WO2021123715A1

WO2021123715A1 - Battery pack

Info

Publication number: WO2021123715A1
Application number: PCT/GB2020/052569
Authority: WO
Inventors: Christopher GASKELL
Original assignee: Dyson Technology Limited
Priority date: 2019-12-19
Filing date: 2020-10-14
Publication date: 2021-06-24
Also published as: GB201918805D0; GB2590464B; GB2590464A; CN114846684A

Abstract

A battery pack (1) has a plurality of battery modules (2) disposed in a row from front to rear of the battery pack (1). The plurality of modules (2) are configured such that current flows in use along a current flow path from the front to the rear of the battery pack, through a first subgroup of the plurality of modules (2), and from the rear to the front of the battery pack (1), through a second subgroup of the plurality of modules (2). At least one module of the second sub-group is located between at least two modules of the first sub-group.

Description

BATTERY PACK

Technical Field

The present invention relates a battery pack comprising battery modules. The battery pack is suitable for an electric vehicle, among other uses.

Background

There is a growing market for battery packs, in particular for electric vehicles. Typically, battery packs may comprise many battery cells, groups of which may be packaged into battery modules within the battery pack. The battery modules may be interconnected by busbars. The battery modules and busbars are ideally packaged within the battery pack to provide high energy storage density, low weight, and safe handling during manufacture, use and maintenance.

Summary

In accordance with a first aspect of the invention there is provided a battery pack comprising: a plurality of battery modules disposed in a row from front to rear of the battery pack, the plurality of modules configured such that current flows in use along a current flow path from the front to the rear of the battery pack, through a first subgroup of the plurality of modules, and from the rear to the front of the battery pack, through a second subgroup of the plurality of modules, wherein at least one module of the second sub-group is located between at least two modules of the first sub-group.

This arrangement may allow both ends of the current path through the row to be situated at the same end of the battery pack, while keeping each busbar short, reducing the need for additional support of the busbars and reducing the effects of thermal expansion in use. The plurality of battery modules may be arranged as pairs of adjacent modules in the row, the modules of each pair being directly connected in series together electrically. This arrangement may allow each busbar to be kept short, avoiding the need for the provision of a longer busbar. Reducing the length of busbar required may reduce mass and cost. Longer busbars typically require more support and can also have greater issues with thermal expansion in use.

The first subgroup of modules may be connected to the second subgroup of modules by a current interruption arrangement at the rear of the battery pack. The current interruption arrangement may comprise the fuse, and/or may comprise a switch.

Arranging the battery modules as two subgroups with a current interruption arrangement between the subgroups may provide for safe disconnection of the two subgroups, limiting the maximum voltage difference across any two points in the modules of the row, to allow safer handling. Location of the fuse between the two subgroups may allow for an arrangement that protects against short circuits between busbars associated with different subgroups. Disposing the current interruption arrangement at the rear of the battery pack may allow a more compact arrangement than would be the case if the current interruption arrangement were disposed between modules mid-way along the battery pack, because the battery modules may be more tightly packed, and ends of the battery pack may be tapered, providing room for the current interruption arrangement between the tapered parts. This may also provide convenient access to the fuse and/or switch during maintenance.

A first end of each battery module may comprise a first terminal and is on a first side of the row of battery modules and a second end of each battery module may comprise a second terminal and is on a second, opposite side of the row of battery modules. The battery modules in the row may be disposed such that adjacent battery modules in the row have opposite polarity terminals on the first side of the row. This may allow interconnection of battery modules without crossing of busbars in some arrangements, which reduces the need for insulation between busbars and allows a passage for routing other circuitry along the length of the battery pack without crossing busbars. For example, the battery pack may comprise battery management circuitry disposed along the row of battery modules in a region between the busbars on the first side of the row and the busbars on the opposite side of the row.

The battery pack may comprise a further plurality of battery modules disposed in a further row from front to rear of the battery pack, the further row being adjacent to the row of battery modules, wherein the further plurality of battery modules is configured such that current flows in use along a further current flow path from the front to the rear of the battery pack through a third subgroup of the further plurality of battery modules, and from the rear to the front of the battery pack through a fourth subgroup of the further plurality of battery modules, wherein at least one module of the fourth sub-group is located between at least two modules of the third sub-group.

The row and the further row may have the same general arrangement of battery modules. In particular, each row may be composed of the same number, type and orientation of modules, providing a balanced design in terms of weight distribution and matched electrical resistance characteristics to facilitate load balancing if the rows are connected in parallel.

The battery pack may be switchable between a first configuration in which the plurality of battery modules is connected in series with the further plurality of battery modules and a second configuration in which the plurality of battery modules is connected in parallel with the further plurality of battery modules.

This arrangement may allow selection of different charging and/or discharging voltages.

An electric vehicle may comprise a battery pack according to any preceding paragraph.

A battery pack according to the previous paragraphs is particularly suited for use in an electric vehicle. Further features and advantages of the invention will become apparent from the following description of examples of the invention, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

In order that the present invention may be more readily understood, examples of the invention will now be described, with reference to the accompanying drawings, in which:

Figure l is a schematic plan view of a battery pack according to an example, showing an arrangement of battery modules;

Figure 2 is a schematic illustration of a battery module of the battery pack of Figure 1;

Figure 3 is a schematic illustration of the battery pack of Figure 1, showing an arrangement of busbars interconnecting the battery modules;

Figure 4 is a schematic illustration of the battery pack of Figure 1, showing battery management circuitry disposed in a region between the busbars;

Figure 5 is a perspective view of part of the battery pack of Figure 1, showing a barrier of insulating material disposed between a busbar connected to a terminal of a battery module from one row and another busbar connected to a terminal of a battery module from an adjacent row;

Figure 6 is a top view of an insulated tray carrying electrical components of the battery pack of Figure 1, providing a barrier of insulating material between adjacent busbars;

Figure 7 is a perspective view of a terminal disposed at a side edge of a battery module in the battery pack of Figure 1, showing an aperture for receiving a busbar; Figure 8 is a perspective view of the terminal shown in Figure 7 disposed at a side edge of a battery module, showing an electrically insulated cover arranged to cover at least part of a busbar when the busbar is received by the aperture;

Figure 9 is a perspective view of part of the top face of the battery pack of Figure 1, showing busbars engaged with terminals of the battery modules, and showing battery modules supported in the battery pack by a frame;

Figure 10 is a schematic side elevation view of an electric vehicle comprising a battery pack as shown in Figure 1; and

Figure 11 is a schematic plan view of an electric vehicle comprising a battery pack as shown in Figure 1.

Detailed Description

Examples of the invention are described in the context of a battery pack for an electric vehicle. A person skilled in the art will realise that the examples are not limited to this purpose. For example, a battery pack as herein described may instead be used to provide and store electrical energy for any kind of industrial, commercial, or domestic purposes, such as for energy storage and delivery, for example, in smart grids, home energy storage systems, electricity load balancing and the like.

In the examples described, the battery pack comprises battery modules, each comprising a plurality of battery cells, which are so-called prismatic cells, and which are generally cuboidal in form. However, in other examples, battery modules may comprise other forms of cell, for example cylindrical cells. The battery cells may be lithium ion, lithium ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, alkaline, or other battery cell type/configuration. The battery cells are connected within a battery module to give a voltage between two terminals of the battery module. The battery modules are mounted on a frame within the battery pack structure.

Figures 1 to 4 illustrate an example of the battery pack and Figures 5 to 9 illustrate in further detail features of the example of the battery pack. Figures 10 and 11 show an electric vehicle comprising the illustrated example of the battery pack. The same reference numeral is used to refer to a feature which is the same or similar in each drawing.

Figure 1 shows that the illustrated example of the battery pack 1 comprises sixteen battery modules 2a - 2p arranged as a first row 3a and a second row 3b of eight battery modules each. Each row 3a, 3b is disposed from front to rear of the battery pack, the front being on the left hand side and the rear being on the right hand side as illustrated. As shown in Figure 1, battery modules 2a and 2i are disposed towards the front of the battery pack, and battery modules 2h and 2p are disposed towards the rear of the battery pack. Each battery module 2a-2p has a first end comprising a first terminal 4a-4p and a second end, opposite the first end, comprising a second terminal 5a-5p. The first terminals 4a-4h of the first row 3 a of battery modules 2a-2h are arranged on a first side of the row 3 a, and the second terminals 5a- 5h of the first row 3a of battery modules 2a-2h are arranged on a second, opposite side of the row 3a. Alternate first terminals along the row 3a have opposite polarities, and, accordingly, alternate second terminals along the row 3a have opposite polarities. In the examples illustrated, terminals 5a, 4b, 5c, 4d, 5e, 4f, 5g and 4h have positive polarity, and terminals 4a, 5b, 4c, 5d, 4e, 5f, 4g and 5h have negative polarity.

Similarly, for the second row 3b, the first terminals 4i-4p of the second row 3b of battery modules 2a-2h are arranged on a first side of the second row 3b, and the second terminals 5i-5p of the second row 3b of battery modules 2a-2h are arranged on a second, opposite side of the second row 3b. Alternate first terminals along the second row 3b have opposite polarities, and, accordingly, alternate second terminals along the second row 3b have opposite polarities. According to the present example, the modules 2a-2p are disposed in a single layer. Other examples may have more than one layer of battery modules.

Figure 2 shows battery module 2a in more detail. Battery modules 2b-2p have similar features. Each battery module, as shown in the example of battery module 2a, is generally cuboidal in form and has a first terminal 4a on a first minor face and a second terminal 5a on a second minor face 15 opposite the first minor face. The battery module 2a is arranged such that the minor faces are parallel to the length of the battery pack. A major dimension of the battery module 2a is orthogonal to the respective row 3a of battery modules and is orthogonal to the length of the battery pack. The terminals 4a, 5a in this example extend upwardly past an upper face of the battery module 2a.

Figure 3 shows that the battery pack 1 of the illustrated example has busbars 6a-6e, 7a- 7e, 8a-8e and 9a-9e interconnecting the terminals of the battery modules 2a-2p, to provide two current flow paths through the battery pack. Each row 3a, 3b of battery modules provides a current flow path. The two current flow paths can be configured to be in series or in parallel. Each busbar provides a low resistance electrical connection path between the terminals of respective battery modules. The busbars are typically made of metal, and may be made of copper or aluminium, for example. The busbars in this example are elongate and substantially planar.

As shown in Figure 3, there is a fuse 10a, 10b provided in the current flow path that passes through each row 3a, 3b of battery modules. In the illustrated example, a disconnection device 14a, 14b, which may be a switch or removable link, is provided in series with each fuse 10a, 10b. Other examples may not be provided with a disconnection device 14a, 14b in addition to the fuse 10a, 10b. The fuse 10a, 10b and/or the disconnection device 14a, 14b may be referred to as a current interruption arrangement. As will be described, each row comprises two subgroups of four modules and the fuse 10a, 10b and the disconnection device 14a, 14b is between each subgroup in a row. In the illustrated example, the first row 3a comprises a first subgroup comprising battery modules 2c, 2d, 2g and 2h and a second subgroup comprising battery modules 2f, 2e, 2b and 2a. Fuse 10a is in the current path between the first subgroup and the second subgroup. The second row 3b comprises a third subgroup comprising battery modules 2i, 2j, 2m and 2n and a second subgroup comprising battery modules 2p, 2o, 2j and 2k. Fuse 10b is in the current path between the third subgroup and the fourth subgroup.

The disconnection device 14a, 14b may be used during maintenance and repair to limit the voltage across any two points in each row of battery modules, by splitting the row into two disconnected parts. In the illustrated example, the voltage between the terminals of each battery module is nominally 50V, so that a maximum of nominally 200V would be present between any two parts of a row when the disconnection device 14a, 14b is set to disconnect the two parts of the row, allowing safer handling than if 400V were present.

In the illustrated example, the battery pack 1 comprises a battery pack control circuit 13, which comprises a battery management system controller and a battery pack reconfiguration circuit. The battery management system controller comprises a processor configured to accept sensor inputs mounted on the battery modules, such as sensors of temperature and/or voltage and to protect the battery pack by controlling charging and/or discharging of the battery pack to keep operating parameters within safe limits. The battery pack reconfiguration circuit comprises semiconductor and/or electromechanical switches to allow the first and second rows of battery modules to be configured to be in series or in parallel.

Figure 3 illustrates the current flow path through the first row 3a of battery modules by means of arrows (superimposed on the respective busbars) indicating current flow direction during discharge of the battery. Current flows: from the battery pack control circuit 13 to the negative terminal of battery module 2c; from the positive terminal of battery module 2c to the negative terminal of battery module 2d; from the positive terminal of battery module 2d to the negative terminal of battery module 2g; from the positive terminal of battery module 2g to the negative terminal of battery module 2h; and, then to the fuse 10a. Then the current flows: through the fuse 10a to the negative terminal of battery module 2f; from the positive terminal of battery module 2f to the negative terminal of battery module 2e; from the positive terminal of battery module 2e to the negative terminal of battery module 2b; from the positive terminal of battery terminal 2b to the negative terminal of battery module 2a; and, then from the positive terminal of battery module 2a to the battery control circuit 13.

The first row of battery modules 2a-2h, which may also be referred to as a half-pack, is divided into two sub-groups, which may also be referred to as quarter-packs: a first quarter pack 2c, 2d, 2g, 2h and a second quarter pack 2f, 2e, 2b, 2a. In this example, each quarter pack comprises four modules, and each quarter pack has an opposite direction of current flow to the other quarter pack of the row This arrangement allows the current interruption arrangement comprising the fuse 10a, 10b and/or the disconnection device 14a, 14b between the two quarter packs to be located at the rear of the battery pack rather than between battery modules in the battery pack. Locating the current interruption arrangement at the rear of the battery pack allows for easier access to the fuse and/or disconnection device even when the modules are packaged and/or covered in housings or the like. The arrangement also allows for the voltages generated across the two rows to be accessible at the same end of the battery pack, in this case at the front of the battery pack. Having the voltages generated across the two rows accessible at the same end of the battery pack allows the rows 3a, 3b to be connected in series or in parallel by the battery pack reconfiguration circuit 13, without the use of long busbar runs from front to rear of the battery pack. Arranging each quarter-pack to comprise two pairs of adjacent modules, the two pairs being separated by a pair of modules from the other quarter-pack of the half-pack, further avoids the use of long busbars. In contrast, the arrangement of the quarter packs as four adjacent battery modules would result in the use of longer busbars. Longer busbars increase cost, may require extra support and may exhibit increased problems with thermal expansion.

If the battery pack reconfiguration circuit in the battery pack control circuit 13 is configured to connect busbars 7a and 8a together, then the two rows of battery modules are connected as sixteen modules in series. Alternatively, if the battery pack is configured so that busbars 6a and 8a are connected together and busbars 7a and 9a are connected together by the battery pack reconfiguration circuit, then the two rows of eight modules are connected in parallel. In the example, as already mentioned, each battery module has a voltage of nominally 50V so that the series arrangement provides nominally 800V and the parallel arrangement provides nominally 400V. In use the two rows of modules may first be connected in parallel to charge from an approximately 400V DC charger and then connected in series to drive the motor from an approximately 800V supply to improve efficiency. Alternatively, the two rows of modules may be connected in series to charge from an approximately 800V charger. Discharge of the battery pack may also be arranged from the two rows of battery modules in parallel at nominally 400V. If a fault is detected in one of the rows the battery pack may be configured so that one row only is used for charging and/or discharging to provide continued use albeit at reduced capacity.

Figure 3 shows that the busbars of each row 3a, 3b are arranged at or near to the edges of each row with space provided along the middle of each row between the busbars on the top face of the battery modules, which is unobstructed by busbars. Considering the first row 3a, busbars 6a, 6b, 6c and 6d are located at or near one edge of the row 3a, and busbars 7a, 7b, 7c and 7d are located on the opposite side of the row 6a. Figure 3 shows that there is a path across the top face of the battery modules 2a - 2h of the row 3a which is unobstructed by busbars. A similar path is provided between the busbars of the second row 3b. The fusing arrangement of the busbars of each row allows them to be packed closely together on each side of the row while providing protection in the event of a short circuit between busbars that are adjacent to one another. This arrangement allows a larger space to be provided between the busbars on each side of the row than would be the case if the busbars were further apart.

Figure 3 shows that, in the illustrated example, at least some of the busbars of each row of battery modules 3 a, 3b are arranged in pairs. In particular, busbars 6c and 6d, 7b and 7c, 8b and 8c and 9c and 9d are arranged in pairs. The members of the pairs of busbars are arranged on the same side as each other of the respective row. The busbars of a pair are disposed in a substantially parallel relationship to each other and are arranged to cross a boundary between the same two neighbouring battery modules in the row. For example, as shown, busbar 6d connects battery modules 2e and 2f, and crosses the boundary 25 between modules 2e and 2f. The busbar 6d is formed in a U-shape in a plane parallel to the top face of the battery modules, the busbar having a straight central elongate section having a substantially constant width, and two end sections which are connected at right angles with the straight central elongate section. One end section is connected to terminal 4e of battery module 2e and the other end section is connected to terminal 4f of battery module 2f. Busbar 6c is also formed in a U-shape in a plane parallel to the top face of the battery modules, and the busbar 6c also has a straight central elongate section having a substantially constant width. The straight central elongate section of busbar 6c is disposed alongside and parallel to the straight central elongate section of busbar 6d. Busbar 6d has two end sections which are connected at right angles with the straight central elongate section. One end section is connected to terminal 4d of battery module 2d and the other end section is connected to terminal 4g of battery module 2g. Accordingly, busbar 6d is longer than busbar 6c, and is arranged not to cross busbar 6c and to leave a substantially constant width of gap between the straight elongate central sections of the two busbars 6c and 6d.

The fuse 10a, 10b is arranged in the current flow path between the busbars of each pair. For example, busbars in the pair of busbars 6a and 6b are protected by fuse 10a, and also busbars in the pair 6c and 6d are also protected by fuse 10a. On the other side of the row 3a, busbars in the pairs of busbars 7e and 7d, and also 7c and 7b, are also protected by fuse 10a. This is because one busbar of a pair connects together battery modules of one subgroup, for example the first subgroup comprising battery modules 2c, 2d, 2g and 2h, and the other busbar of a pair connects together modules of the other subgroup of the row, for example the second subgroup comprising battery modules 2f, 2e, 2b and 2c. As a result, if the busbars of a pair are accidentally short circuited together, current will flow in a circuit that includes the fuse between the two sub-groups and the fuse will blow, stopping the current flow. Similarly, in the second row, busbars in the pairs of busbars 8b and 8c, 8d and 8e, 9a and 9b and 9c and 9d are protected against short circuit to one another by fuse 10b. Figure 3 shows that there are busbars 7a-7e of the first row 3a which are adjacent to busbars 8a-8e of the second row 3b. In particular, busbars 7a and 8a, 7b and 8b, 7c and 8c, 7d and 8d and 7e and 8e are adjacent where the busbars connect with the terminals which are disposed between the rows. In the event that the first row 3a and the second row 3b are configured to be connected in series, the voltages as shown in Table 1 are present on the busbars. If the first row 3a and the second row 3b are configured to be connected in parallel, the voltages as shown in Table 2 are present on the busbars.

There are busbars of the first row 3 a which are adjacent to busbars of the second row 3b which are protected by one or more fuses in the event that the adjacent busbars are short- circuited together when the first row 3a and the second row 3b are connected in series. For example, if the adjacent 50V busbar 7c and 750V busbar 8c were short-circuited together, the resulting current would flow through both fuses 10a and 10b and at least one of the fuses would blow, stopping the current. Also, if the adjacent 150 V busbar 7e and 650V busbar 8e were short-circuited together, or if adjacent 200V busbar 7d and 600V busbar 8d were shorted together, then one or both of fuses 10a and 10b would blow. There are also busbars of the first row 3a which are adjacent to a busbar of the second row 3b which are not protected by fuses in the event that the adjacent busbars are short- circuited together when the first and second rows are in a configuration in which they are connected in series, for example the adjacent 300V busbar 7b and 500V busbar 8b. Additional electrical insulation 12a, 12b is provided for these busbars as compared with adjacent busbars between which there is provided a fuse. The additional electrical insulation 12a, 12b will be described in more detail in connection with Figure 5.

Additional electrical insulation 11 is provided between adjacent busbars 7a of the first row 3a and busbar 8a of the second row 3b. Busbar 7a is an individual busbar that is not arranged as a pair of busbars connecting battery modules of the first row, and busbar 8a is an individual busbar that is not arranged as a pair of busbars connecting battery modules of the second row. If the rows 3 a and 3b are connected in the series configuration, both busbars are at the same voltage, 400V, but when rows 3a and 3b are connected in the parallel configuration, busbar 7a is at 400V and busbar 8a is at 0V. The additional electrical insulation 11 between busbar 7a and busbar 8a will be described in more detail in connection with Figure 6.

When the first row 3a and second row 3b are connected in series, the fuses 10a, 10b are located at 200V and 600V points within the pack. Where there are adjacent busbars, with one having a voltage below or equal to 200V and the other having a voltage above or equal to 600V, the busbars are protected by at least one of the fuses. Where there are adjacent busbars with one having a voltage above 200V and the other having a voltage below 600V, extra electrically insulating components are located between the busbars to prevent short circuits.

Figure 4 shows that the unobstructed space provided between the busbars may be used for the location of components of the battery pack such as, in the illustrated example, a wiring harness 16 of a battery management system. The wiring harness 16 is routed along the row 3a between the busbars, which have the same reference numerals as in Figure 3. The battery management controller of the battery pack control circuit 13 at the front of the battery pack is connected via the wiring in the wiring harness 16 of the battery management system to sensors 17a, 17b. In this way, the wiring harness need not cross a busbar. Crossing a busbar may induce electrical noise, and/or present an electrical safety hazard.

Figure 5 shows the additional electrical insulation 12a between busbars 7b and 8b in the illustrated example. The additional electrical insulation is in the form of a physical barrier of insulating material comprising a substantially planar wall disposed between the respective terminal connectors of the battery modules to which the busbars are connected. As shown in Figure 5, in this example parts of the busbars are covered with electrical insulation, but the ends of the busbars which are connected to the connection terminals of the modules are not covered with electrical insulation.

Figure 6 illustrates additional detail of the additional electrical insulation 11 provided between busbars 7a and 8a in the illustrated example. The additional electrical insulation 11 is in the form of a physical barrier of insulating material comprising an insulated tray carrying electrical components of the battery pack providing a barrier of electrically insulating material between adjacent busbars. The support of the tray (not shown) is disposed between the respective terminals of the battery modules 2a, 2i to which the busbars are connected. The support of the tray provides an insulating wall between the busbars 7a and 8a. In an alternative example, the additional electrical insulation between busbars 7a and 8a may comprise a substantially planar wall disposed between the respective terminals of the battery modules to which the busbars are connected in a similar configuration to the arrangement shown in Figure 5. It will be appreciated that additional electrical insulation, in the form of physical barriers or walls of insulating material, may be provided anywhere in the battery pack where short circuiting could occur.

Figures 7, 8 and 9 show perspective views of terminal 4a of the battery module 2a, as a representative example of terminals 4a-4p and 5a-5p in the first and second examples. The terminal 4a is also referred to as a terminal connector 4a. As can be seen, the terminal 4a extends upwardly past an upper face of the battery module 2a. Figure 9 shows that the busbars 6d, 7b, which are substantially planar, elongate, inter-module connectors are connected to respective terminals 4e, 4f and extend across the upper faces of the battery modules. It can be seen that the terminal of each of the battery modules is disposed nearer to a first side of the row than to the other side of the row, at a side edge of the respective battery module.

Figures 7, 8 and 9 also show that each terminal 4a, 4e, 4f, 5e has an aperture 21, substantially aligned with the upper face of the respective battery module, configured to receive the busbar 6d, 7b. Each terminal has an electrically insulating cover 19 arranged to cover at least part of the busbar adjacent to the aperture.

In the illustrated example, each terminal 4a, 4e, 4f, 5e protrudes from the side edge of the respective battery module 2a, 2f, 2e and the aperture 21 faces the respective battery module. The terminal has a substantially rectangular cross-section in the plane of the top face of the respective battery module. The aperture 21 for receiving the busbar is located at or slightly above a top edge of the modules, such that the busbars may be disposed along the top face of the modules. The electrically insulating cover 19, which may be referred to as a hood, extends over a part of the busbar not covered with electrical insulation to an insulated part, which provides electrical safety during assembly and maintenance.

Figure 9 shows that the battery modules 2e, 2f are supported in the battery pack by a frame 22.

Figures 10 and 11 show a schematic side elevation view and a schematic plan view of an electric vehicle 23 having the battery pack 1 according to the illustrated example. The battery pack 1 is mounted on the underside of the vehicle 23, allowing for easy maintenance and providing a low centre of mass to aid stability of the vehicle when cornering.

The above examples are to be understood as illustrative examples of the invention. Further examples of the invention are envisaged, for example, there may be a single row of battery modules, and there may be more than two rows of battery modules. There may be more or less than 8 modules in a row, and the various nominal voltages at the terminals of the battery modules may be provided. For example, a nominal voltage of 25 V, or another voltage, may be provided. The actual voltage provided by a battery module will in use differ from the nominal voltage according to the state of charge of the battery module. In other examples, the battery modules may have a different shape than those in the examples described, for example the battery modules may not have a major dimension orthogonal to the respective row of battery modules. For example, the battery modules may be shaped such that a major dimension is parallel to the row of battery modules, and the terminals may not be positioned on a minor face of the battery modules.

It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A battery pack comprising: a plurality of battery modules disposed in a row from front to rear of the battery pack, the plurality of modules configured such that current flows in use along a current flow path from the front to the rear of the battery pack, through a first subgroup of the plurality of modules, and from the rear to the front of the battery pack, through a second subgroup of the plurality of modules, wherein at least one module of the second sub-group is located between at least two modules of the first sub-group. and wherein the first subgroup of modules is connected to the second subgroup of modules by a current interruption arrangement at the rear of the battery pack

2. A battery pack according to claim 1, wherein the plurality of battery modules is arranged as pairs of adjacent modules in the row, the modules of each pair being directly connected in series together electrically.

3. A battery pack according to claim 1 or claim 2, wherein the current interruption arrangement comprises a fuse.

4. A battery pack according to any preceding claim, wherein the current interruption arrangement comprises a switch.

5. A battery pack according to any proceeding claim, wherein a first end of each battery module comprises a first terminal and is on a first side of the row of battery modules and a second end of each battery module comprises a second terminal and is on a second, opposite side of the row of battery modules.

6. A battery pack according to claim 5, wherein, the battery modules in the row are disposed such that adjacent battery modules in the row have opposite polarity terminals on the first side.

7. A battery pack according to any preceding claim, comprising a further plurality of battery modules disposed in a further row from front to rear of the battery pack, the further row being adjacent to the row of battery modules, wherein the further plurality of battery modules is configured such that current flows in use along a further current flow path from the front to the rear of the battery pack through a third subgroup of the further plurality of battery modules, and from the rear to the front of the battery pack through a fourth subgroup of the further plurality of battery modules, wherein at least one module of the fourth sub-group is located between at least two modules of the third sub-group.

8. A battery pack according to claim 7, wherein the row and further row have the same general arrangement of battery modules.

9. A battery pack according to claim 7 or claim 8, wherein the battery pack is switchable between a first configuration in which the plurality of battery modules is connected in series with the further plurality of battery modules and a second configuration in which the plurality of battery modules is connected in parallel with the further plurality of battery modules.

10. An electric vehicle comprising a battery pack according to any preceding claim.