BATTERY PACK
20230207926 · 2023-06-29
Assignee
Inventors
Cpc classification
H01M50/24
ELECTRICITY
H01M50/258
ELECTRICITY
H01M10/6556
ELECTRICITY
H01M10/6568
ELECTRICITY
H01M50/289
ELECTRICITY
Y02E60/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01M50/213
ELECTRICITY
H01M10/6566
ELECTRICITY
H01M50/20
ELECTRICITY
International classification
H01M10/6568
ELECTRICITY
H01M50/213
ELECTRICITY
H01M50/289
ELECTRICITY
H01M10/6551
ELECTRICITY
Abstract
a There is disclosed a battery pack comprising: a first battery cell layer comprising a structure for locating battery cells and providing a flow path for a coolant so that the coolant passes across the battery cells; a gasket of a first gasket type located adjacent a first face of the first battery cell layer; and a gasket of a second gasket type located adjacent a second face of the first battery cell layer. Each of the first gasket type and the second gasket type comprises a first side and a second side. The first gasket type comprises holes for the coolant located on the first side of the first gasket type; and the second gasket type comprises holes for the coolant located on the second side of the second gasket type. The gaskets enable the coolant to flow from a first end of the battery pack to a second end of the battery pack via the flow path.
Claims
1. A battery pack comprising: a first battery cell layer comprising a structure for locating battery cells and providing a flow path for a coolant so that the coolant passes across the battery cells; a gasket of a first gasket type located adjacent a first face of the first battery cell layer; and a gasket of a second gasket type located adjacent a second face of the first battery cell layer; wherein each of the first gasket type and the second gasket type comprises a first side and a second side; and wherein: the first gasket type comprises holes for the coolant located on the first side of the first gasket type; and the second gasket type comprises holes for the coolant located on the second side of the second gasket type; whereby the gaskets enable the coolant to flow from a first end of the battery pack to a second end of the battery pack via the flow path.
2. The battery pack of claim 1, comprising a plurality of battery cell layers, wherein each battery cell layer comprises a structure for locating battery cells and providing a flow path for a coolant so that the coolant passes across the battery cells.
3. The battery pack of claim 2, wherein at least two of, and/or each of, the plurality of battery cell layers have a gasket of the first gasket type located adjacent a first face of said layer and a gasket of the second gasket type located adjacent a second face of said layer.
4. The battery pack of claim 1, wherein the first face and the second face are opposing faces.
5. The battery pack of claim 2, wherein at least one pair of, and/or each pair of neighbouring battery cell layers has a gasket of a third gasket type located between said pair of battery cell layers, wherein the third gasket type comprises holes for the coolant located on both the first side and the second side of the third gasket type.
6. (canceled)
7. (canceled)
8. (canceled)
9. The battery pack of claim 1, wherein each battery cell layer comprises a scaffolding.
10. (canceled)
11. The battery pack of claim 9, wherein each scaffolding comprises a plurality of channels, wherein each channel is arranged to locate a plurality of battery cells and to provide a flow path for a coolant so that the coolant passes across the cells.
12. The battery pack of claim 11, wherein the gaskets are arranged such that coolant is able to flow through the holes in each gasket and into and/or out of the channels of the scaffolding of each battery cell layer.
13. The battery pack of claim 11, wherein the scaffoldings and the gaskets are together arranged to define a flow path for the coolant.
14. (canceled)
15. The battery pack of claim 1, being arranged such that the pressure of the coolant at the first side of the battery pack is greater than the pressure of the coolant at the second side of the battery pack, such that the coolant flows from the first side of the battery pack to the second side of the battery pack.
16. The battery pack of claim 1, comprising an enclosure, wherein each battery cell layer and each gasket is located within the enclosure, wherein each battery cell layer comprises a housing segment, wherein the housing segments are arranged to cooperate so as to form part or all of the enclosure of the battery pack, wherein: the housing segment of each battery cell layer comprises a structure for locating a gasket adjacent said housing segment; and/or; the gaskets between each pair of battery cell layers form a seal between said pair of battery cell layers and/or a seal between a/the housing segments of said pair of battery cell layers.
17. (canceled)
18. (Canceled)
19. (canceled)
20. The battery pack of claim 1, comprising a first end plate, wherein: the first end plate is located adjacent to a gasket of the first type or a gasket of the second type; and/or wherein the first end plate comprises a structure for locating a gasket adjacent the first end plate such that said gasket forms a seal between the first end plate and one of the battery cell layers.
21. (canceled)
22. The battery pack of claim 20, wherein the first end plate comprises one or more of: a reservoir arranged to accommodate an expansion of the coolant due to temperature fluctuations when the battery pack is in use; and a vent arranged to: provide an outlet for air to accommodate expansion of the coolant when the temperature of the coolant increases; and/or provide an inlet for air to accommodate compression of the coolant when the temperature of the coolant decreases; a pump, which pump is arranged to promote the flow of the coolant through the battery pack; and vanes to promote the transfer of heat from the first end plate to the surroundings of the battery pack.
23. The battery pack of claim 20, wherein the first end plate comprises a plurality of first end plate channels, wherein the first end plate channels correspond to channels in the battery cell layer(s), and wherein the first end plate channels are arranged such that the coolant is able to flow from a/the pump to the holes of a gasket, via the first end plate channels.
24. The battery pack of claim 23, wherein the first end plate channels are arranged such that, in use, the volumetric flow rate of the coolant through each of the first end plate channels is substantially the same.
25. (canceled)
26. (canceled)
27. (canceled)
28. (canceled)
29-38. (canceled)
39. The battery pack of claim 1, wherein one or more of the gasket types, and/or each of, the gasket types comprises a fluid return hole, wherein the battery pack is arranged such that the coolant is able to flow from the second end of the battery pack to the first end of the battery pack via the fluid return holes.
40-45. (canceled)
46. The battery pack of claim 1, comprising one or more temperature sensors and/or comprising one or more temperature sensors located at the exits and/or entrances of one or more channels of one or more battery cell layers.
47. (canceled)
48-54. (canceled)
55. The battery pack of claim 1, comprising a plurality of heating elements, wherein the heating elements are distributed across the battery pack so as to provide even heating of the coolant.
56-97. (canceled)
98. A kit of parts for a battery pack, the kit of parts comprising: a first battery cell layer comprising a structure for locating battery cells and providing a flow path for a coolant so that the coolant passes across the battery cells; a gasket of a first gasket type; and a gasket of a second gasket type; wherein each of the first gasket type and the second gasket type comprises a first side and a second side; and wherein: the first gasket type comprises holes for the coolant located on the first side of the first gasket type; and the second gasket type comprises holes for the coolant located on the second side of the second gasket type.
99-163. (canceled)
164. A vehicle comprising the battery pack of claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0242] Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings of which:
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DETAILED DESCRIPTION
[0277] A battery pack 300 is shown schematically in
[0278] The housing 310 is made from a plurality of parts including at least two parts 311, 312. The two parts consist of a left part 311 and a right part 312. The two parts 311, 312 are sealed mechanically to form the housing 310 such that no air or liquid can enter or escape to or from within the housing at the points at which the two parts are joined. The liquid coolant 307 is therefore prevented from leaking from the battery pack, and contaminants, such as moisture, are prevented from entering. The mechanical connection is achieved through bolting the two parts together, with a gasket or O-ring provided between them in order to provide the sealing. Other mechanical joining and sealing means may be used. The housing can be scaled in a lateral direction (i.e. along the Y axis) through the replacement of one or both of the two parts 311, 312 with longer or shorter variants or the addition of one or more centre sections between 311 and 312. In this manner the housing 310 can be scaled for various use cases, for example different sized forms of transport or different energy storage requirements. With longer battery packs additional pumps 305 can be added in parallel. Additional pumps can increase liquid volume flow as discussed below.
[0279] In an alternative example the housing comprises a top or lid affixed to a “bucket” housing, possibly with a gasket or seal and bolts. In other examples the housing may be formed from more than two parts, for example a bottom section, a centre section and a top lid. All the parts are sealed together such that no air or liquid can enter or escape to or from within the housing at the points at which the parts are joined.
[0280] An internal reservoir 314 is provided at the top of the battery pack and a pressure relief valve 313 is provided above the internal reservoir 314 in the top surface 301 of the battery pack. The reservoir and pressure relief valve together allow the liquid coolant 307 to expand and contract when the temperature increases or decreases. Whilst the reservoir and pressure relief valve are shown in the top 301 of the battery pack in this example, they may alternatively be situated elsewhere above the main body of the housing.
[0281] A burst disc may also be provided to provide an emergency pressure release in case of pressure fluctuations being too large for the reservoir and pressure release valve to accommodate. The burst disc may be provided in a flat wall, and preferably on the bottom 302 of the housing so that any coolant liquid that is released from the pack can be more readily directed away from the pack, and away from any passengers should the pack be installed in a vehicle, rather than being allowed to pool on the surface or otherwise run along surface as may be the case if the burst disc is situated on the top or sides of the pack.
[0282] The housing 310 is configured to act as a heat exchanger. The walls of the housing 310 are made (at least in part) from a thermally conductive material such as metal. The thermally conductive material improves the rate of heat transfer from the coolant within the housing 310 to the environment outside of it. This improves temperature regulation over a battery pack that uses thermally insulating materials. The material is also minimally reactive or non-reactive and is therefore protected from reacting with the liquid coolant 307 within the housing 310 or the environment without it. A suitable material may be aluminium for example. Ribs, vanes, and/or fins 306 are also provided on one or more of the external surfaces of the housing 310. The fins 306 increase the external surface areas of the housing 310, therefore increasing heat transfer from the housing to the external environment. In use cases in which the battery pack is to be mounted on a vehicle, the fins can be arranged such that they run in parallel to the intended predominant direction of travel of the vehicle. In this way air flow can pass along the fins as the vehicle moves, further increasing heat transfer. Ribs, vanes, and/or fins can also be provided on one or more of the internal surfaces of the housing, thereby increasing the internal surface area of the housing and therefore increasing heat transfer from the bath of liquid coolant to the housing, from where the heat can be dissipated into the environment.
[0283] Additional, active heat transfer means may optionally also be provided. For example, a Peltier cooler or cooling plate with heat pipes may be provided on a surface of the housing. Fans may also be used to provide forced air convention across the surface of the housing 310. Optional features such as this can further improve heat transfer and the dissipation of excess heat from within the housing.
[0284] A controller 320, temperature sensor 321 and tilt sensor 322 are provided. The controller 320 is in communication with the pumps 305 and configured to control their operation. The controller determines the operation of the pumps 305 in dependence on inputs received from the temperature sensor 321 and the tilt sensor 322. The temperature sensor is positioned such that it can measure a temperature of the liquid coolant 307 within the housing 310. Alternatively, the temperature sensor may be situated elsewhere in or on the housing. The temperature sensor may be configured and positioned to measure a temperature of the housing or other part of the battery pack, a temperature of the liquid coolant may then be inferred from the measured temperature, and the control of the pumps may then be implemented based on the measured temperature. Multiple temperature sensors are preferably used in order to take temperature readings at different positions of the battery pack. The tilt sensor is arranged to measure a variation in one or both of pitch (angular movement about the Y axis in this example) and roll (angular movement about the X axis in this example). Multiple tilt sensors may be used in order to measure the different tilt about different axes. Measuring tilt may comprise measuring a magnitude and/or an acceleration of tilt. Measuring the tilt of the battery pack may allow the controller to 320 determine the likelihood of the pumps 305 being affected by air pockets and the risk of dry pumping, which can cause damage to the pumps 305. If tilt over a certain threshold occurs, at which air pockets are likely to interfere with the pumps, then the controller may temporarily pause or deactivate the pumps 305. This therefore provides increased durability of the device during use, particularly in vehicles (two-wheeled vehicles even more so) which may be subject to large tilt variations.
[0285] In order to mitigate the risk of air accumulating within the pumps 305, the battery pack can be mounted or installed such that the pumps have an axis that is non-horizontal and the liquid inlet and/or liquid outlet holes of the pump are displaced vertically above the body of the pump. This can prevent air bubbles accumulating within the pumps, which may occur if the pumps are horizontal. In some examples the walls of the housing are inclined, such that the housing tapers from top to bottom. The surface mounted pumps therefore are also inclined upwards within the housing. In other examples the pumps may be constructed such that a body of the pump has an axis that is non-orthogonal to a plane of a flange of the pump, such that the pump is naturally inclined when installed on a vertical face.
[0286] The tilt sensors 322 may comprise or be supplemented by accelerometers. As changes in acceleration may result in ‘sloshing’ of the coolant liquid and displacement of air within the housing, the use of accelerometers can also be used to provide inputs to the controller in order to control the operation of pump 305.
[0287] The pumps 305 and other components are typically mounted on the external surface of the housing 310 in order to facilitate easier servicing and repairs than if the components were fixed internally to the housing 310. Whilst the majority of components are fitted to the surface of the housing the number of components requiring cut-outs or holes in the walls of the housing is kept as low as possible. As each of these require sealing, this therefore reduces the risks of a sealing failure.
[0288] In some configurations a single pump may be used, however multiple pumps are preferred. Multiple pumps provide increased volumetric flow as well as redundancy in case of failure of any one of the pumps.
[0289] One of the pumps 305 is shown in more detail in
[0290] The pump 305 is typically a centrifugal pump. A sectional view of an example of a suitable pump is shown in
[0291] A region of the housing 310 is shown in
[0292] The installation of the pump is shown in a blown apart and partially sectional view in
[0293] In this way the pump can be surface mounted directly onto the surface of the housing. This provides a single sealed interface which in turn avoids the need for any tubes/fittings reducing part count, assembly costs and the risk of a leakage. The battery pack uses the housing's internal construction in order to keep the inlet and outlet flows separated and direct these flows to internal cooling channels within the housing.
[0294] Various means for mounting the pump 305 to the housing can be used. For example, the pump manifold can be welded to the housing and/or a threaded hole or recess can be provided in the housing to correspond to a bolt associated with the pump. Any means that ensure a sealed fit between the housing 310 and the pump 305 may be used.
[0295] A cross sectional view of a configuration of the battery pack 300 providing a view from inside the housing 310 is provided in
[0296] The housing 310 and scaffolding 501 together also create internal channels and flow paths 504 for the liquid coolant to flow through on the inside of the housing. The channels created internally by the arrangement and construction of the housing 310, the scaffolding 501 and the cells 502, direct liquid across the cells to take up heat from cells, and then around the internal surface of the housing. Heat is therefore transferred from the cells to the liquid coolant, from the coolant to the walls of the housing, and from the housing to the external/ambient environment.
[0297] The internal construction 414 of the housing that separates the inlet 412 from the outlet 413 abuts the scaffolding to further define the flow channels 416, 417. The internal construction 414 may comprise a fitting and/or locating means that corresponds to a fitting and/or locating means on the scaffolding. The scaffolding is fitted to the housing to define the channels and to space and/or locate the cells within the housing.
[0298] Ribs 503 (or other protrusions) are provided on the inside of the housing. These increase the surface area of the internal walls of the housing, which in turn increases the rate of heat transfer from the coolant to the housing. Similarly, fins 306 or other suitable protrusions such as vanes or ribs increase the surface area on the outside surface of the housing and therefore increase the transfer of heat from the housing to the external environment.
[0299] The construction of the housing and scaffolding is arranged to reduce the volume of coolant required whilst still providing adequate heat exchange. The pathways formed by the negative space defined by the arrangement of the housing and scaffolding (and the cells themselves) are therefore narrow. Where larger voids or pockets are formed due to construction techniques (or otherwise) then the scaffolding may be arranged to fill those voids. In this and other configurations foam blocks 506, or other suitable filling material, is provided and affixed to reduce the empty volume within the housing. The space filling material (in this case foam) is selected based on its lightweight properties. Low density materials are therefore preferred for this purpose.
[0300] For example, the housing 310 when empty may have a volume of about 30 litres. The battery cells may have a combined volume of about 10 litres. The remaining space for coolant liquid would therefore be about 20 litres. However, the scaffolding 501 has a volume also. The volume of the scaffolding to perform its battery cell mounting, positioning and locating function can be quite low, but we may choose to have it deliberately have a bigger volume when defining not only the direction and existence of coolant liquid flow paths but also their cross section (in combination with the housing and the battery cells so as to achieve a desired volume of coolant adjacent the battery cells and housing without having too much liquid present. For example, the scaffolding might have a volume of 13 litres, which means that instead of about 20 litres volume of liquid we have 7 litres volume of liquid. We have realised that we can get good performance whilst at the same time reducing the volume of (expensive) coolant liquid that is needed, up to a certain point anyway—i.e. avoiding “excess” liquid in the places where it is not needed.
[0301] The arrangement of the cells 502 within the scaffolding 501 is shown in more detail in
[0302] A cross sectional view of another configuration of the battery pack is shown in
[0303] As the temperature within the battery pack fluctuates the pressure also changes. Arrangements to accommodate for these changes in pressure are shown in
[0304]
[0305] The divider 710 is shown by itself in
[0306] Angles that may allow air to pass from the reservoir into the main housing body are extremely unlikely to be reached in most uses of a battery pack, such as in a vehicle, for example a motorbike or scooter. Because such angles are not reached, air is prevented from entering the housing and therefore kept away from the coolant liquid channels and the pumps. Air may also reduce the operating efficiency of the coolant as it may act as an insulator. The pressure relief valve 308 is provided at the top of the reservoir 314. In this way only air, and not the coolant, is expelled in high pressure (due to high temperature) events. In certain arrangements (for example where the battery is used for building energy storage) the reservoir can be implemented without a divider. The divider militates against tilt events. A stationary battery pack 300 should not tilt and so a divider may not be implemented. The configuration of the reservoir and divider is therefore dependent on the use case for the battery pack 300, and in particular the variation of the orientation of the battery pack 300 and any acceleration forces it may be subjected to in use.
[0307] In another configuration the reservoir may instead be provided as a separate component and connected via a tube to the housing.
[0308] In other arrangements no air pocket is provided and coolant expansion and/or contraction is managed through the use of a diaphragm 811 or bellow.
[0309] Referring to
[0310]
[0311] Exemplary flows across the channels 512-1 . . . 512-5 of the scaffolding are shown in
[0312] In order to promote the flow of coolant through the scaffolding channels 512-1 . . . 512-5 from a first side of the battery pack to a second side of the battery pack, the battery pack is arranged so that, during use, the pressure on a first side of the scaffolding channels is greater than the pressure on the second side of the channels; therefore, there is a continuous flow of coolant through the channels in the desired direction.
[0313] In practice, the scaffolding 501 is typically a part of a battery cell layer, where in order to manufacture the battery cell layer battery cells are lowered into the receptacles of a lower part of the scaffolding 501 a, and then after the cells have been inserted into the cell receptacles (as shown in
[0314] The upper part of the scaffolding 501b typically comprises channel dividers and/or cell receptacles that align with the channel dividers and the cell receptacles of the lower part so that the lower part of the scaffolding 501a and the upper part of the scaffolding cooperate to form the channels and the cell receptacles.
[0315] Referring to
[0316] Each of these components may be lowered into, and then secured in, a housing segment 503 associated with the battery cell layer using a fixing means, such as screws. The process of building up the battery cell layer is shown clearly by the perspective views in
[0317] Within this battery cell layer, the battery cells in the scaffolding 501 are typically arranged so that the coolant flows transversely across the cells. This enables the battery cells and the busbar to be arranged so that the coolant does not flow between the cells and the busbar 518.
[0318] While each battery cell layer typically comprises a scaffolding for locating the battery cells and providing channels, more generally there may be provided a battery cell layer in which battery cells can be located such that coolant flows across these battery cells. Typically, each battery cell layer is associated with a top cover and a busbar, but this is not required. Typically, the battery cell layers each comprise a plurality of channels, which channels are typically part of a scaffolding (but equally the channels could be formed in another manner). Where the description refers to channels of a battery cell layers, the disclosure equally applies to channels of scaffoldings and vice versa.
[0319] According to the present disclosure, a plurality of battery cell layers, and/or a plurality of layers of scaffolding are provided in order to form a battery pack of a desired size and capacity. A method of arranging this plurality of battery cell layers to form a battery pack is described with reference to
[0320] Specifically, the battery pack comprises a bottom gasket 522, a plurality of battery cell layers 524a, 524b that are separated by a middle gasket 526, and a top gasket 528.
[0321] Typically, each of the battery cell layers comprises a structure for locating a gasket adjacent the battery cell layer (and/or adjacent the housing segment associated with the battery cell layer). Such a structure is useable to ensure each gasket is properly positioned so that in use the gasket forms a seal between the battery cell layer and a neighbouring component (e.g. a neighbouring battery cell layer).
[0322] The bottom gasket 522 is shown in more detail in
[0323] The battery pack, and each gasket 522, 526, 528, has four sides, including a first side 522-1, 526-1, 528-1 and a second side 522-2, 526-2, 528-2 located on opposing sides of the gasket and a third side 522-3, 526-3, 528-3 and a fourth side 522-4, 526-4, 528-4 located on opposing sides of said gasket. The gaskets are arranged in the battery pack so that the first sides of each gasket are aligned, the second sides of each gasket are aligned, etc. As shown in
[0324] The bottom gasket 522 comprises one or more holes along the first side 522-1 of the bottom gasket (e.g. only along the first side).
[0325] The middle gasket 526 comprises one or more holes along both the first side 526-1 and the second side 526-2 of the middle gasket.
[0326] The top gasket 528 comprises one or more holes along the second side 528-2 of the top gasket (e.g. only along the second side).
[0327] Therefore, when the battery pack is assembled the one or more holes along the first side 522-1 of the bottom gasket 522 align with the one or more holes on the first side 526-1 of the middle gasket 526 and the one or more holes along the second side 528-2 of the top gasket 528 to align with the one or more holes on the second side 526-2 of the middle gasket 526.
[0328] The holes of the gaskets are arranged to correspond to the channels of the battery cell layers 524a, 524b. Specifically, each gasket comprises a number of holes that is related to and/or equal to a number of channels of the battery cell layers so that coolant is able to flow through the holes of each gasket into an associated battery cell layer channel. Therefore, where the battery cell layers (e.g. the scaffoldings in the battery cell layers) comprise five channels, the gaskets typically comprise five holes arranged so that coolant can flow through the five holes into these five channels.
[0329] Each battery cell layer is arranged in the battery pack such that the channels of the battery cell layers 524a, 524b provide a flow path between the first sides of the gaskets 522-1, 526-1, 528-1 and the second sides of the gaskets 522-2, 526-2, 528-2. Therefore, coolant is able to flow from a first end (e.g. the bottom) of the battery pack to a second end (e.g. the top) of the battery pack via the gaskets and coolant is able to flow from a first side (e.g. the left) of the battery pack to a second side (e.g. the right) of the battery pack via the channels in the battery cell layers.
[0330] In order to allow the flow of coolant between the channels of the battery cell layers 524a, 524b and the gaskets, the busbar 518 and/or the top cover typically comprise transfer holes that align with the holes of the gaskets in use. The transfer holes are typically arranged along both a first side and a second side of the top plate and the busbar to provide compatibility with each type of gasket. Equally, the top plate and/or the busbar may be sized so that coolant can flow around the top plate and/or the busbar. In this regard, in some embodiments instead of holes the busbar and the top cover comprise cut-outs that enable coolant to flow past these components (e.g. semi-circular cut-outs at the sides of the busbar/top cover).
[0331] It will be appreciated that the battery pack may not have a quadrilateral cross-section, so while
[0332] In some embodiments, only one battery cell layer is provided and no middle gasket is provided. Therefore, coolant is able to: flow through the holes in the first side of the bottom gasket 522; then flow through the channels of the battery cell layer to the second side of the gaskets; and then flow through the holes in the second side of the top gasket 528.
[0333] Where multiple battery cell layers and one or more middle gaskets are provided, the flows of the coolant are as shown in
[0334] With this arrangement, where flow moves from a first end of the battery pack to a second end of the battery pack, and from the first side of the battery pack to the second side of the battery pack, a plurality of battery cell layers may be provided while maintaining consistent cooling of the battery cells located therein (and avoiding hot-spots). To avoid back-flows and achieve a consistent flow, the pressure at the entrance of each channel at the first side of the battery pack is arranged to be higher than the pressure at the exit of that channel at the second side of the battery pack. This is achieved using the pump 305.
[0335] As shown in
[0336] In some embodiments, one or more of the gaskets 522, 526, 528 is sized so that the passage for fluid return is outside of the corresponding battery cell layers. Such gaskets may be provided without a fluid return hole.
[0337] As can be seen in
[0338] Referring to
[0339]
[0340] In order to manufacture the battery pack, the bottom gasket 522 is provided and the first battery cell layer 524a is then provided on top of the bottom gasket (where the first battery cell layer typically contains a lower part of a scaffolding, an upper part of the scaffolding, a plurality of cells, a busbar, and/or a top cover); the middle gasket 526 is then placed onto the first battery cell layer, and the second battery cell layer 524b is placed on top of the middle gasket. This process of placing battery cell layers and middle gaskets may be repeated with a plurality of battery cell layers, with each battery cell layer being separated by a middle gasket. The top gasket 528 is then placed on top of an uppermost battery cell layer. This method provides a straightforward way of manufacturing batteries of different sizes.
[0341] Each battery cell layer is typically associated with a separate housing segment, where these housing segments cooperate to form an outer housing (or an ‘enclosure’) of the battery pack. Equally, there may be provided a separate enclosure, where each of the battery cell layers and the gaskets are placed into this enclosure.
[0342] ‘Placing’ the components of the battery pack typically comprises lowering the components onto each other. This enables a straightforward method of manufacturing and results in each gasket being deformed by the weight of the components on top of that gasket. This deformation of the gaskets leads to each gasket forming a seal between the components to either side of that gasket. For example, each middle gasket forms a seal between two neighbouring battery cell layers. Typically, the formation of the seals is further encouraged by inserting fastenings (e.g. screws or bolts) through holes in the housing segments and/or end plates and tightening these fixings to press the layers of the battery pack together.
[0343] In order to secure each component in place and to complete the enclosure, a bottom end plate and a top end plate are located adjacent the bottom gasket 522 and the top gasket 528 respectively. Embodiments of these end plates are described below with reference to
[0344] Referring to
[0345] With such an arrangement, the entirety of the coolant flows through the channels in each battery cell layer so that the coolant moves:
1. through the holes in the first side of a first bottom gasket 522a;
2. between the first side and the second side of the battery pack via the channels in a first battery cell layer 524a;
353. through the holes in the second side of a top gasket 528;
4. between the second side and the first side of the battery pack via the channels in a second battery cell layer 524b; and
5. through the holes in the first side of a second bottom gasket 522b.
[0346] It will be appreciated that with such an arrangement, a ‘bottom’ gasket might be above a ‘top’ gasket. In practice, the battery pack comprises a plurality of gaskets, including: gaskets of a first gasket type (‘bottom’ gaskets), gaskets of a second gasket type (‘top’ gaskets), and optionally gaskets of a third gasket type (‘Middle’ gaskets).
[0347] As with the arrangement using middle gaskets, this arrangement with alternating bottom and top gaskets enables the provision of a battery pack of any size.
[0348] Typically, in such embodiments, the gaskets are arranged so that the coolant still flows from the first side of the battery pack to the second side of the battery pack, e.g. so that the lowermost gasket is a bottom gasket and the uppermost gasket is a top gasket (as shown in
[0349] This enables the use of the same endplate for battery packs using alternating arrangements of top and bottom gaskets and battery packs that use middle gaskets as described with reference to
[0350] It will be appreciated that any combination of bottom, middle, and top gaskets may be used. For example, the first top gasket 528a of
[0351] Referring to
[0352] The bottom end plate typically comprises cooling fins and/or vanes on an outer surface to improve heat transfer from the battery to a fluid (typically air or water) surrounding the battery pack.
[0353] As shown in
[0354] More generally, the ‘pressure release valve’ described in this document may comprise any vent that allows the passage of air through the vent. Therefore, air may escape via the vent as the coolant heats up and then air may enter via the vent as the coolant cools down. Typically, the vent is arranged to enable both the ingress and exit of air. The vent may be a breather vent that has a semi-permeable membrane that allows air through in either direction but blocks the passage of liquid in either direction.
[0355] Typically, the pump 305 is integrated with, mounted on, and/or located on the bottom end plate 532 such that the coolant flows through the pump into a series of bottom end plate channels 536 in the bottom end plate. The pump may be located on the outside of the bottom end plate and/or on the inside of the bottom end plate. The pump being on the inside of the bottom end plate relates to the pump being located within the interior of the battery pack when the battery pack is assembled so that the pump is not exposed to the surroundings of the battery pack. In this regard, the bottom end plate typically forms an outer wall of the battery pack, so the pump being within the interior of the battery pack typically comprises the pump being within this outer wall. An example of an exterior mounted pump is visible in
[0356] Arrangements of a pump that may be used with the bottom end plate, and in particular ways of mounting a pump on a surface, have been described above in more detail with reference to
[0357] The bottom end plate channels 536 correspond to the channels in the battery cell layers and the holes in the bottom gasket 522 such that coolant is able to flow from the pump 305 into the bottom end plate channels and then through the holes on the first side 522-1 of the bottom gasket into the channels of a battery cell layer.
[0358] The bottom end plate channels 536 are typically each arranged in a serpentine arrangement in order to maximise the flow time required for the coolant to pass between the pump 305 and the bottom gasket 522 so as to maximise the time during which the coolant in the bottom end plate channels transfers heat to the surroundings of the battery pack via the bottom end plate 532.
[0359] Furthermore, the bottom end plate channels 536 are typically arranged so that the volumetric flow rate of the coolant passing from the pump 305 to the holes in the first side 522-1 of the bottom gasket 522 is the same for each channel of the bottom end plate channels, that is, per unit time, the same volume of coolant passes into each of the bottom end plate channels and therefore the same volume of coolant passes through each of the channels of the battery cell layers 524a, 524b (more specifically, the average volumetric flow rates are the substantially equal—and it will be appreciated that even where the average volumetric flow rates are equal there may be a small variation in the rates at any given moment). This ensures that the temperature distribution across the battery pack is substantially uniform, and thus the use of equal (or similar) volumetric flow rates reduces the likelihood of hot-spots in the battery pack. The equal volumetric flow rates are typically achieved by arranging the bottom end plate channels such that the pressure drop across each channel (e.g. between the pump and the holes on the first side of the bottom gasket) is the same.
[0360] The reservoir 538 of the bottom end plate 532 is typically located out of the flow path of the coolant (e.g. not in line with the bottom end plate channels 536). Therefore, coolant only flows into the reservoir once the battery cells, and thus the coolant, begins to heat up (where the coolant expands due to this heating). The reservoir may contain a raised step to ensure that the coolant does not flow into the reservoir when the coolant is at a low temperature.
[0361] Referring to
[0362] As with the bottom end plate 532, the top end plate 542 typically comprises cooling fins and/or vanes on an outer surface of the top end plate that improve heat transfer from the battery pack to a fluid (typically air or water) surrounding the battery pack.
[0363] The top end plate 542 comprises top end plate channels 546 that correspond to the channels in the battery cell layers 524-1, 524-2 such that coolant flows from the channels in a battery cell layer into the top end plate channels via the holes in the second side 528-2 of the top gasket 528. The top end plate channels are arranged such that the coolant then flows from these top end plate channels into the pump 305 via the fluid return holes 522-5, 526-5, 528-5 in each gasket and the fluid return channels of the battery cell layers and/or enclosure (and the coolant then flows from the pump into the bottom end plate channels 536).
[0364] In some embodiments, there is provided a reversibly sealable hole 543 on the top end plate 542 that aids the insertion of coolant into the battery pack and/or the removal of coolant from the battery pack. The reversibly sealable hole is arranged to be sealed during normal operation of the battery pack. More generally, there may be provided two holes on the battery, where one of these holes may be the vent 539 and one of these holes is the reversibly sealable hole 543.
[0365] The use of the reversibly sealable hole 543 enables coolant to be inserted into the battery pack in a straightforward manner. In particular, the battery pack can be oriented so that the reversibly sealable hole is at the top of the battery pack and then coolant can be inserted into the reversibly sealable hole. The air displaced by this coolant is able to escape through the vent 539. Once the coolant has been inserted into the battery pack, the reversibly sealed hole is sealed to prevent coolant from escaping out of this hole.
[0366] The provision of two holes thus enables the battery pack to be easily filled after assembly of the battery pack. This enables the battery pack to be assembled at a factory and then filled at another location, which may reduce the transportation costs and/or the difficulty of transporting the battery pack.
[0367] In order to remove the coolant (e.g. in order to recycle or repurpose the battery pack as described further below), the reversibly sealable hole 543 is unsealed and a gas (such as air) is pumped into either the reversibly sealable hole or the second hole (e.g. the vent 539). The air pushes the coolant out of the battery pack.
[0368] Typically, the air is pumped into the vent 539 and so the coolant flows out of the reversibly sealable hole 543. As described previously, the vent is typically a semi-permeable vent that permits the passage of air but prevents the passage of coolant. By pumping air into the vent and collecting coolant from the reversibly sealable hole, no coolant flows through the vent and so no alterations are required to the vent. Therefore, removing coolant from the battery simply involves unsealing the reversibly sealable hole, pumping air into the vent, and then re-sealing the reversibly sealable hole.
[0369] Typically, before air is pumped into the battery pack the battery pack is oriented so that the vent 539 is at the top of the battery pack; therefore coolant is also encouraged to flow out of the reversibly sealable hole 543 by gravity.
[0370] To ensure the removal of all coolant, the coolant may be sucked out of the reversibly sealable hole using a suction pump.
[0371] Furthermore, to ensure that all of the coolant can be removed from the battery pack, the reversibly sealable hole 543 is typically arranged to be level with, or below, the level of the top end plate channels 546. In particular, the reversibly sealable hole is arranged so that the reversibly sealable hole is below the lowest level of the coolant in the top end plate when the battery is oriented so that the top end plate is at the bottom of the battery.
[0372] The battery pack may comprise a sealing structure for sealing the reversibly sealable hole 543, for example the battery pack may comprise a seal that can be rotated between a first position where the hole is covered and a second position where the hole is uncovered. Equally, a separate sealing structure may be used to seal the reversibly sealable hole, such as a removable plug.
[0373] While the reversibly sealable hole 543 is described here as being on the top end plate 542, more generally there are provided two holes on the battery pack, where one of these holes is typically reversibly sealable. Providing the holes on opposing ends of the battery pack (e.g. on opposing end plates) ensures that the insertion of air into the battery pack pushes coolant out of the battery (whereas the use of two nearby holes might result in the air simply flowing in and out of the battery by flowing directly between the holes).
[0374] With the components described above, and using the arrangement of
[0375] As with the bottom end plate channels 536, the top end plate channels 546 are typically arranged in a serpentine arrangement and are typically arranged so that the volumetric flow rate of the coolant in each of the top end plate channels is substantially the same for each top end plate channel. This ensures that, per unit time, the same amount of coolant passes through each of the channels so that the temperature distribution across the battery pack is substantially uniform (e.g. the use of the similar flow times reduces the likelihood of hot-spots in the battery pack).
[0376] Using the described arrangement, a single bottom end plate 532 (which comprises a pump and a reservoir) and bottom gasket 522, and a single top end plate 542 and top gasket 528 can be combined with a plurality of battery cell layers 524a, 524b, 524n and middle gaskets 526 to provide a battery pack of any size.
[0377] When assembled, the bottom gasket 522 forms a seal between the bottom end plate 532 and a lower battery cell layer and the top gasket 528 forms a seal between the top end plate 542 and an upper battery cell layer. Each pair of battery cell layers is then sealed using either a middle gasket, as described with reference to
[0378] In this way, a small battery pack (e.g. containing a single battery cell layer and no middle gaskets) and a large battery pack (e.g. containing five battery cell layers and four middle gaskets) can be manufactured on the same assembly line, with the large battery pack simply being cycled through a battery cell layer/middle gasket inserting apparatus a plurality of times, where each cycle involves a middle gasket being lowered onto a battery cell layer and then a further battery cell layer being lowered onto the middle gasket. The middle gasket then deforms to provide a seal between these two battery cell layers (this deformation may occur when the layers of the battery pack are secured/pressed together).
[0379] It will be appreciated that while the above description has referred to ‘top’ and ‘bottom’ gaskets and end plates, in practice the battery pack may have a different orientation so that these gaskets and end plates are located differently. More generally the battery pack comprises a first and second end plate and a first gasket type and second gasket type (and optionally, a third gasket type that relates to the middle gasket).
[0380] Indeed, referring to
[0381] While the pump 305 and the reservoir 538 have been described as both being on the bottom end plate 532, it will be appreciated that these components may be distributed between the bottom end plate and the top end plate 542 in any arrangement (e.g. both of these components may be on the top end plate, or the reservoir may be on the bottom end plate while the pump is on the top end plate).
[0382] The end plates 532, 542 of the battery pack typically comprise fins and/or vanes, which vanes increase the heart transfer between the end plates and the external surroundings. The sides of the battery packs typically do not have vanes and are arranged to present a flat surface. This enables battery packs to be placed side by side to form a battery arrangement.
[0383] Referring to
[0384] While
[0385] Referring to
[0386] A plurality of battery packs may be placed adjacent each other with respect to the z-direction; however, such an arrangement typically reduces the heat transfer from one of the end plates of each battery pack (since the end plates of two battery packs will be near to each other). Therefore, where a plurality of battery packs are placed next to each other in the z-direction these battery packs are typically separated by at least 1 m, at least 500 mm, at least 250 mm, and/or at least 50 mm (depending on the system in which the battery arrangement is being implemented).
[0387] Where a plurality of battery packs is provided so as to form a battery arrangement, these battery packs may be connected to each other using an electrical connector. The electrical connector is typically connected to the busbars of a plurality of battery packs and therefore the electrical connector can be used to control the operation of this plurality of battery packs from a single location, e.g. to turn on or off any one of the battery packs. The electrical connector may also be arranged to provide information about the battery packs in the battery arrangement (e.g. to provide measurements from temperature sensors within these battery packs).
[0388] As shown in
[0389] Typically, the battery packs are arranged so that the pump of each battery pack is at the bottom of that battery pack in use and/or so that the reservoir of each battery pack is at the top of that battery pack in use. Therefore, the ‘bottom’ end plate 532 of each battery pack is typically arranged to be either on a side of that battery pack (with the reservoir at the top of the bottom end plate) or on the top of that battery pack.
[0390] Where the battery arrangement is oriented such that the ‘bottom’ end plate 532 is on the side of the battery pack, the vent 539 is typically provided in the uppermost side of the bottom end plate adjacent the reservoir 538, so that air can escape upwards through the vent—this is shown in
[0391] Where the battery arrangement is oriented such that the ‘bottom’ end plate 532 is on the top of the battery pack, the vent is still typically provided in the uppermost side of the bottom end plate adjacent the reservoir (so that gas can escape upwards through the vent)—this is shown in
[0392] Referring to
[0393] Typically, there is greater variation of temperature between the exits of the channels than between the entries of the channels. Therefore, as shown in
[0394] The temperature sensors may be used to determine a temperature distribution at the entrances and/or exits of the channels. This distribution is useable to identify a damaged cell (e.g. if one channel does not fit neatly into the distribution) and is also useable to identify trends in the heating of the cells. For example, the distribution may show that the outer channels are cooler than the inner channels, and this may result in additional coolant being diverted to the inner channels.
[0395] In some embodiments, the battery pack comprises flow rate sensors in one or more of the channels of the battery cell layers, the channels of the end plates, and the pump 305. As with the temperature sensors, flow rate sensors can be used to identify potential faults in the battery pack. In particular, flow rate sensors can be used to identify sub-optimal flow of coolant through a channel. The operation of the battery pack can then be altered accordingly (e.g. to divert more coolant through this channel).
[0396] Equally, because the bottom end plate channels 536 are arranged so that the volumetric flow rate through each channel is equal, the flow rate in each channel can be determined based on a flow rate through the pump 305.
[0397] The temperature sensors are typically arranged to measure the temperature of the coolant in each channel. By combining the temperature measurements with the determined flow rates of the channels, the temperatures in each of the battery cells can be determined. This enables the operation of the pump 305 and/or the operation of the battery cells to be altered to ensure that the temperature of each battery cell is within a desired range. In particular, if the cells are becoming undesirably hot, additional power may be provided to the pump to increase the rate of flow of coolant through the battery pack and/or less current may be drawn from the battery cells to reduce the rate of heating. The pump and/or the battery cells are typically arranged to operate in dependence on the measurements taken by the temperature sensors. This may comprise the temperature sensors providing these measurements to a control module that controls the pump and the battery cells.
[0398] The control module of the battery pack is typically arranged to determine and/or alter the operation of a battery cell or a plurality of battery cells in dependence on a combination of readings from the temperature sensors as well as current and/or voltage readings. This enables the control module to identify faulty battery cells. As described above, these faulty cells may then be deactivated. In some embodiments, cells can be individually controlled; however, typically cells are controlled in groups so that deactivating a faulty cell comprises deactivating a plurality of cells including the faulty cell (e.g. all of the cells in a channel and/or all of the cells in a battery cell layer). Furthermore, the user or supplier of the battery pack may be shown an indication of the faulty cells so that the user or supplier can repair and/or replace the battery cell layer or the battery pack in which the faulty cells are located.
[0399] The temperature sensors may be associated with the busbars of the battery cell layers. For example, the temperature sensors may be distributed across the busbars. Temperature sensors may be provided on an inner face of the busbar (e.g. a face that is facing towards the centre of the battery cell layer associated with the busbar) and/or an outer face of the busbar (e.g. a face that is facing away from the centre of the battery cell layer associated with the busbar). Equally, temperature sensors may be associated with and/or provided on the gaskets or the scaffoldings of the battery cell layers. Indeed, as described above, typically the temperature sensors are located at, or associated with, the entrances and/or exits of channels of the scaffoldings.
[0400] The operation of the battery cells is typically dependent on the temperature of these cells, where the battery cells have a maximum optimal operating temperature. Therefore, the coolant is used to transfer heat away from the battery cells to the surroundings of the battery in order to avoid overheating. As well as having a maximum optimal operating temperature, the battery cells may have a minimum optimal operating temperature. Therefore, as shown in
[0401] The battery pack may comprise a plurality of heating elements 554 distributed across the battery pack. More specifically, the battery pack may comprise a plurality of heating elements associated with the busbars of each battery cell layer of the battery pack. The heating elements are typically distributed across the busbars so that they provide heat evenly to the coolant throughout the battery pack. In this way, the distributed heating elements are arranged to provide even heating of the coolant (and therefore the battery cells).
[0402] The heating elements are typically arranged in dependence on the battery cells (or the cell receptacles 514), where there may, for example, be a heating element located between a plurality of cells or between each pair of cells.
[0403] As described above, the heating elements are typically provided on the busbar(s). Equally, the heating elements may be associated with and/or provided on the gaskets or the scaffolding parts 501a, 501b. Each scaffolding part may be associated with its own plurality of heating elements to ensure even heating across the whole of the battery.
[0404] Where heating elements are provided on the busbar(s), the heating elements may be provided on an inner face of the busbar (e.g. a face that is facing towards the centre of the battery cell layer associated with the busbar) and/or an outer face of the busbar (e.g. a face that is facing away from the centre of the battery cell layer associated with the busbar).
[0405] Providing distributed heating elements rather than a single heating element leads to uniform heating throughout the battery pack and so avoids undesirable hotspots and related safety risks. The use of a dielectric coolant enables the heating elements 524 to be exposed to the coolant, enabling a plurality of heating elements to be provided, and enabling these heating elements to be provided within the battery cell layers and close to the battery cells.
[0406] An example of a vehicle 900 comprising the battery pack 300 of the present disclosure is shown in
[0407] The liquid coolant that circulates inside the battery pack is a dielectric fluid. The liquid coolant is an electrically non-conductive but thermally conductive fluid. The coolant is initially channelled through one or more chambers within the housing, where it flows past the battery cells housed in these chambers. Once the coolant leaves these chambers it is then channelled across the inner surface of the battery housing—to transfer heat to the housing and thereby cool the coolant down—before it is then pumped back into the cell chambers.
[0408] The housing is made of aluminium with ribbing on the inside and fins on the outside. The ribs on the inside increase the surface area for heat transfer from the coolant to the aluminium. The fins on the outside increase the surface area for heat transfer from aluminium housing to the external environment or surrounding air.
[0409] The fins are exposed to horizontal airflow when the vehicle is moving, extracting heat from the housing (in a motorcycle or small vehicle we can expose the battery system directly avoiding the need for a separate radiator). In some arrangements, fans can be installed onto or proximal to the housing to drive air past the fins if natural air flow is not sufficient. In other arrangements the fins can be removed from the outside of the housing and instead thermoelectric plates, liquid cooling plates, heat-pipes or any other similar thermal management systems can be installed onto or proximal to the housing to dissipate heat from the surface of the housing.
[0410] The thermal capacity of the liquid coolant provides a much greater reduction in overall temperature rise than if the system were filled air.
[0411] A heater, such as a resistive heater, can also be embedded inside the housing to heat the liquid coolant as it circulates internally. This is particularly useful when the battery is operating at a low temperature.
[0412] The volume of the housing that is not contained within the chambers is configured to be kept small within operational limits, this reduces the amount of coolant required, which reduces weight and the volume fluctuations that may be accounted for in the design.
[0413] An example of a suitable coolant liquid is the Novec 7300 Engineered Fluid which is available from 3M.
[0414] Recycling
[0415] A process for recycling battery packs will now be described.
[0416] The battery packs described above may be manufactured so as to have improved recyclability over battery packs known in the art. The process of recycling the battery pack is dependent upon its configuration.
[0417]
[0418] In some examples the pumps 305 may be replaced with air pumps instead of the cover. In other examples one or more pumps may be replaced with air pumps and one or more pumps may be covered. In some examples only the pumps are replaced, along with the removal of the coolant liquid.
[0419] Using air pumps and removing the coolant liquid provides the battery pack with means to be operated as an air-cooled battery pack with forced convention. The structure of the battery pack being arranged to have contact between the cells and the fluid within the battery pack makes this conversion particularly effective. This is because the air can flow directly over the surface of the cells, in place of where the coolant liquid used to flow. In water-cooled systems the cells are not in contact with the coolant (i.e. the water) and so replacement of the coolant with air would not be as effective.
[0420] The fluid communication between the battery pack 300 and liquid recovery equipment 520 is shown in
[0421] While
[0422]
[0423] Various ways of reusing the battery pack and its components are envisaged. These pathways include modifying the battery pack in order to repurpose it for another use case and reusing one or more of the components of the battery pack in a further liquid-cooled battery pack.
[0424]
[0425] If the battery pack is to be re-used then an optional fourth step 1004 is enacted, as shown in
[0426] Thus, we produce an air-cooled battery in the same housing as was used for the liquid-cooled battery pack without having to take the battery cells out of the housing. This allows us to use the same housing as a transport container to carry the battery cells to their new position (geographic position) of use. Once the recycling process is complete the battery pack can therefore be transported as a single unit, as a functional battery pack. There is no requirement to extract the battery cells, store them, transport them and then rehouse in a new carrier, as required in current recycling solutions known in the art. The cells are not removed, taken to another place and inserted into a housing. Instead, the cells are already in a box/housing that can just be picked up. In some examples the scaffolding remains in place so as to continue to secure and space the cells. It also avoids us having to disconnect electrical leads from the battery cells and connect new ones—for example the leads connecting the battery cells to a busbar, and the busbar to an electrical input and output terminal. This saves a lot of time and expense, and waste materials. The air-cooled battery has the same battery cells connected by the same leads to the same busbars and electrical terminals.
[0427] The step of extracting 1002 the coolant liquid can be broken down into multiple constituent steps. These steps are shown in
[0428] In some variations of the method multiple components are removed, providing multiple apertures for the liquid recovery apparatus to be attached to. Increasing the number of connections can increase fluid flow—both coolant liquid out and air in.
[0429] Completion of the extraction is detected using a senor. The sensor detects when a sufficient amount of liquid is extracted. Whether the amount of liquid extracted qualifies as a sufficient amount is dependent at least in part on the next use case for the battery pack. There may still remain some remnants of the liquid in the system; sufficient extraction may be defined as recovering at least 95% of the liquid. If the battery pack is to be fitted with air pumps in order to be operated as a forced air-cooled battery pack then substantially all of the liquid should be extracted such that the air pumps are not affected by the presence of liquid within the battery pack. If the battery pack is to be used as a passive air-cooled battery pack then there can be more tolerance for leftover coolant liquid. As an objective of extracting the coolant liquid is to reuse it then the amount of coolant liquid extracted is prioritised. The sensor is the liquid level sensor on the battery pack. Alternatively a further liquid sensor can be used as well or instead. The further liquid sensor is a component of the liquid recovery apparatus. The further liquid sensor may comprise a sensor on the pumps pumping the liquid out of the battery pack, and may be configured to detect when the pumps are dry pumping. Dry pumping is indicative that the coolant liquid has been removed and so the pumping can be stopped. Another possible sensor could be a weight sensor, with the weight of the extracted liquid being determined.
[0430] Once pumping is complete the sensor passes a signal to the controller to switch a mode of operation of the controller to either a forced air-cooled mode or a passive air-cooled mode. The controller controls the battery pack to have a different charge and discharge performance when it is air-cooled than when it was liquid-cooled.
[0431] The components removed in this example are the pumps. Other suitable components for removal include the reservoir, pressure relief valve or vent and burst disc Where each of the components are removed they are either refitted or replaced with an alternative component suited for the requirements of an air-cooled battery pack. This may simply be a cover, or a less complex pressure management system, as an air-cooled battery pack does not have the problems associated with liquid coolant being present, such as having to accommodate large volume changes in the liquid coolant in high temperature scenarios.
[0432] The components removed from the battery pack can then be repurposed into a further battery pack. The removed components usually have a longer serviceable life than the cells, and so can be reused with new cells in a new battery pack, therefore reducing the components and manufacturing costs of the new battery pack, as well as reducing the CO2 footprint of the battery packs.
[0433] The controller is configured to operate in one of a plurality of modes. The controller in this example is operable in one of three modes: a first mode is a liquid-cooled mode; a second mode is a forced air-cooled mode and a third mode is a passive air-cooled mode. The liquid-cooled mode is the mode in which the battery pack operates when it is filled with the coolant liquid. This first mode is the mode that the battery pack operates in in a first phase of its lifecycle. In the forced air-cooled mode the liquid pumps are replaced with air pumps. The passive air-cooled mode is used when the pumps are replaced with a simple cover. The passive air-cooled mode may be used after or instead of the forced air-cooled mode. In other words, the lifecycle of the battery pack may begin with liquid-cooled and then move to forced air-cooled and finally passive air-cooled. Alternatively, the battery pack's life cycle may begin with liquid-cooled and then move to forced air-cooled or passive air-cooled. Which mode is chosen may be dependent upon the effectiveness of the cells at that point in the lifecycle. For example, if the cells are still able to operate at medium power requirements then it may be viable to configure the battery pack to operate in a forced-air-cooled mode. However, if the cells are only suitable for low-power requirements then it may be more economically viable to operate the battery pack in a passive air-cooled mode. As the cells can only discharge at a low rate, overheating becomes less likely and the additional cost and complexity of fitting air pumps is not required.
[0434] In some configurations of the battery pack the pumps of the battery pack itself are used to suck the liquid out of the enclosure outlet hole
[0435] Switching the controller between modes may be implemented either by the liquid sensor as described above or by various other means. For example, as part of the recycling process a signal may be provided. The signal could be provided over Bluetooth (RTM) or other wireless signal, or via a wired connection to the controller. A simple toggle switch may also be provided to switch the controller between modes. The recycling process may comprise re-flashing the controller with new parameters and/or operating conditions to fit with the intended end purpose, dependent upon how the battery pack is modified during the recycling process.
[0436] Various modifications can be made to the examples and embodiments described above without departing from the scope of the appended claims. For example, where parts fit together in a male/female relationship it is also envisaged that the relationship is reversed. Features of the examples and embodiments may be exchanged, combined, omitted or adapted. The teaching of the specification should be taken as a whole with no limitation placed on the scope of the appended claims by reference to the included description and drawings.
[0437] As described above, the coolant may be extracted from the battery with the battery being reusable as an air-cooled battery. The modification of the battery to an air cooled battery may comprise the pump being changed for an air pump. This may comprise an end plate of the battery being changed. In particular, a ‘normal’ bottom end plate may be removed from the battery and an air-cooling bottom end plate may be added to the battery, which air-cooling bottom end plate comprises an air pump. This air-cooling bottom end plate is typically similar to the normal bottom end plate apart from the pump. In some embodiments, a vent is provided on the air-cooling bottom end plate, but no reservoir is provided—this is because with an air cooled battery air may be allowed to pass freely through the vent as the air inside the battery expands and contracts and there is no need to provide an expansion volume for a liquid coolant.
[0438] In some embodiments, the pump 305 is detachable from the battery pack and/or from the bottom end plate 532. This enables the simple exchange of a liquid pump for an air pump so that the battery pack can more easily be repurposed as an air-cooled battery.
[0439] In some embodiments, the battery pack and/or the bottom end plate 532 is provided with both a liquid pump and an air pump. Therefore, once the coolant has been extracted the battery may be optimised for use with air simply by switching an operation mode of the battery pack (where different operation modes use different pumps).
[0440] Where the methods of