Battery pack connector

Abstract

A battery pack (100), comprising: a plurality of cells (110) enclosed in at-least a casing (130) for placement of plurality of cells (110); wherein the plurality of the cells (110) having both positive (140) contact and negative contact (150) oriented towards a same side of the battery back; at-least a connector (160) connecting the positive contact (140) of one cell (110) with the negative contact (150) of the other cell (110); wherein the connector (160) has at-least one extension (170, 210) at one end for connecting the connector (160) with the cells (110).

Description

BATTERY PACK CONNECTORFIELD OF INVENTON

[0001] The invention relates to a battery pack & and more particularly, it relates to connectors for cells in a battery pack of electric vehicles.CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This invention takes priority from an earlier filed provisional patent application no. 202421095713 filed on December 04, 2024; which is incorporated herein as reference.BACKGROUND OF THE INVENTION

[0003] The development of electric vehicles has led to the need for advanced battery packs. An efficient battery pack is essential for electric vehicles (EVs) because it directly impacts performance, range, safety, and the overall lifespan of the vehicle. Effective enhancement of vehicle range is possible due to a battery pack comprising multiple cells connected together.

[0004] A connector assembly in a battery pack is a system designed to connect multiple battery cells to each other within the pack, further to a Battery Management System (BMS), and to external devices. It provides both electrical and physical connections that enable safe, efficient, and modular linking of cells, allowing the pack to function as a unified power source. This assembly can consist of connectors, busbars, wiring harnesses, balance leads, and insulating materials. The connector ensures the cells are properly inter-connected, allowing the pack to deliver the necessary power and energy to the vehicle.

[0005] Interconnecting cell terminals in a large battery pack presents several key challenges that can impact efficiency, safety, and longevity. One of the primary issues is high resistanceand power loss. These losses not only reduce the overall energy available but also convert into heat, which can diminish the efficiency of the pack and reduce the overall driving range of an electric vehicle. Connectors used in high-current applications, particularly in connections between cell terminals, often encounter issues like high contact resistance and short circuits. High current conduction challenges primarily stem from contact resistance, where resistance at the connection points impedes efficient current flow, leading to heat buildup and potential failure. Contact resistance issues can arise from oxidation, improper surface treatment, or using low-quality materials that lack sufficient conductivity. Further, when connectors are not designed with proper thermal management, they can become a conduit for heat transfer between the cells. This issue is particularly critical in tightly packed battery configurations, where heat generated by one cell (due to high current, poor connection, or internal faults) can easily propagate to neighboring cells. Factors like high contact resistance, insufficient thermal dissipation, or poor connector material choices can worsen this issue.

[0006] Mechanical stress and vibration also pose problems in battery packs, especially for applications like electric vehicles that face constant motion and road vibrations. These vibrations can loosen or damage connections between the cells over time, leading to intermittent connections, power drops, or even complete disconnection of cells within the pack. This not only impacts the performance of the pack but can also lead to safety hazards due to potential arcing or short-circuiting. In a large battery pack, individual cells naturally vary slightly in capacity, voltage, and temperature. Without proper cell voltage balancing, some cells can become overcharged or over-discharged, leading to uneven ageing and a reduction in the overall capacity of the pack.

[0007] Conventional battery packs, has cells connected with two bus bars at opposite terminals (positive and negative), with several inherent drawbacks. One significant issue is the increased electrical resistance and heat generation. Since, the current must travel across the entire length of each cell, it creates additional resistance, which in turn produces more heat during operation. The opposite-terminal bus bar setup also has implications for the pack’s physical dimensions. Requiring space at both ends of each cell for bus bar connections can increase the overall size and weight of the battery pack, which is particularly disadvantageous in applications where compactness and weight are critical and also impacting thermal management of the entire battery pack, which is constrained of space. In electric vehicles, for instance, this configuration can limit energy density and reduce the vehicle’s efficiency due to the additional weight and space requirements. Furthermore, this opposite-terminal bus bar design complicates cooling system implementation. Cooling systems in battery packs must account for heat dissipation across both ends, requiring more complex and sometimes costlier designs to keep cells within a safe operating temperature range.

[0008] Connecting both the positive and negative terminals at the same end of a battery cell, while beneficial for compact design and improved cooling, presents some constraints and challenges. There is a greater risk of short-circuits, as the contact terminals are positioned closer to each other; this requires careful insulation and spacing to prevent accidental contact. Further, uneven spacing of positive and negative terminal at the same end especially limited space for negative terminal welding complicates the welding of connectors or bus bars, as precise alignment is critical to ensure a reliable connection. Misalignment can result in weak or uneven welds, which may compromise electrical conductivity, leading to higherresistance, or even cause mechanical failures under stress. Such irregularities in the weld can contribute to increased heat generation at the connection points, further exacerbating thermal management challenges and potentially impacting the longevity and safety of the battery pack.

[0009] Moreover, the non-uniform spacing requires additional attention to insulation, as varying distances between terminals can increase the risk of short circuits if connectors accidentally bridge the gap.

[0010] Hence, there is a need to provide a proper a connector assembly for battery pack, to address the aforementioned challenges by providing a novel design for construction of a connector assembly suitable for multifarious applications & especially for automotive vehicles.OBJECT OF THE INVENTION

[0011] An object of the invention is to provide an effective terminal connection system for cells in large, high-current battery packs to minimize electrical resistance and heat generated at terminal connections, ensuring efficient current flow.

[0012] Another object of the invention is to prevent thermal propagation between cells in a terminal connection system.

[0013] A further object of the invention is to have a terminal connection system in a battery pack so as to have an enhanced thermal management system.

[0014] Another object of the invention is to have an electrical connection between cells in a battery pack that is compact and easy to manufacture, with effective cell arrangement.

[0015] A further object of the invention is to eliminate welding failures by achieving accurate positioning of connector over the cell terminals.

[0016] Yet another object of the invention is to have a streamlined manufacturing process which aims to lower production costs, assembly time and improve battery pack safety to abnormal events while maintaining robust protection standards.

[0017] Another object of the invention is to prevent short circuit condition inside the battery pack and eliminate damaged cell in the pack for effective replacement.

[0018] Still another object of the invention is to overcome lacunas of existing systems explained in background section.SUMMARY OF THE INVENTION

[0019] With the above objectives in view, the present invention provides a battery back, comprising a plurality of cells arranged in series and parallel configurations; wherein the cells having both positive and negative terminals oriented towards an identical side of the battery back ; at-least a connector electrically connecting the positive terminal of one cell with the negative terminal of the other cell; wherein the connector includes at-least one extension having contoured leg extensions at one end for joining the connector with one or more cell terminal.

[0020] The connector includes a second end opposite to the leg extensions, the second end comprising elliptical extensions configured for joining the connector with one or more cell terminals.

[0021] The elliptical extensions are circular in shape and comprises of plurality of dimples for joining positive cell terminals with the connector.

[0022] The contoured leg extensions comprises of at-least one dimple welded to the respective negative terminal of each cell.

[0023] The connector is welded to the cell terminals, wherein there is a weld joint formed along a uniform line contact between mating surfaces.

[0024] The plurality of connectors are connected with one another through soldering or welding forming a PCB assembly or a bus bar assembly on a cell holder.

[0025] Each connector comprises of at-least a guide hole for mounting on the cell holder wherein the guide hole being configured to ensure controlled current flow through the connector by restricting current passage through a narrow connector path.

[0026] The connector comprises of at-least a fuse positioned on it to limit overcurrent flow in series circuit configuration from one cell to another.

[0027] The PCB assembly or a bus bar assembly comprises a track fuse to prevent short circuit and prevent thermal propagation from one cell to another.

[0028] The battery pack comprises of a centralized fuse at the end of the PCB or busbar assembly for all the cells connected in parallel circuit configuration.

[0029] The battery pack is a scalable battery pack comprising: a configuration providing power capacity of 3.5 kW, 3 kW, 2.5 kW consisting of at least plurality of cells connected in parallel and at least plurality of cells connected in series.

[0030] The battery pack of 10-20 cells in a cell holder configured to receive and secure the plurality of cells wherein the electrical interconnection network configured to electrically connect the cells in a combination of series and parallel connections.

[0031] The batery pack comprises of at least a voltage sensor positioned on the PCB assembly or a bus bar assembly to monitor voltage across the respective cells connected in parallel circuit configuration to detect and measure the electrical potential difference across individual cells or groups of cells within the battery pack.

[0032] The connector material is nickel plated steel and ranges from 0.1 to 0.4 mm in thickness.

[0033] The batery pack comprises of at least one thermistor for monitoring the temperature of the cells mounted on the PCB assembly or a bus bar assembly via soldered electrical leads or direct surface mounting, in thermal contact with the cell.

[0034] The batery pack comprises of at least one communication interface (CAN) for relaying parameters including voltage, current & temperature for the respective cells from the PCB assembly or a bus bar assembly to the batery management system.

[0035] The batery pack comprises of at least one current sensor mounted on the PCB assembly or a bus bar assembly to monitor current through the cells connected in series circuit configuration.

[0036] The battery pack comprises of at least a heat sink positioned on the opposite side of the PCB or bus bar assembly to dissipate heat generated from the cells.

[0037] The PCB assembly is made from FR4, polyimide, or metal-based substrates.

[0038] The PCB assembly has indicators comprising LEDs to indicate individual cell status or PCB functionality.

[0039] The PCB assembly has shock-absorbing features comprising rubber damper mounted between the printed circuit board assembly and a supporting chassis to atenuate vibration or mechanical shock transmited to the printed circuit board.BRIEF DESCRIPTION OF DRAWINGS:

[0040] The above and other objects, features, and advantages of the present disclosure will be more apparent from the detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by way of example only with reference to the accompanied drawings wherein like reference numerals represent like elements.

[0041] Fig. 1 illustrates an exploded view of a battery pack, according to one embodiment of the invention;

[0042] Fig. 2 illustrates a connector of the battery pack used for joining cell contacts;

[0043] Fig. 3 illustrates a cell contacting system comprising plurality of the connectors connected on the PCB tab; and

[0044] Fig. 4 illustrates circuit connections for the cell contacting system connecting plurality of the connectors.DETAILED DESCRIPTION:

[0045] The invention along with preferred embodiments will now be described in detail with reference to the accompanying drawings. The preferred embodiment does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

[0046] It will be readily understood that components of the present invention, as generally described and illustrated in figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention as represented in the figures is not intended to limit the scopeof the invention but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

[0047] Fig.1 illustrates an exploded view of a battery pack (100) according to an embodiment of the invention. The battery pack (100) comprises of a plurality of cells (110) forming at least a cell assembly (120) housed inside the battery pack (100) in a horizontal plane. The battery pack (100) comprises of plurality of cells (110) connected in series and parallel configurations. The scalable battery pack (100) comprising: a configuration providing power capacity of 3.5 kW, 3 kW, 2.5 kW consisting of at least plurality of cells (110) connected in parallel and at least plurality of cells (110) connected in series. Preferably, 10-20 cells (110) are connected in parallel and series connection.

[0048] The battery pack (100) comprises a plurality of casings (130) enclosing the cells (110) of the battery pack (100). All the cells (110) have both positive contact (140) and negative contact (150) in a single direction. Due to this arrangement, there is a significant reduction in assembly time, and all cells (110) have similar electrical polarity at one end. This also results in significant reduction in cell packaging errors during assembly. In a preferred embodiment, a connector (160) is used to connect the positive contact (140) of one cell (110) with the negative contact (150) of the other cell. The connector (160) includes at-least one extension having contoured leg extensions (170) at one end for joining the connector (160) with one or more cell terminal. The connector (160) includes a second end opposite to the leg extensions (170), the second end comprising elliptical extensions (210) configured for joining the connector (160) with one or more cell terminals.

[0049] The cell contacting system (180) comprising of electrical circuit connections for the entire battery pack (100) is mounted preferably on the top surface of the battery pack (100), leading the bottom surface empty. The battery pack (100) comprises of a heat sink (190) is positioned on the opposite side of the cell contacting system (180). When electrical circuit connections for a battery pack (100) are arranged on the top surface of the cell assembly (120), it brings several practical benefits. One of the primary advantages of this packaging is optimal space utilization. With the bottom surface left empty, the design allows for easy mounting onto flat surfaces or integration into compact enclosures. Another key benefit is improved ease of maintenance. Placing all connections on the top surface ensures straightforward access for troubleshooting, wiring adjustments, or repairs. The serviceability for the electrical components can be conveniently made without needing to disassemble the entire assembly, reducing downtime and effort during servicing. Additionally, this layout often enhances safety and thermal performance. Keeping the bottom free of electrical components, it minimizes exposure to potential damage from external factors, such as vibrations or heat conduction from mounting surfaces. Multi-level safety provision on connector and cell contacting system (180) with fuses ensure high level of safety is offered to the end user. Overall, this design choice streamlines installation, maintenance, and operational reliability.

[0050] According to Fig. 2 of the present invention, the connector (160) used for connecting the cell polarity contacts may be described. The negative contact (150) of the cells (110) is having a 1.5 mm narrow curved surface, which leads to difficulty in defect free welding. Welding in narrow spaces presents several challenges that can affect both safety and weld quality. Limited access makes it difficult to position tools properly and ensure precisewelding, often requiring awkward angles and leading to ergonomic strain for the welder. These constraints can result in inconsistent welds and inadequate fusion, compromising the strength and durability of the joint.

[0051] The connector (160) has the elongated leg extension (170), which further includes the linear dimples (200). The connector (160) material is 0.25 mm thick. Particularly, an electro nickel-plated diffusion annealed steel strip which has low contact resistance and high corrosion resistance is preferred as a connector (160). According to a preferred embodiment, the leg extensions (170) are welded to the respective negative contact (150) of each cell (110). Since, there is not enough flat area on the negative terminal, laser welding will cause a lot of rejections. In another preferred embodiment, resistance welding is used. Hence, to get consistent and reliable joining, negative terminal is resistance extension welded with a connector (160) having innovative leg extensions (170). Further, the leg extensions (170) have plurality of the linear dimples (200) for improved weld strength and reduction in welding failure modes of joining the cells (110) to connector (160).

[0052] The connector (160) also comprises of at-least the circular extension (210), wherein the circular extension (210) has a plurality of circular dimples (220). The circular extensions (210) with the circular dimples (220) are welded to the respective positive contact (140) of the each cell (110). According to another embodiment, the connector (160) is having a Circular, hexagonal, or flexible shapes depending on battery pack (100) geometry.

[0053] The connector (160) comprises of at-least a guide hole (280) for mounting on the cell holder; wherein the guide hole (280) is a circular hole allowing limited current flow through the connector (160). The connector (160) is soldered or may be press fitted to a PCB assembly (230) or a bus bar assembly. During overcurrent condition, this acts to disconnectthe series connection of the cells (110) and prevents short circuit, providing protection to the battery pack (100) from thermal runaway. In a preferred embodiment, the connector (160) also comprises of at-least a track fuse (270) to limit overcurrent flow in series circuit configuration from one cell (110) to another.

[0054] According to Fig.3 of the present invention, a cell contacting system (180) comprising plurality of the connectors (160) connected on the PCB tab is described. The cell contacting system (180) is made from FR4, polyimide, or metal-based substrates.

[0055] According to another embodiment of the present invention, a bus bar may also be used. The plurality of connectors (160) connected with one another through the PCB assembly (230) or the bus bar assembly forming a cell contacting system (180) are positioned on the cell holder. The connector (160) is soldered or may be press fitted to the PCB assembly (230) or the bus bar assembly. The connector (160) comprises of the plurality of legs for soldering on the PCB assembly (230) or the bus bar assembly.

[0056] The battery pack (100) has at-least one thermistor positioned on the cell contacting system (180) for detecting the temperature of the cells (110). The thermistor plays a critical role in preventing overheating, which can lead to thermal runaway — a dangerous condition where the battery temperature rises uncontrollably. It also helps in detecting excessively low temperatures that can impact battery performance or cause internal damage. With this data, the BMS can regulate charging and discharging rates or activate cooling mechanisms to maintain the pack within its safe operating temperature range. This proactive temperature monitoring not only enhances the pack's safety but also contributes to improving efficiency and extending its lifespan.

[0057] The battery pack (100) comprises of communication interfaces (240) (CAN) for relaying various parameters including but not limited to voltage, current & temperature for the battery pack (100) and the respective cells (110) to a Battery Management system. This facilitates efficient data exchange between the battery management system (BMS) and external devices. This capability is essential for modern applications, where real-time monitoring and control are critical. The CAN interface enables the relay of various parameters, including voltage, current, temperature, state of charge (SOC), state of health (SOH), and fault diagnostics. This information is crucial for system integration, particularly in electric vehicles,

[0058] According to another embodiment of the invention, the cell contacting system (180) has indicators to indicate individual cell status or PCB functionality. The indicators may be LED’s. The cell contacting system (180) may also include shock-absorbing features for high- vibration environments.

[0059] According to Fig.4, the circuit connection for the cell contacting system (180) connecting the plurality of connectors (160) is displayed. In a preferred embodiment, the circuit connection is formed on the PCB assembly (230). The cell contacting system (180) may also comprise of a centralized fuse (260) for all the cells (110) connected in parallel circuit configuration. The battery pack (100) comprises of the voltage sensor (250) positioned on the cell contacting system (180) to monitor voltage across the respective cells (110) connected in parallel circuit configuration. The voltage sensors (250) plays a vital role in ensuring the safety and efficiency of the system. These sensors monitor the voltage of the individual cells (110) or the groups of cells (110), providing real-time data essential for the battery management system (BMS). By tracking the voltage, the sensors enable accurateassessment of the battery’s state of charge (SOC) and state of health (SOH), which are critical for maintaining optimal performance. Another significant function of voltage sensors (250) is their role in safety. They detect overvoltage conditions that could lead to overheating or even thermal runaway, as well as under- voltage scenarios that may damage the cells (110) or reduce their lifespan. This monitoring ensures timely intervention by the BMS to prevent these risks. Additionally, the data collected can be used for balancing the cells (110), ensuring uniform voltage levels across the pack and extending the overall lifespan of the battery. According to another embodiment, the battery pack (100) comprises of current sensor positioned on the cell contacting system (180) to monitor current through the cells (110) connected in series circuit configuration.

[0060] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in respects as illustrative and not restrictive.

[0061] Within this patent specification, it is crucial to acknowledge the versatility and potential variations of the invention. Other embodiments may incorporate a variety of component units, logical units, and switching units to achieve similar or modified functionalities. These embodiments may involve different arrangements, configurations, or combinations of these units, depending on specific application requirements or design preferences. The scope of the invention encompasses such alternative embodiments, wherein the essential features and principles remain applicable, albeit with potential modifications to suit particular contexts or objectives. Thus, while the embodiments described herein serve as examples, it is understood that numerous other configurations and arrangements are feasible and fall within the scope of the invention as defined by the claims.Reference Numerals:-100 - Batery Pack110 - Cells120 - Cell Assembly130 - Casings140 - Positive Contact150 - Negative Contact160 - Connector170 - Leg Extension180 - Cell Contacting System190 - Heat Sink200 - Linear Dimples.210 - Elliptical / circular Extensions220 - Circular Dimples230 - PCB Assembly240 - Communication Interfaces (CAN)250 - Voltage Sensor260 - Fuse270 -Track Fuse280- Guide hole

Claims

We Claim:-1. A battery pack (100), comprising: a plurality of cells (110) arranged in series and parallel configurations; wherein the cells (110) having both positive and negative terminals (140, 150) oriented towards an identical side of the battery back (100); at-least a connector (160) electrically connecting the positive terminal (140) of one cell with the negative terminal (150) of the other cell; wherein the connector (160) includes at-least one extension having contoured leg extensions (170) at one end for joining the connector (160) with one or more cell terminal.

2. The battery pack (100) as claimed in claim 1, wherein the connector (160) includes a second end opposite to the leg extensions (170), the second end comprising elliptical extensions (210) configured for joining the connector (160) with one or more cell terminals.

3. The battery pack (100) as claimed in claim 2, wherein the elliptical extensions (210) are circular in shape and comprises of plurality of dimples (220) for joining positive cell terminals (140) with the connector (160).

4. The battery pack (100) as claimed in claim 1, wherein the contoured leg extensions (170) comprises of at-least one linear dimple (200) welded to the respective negative terminal (150) of each cell (110).

5. The battery pack (100) as claimed in claim 1, wherein the connector (160) is welded to the cell terminals (140, 150), wherein a weld joint is formed along a uniform line contact between mating surfaces.

6. The battery pack (100) as claimed in claim 1, wherein the plurality of connectors (160) are connected with one another through soldering or welding to form a PCB assembly (230) or a bus bar assembly on a cell holder (130).

7. The battery pack (100) as claimed in claim 1 , wherein each connector (160) comprises of at-least a guide hole (280) for mounting on the cell holder (130); wherein the guide hole (280) being configured to ensure controlled current flow through the connector (160) by restricting current passage to a narrow connector path.

8. The battery pack (100) as claimed in claim 1, wherein the connector (160) comprises of at-least a fuse (260) positioned on it to limit overcurrent flow in series circuit configuration from one cell (110) to another.

9. The battery pack (100) as claimed in claim 6, wherein the PCB assembly (230) or the bus bar assembly comprises a track fuse (270) to prevent short circuit and prevent thermal propagation from one cell (110) to another.

10. The battery pack (100) as claimed in claim 1, comprises a centralized fuse (260) positioned at the end of the PCB or the busbar assembly for all the cells (110) connected in a parallel circuit configuration.

11. The battery pack (100) as claimed in claim 1, wherein the battery pack (100) is scalable to provide power capacities of 3.5 kW, 3 kW, 2.5 kW and consisting of a plurality of cells (110) connected in parallel and a plurality of cells (110) connected in series.

12. The battery pack (100) as claimed in claim 6, comprises of 10-20 cells (110) in a cell holder (130) configured to receive and secure the plurality of cells (110), wherein theelectrical interconnection network configured to electrically connect the cells (110) in a combination of series and parallel connections.

13. The battery pack (100) as claimed in claim 1, comprises of at least a voltage sensor (250) positioned on the PCB assembly (230) or a bus bar assembly to monitor voltage across the respective cells (110) connected in parallel circuit configuration to detect and measure the electrical potential difference across individual cells (110) or groups of cells (110) within the battery pack (100).

14. The battery pack (100) as claimed in claim 1, wherein the connector (160) is made- up of nickel plated steel and thickness ranges from 0.1 to 0.4 mm.

15. The battery pack (100) as claimed in claim 6, comprises of at least one thermistor mounted on the PCB assembly (230) or a bus bar assembly via soldered electrical leads or direct surface mounting, wherein the thermistor in thermal contact with the cell for monitoring the temperature of the cells (110).

16. The battery pack (100) as claimed in claim 6, comprises of at least one communication interface (CAN) (240) configured to relay parameters including voltage, current & temperature for the respective cells (110) from the PCB assembly (230) or a bus bar assembly to the battery management system.

17. The battery pack (100) as claimed in claim 6, comprises of at least one current sensor mounted on the PCB assembly (230) or a bus bar assembly to monitor current through the cells (110) connected in series circuit configuration.

18. The battery pack (100) as claimed in claim 6, comprises of at least a heat sink (190) positioned on the opposite side of the PCB or bus bar assembly to dissipate heat generated from the cells (110).

19. The battery pack (100) as claimed in claim 6, wherein the PCB assembly (230) is made from FR4, polyimide, or metal-based substrates.

20. The battery pack (100) as claimed in claim 6, wherein the PCB assembly (230) includes indicators comprising LEDs configured to indicate individual cell status or PCB functionality.

21. The battery pack (100) as claimed in claim 6, wherein the PCB assembly (230) has shock-absorbing features comprising a rubber damper mounted between the printed circuit board assembly (230) and a supporting chassis to attenuate vibration or mechanical shock transmitted to the printed circuit board.

Images