DESC:TECHNICAL FIELD
[0001] The present invention generally relates battery packs. More specifically, it relates to the electrical connections of the battery packs.

BACKGROUND
[0002] A battery pack is a configuration of a set of any number of identical or non-identical battery cells. A battery pack usually consists of hundreds of battery cells connected in series and parallel, including battery packs made up of several battery modules, with each battery module containing multiple battery cells in series, parallel, or series-parallel configuration. A well-designed battery pack should have the following features: 1) the battery cells are reasonably well balanced with means for regular cell balancing, and 2) the battery pack should be effectively cooled/heated so that the battery pack does not encounter uncontrolled temperature variations. The individual battery cell maybe a lead-acid battery, or a nickel-zinc battery or a lithium-ion (Li-ion) battery.
[0003] A battery pack, in addition to the individual cells or batteries, also includes the interconnectors that connect the leads of the battery cells. Such interconnectors can be made out of wires, fashioned into a wiring harness, or made out of metallic plates. The metallic planar interconnectors are also sometimes referred to as busbars. Additionally, battery packs are also connected to some form of a battery management system which monitors the health of the battery pack. It is vial to ensure that the cells in the battery pack charge and discharge uniformly, and don’t heat too much. Heating is the nemesis of battery packs.
[0004] The prior art disclosed in this subject matter addresses many issues, including a busbar with adjustable connecting leads configured to have two metallic planes at an obtuse angle to one another fixed on a pivot which is fixed to the busbar, so that the lead can rotate around the pivot which would help ease the assembly process because the individual unit cells are not necessarily required to be at the same height, and other such inventions. There are however, certain fundamental problems in existing prior arts, including non-uniform heat transmission from the busbar to the unit cells along their linear alignment, uneven lifecycle of the unit cells, and inaccurate measurement of the electric potential at the bus bar terminals due to the output terminal of the battery pack being aligned in the same direction as the busbar.

BRIEF DESCRIPTION OF DRAWINGS
[0005] The details are described with reference to an embodiment of A busbar Configuration In A Battery Pack along with the accompanying diagrams. The same numbers are used throughout the drawings to reference similar features and components.
[0006] Figure 1 exemplarily illustrates a top perspective view of the busbar configuration being disclosed in the present invention.
[0007] Figure 2 exemplarily illustrates a top perspective view of the said busbar configuration, wherein the leads on the said busbar are connected to a linear alignment of a at least one unit cell.
[0008] Figure 3 exemplarily illustrates a top perspective exploded view of the battery pack assembly.
[0009] Figure 4 exemplarily illustrates configuration of the busbar being disclosed in the present invention and its mounting on the battery pack.

DETAILED DESCRIPTION
[0001] A battery pack consists of a plurality of an at least one unit cell, wherein a unit cell has a positive electrode terminal and a negative electrode terminal, wherein an electrode terminal of a unit cell is connected with at least one electrode terminal of another at least one unit cell. The cells in a battery pack are so arranged that one of the two electrode terminals of each unit cell is linearly aligned with one another and the other electrode terminal is linearly aligned with one another. Each set of electrode terminals that are linearly aligned with one another are connected using metallic conductors, either in the form of wires or plates. Such a metallic conducting plate is commonly referred to as a busbar. A busbar module, comprising a plurality of busbars and interconnectors, each electrically connecting a linear alignment of electrodes, adjacent to each other. Such busbars usually have a planar shape, and are configured to have connecting leads which are welded to the electrode terminals to establish a continuous conducting path for the electric current.
[0002] A battery management system is usually in place to monitor the health of the battery. A battery management system is an electronic system that manages a rechargeable battery by ensuring that the battery pack does not operate outside its safe operating parameters. It is also configured to manage important functions such as energy recovery in vehicles, and cell balancing. Cell balancing, as mentioned above, is an important aspect of a well-designed battery pack. Cell balancing is a technique that improves battery life by maximizing the capacity of a battery pack with multiple cells in series, ensuring that all of its energy is available for use.
[0003] Typically, individual cells of a battery pack have different capacities and are at different State of Charge (SoC) levels. Without redistribution, discharging must stop when the cell with the lowest capacity is empty, even though the other cells are still not empty. This limits the energy delivering capability of the battery pack. Cell balancing may be active or passive. With passive and active cell balancing, each cell in the battery stack is monitored to maintain a healthy battery SoC. This extends battery cycle life and provides an added layer of protection by preventing damage to a battery cell due to deep discharging over overcharging. Passive balancing results in all battery cells having a similar SoC by simply dissipating excess charge in a bleed resistor; it does not however, extend system run time. Active cell balancing is a more complex balancing technique that redistributes charge between battery cells during the charge and discharge cycles, thereby increasing system run time by increasing the total useable charge in the battery pack, decreasing charge time compared with passive balancing, and decreasing heat generated while balancing.
[0004] Another important aspect of a well-designed battery pack is a temperature control system. Generally, this refers to a cooling system. Available cooling methods for battery packs include air cooling, liquid cooling and phase changing material (PCM) cooling. It has been found that the best operating range of temperature for Li-ion batteries is between 25 °C and 40 °C. The efficiency of the system depends on how much stored energy can be drawn from the battery pack before it is required to be recharged. A battery pack is essentially a plurality of battery cells densely disposed in a housing. Each individual cell has to work in an optimum operating range. Energy is lost during transmission through the interconnectors and busbars as heat. Such heat is lost to the atmosphere, as well as transmitted to the battery cells in the vicinity of such connectors. Such heating of the cells reduces the life cycle of the individual cells, thus reducing the effective life of the battery pack.
[0005] As automobiles are moving towards electric propulsion from internal combustion engines, the design and efficiency of battery packs become more and more important. Electric propulsion in two wheeled vehicles is not as popular as electric propulsion in four wheeled vehicles. One of the primary reasons for this is the space constraints in a two wheeled vehicle to fit the battery pack since battery packs are bulky and heavy by necessity. Each and every component added to the battery pack increases its dimensions and therefore it’s weight, which decreases the power to weight ratio of the vehicle.
[0006] Ideally, each unit cell in the battery pack should have an equal impedance value with respect to the output terminals of the busbar. The existing configurations of the busbar however provides for different voltage drop from different unit cells to the output terminal on the bus bar. Metallic leads are connected to the busbars along the same direction as the busbar, which serve a dual purpose of connecting to the battery management system (BMS), as well as functioning as the output terminal. This results in a discrepancy in the measurement of voltage and current for the BMS.
[0007] Using metallic wires instead of metallic plate busbars would solve the above-mentioned problems of energy loss and incorrect measurements. However, such configurations would increase the mass and volume of the battery pack due to the wires as well as the extra fasteners that are required to connect the wires.
[0008] The present invention has been made in view of the foregoing, and it is an objective of the present invention to disclose an improved configuration of a busbar for a battery pack which would result in optimum discharge of all the unit cells in a battery pack, minimalizing localised heating of the busbar, improving the durability of the pack. It is another objective to provide a configuration which eases the assembly of the battery pack. It is yet another objective to provide a configuration to increase the accuracy of measurement of data by the BMS.
[0009] In an embodiment of the present invention, a battery pack for a two-wheeler comprising at least one battery module, at least one busbar module, and a housing for the cells.
[00010] In an embodiment of the present invention, the busbar module comprises of at least one interconnector, which electrically connects one linear alignment of unit cells to another linear alignment of unit cells, and at least a busbar, which electrically connects one linear alignment of unit cells to the output terminal of the battery pack.
[00011] In an embodiment of the present invention, the battery module comprising the arrangement of the plurality of the unit cells, configured so that one of the two electrode terminals of each unit cell are linearly aligned with one another and the other electrode terminal is linearly aligned with one another. Each set of electrode terminals that are linearly aligned with one another are connected using at least one interconnector to another set of electrode terminals.
[00012] In another embodiment of the present invention, the at least one busbar has an at least one primary member and an at least one secondary member, parallel to each other. The at least one primary member and the at least one secondary member are connected to each other by at least one junction member.
[00013] In yet another embodiment of the invention, the at least one secondary member of the busbar is configured to have an extending member to be the output terminal of the battery pack, and it is configured to the shape of the contour of the battery pack housing so that the output terminal can be disposed separately from the BMS data measurement terminal.
[00014] In yet another embodiment of the invention, the output terminal for the BMS data measurement terminal is configured on one end of the at least one primary member of the busbar.
[00015] In another embodiment of the invention, the at least one primary member, the at least one secondary member and the at least one junction member are on the same plane.
[00016] In yet another embodiment of the invention, the extended member of the at least one secondary member is configured to be on a plane perpendicular to the reference plane of the secondary member so that the extended part of the secondary member conforms to the contours of the battery housing.
[00017] In an embodiment of the present invention, the at least one secondary member of the busbar is configured on a plane perpendicular to the plane of the at least one primary member.
[00018] In an embodiment of the invention, the plurality of units of the at least one junction members are disposed on the primary member so that there is an equal current distribution across all the at least one unit cells.
[00019] In yet another embodiment of the present invention, the at least one busbar is mounted by the fasteners attached to the secondary member at the output terminal.
[00020] In yet another embodiment of the invention, the busbar is made of copper.
[00021] In yet another embodiment of the present invention, the electrode terminals on the at least one unit cells are made of nickel.
[00022] In another embodiment of the invention, the connecting leads on the busbar are joined to the electrode terminals on the unit cells by welding.
[00023] In an embodiment of the invention, the unit cells are disposed on the housing of the battery pack so that the electrode terminals on the unit cells are at an equal height.
[00024] In another embodiment of the present invention, the battery pack housing has at least a first part and at least a second part.
[00025] In yet another embodiment of the present invention, the first part and the second part of the battery pack housing in configured to be held together by means of appropriate fasteners.
[00026] In another embodiment of the present invention, the first part and the second part of the battery pack housing are configured to have at least one slots cut out of the outer surface for fastening the at least one busbar, which are also configured to function as the measurement terminal for the BMS.
[00027] In an embodiment of the present invention, the interconnectors and the primary member of the busbar are configured to function as the signal channel of the assembly, and the secondary member of the busbar is configured to function as the output channel of the assembly.
[00028] The embodiments of the present invention will now be described in detail with reference to busbar configuration of a battery pack along with the accompanying drawings. However, the present invention is not limited to the present embodiments. The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00029] Figure 1 exemplarily illustrates a front view of the busbar (100). In the present embodiment, the busbar (100) comprising a primary member (102), a secondary member (106), a junction member (106b), at least one connecting leads (104) disposed on the primary member, the extension (106c) of the secondary member (106) of the busbar (100), and a output terminal for the BMS connected to the primary member (108), wherein the output terminal (108) is configured to have a fastening hole.
[00030] In an embodiment of the present invention, the busbar is configured to have connecting leads (104) depressed from the primary member (102) of the busbar.
[00031] Fig. 2 exemplarily illustrates the top perspective view of a linear alignment of unit cells (202), wherein the electrode terminals on the unit cells are electrically connected to the at least one leads (104) on the busbar (100).
[00032] In an embodiment of the present invention, the busbar is made of copper, and the electrode terminals on the unit cells are made of nickel, and they are electrically connected as shown in figure 2, by welding the electrode terminals to the connecting leads (104) on the primary member of the busbar.
[00033] In another embodiment of the present invention, unit cells (202) in the linear alignment as shown in figure 2 are all at the same height.
[00034] In an embodiment of the invention, the plurality of units of the at least one junction members (106b) are disposed on the primary member (102) so that all the at least one connecting leads (104) are at an optimum impedance to the secondary member (106) ensuring equal current distribution across all the unit cells in a linear alignment of unit cells.
[00035] Fig. 3 exemplarily illustrates an exploded view perspective of the battery pack, comprising a battery module (202), a busbar module (100, 302, 303), and a housing (304, 305) for the unit cells (202).
[00036] In an embodiment of the present invention, the busbar module comprising at least one busbar (100) and at least one interconnector (302), wherein the interconnector electrically connects the electrode terminals on one side of a dual linear alignment of at least one unit cells (202), and the busbar (100) electrically connects the electrode terminals on one side of a single linear alignment of unit cells (202).
[00037] In another embodiment of the present invention, the battery pack housing has at least a first part (304) and at least a second part (305).
[00038] In yet another embodiment of the present invention, the first part (304) and the second part (305) of the battery pack housing in configured to be held together by means of appropriate fasteners (306).
[00039] In another embodiment of the present invention, the first part (304) and the second part (305) of the battery pack housing are configured to have at least one slots cut out of the outer surface for fastening the at least one interconnector (302, 303), which are also configured to function as the measurement terminal (302b, 303b) for the BMS.
[00040] In an embodiment of the present invention, each at least one unit cells (202) have two electrode terminals (202a, 202b).
[00041] In another embodiment of the present invention, each linear alignment of unit cells is configured so that the at least one unit cell (202) is disposed next to another at least one unit cell with the same type of electrode terminal along the same direction.
[00042] In another embodiment of the present invention, a linear alignment of unit cells is disposed next to another linear alignment of unit cells (202) with the opposite type of electrode terminal along the same direction.
[00043] In an embodiment of the present invention, an interconnector (302, 303) is disposed to electrically connect a duality of linear alignment of unit cells (202).
[00044] In another embodiment of the present invention, the interconnector (302, 303) is configured to have connecting leads depressed from the interconnector, which are disposed on the electrode terminal of an unit cell.
[00045] In an embodiment of the present invention, the interconnector (302,303) is made of copper and the leads on the interconnector are welded to the electrode terminals (202a, 202b) on the unit cells (202).
[00046] Fig. 4 exemplarily illustrates a top view perspective of the assembled battery pack (400), comprising the battery module (202), the busbar module (100, 302, 303) and the housing unit (304,305).
[00047] In an embodiment of the present invention, a battery pack has a duality of busbars configured as described in Fig. 1.
[00048] The first part (304) of the housing unit is joined to the second part (305) of the housing unit, configured to protect the unit cells from wear and tear.
[00049] The extended part of the secondary member of the busbar (106) is configured along the contours of the housing unit.
[00050] In an embodiment of the present invention, the interconnectors and the busbar are configured so that the primary member of the busbar and the at least one interconnector functions as a signal channel for the battery pack assembly, and the secondary member of the busbar and the extended part thereof functions as the output channel of the battery pack assembly.
[00051] In another embodiment of the present invention, at least one output channel is configured with a fuse on the battery pack housing assembly.
[00052] In an embodiment of the present invention, the configuration of the battery pack and the individual components therein as described in the foregoing descriptions ensure ease of assembly due to reduction in the number of parts, fasteners and components.
[00053] In an embodiment of the present invention, there are mounting points on the housing unit for disposition of the same in a two-wheeler vehicle.
[00054] In another embodiment of the present invention, the housing unit is configured to have secondary mounting points to dispose other parts on the housing unit.
[00055] The advantages of the present invention are as follows: localised heating due to transmission loss in the busbar is minimized with optimally uniform discharging of the unit cells in the battery pack, which improves the life cycle and durability of the battery pack. The busbar being configured as described in the above description enables ease of assembly, being shaped around the contours of the battery pack. Using the busbar instead of wires prevents the assembly from being bulky and heavy. Separating the output terminal from the BMS terminal means the BMS makes more accurate readings.

List of Reference numerals

100: Busbar
102: Primary member of the busbar
104: Connecting lead on the busbar
106: Secondary member of the busbar
106b: Junction member of the busbar
106c: Extended part of the secondary member of the busbar
108: Extended part of the primary member of the busbar
202: Unit cell of the battery module
202a, 202b: Electrode terminal of a unit cell
302, 303: Interconnector
302b, 303b: Extended member of the interconnector
304: First part of the housing unit
305: Second part of the housing unit
306: Fastener
400: Battery Pack

,CLAIMS:We claim:
1. A battery pack (400) comprising:
a housing unit (304, 305),
a plurality of cells (202) disposed in said housing unit (304, 305);
a busbar module (100, 302, 303) configured to connect said plurality of cells (202) with each other to form an output channel of the battery pack (400), said busbar module comprising at least one busbar (100), and an at least one interconnector (302, 303), being configured to form said output channel;
wherein said busbar (100) being configured to have a primary member (102) and a secondary member (106),
said primary member (102) being configured to have at least one connecting lead(s) (104), and
said secondary member (106) being configured to have an extended member (106c),
wherein, said primary member and said secondary member joined by at least one junction member (106b).
2. The invention as claimed in claim 1, wherein said interconnector (302, 303) and said primary member (102) of said busbar (100) being configured as a signal channel, and said secondary member (106) of said busbar (100) being configured as a single channel output of the battery pack (400).
3. The invention as claimed in claim 3, wherein said battery pack (400) being configured to have at least a duality of said single channel outputs.
4. The invention as claimed in claim 2, wherein said extended part (106c) of said secondary member (106) being configured to be disposed along a contour of said battery pack (400) to facilitate ease of assembly.
5. The invention as claimed in claim 2, wherein said extended member (302b) of said interconnector (302), and said extended member (108) of said primary member (102) of the at least one busbar (100) being configured as a single channel output.
6. The invention as claimed in claim 6, wherein a plurality of single channel output being connected to a Battery management system.