Related Applications

[001] This application claims priority from Australian provisional patent application no. 2021902367 filed on 31 July 2021 and Australian innovation patent no. 2021106349 filed on 21 August 2021, the contents of which are incorporated by reference.

Technical Field

[002] The invention relates to a battery apparatus. In particular, the invention relates to a battery apparatus including an enclosure for battery cells.

Background

[003] Battery cells such as lithium-ion battery cells may be secured in use within a housing that contains a bank of battery cells. Such housings may include a housing body adapted to generally isolate the battery cells from the external environment and connection points on the housing body that allow electrical connection to the internal battery cells. Within such enclosures, the battery cells may become overheated and, as such, temperature management features such as temperature sensors and cooling plates may be provided to assist to cool the battery cells to inhibit thermal runaway.

[004] A problem with such housings is that the isolation from the external environment may be insufficient in some circumstances such as a hazardous or gaseous environment. Another problem with such housings relates to the ability of the housing to contain thermal runaway and a possible resulting pressure or explosive event that may originate from inside the housing which may ignite internal or external gases.

[005] The invention disclosed herein seeks to overcome one or more of the above identified problems or at least provide a useful alternative. Summary

[006] In an aspect of the present disclosure there is provided, a battery apparatus including a first enclosure in which one or more battery cells are located, and a second enclosure adapted to receive and substantially conceal the first enclosure therein. The first and second enclosure may each contain fluid, that may be a dielectric fluid, and the second enclosure may include a fluid expansion means adapted to accommodate expansion and contraction of the dielectric fluid.

[007] In accordance with a more specific aspect of the present disclosure there is provided, a battery apparatus for containment of an internal pressure event. The battery apparatus may include a first enclosure in which one or more battery cells are locatable, the first enclosure having one or more first walls supporting a first removable lid through which the one or more battery cells are accessible, and a second enclosure having one or more second walls and a second removable lid adapted to receive and substantially seal the first enclosure therein. The internal pressure event may include a rapid pressure expansion from within the first enclosure associated with the one or more battery cells such as a result or thermal runway or ignition of environmental gasses.

[008] The first and second enclosures may each contain dielectric fluid and an aperture may be provided between the first and second enclosures to allow exchange of the dielectric fluid between the first and second enclosures, and the second enclosure includes a fluid expansion means adapted to accommodate expansion and contraction of the dielectric fluid.

[009] The one or more first and second walls and the first and second lids may be arranged adjacent and at least partially spaced apart from one another such that the one or more second walls and the second lid are able to support the one or more first walls and the first lid to contain the internal pressure event and provide a gap for the dielectric fluid between the one or more first and second walls and the first and second lids.

[0010] In an aspect, the apparatus includes a third enclosure adjacent at least one of the first enclosure and the second enclosure in which one or more electrical interface components are located, the one or more electrical interface components being in electrical communication with the one or more battery cells.

[0011] In an aspect, the third enclosure is fitted at least partially within the second enclosure.

[0012] In another aspect, the third enclosure includes a removable panel and one or more third walls with sealed apertures to provide external electrical connections.

[0013] In yet another aspect, the one or more electrical interface components include fuses accessible through the removable panel.

[0014] In yet another aspect, the aperture is arranged such as the fluid expansion means functions to maintain the first enclosure substantially filled with the dielectric fluid.

[0015] In yet another aspect, the aperture is located toward, at or within the first removeable lid.

[0016] In yet another aspect, the aperture is located through the first removable lid.

[0017] In yet another aspect, the fluid expansion means includes a diaphragm.

[0018] In yet another aspect, the second enclosure includes a recess, and the diaphragm is provided by a flexible material or material spanning the recess.

[0019] In yet another aspect, the diaphragm is located at or on an underside of the second lid.

[0020] In yet another aspect, the second lid includes a recess on an underside thereof and the diaphragm is provided by a flexible membrane extending over the recess.

[0021] In yet another aspect, the gap between the one or more first and second walls is less than about 15mm, preferably in the range of about 5mm to 15mm, and most preferably about 5mm. [0022] In yet another aspect, the gap between the one or more first and second walls is sized such that the one or more first walls at least partially engage with the one or second walls in the internal pressure event.

[0023] In yet another aspect, at least the one or more first and second walls are formed of a metal material.

[0024] In yet another aspect, the second enclosure is sealed.

[0025] In yet another aspect, the first enclosure is shaped to be fittingly received by the second enclosure.

[0026] In yet another aspect, the first enclosure and the second enclosure are generally rectangular.

[0027] In yet another aspect, the second enclosure includes one or more passages to enable circulation of a cooling fluid to facilitate non-contacting heat exchange between the dielectric fluid and the cooling fluid.

[0028] In yet another aspect, at least one or the one or more second walls include the one or more passage.

[0029] In yet another aspect, the first enclosure includes a plurality of the battery cell arrangements each including the one or more battery cells.

[0030] In yet another aspect, the first enclosure includes a plurality of slots arranged to support each of the plurality of the battery cell arrangements.

[0031] In yet another aspect, the first enclosure includes a connection board electrically arranged to connect with each of the plurality of the battery cell arrangements.

[0032] In yet another aspect, the first enclosure includes an interface board adapted to interface with the one or more electrical interface components in the interface enclosure.

[0033] In yet another aspect, the one or more electrical interface components in the interface enclosure include one or more fuses. [0034] In yet another aspect, the interface board of the first enclosure includes further one or more fuses in electrical communication with the one or more fuses of the interface enclosure.

[0035] In yet another aspect, the interface enclosure includes one or more external contacts arranged to enable electrical connection between the one or more electrical interface components and an external environment.

[0036] In yet another aspect, the first enclosure includes a first base arranged to seat with a second base of the second enclosure.

[0037] In yet another aspect, the first and second enclosure are substantially formed of a metal material.

[0038] In yet another aspect, the third enclosure is defined between one of the one or more second walls and the removable panel of the third enclosure.

[0039] In yet another aspect, the one or more first walls includes first opposing side walls and first opposing end walls, and the one or more second walls include second opposing side walls and second opposing end walls.

[0040] In accordance with a further more specific aspect of the present disclosure there is provided, a battery apparatus for containment of an internal pressure event such as a thermal or explosive event inside the battery apparatus. The battery apparatus may include a first enclosure in which one or more battery cells are locatable, the first enclosure having one or more first walls supporting a first removable lid through which the one or more battery cells are accessible; and a second enclosure having one or more second walls and a second removable lid adapted to receive and substantially seal the first enclosure therein, the second removable lid providing access to the first removable lid; and a third enclosure adjacent at least one or the first and second enclosures in which one or more electrical interface components are located, the one or more electrical interface components being in electrical communication with the one or more battery cells. [0041] The first and second enclosures may each contain dielectric fluid and an aperture formed between the first and second enclosures to allow exchange of the dielectric fluid between the first and second enclosures, and a fluid expansion means is provided to accommodate expansion and contraction of the dielectric fluid. The one or more first and second walls and the first and second lids may be arranged in a closely spaced arrangement such that the one or more second walls and the second lid are able to support the one or more first walls and the first lid to contain the internal pressure event and provide a gap for the dielectric fluid between the one or more first and second walls and the first and second lids. The second enclosure may include one or more passages to enable circulation of a cooling fluid to facilitate non-contacting heat exchange between the cooling fluid and dielectric fluid in the gap.

Brief Description of the Figures

[0042] The invention is described, by way of non-limiting example only, by reference to the accompanying figures, in which;

[0043] Figure 1 is an exploded isometric view illustrating the battery apparatus;

[0044] Figure 2 is another exploded isometric view illustrating the battery apparatus with surfaces removed to reveal internal features;

[0045] Figure 3 is an isometric view illustrating the battery apparatus;

[0046] Figure 4 is another isometric view illustrating the battery apparatus;

[0047] Figure 5a to 5e are respectively top, side, bottom and opposing end views illustrating the battery apparatus;

[0048] Figure 6 is a hidden detail isometric view illustrating the battery apparatus;

[0049] Figure 7 is a side hidden detail view illustrating the battery apparatus;

[0050] Figure 8 is an end view illustrating the battery apparatus along section A-A as shown in Figure 7;

[0051] Figure 9 is an isometric view illustrating the battery apparatus with a lid removed from a second enclosure;

[0052] Figure 10 is a bottom view illustrating the lid of the second enclosure;

[0053] Figure 11 is a side view illustrating the lid;

[0054] Figure 12 is isometric view illustrating the battery apparatus;

[0055] Figure 13 is isometric view illustrating the battery apparatus with an end covering removed from an interface enclosure;

[0056] Figure 14 is an isometric view illustrating a first enclosure of the battery apparatus removed from the second enclosure;

[0057] Figure 15 is an isometric part cut away view illustrating the first enclosure showing an internal battery arrangement and an interface board;

[0058] Figure 16 an isometric view illustrating the interface board; and

[0059] Figure 17 an isometric view illustrating an example battery arrangement.

Detailed Description

[0060] Referring initially to Figures 1 to 5e, there is shown a battery apparatus or enclosure arrangement 10 including a first or inner enclosure 12 in which one or more battery cells 14 are located or housed, a second or outer enclosure 16 adapted to receive and substantially conceal the first or inner enclosure 12 therein, and a third or interface enclosure 18 adjacent the first enclosure 12 in which one or more electrical interface components 20 are located, the one or more electrical interface components 20 being in electrical communication with the one or more battery cells 14. [0061] The first and second enclosures 12, 16 each contain fluid such as, but not limited to, a dielectric fluid or single-phase liquid immersion fluid, and the second enclosure includes a fluid expansion means 11, in this example a diaphragm 22 (shown best in Figure 10), adapted to accommodate expansion and contraction of the fluid. The function of the expansion diaphragm 22 is to manage the increase in volume of the fluid due to increase fluid increasing in heat as the fluid expands and contracts based on temperature. Such heat may arise from the one or more battery cells 14 and there may be pressure generated by the expansion and contraction of the one or more battery cells 14 themselves as well as the expansion of any heated fluid.

[0062] The function of the dielectric fluid is to manage any heat generated during the normal operation of the one or more battery cells 14 and to manage any heat generated during abnormal conditions that may arise. There is an aperture or breather 15 between the first and second enclosures 12, 16 to allow fluid from the first enclosure 12 to breathe into and communicate with fluid of the second enclosure 16. The diaphragm 22 functions to keep the first enclosure 16 always full of the fluid. The aperture 15 may be relatively small and may have a diameter of about 5mm.

[0063] The first enclosure 12 generally functions to hold and contain the one or more battery cells 14 and other electronic components, the second or outer enclosure 16 generally functions as a blast, explosion or energy containment enclosure and the third or interface enclosure 18 functions to provide an interface ultimately between the one or more battery cells 14 and an external environment to enable connection of the battery apparatus 10 to a load or other system such as a vehicle or the like.

[0064] As shown in Figure 2, the first enclosure 12 includes a removable top or lid 24, bottom 26, and one or more walls 27 that include opposing side walls 28 and opposing end walls 30 to provide a generally sealed internal environment capable of holding the dielectric fluid. Preferably, the fill level of the dielectric fluid is such that the first enclosure 12 is entirely filled without any air gaps. The aperture or breather 15 may be in the top or lid 24, or at one of the opposing sides 28, or opposing ends 30. The aperture or breather 15 may preferably be at a centre line or centre of the top or lid 24. It is noted that the aperture or breather 15 being located at or near the lid 24 assists to ensure the first enclosure 12 is substantially filled with the fluid at all times. [0065] The first enclosure 12 has a generally rectangular shape. The lid or top 24 may be removeable to reveal the internal components such as battery arrangements 30 that includes the or more battery cells 14, slots 34 to support the battery arrangements 32, a connection board 36 and battery interface arrangement 38. The battery interface arrangement 38 includes a first set of internal fuses 39.

[0066] As shown in Figures 3 and 4, the second enclosure 16 includes a removable top or lid 40, a bottom 42, and one or more walls 43 including opposing side walls 44 and opposing end walls 46 to provide a generally sealed internal environment capable of holding the dielectric fluid. The second enclosure 16 has a generally rectangular shape with internal dimension shaped to fittingly receive the first enclosure 12 with the first enclosure 12 nested within the second enclosure 16. The second enclosure 16 is generally a blast and flame proof enclosure.

[0067] The top or lid 40 may be removeable to reveal and access the first enclosure 12 and also allow access to and removal of the lid 24. The one or more walls 43, or other suitable surface, may be adapted to promote heat transfer or include integral cooling means such as a circulating cooling fluid. In this example, the one or more walls 43 include passages 45 (shown best in Figure 2) to allow the circulation of the cooling fluid. The passages 45 may extend lengthwise within and cover most of one or both of the opposing side walls 44. The cooling fluid may be circulated with an external heat exchanger or the like (not shown) using a pump (not shown) via ports 47 shown in Figure 4. The passages 45 allow for non-contact heat exchange between the cooling fluid and the dielectric fluid within the second enclosure 16.

[0068] The second enclosure 16 also contains the dielectric fluid which resides between the first and second enclosures 12, 16. Preferably, the fill level of the dielectric fluid is such that the second enclosure 16 is entirely filled without any air gaps. The second enclosure 16 enclosure does not house any switching or electronic parts which is essentially an avoidance technique, and the construction of the second enclosure 16 enclosure utilises the principles of the containment technique thus achieving the desired multiple explosion protection techniques. It is noted that dielectric fluid which resides between the first and second enclosures 12, 16 is fully sealed within the first and second enclosures 12, 16 and is not in this example circulated aside from being able to pass between the first and second enclosures 12, 16 via the aperture 15.

[0069] Accordingly, it may be appreciated that the first and second enclosures 12, 16 provide a sealed box within a box type structure being generally double walled, with closely spaced or adjacent walls. The material of the first and second enclosures 12, 16 may generally be a metal such as steel or aluminium. A welded construction may be used such that the only joins are for the respective tops or lids.

[0070] In more detail, when fitted together, the one or more walls 27 and lid 24 of the first enclosure 12 and the one or more walls 43 of the second enclosure 16 and the lid 40 are arranged adjacent and at least partially spaced apart from one another such that the one or more walls 43 and the lid 40 are able to support the one or more walls 27 and the first lid 24 to contain the internal pressure event (such as that from a blast, explosion or thermal cause such as thermal runaway of the one or more battery cells 14). The arrangement and spacing between the one or more walls 27 and lid 24 of the first enclosure 12 and the one or more walls 43 of the second enclosure 16 and the lid 40 provides a gap 49 for the dielectric fluid between the one or more walls 27, 43 walls and the lids 24, 40.

[0071] During an internal pressure event, such that caused by excessive heating of the one or more battery cells 14 and resulting thermal runway - the generally sealed first enclosure 12 may absorb and contain at least part of the pressure which may cause one or more of elastic or plastic deformation of, for example, the one or more walls 27 of the first enclosure 12, and result in the outward deflection of the one or more walls 27 toward the one or more walls 43 of the second enclosure 16.

[0072] The one or more walls 43 of the second enclosure 16 are located closely spaced to the one or more walls 27 such that if the one or more walls 27 deflect outwardly, one or more walls 27 will, at least at some parts thereof, engage with the one or more walls 43 of the second enclosure 16 which provide additional support.

[0073] The gap 49 between, for example, the one or more walls 27 and one or more walls 43 may be less than about 15mm and may be in the range of 3mm to 20mm, and preferably about 5mm to 10mm, and most preferably about 5mm between the one or more walls 27 and 43, namely, the respective opposing side walls 28, 44. This provides space for the dielectric fluid and a fluid volume for each exchange with externally circulated cooling fluid. However, the gap 49 is sufficiently small such support is offered from the one or more walls 43 to the one or more walls 27 in a pressure event to assist to contain the internal pressure event.

[0074] For example, purposes, it is noted that the first and second enclosures 12, 16 may have a material wall thicknesses, such as for the one or more walls 27, 43, in the order about 25mm to 35mm when a steel alloy material is used. The length of the first and second enclosures 12, 16 may be about 1000mm in the provide examples with a width of about 300mm. Of course, other suitable dimensions and material thicknesses may be utilised, and the above-mentioned dimensions are for non-limiting example purposes only. In the above example configuration, the first and second enclosures 12, 16 may contain an internal blast pressure in the order of about 700 kPa.

[0075] The third enclosure 18 as shown in Figure 2 is defined between one of the opposing ends 46 of the second enclosure 16, a removable end panel 48 thereof, an opposing top and bottom 50, and opposing sides 52. These surface or walls may be shared with the second enclosure 16 or separate depending on the configuration. In some examples, the third enclosure 18 may be generally within the walls 43 that define the second enclosure 16, and separated from the second enclosure 16 by the end wall 46 of the second enclosure.

[0076] 14. The one or more electrical interface components 20 in the third enclosure 18 include a second set of fuses 54 that are, of course, external to the first enclosure 16, and include internal and external ports 55, 56 to enable sealed electrical communication via terminals 57 ultimately between the battery arrangements 30 within the first enclosure 12 and the external environment via the third enclosure 18. The sealing of the third enclosure 18 is such that the third enclosure 18 is a flame proof enclosure. The third enclosure 18 is preferably not filled with the dielectric fluid.

[0077] It is noted that the use of the third enclosure 18 being sealed from the external environment and sealed from the first and second enclosures 12, 16, which are themselves sealed, assists to place barriers between electrical components and the external environment that may be hazardous, such as having flammable gasses or the like.

[0078] Referring additionally to Figures 6 to 11, this example the diaphragm 22 is located toward the ordinarily oriented top 40 of the second enclosure 16. More specifically, in this example, the diaphragm 22 is provided by a recess 60 that is located on an internally facing side 59 of the lid 40 and a flexible membrane 62 that spans over the recess 60. The recess 60 may include air or other gas and allow for the membrane 62 to move to accommodate expansion and contraction of the dielectric fluid. The diaphragm 22 therefore functions to maintain the fluid levels of the first and second enclosures 12 and 16. The diaphragm 22, namely the membrane 62, may be formed of rubber or other suitable material.

[0079] Turning now to Figures 12 to 17, disassembly of the battery apparatus 10 is shown with the first enclosure 12 fully removed as shown in Figure 14 and its internal configuration revealed in Figure 15 showing an example battery arrangement 32 fitted in the slots 34, the connection board 36, and the battery interface arrangement 38 with the internal fuses 39. The connection board 36 provides a plug-in connection for the battery arrangements 32 and the battery interface arrangement 38. The design of the backplane connection board 36 is such that it may be impossible to insert the battery arrangements 32 incorrectly, and hence create a reverse polarity. A layer of Nomex sheet (not shown) 0.5mm thick provides a layer of insulation between the connection board 36 and the metallic material of the first enclosure 12.

[0080] It is noted that only one battery arrangement 32 is shown, however in use a plurality of removable battery arrangements 32 may be installed to provide a battery bank. It may be appreciated that the first enclosure 12 houses all the main components, other than interconnecting cables.

[0081] A method of assembly of the battery apparatus 10 may generally include firstly forming the first enclosure 12, and second enclosure 16, with the associated third enclosure 18. The first enclosure 12 may be fitted with its battery cell arrangements 32 fitted in the slots 34 and to the connection board 36. The battery interface arrangement 38 may also be fitted. [0082] The first enclosure 12 may then be fitted within the second enclosure 16 and any electrical connections may be made between the battery interface arrangement 38 and the electrical components 20 within the third enclosure 18 and the via the internal ports 55. The electrics may then be tested. The first enclosure 12 and the second enclosure 16 may then be filled with the dielectric fluid. The lid 24 of the first enclosure may be secured and sealed, and the lid 40 of the second enclosure 16 may also be secured and sealed. Further connections may be made to the electrical components 20 within the third enclosure 18 via the external ports 56 and the end panel 48 may be fitted. In use, a circulation system may be connected to cooling ports 47 to circulate the cooling fluid through the passageways 45. The first enclosure 12 can be accesses and maintained by removable of the lid 24, 40.

[0083] The battery interface arrangement 38 is best shown in Figure 16 and further includes interlock relays 64, isolation contactors 66, a communication connector 68 and power connectors 70 in addition to the fuses 39 supported by printed circuit board 71. The control connector 68 is used to communicate between the battery interface arrangement 38 and each of the battery arrangements 32.

[0084] The isolation contactors 66 function to trip the power from the battery both for operational and safety reasons. A high methane detection received from a gas sensor (external to the apparatus 10) may trip the safety contactors 66. The fuses 39 are provided to detect and clear short circuit faults that may occur in the field connection enclosure and provide a graded backup protection to the fuses 54 located within the field or third connection enclosure 18. The battery interface arrangement 38 includes SIL2 (Safety Integrity level 2) safety interlocks (not shown) and an IS circuit for methane interlock (not shown).

[0085] Part of an overall battery management system resides in the battery interface arrangement 38 and the battery interface arrangement 38 may include a central processor (not shown) adapted to communicate with the individual battery arrangements 32 via a dedicated controller area network. The central processor may receive, and store information received to calculate the differential voltage across the battery interface arrangement 38 or each battery arrangement 32, whether a particular cell 14 needs balancing or whether the voltage of a particular cell 14 is reaching the limit of its operational voltage or temperature range. It also monitors the pack voltage and total load current to ensure that the battery system operates within its design parameters.

[0086] Referring to Figure 17, each of the plurality of the battery cell arrangements 32 includes a printed circuit board 80 in electrical communication with the one or more battery cells 14. The battery cells 14 in this example may be, but not limited to, lithium- ion battery cells or pouches. The circuit board 80 carries all or most of the electronic components and cells 14 that make up the battery cell arrangements 32.

[0087] In this example, there are two lithium-ion cells 14 mounted to the circuit board 80. The cells 14 are arranged to form a series circuit between the two cells 14 giving an output to the connection board 36 of the two cells. Each cell may be, but not limited to, an NMC Lithium-Ion pouch type cell having a 75AmpHour capacity. The cell tabs are clamped via clamps 82 to the power connections on the board 80 by copper busbars. Of course, other types of cells and capacities may be used.

[0088] A further part of the battery management system may be located on the battery arrangement 32. The battery management system comprises a central processing unit (not shown) and the necessary hardware to operate the system. The battery management system monitors the cell temperature, cell voltage and conducts passive balancing of the cells. In some examples, a pressure exerted by the cells upon the board 80 may also be monitored. The power supply for the electronics is derived from the cells themselves meaning that each battery arrangement 32 is essentially self-sufficient. Each battery arrangement 32 communicates its status to the battery interface arrangement 38 by the controller area network.

[0089] Each battery arrangement 32 has four power connectors 84 and one control connector 86. Two of the connectors are used for the positive connection and two are used for the negative connection. Each connector may be rated at 60 amps. There may be a total of twelve battery arrangement 32 giving a total capacity of 720 Amps. The control connector 86 is used to communicate between the battery arrangements 32 and the battery interface arrangement 38. [0090] Further features including outputs of the battery apparatus 10 and example uses are now described. Such further features and example uses are for non-limiting explanatory purposes only. Firstly, there may be an intrinsically safe circuit provided by the sealed relays 64 of the battery interface arrangement 38 for the purpose of interfacing with the vehicle safety circuits (not shown). The circuit may be Ex ia (Intrinsically Safe) and SIL2 (Safety Integrity level 2). It is noted that Ex ia and SIL may be both the same circuit but are different features of the circuit. A circuit may be intrinsically safe Ex ia without being SIL2 compliant and vice versa. The Ex ia is its feature to not ignite a hazardous atmosphere and the SIL2 is the safety function in is the integrity of the circuit to operate, as designed.

[0091] It is intended to connect all safety devices that may be exposed in a hazardous area into the circuit relays 64 such as Methane Trip Circuits, Vehicle DCB (Distribution Control Enclosure) door interlocks, Emergency Stop systems, Whole Current Isolator Auxiliary Contacts as well as an interlock on the Field Interface Enclosure cover.

[0092] The control supply for the vehicle, or other load, is derived from a DCDC converter (not shown) having a 24VDC output housed on the battery interface arrangement 38 in the first enclosure 12. Contacts 66 from the safety interlock circuit are connected into the 24VDC control circuit so that the supply to the vehicle is not present unless the interlock circuit is healthy. The contact arrangement is designed and verified as a SIL2 safety circuit. The 24VDC control circuit is also used to trip the main power contactors in case of a fault or abnormal situation that arises. The contactors 66 will also open if required to do so by the battery management system. There are two contactors in the positive leg and two in the negative leg giving a total of four individual breaks per battery. The main form of communications between the battery and the vehicle is by a controller area network.

[0093] The main form of communications between the battery and the vehicle is by a controller area network (CAN). The CAN is not intrinsically safe and contacts from the interlock circuit are connected to prevent the controller area network exiting the battery until the interlocks are healthy. The circuit is arranged as a SIL2 safety circuit. [0094] There is the provision for safety interlocks within a vehicle control system (not shown), e.g.. Ground Fault Monitoring. The contacts for this interlock, including the fuses 54, are located in the third enclosure 18 and is designed to break the safety contactors on the when an abnormal situation arises within the vehicle.

[0095] In use, the battery apparatus 10 may be fitted to a vehicle (not shown) as an electrical power source. Although each application may vary the operating principle will be similar. An example of a vehicle start-up is provided below.

[0096] With the vehicle in a parked state, a methane system (not shown) will be asleep as the methane system may time out and shut down if it is not being used. In order for the system to become healthy, the methane system must be reset, the methane system will then provide power to the third party CH4 sensors (not shown) that will close their contacts for the SIL2 circuit when they are healthy.

[0097] Provided that the methane monitoring system is healthy, and all door interlocks are closed, the SIL2 circuit is ready. A selector switch in the dash must first be turned to OFF, then to START and finally to RUN. In this position relays SRI and SR3 will be energised and SR2 will be de energised thus closing the contacts in the 24VDC control circuit and enabling the control supply to the Vehicle. The 24VDC control supply energises the ground fault monitor and vehicle control unit. When all is healthy hard-wired safety external interlocks (not shown) will be closed and the vehicle control unit will initiate the safety contactors on the battery interrace arrangement 38 to close. The main battery contactors 66 will close and provide power to the on-board machine DCB (Distribution Control Board).

[0098] Advantageously, the battery apparatus combines hazardous area techniques such as exclusion, energy limitation, and containment. The battery apparatus is designed to maintain the temperature of the battery cells within their operating range. The design is such that a catastrophic thermal runaway is inhibited as the temperature generated in the early stages of such an event will be absorbed by the dielectric fluid. Therefore, the battery apparatus may maintain its explosion protected properties under all known failure modes. [0099] Most advantageously, the battery apparatus includes a generally dual walled structure in which both enclosures contain the dielectric fluid with the outer one of the enclosures having a diaphragm to maintain fluid levels and adapt to changes in pitch of the battery, thermal expansion, and contraction. The dual walled structure provides a gap for the dielectric fluid, and the outer enclosure. Walls of the outer enclosure are positioned closely adjacent to the walls of the inner enclosure to provide support to the inner enclosure in a pressure event such as a thermal runway event and potential explosion and resulting energy are contained within the first and second enclosures. The overall arrangement serving to contain the internal pressure event.

[00100] Furthermore, advantageously, the battery apparatus includes two sets of fuses, one set inside the first enclosure and one outside the first enclosure in the third enclosure, and the battery apparatus includes interlocks including methane and safety interlocks.

[00101] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[00102] The reference in this specification to any known matter or any prior publication is not, and should not be taken to be, an acknowledgment or admission or suggestion that the known matter or prior art publication forms part of the common general knowledge in the field to which this specification relates.

[00103] While specific examples of the invention have been described, it will be understood that the invention extends to alternative combinations of the features disclosed or evident from the disclosure provided herein.

[00104] Many and various modifications will be apparent to those skilled in the art without departing from the scope of the invention disclosed or evident from the disclosure provided herein.