] Further, the battery pack 32 has a total storage capacity of 4OkWh. However to maintain lead acid batteries of this type in good condition for a long service life, it is preferred to avoid the battery pack dropping below a 50% charge, although this parameter differs for different battery types.

[62] The maximum output power for a continuous load of the battery pack 32 is lOkVA, although a peak output of 2OkVA is possible for 5 seconds, Thus, it will be appreciated that the power output for the battery pack 32 is significantly lower (approx. l/6th1) the power output of the engine 15 and alternator 16.

[63] In this embodiment, one of the chargers 26c is a combination inverter/charger.

Thus, charger 26c is able to convert the DC power from the battery to single phase AC to be supplied to a further outlet socket 50, hereinafter referred to as a hybrid socket.

[64] In this embodiment the two chargers 26a and 26b are Skylla 1 model chargers from Victron Energy of Almere Haven, The Netherlands. The inverter charger is a Victron Quattro model. In addition, the three chargers comprise an inbuilt control capability which works in conjunction with a main control module 52 to ensure the genset runs as intended. Specifically, the chargers 26a to 26c operate in conjunction with a battery monitor 54 to be aware of various battery parameters including percentage charge and battery temperature. In addition, the chargers may be set such that when the three phase outlet 48 is consuming a maximum amount of the power generated by the alternator 16, no power is taken and converted to DC for the charging tO of the battery pack. Further, the inverter charger 26c is capable of signalling that the engine 15 needs to be started to supply this demand.

[65] The main control module 52 is in this embodiment, a microprocessor controller of a type known for use in the control of prior art generators, but with additional functionality added thereto. In this embodiment the control module is a DSE741O model manufactured by Deep Sea Electronics plc of Filey, North Yorkshire, UK.

[66] The main control module 52 is capable of communicating with the engine 15, alternator 6 and chargers 26a to 26c via a CAN bus, alternatively this communication may be via direct analogue connectors. As such, it is capable of receiving operating parameters of the aforesaid components, such as engine speed, engine load, loading on each phase, battery data and fuel level, and is also capable of signalling engine start and controlling the fuel supply to the engine 15, In addition, the control module 52 is further capable of sensing a load applied to the three phase outlets and on receipt of this signal, instructs engine start.

[67] In addition, in this embodiment, the genset 10 comprises a telemetry module 56.

The telemetry module 56 comprises a transmitter capable of communicating via a cellular radio network using a suitable protocol, such as GPRS, UMTS or LIE, and the internet 58 with a central server 60 at a remote location, such that operating parameters of the machine may be presented to authorised users and, for example, reports generated of machine usage, machine location etc. To enable this, the telemetry module 56 is capable of collecting data from the engine 15, alternator 16, control module 52 and the chargers 26a to 26c. ii

Genset operation [68] With reference in particular to Figures 5 and 6, operation of the genset 10 is as follows: [69] Upon delivery to a particular operating site, for example a construction site, an operator initially determines which electrical devices are to be attached to which outlet sockets. For example, site office devices would typically be connected to the hybrid outlet socket 50 since heating, cooling, security cameras, computers and lighting are usually relatively low demand devices which are on for extended periods of time. In addition, certain of these functions, such as security cameras and computers require a supply that is instantly available and not interruptible.

[70] Other devices on a site, such as cranes, concrete mixers and large power tools would typically be used intermittently but require a significantly larger supply of power. Accordingly, such devices are plugged into the three phase outlet sockets 48.

[71] Thus, starting the process at step St 00, assuming the genset tO is fuelled with diesel, has some battery charge and is turned on, the user can select various operating modes using inputs 22.

[72] If at step S102 a switch to select whether power from the hybrid socket is available is turned to off, then no power is supplied to the hybrid outlet at step S103 and only power may be provided via the three phase outlets 48.

[73] Then if at step 5104 the user selects the manual running mode by selecting a manual switch to on, the engine 15 starts and runs permanently at step S 106. If the manual switch is not on, the operator may instead have selected a timer mode at step S108 to, for example, run the engine for the working hours of a construction site in order to provide permanent three phase power to the outlets 48. If the timer is operational and set to on, then the engine is set to run at step 106.

[74] If at step Si 10 the timer is not on, but the charge on the battery pack 32 is detected by the battery monitor 54 as being less than a predetermined desirable value (in this embodiment less than 50%) then the control module 52 signals the engine to run at step 106.

[75] If at step SI 12 the battery charge is at greater than 50%, but the inverter charger 26c determines that the load on the hybrid socket 50 is greater than a predetermined threshold, in this embodiment, greater than 7kW then the inverter charger 26c signals the control module 52 accordingly and the control module signals the engine to run at step S106.

[76] An operator may also select whether the "start on demand" fUnction is available, and at step S114 the control system confirms if this is enabled. If start on demand is on and the control module 52 determines there is a load on the three phase outlet 48, at step SF16 the control module 52 in turn signals the running ofthe engine at step S106.

[77] At step S118, once the engine is running, power becomes available at the three phase outlets 48. Typically the time from detecting a demand to being able to supply power to meet that demand is five seconds or less.

[78] At step S120 the control module 52 determines if the load on the alternator 16 is greater than a predetermined threshold, In certain embodiments, this may cause IS charging to cease. However, in preferred embodiments, this may cause charging to reduce in stages. Thus, once an average load of 80% of maximum is reached, for example, the phase with the highest load ceases to charge. Then, if the average load reaches 85% another charger ceases to charge, and finally if the average load reaches 90%, the final, most heavily loaded charger ceases to charge. As well as ensuring that the alternator 16 and engine 15 are not too heavily loaded, this approach assists in balancing the phases, It will also be appreciated that due to hysteresis, transient spikes in load on a phase may not cause charging to cease on that phase.

[79] Nevertheless, if the upper limit is reached, then at step S122 the control module 52 signals the chargers 26a to 26c to stop charging the batten' pack in order to provide available capacity to the three phase outlets 48.

[80] If however, capacity is available, at step S124 the control module 52 signals the chargers to charge the batteries. If, at step S 126, the battery charge is above a predetermined value the control module 52 signals the chargers to stop charging the batteries. If the engine is running, at step S 0 due to the battery charge being less S than 50% then the predetermined value is 80%. If however, the engine is running at steps SI 12 or SI 16 due to a load on the genset then the predetermined value is I00%.

This is because, despite charging being less efficient above 80%, if spare power is available it is sensible for it nevertheless to be used for charging.

[81] In this embodiment this approach is preferred because lead acid batteries become less efficient to charge when above 80% battery charge. As such, this approach is used to increase the overall efficiency of the genset.

[82] Whilst the flow chart of Figure 6 shows a single cycle of operation, it will be appreciated that the steps may operate as a continuous loop, By way of example, after a delay of, for example, one minute step S116 is repeated and if no load, is detected, then the control module 52 signal the engine to stop. It will further be appreciated that the predetermined parameters may be overridden automatically, or by operator override in some circumstances, For example, if the engine is unable to run due to lack of fuel or malfunction, the control module may be programmed to continue the supply of power to the hybrid outlet until the battery is exhausted or a lower absolute minimum charge level is reached, In this instance, the control module 52 emits an alarm on the machine or remotely via the telemetry module 56 which sends an alert to a remote operator via the internet 58 and server 60, Two part generator set [83] Figure 7 illustrates a genset according to a second embodiment of the present invention in which like parts are labelled by like numerals as the first embodiment, but with the addition of the prefix "2". Only differences with the first embodiment are discussed in more detail.

[84] The second embodiment of Figure 7 differs principally in that the genset 210 comprises two separate parts a main part 210a housing the engine 215, alternator 216, control module 252 and outlets 248 and a separate "battery box" 21Db which houses the battery pack 232 and a charger/inverter 226c, as well as a cooling mechanism (fans not shown).

[85] This arrangement permits an existing conventional generator (either from the present applicant or a third party) to be converted into a hybrid generator that may share many of the advantages of the first embodiment quickly and at reasonable expense. In this embodiment the battery box 21Db has a plug to plug into an outlet socket 248 of the main part 210a and draw power therefrom.

[86] The AC power is fed into a single phase charger/inverter 226, which in this embodiment is a Victron Quattro similar to the first embodiment, to convert AC to DC to charge the batteries, and in reverse to supply power to the hybrid outlet with single phase AC when required. The use of single phase power for charging slows the process somewhat, but enables the battery box 21Db to be compatible with a broad range of generators. In other embodiments a three phase arrangement similar to the first embodiment may be used.

[87] The charger/inverter 226 is connected to a battery monitor 254 so to have data on battery condition, In this embodiment, the only signal line between battery box is a two-wire remote start connection, again so as to maintain broad compatibility with a range of generators, some of which may not have a CAN bus (although a CAN connection could be provided in other embodiments).

[88] Nevertheless, this arrangement permits the charger/inverter 226 to signal to the control module 252 to start the engine in order to maintain a desired battery charge level, Further, assuming the engine 215 and generator 216 have a greater output capacity than the battery pack 232, the generator is still capable of supplying power to the remaining three phase outlets which also charging the battery.

Variants [89] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

Claims A generator set for supplying power to an outlet for electrical energy, the generator set comprising a first portion and a second portion, the first portion comprising a prime mover and a generator, wherein the generator is driven by S the prime mover, the second portion comprising a battery pack, wherein the battery pack is connected to the generator to receive power from the generator to charge the battery pack, and wherein the second portion is located substantially underneath the first portion.
2. A generator set according to claim 1, wherein the second portion comprises a second portion housing to enclose the battery pack, the second portion housing having at least one inlet and at least one outlet to allow air to flow therethrough.

3 A generator set according to claim 2, wherein the second portion further comprises a fan, 4. A generator set according to claim 2 or claim 3, wherein one of the inlet and outlet are located on an end face and the other of the inlet and outlet are located on a side face of the second portion housing.5. A generator set according to any preceding claim, wherein the second portion housing comprises an opening in an upper surface thereof to allow cabling to pass therethrough.6. A generator set according to claim 5, wherein the first portion further comprises a bund located at a bottom thereof, the bund comprising a duct located substantially over the opening to enable the electrical cables to pass therethrough and the bund to remain liquid tight.7. A generator set according to any preceding claim, wherein the first portion comprises a first portion housing to enclose the prime mover and the generator, the first portion housing comprising a first portion inlet and a first portion outlet defining an air flow path to allow air to pass therethrough past the generator and prime mover.8. A generator set according to claim 7 comprising a fan to provide forced air flow on the air flow path.9, A generator set according to any preceding claim, wherein the first portion comprises a charger to convert AC power from the generator to DC power to charge the battery pack.10. A generator set according to claim 9 when dependent upon claim 7 or claim 8, wherein the charger is located in the air flow path.11. A generator set according to claim 10 wherein the charger is located upstream of the prime mover in the air flow path.12. A generator set according to any preceding claim, wherein the generator produces three phase AC power.13. A generator set according to claim 12, wherein the first portion housing further comprises three chargers to convert the three phase AC power from the generator into DC power so as to charge the battery.14. A generator set according to any preceding claim, wherein the generator is an alternator.15. A generator set according to any preceding claim further comprising a power outlet powered directly from the generator.16. A generator set according to any preceding claim, frirther comprising a power outlet powered from the battery pack 17. A generator set according to any preceding claim, further comprising a connection for mounting an external battery pack thereto.18. A generator set according to any preceding claim, wherein the prime mover is a diesel engine.19. A generator set according to any preceding claim, wherein the prime mover and generator are capable of producing a greater amount of electricity than can be supplied to the battery pack for charging.20. A generator set according to any preceding claim wherein the first portion is releasably securable to the second portion.21. A generator set for supplying power to an outlet for electrical energy, the generator set comprising a first portion and a second portion, the first portion comprising a prime mover and a generator, wherein the generator is driven by the prime mover, the second portion comprising a battery pack, wherein the battery pack is connected to the generator to receive power from the generator to charge the battery pack, wherein the first portion comprises a first portion housing to enclose the prime mover and the generator, the first housing comprising a first portion inlet and a first portion outlet defining an air flow path to allow air to pass therethrough past the generator and prime mover, and IS the first portion comprises a charger to convert AC power from the generator to DC power to charge the battery pack, and the charger is located in the air flow path.22. A generator set substantially as hereinbefore described and/or with reference to the accompanying drawings.