WO2023187812A1

WO2023187812A1 - A battery pack

Info

Publication number: WO2023187812A1
Application number: PCT/IN2023/050134
Authority: WO
Inventors: V S Kumar Gundavarapu; Garg Manish; Pattabiraman V
Original assignee: Tvs Motor Company Limited
Priority date: 2022-03-27
Filing date: 2023-02-09
Publication date: 2023-10-05

Abstract

The present invention is related to a battery pack (101). The battery pack (101) comprising a plurality of battery modules (201), one or more of said battery modules (201) includes one or more electrochemical cells (202). A plurality said baffle structure (403) being attached to said battery module (201). A casing assembly (102) being configured to accommodate the plurality of battery modules (201). The casing assembly (102) includes a bottom casing (102C) being configured to have a plurality of fins (103). According to the above architecture, the improved thermal management system provides a controlled recirculation of air through the baffle structure (403) which provides a serpentine path of a recirculated air between the battery modules (201) to provide uniform cooling throughout the battery pack (101). Further, recirculated air exchanges heat with outside air due to heat convection when passes through the bottom casing (102C).

Description

A BATTERY PACK

TECHNICAL FIELD

[0001] The present subject matter relates to a battery pack. More particularly, to a thermal management system of a battery pack.

BACKGROUND

[0002] Existing research in battery technology is directed to rechargeable batteries, such as sealed, starved electrolyte, lead/acid batteries, which are commonly used as power sources in different applications, such as, vehicles and the like. However, the lead-acid batteries are heavy, bulky, and have short cycle life, short calendar life, and low turnaround efficiency, resulting in limitations in applications.

[0003] Thus, to overcome problems associated with conventional energy storage devices including lead-acid batteries, the lithium-ion battery has emerged as a preferred solution that provides an ideal system for high energy-density applications, improved rate capability, and safety. Further, the rechargeable energy storage devices like - lithium-ion batteries, exhibit one or more beneficial characteristics which make them useable on powered devices. First, for safety reasons, the lithium-ion battery is constructed of all solid components while still being flexible and compact. Secondly, the energy storage device including the lithium-ion battery exhibits similar conductivity characteristics to primary batteries with liquid electrolytes, i.e., deliver high power and energy density with low rates of self-discharge. Thirdly, the energy storage device such as the lithium-ion battery is readily manufacturable in a manner that is both reliable and cost-efficient. Finally, the energy storage device including the lithium-ion battery can maintain a necessary minimum level of conductivity at subambient temperatures.

[0004] In a known structure for a battery pack, one or more battery modules includes one or more energy storage cells. The energy storage cells are disposed of in at least one holder structure in series and parallel combinations using at least one interconnecting structure. The interconnecting structure is adapted for electrically interconnecting the energy storage cells with a battery management system (hereinafter “BMS”). An output voltage and an output current generated by the battery pack are transmitted to one or more electronic and electrical components configured to be powered by the battery pack via end connections after being monitored and regulated by the BMS.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention is described with reference to an exemplary embodiment of a battery pack. The same numbers are used throughout the drawings to reference features and components. Further, the inventive features of the invention are outlined in the appended claims.

[0007] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein reference numerals refer to like parts throughout the various views unless otherwise specified. It should be appreciated that the following figures may not be drawn to scale.

[0008] Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as a discussion of other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.

[0009] Figure la illustrates a top-side perspective view of a battery pack, as per embodiment, in accordance with one example of the present subject matter.

[00010] Figure lb illustrates a bottom side perspective of the battery pack, as per embodiment, in accordance with one example of the present subject matter.

[00011] Figure 2a illustrates a cut section of the battery pack across an A-A’ axis, as per embodiment, in accordance with one example of the present subject matter. [00012] Figure 2b illustrates an exploded view of the battery pack, as per embodiment, in accordance with one example of the present subject matter.

[00013] Figure 3a illustrates side perspective views of the battery pack where few parts are omitted from figure la or figure lb, as per embodiment, in accordance with one example of the present subject matter.

[00014] Figure 3b illustrates an exploded view of the battery pack, where few parts are omitted from figure 2b as per embodiment, in accordance with one example of the present subject matter.

[00015] Figure 4a illustrates an exploded view of the battery pack where few parts are omitted from figure 3b, as per embodiment, in accordance with one example of the present subject matter.

[00016] Figure 4b illustrates an exploded view of the battery pack, where few parts are omitted from figure 3b as per embodiment, in accordance with one example of the present subject matter.

[00017] Figure 5 illustrates a localized view of a portion of the battery pack wherein baffle structure is omitted from the figure, as per embodiment, in accordance with one example of the present subject matter.

[00018] Figure 6a illustrates a perspective view of the battery pack, wherein a few parts are omitted from figure 5, as per embodiment, in accordance with one example of the present subject matter.

[00019] Figure 6b illustrates a side view of the battery pack, wherein a few parts are omitted from figure 5, as per embodiment, in accordance with one example of the present subject matter.

[00020] Figure 7a illustrates a perspective view of the battery pack, wherein the top casing and the intermediate casing are omitted from the figure la to show the airflow in the battery pack, and a localized view of a horizontal channel integrated to the vertical channels as per embodiment, in accordance with one example of the present subject matter.

[00021] Figure 7b illustrates a cut section view of the battery pack across a B-B’ axis shown in figure la, as per embodiment, in accordance with one example of the present subject matter. [00022] Figure 8a illustrates air velocity distribution between the battery modules in the battery pack, as per embodiment, in accordance with one example of the present subject matter.

[00023] Figure 8b illustrates a graphical representation of temperature in the conventional battery pack and proposed battery pack, as per embodiment, in accordance with one example of the present subject matter.

DETAILED DESCRIPTION

[00024] In the following description, numerous details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[00025] Typically, the high costs of fossil-based fuel and its impact on pollution are leading to research and development of renewable energy storage technologies. The lithium-ion battery pack stands out from other batteries due to its higher energy density than lead-acid batteries or nickel-metal hybrid batteries. This leads to a reduction in battery size while retaining the same storage capacity. Therefore, lithium-ion batteries have transformed the consumer electronics sector, and are beginning to power the electrification of the automotive sector. The lithium-ion battery pack has started to be used in several automotive passenger and cargo vehicles. More specifically, being used for electric vehicles, hybrid electric vehicles, and plug-in hybrid vehicles. Typically, to meet range and power requirements the battery pack consists of a large number of battery modules where each battery module further comprises a plurality of battery cells. In other words, individual cells are mounted into several battery modules, which are then assembled into the complete battery pack. Importantly, these cells are assembled with robust mechanical and electrical joints through a metallic interconnect. However, it is observed that the weld joints tend to fail due to vibration.

[00026] Further, it is observed that during the charging/ discharging process, the lithium-ion batteries modules produce lots of heat, which causes an increase in the temperature of the battery pack. This is further aggravated in higher operating current conditions. Heat is also generated due to the joule’s heating effect. As described above, the battery pack comprises a plurality of modules installed in a confined space. The heat generated due to internal resistance and electrochemical reactions inside cells at a high discharge rate cannot be dissipated to the ambient promptly by itself and is accumulated in the modules, resulting in a further increase temperature inside the battery pack and leads to thermal instability across the modules. Further, the same phenomenon is observed during charging. More specifically, the marketable feature of fast charge increases the temperature of the batteries significantly as the current batteries require a relatively long time to recharge.

[00027] Typically, a rise in battery temperature exponentially increases the degradation rate of the battery. Further, it decreases the battery life and could result in thermal runaway. Hence, cooling of batteries is essential to maintain the batteries in a specific temperature range.

[00028] It is known in the prior arts to provide a thermal management system to prevent the rapid increase of cell temperature by removing the heat generated during the charge and discharge process opportunely.

[00029] It is known in the prior art to limit temperature rise in batteries by circulating a liquid to the battery which is thermally conductive and electrically insulated. The liquid is stored in the liquid container and whenever the battery stops discharging, the BMS will allow liquid to flow into the battery through a valve VI/ pump. The liquid flows around the heated cells and comes to contact with the casing which can dissipate the heat out. More specifically, while charging/discharging of battery if the battery temperature rises to a predetermined temperature, the BMS will open the valves and circulate the fluid around the cells to bring down the temperature to avoid thermal runaway. The liquid is circulated back to the container once the battery reaches atmospheric temperature. In this case, the BMS will allow the flow of liquid from the battery to the container by opening a valve V2. This way the temperature can be controlled inside the battery to get more life. However, said system includes a plurality of control valves, pumps, and complex algorithms which makes the whole system design complicated and bulky. Besides the leakage of coolant in the said systems has always been a challenge for designers since it can cause a short circuit failing the cooling system which can become a safety concern for the customers. Moreover, it is typically observed that said system is not effective and still the temperature tends to rise. Further, this increased temperature leads to a capacity loss in lithium -based batteries.

[00030] Further, it is known in the art, to use ambient air to cool the battery pack wherein fresh air is drawn inside the battery pack through the intake duct to maintain an optimum temperature of the battery pack. Additionally, an exhaust duct is provided to discharge the heated air. However, it is observed that uncontrolled airflow does not flow past each battery module at the same rate. This results in uneven temperature distribution across the battery pack. The uneven temperature distribution reduces life of the battery pack significantly.

[00031] Therefore, there is a need to provide an improved thermal management system for a battery pack overcoming all the above problems & trade-offs as well as overcoming problems of the known art.

[00032] It is an object of the present invention to develop an improved thermal management system for a battery pack that dissipates the heat effectively and efficiently without an increase in parasitic power consumption to improve life specifically calendar life, and safety.

[00033] It is yet another object of the present invention to develop a simple and cost- effective thermal management system that provides temperature reduction and temperature uniformity of the cells.

[00034] To this end, the present invention discloses an improved battery pack. The battery pack comprising a plurality of battery modules, a plurality of baffle structures, and a casing assembly. The casing assembly being configured to accommodate a plurality of battery modules. The plurality of battery modules being stacked adjacently. The battery module includes one or more electrochemical cells. The baffle structure being attached between the said battery module and being disposed between each set of adjacent battery modules. The baffle structure being configured to provide a serpentine flow of cooling air therein. The flow of air being at a controlled flow rate for achieving effective cooling of said battery pack. [00035] As per an embodiment of the present invention, wherein each one of said plurality of battery modules includes one or more connecting members, each one of said connecting members being disposed on opposite sides of a plurality of electrochemical cells for electrically connecting said plurality of electrochemical cells. Each baffle structure being attached to a portion of each said connecting members wherein the baffle structure being disposed between the battery modules in an assembled condition of said battery pack (101).

[00036] As per an embodiment of the present invention, said connecting member is configured to have a substantially U-shaped cross-section, and being made up of conductive material.

[00037] As per an embodiment of the present invention, said connecting member being configured to have an upper flange and a lower flange.

[00038] As per an embodiment of the present invention, said battery pack includes a supporting assembly structure. The supporting assembly structure comprises a leftside support member, a right-side support member, a front-side support member, a rear-side support member, and a top-side support member. The top side support member being configured to cover a top portion of said plurality of battery modules.

[00039] As per an embodiment of the present invention, said battery pack includes a blower, one or more air flow horizontal channels, and a plurality of vertical air flow channels, wherein said plurality of vertical air flow channels being connected to said horizontal air flow channel and said baffle structure.

[00040] As per an embodiment of the present invention, each one of said vertical channels being provided with an opening of varying dimensions for achieving a uniform flow of air being circulated in the battery pack.

[00041] As per embodiment of the present invention, said horizontal channel being integrated to said plurality of vertical channels forming a unified structure.

[00042] As per embodiment of the present invention, said horizontal channel and said vertical channel being made up of plastic.

[00043] As per embodiment of the present invention, said casing assembly includes a top casing, an intermediate casing, and a bottom casing, wherein bottom casing being configured to have a plurality of external fins for effectively dissipating the heat and for cooling air being recirculated in said battery pack.

[00044] As per embodiment of the present invention, said adjacent battery modules being connected through said connecting members. The each connecting member having an upper flange, and a lower flange. The connection being through said upper flange and said lower flange together forming a predetermined gap therein.

[00045] As per embodiment of the present invention, said baffle structure being disposed between said predetermined gap formed between battery modules when assembled.

[00046] As per embodiment of the present invention, said baffle structure being disposed in a predetermined gap formed between said left side support member located at a left side of the battery pack and said connecting member of said battery module.

[00047] As per an alternate embodiment of the present invention, said baffle structure being disposed of in said predetermined gap formed between said right side support member, located at a right side of the battery pack and said connecting member of said battery module.

[00048] As per a preferred embodiment of the present invention, said predetermined gap ranges between 7 millimeters to 15 millimeters.

[00049] As per embodiment of the present invention, said baffle structure being configured to have a predetermined shape for guiding the air in a serpentine flow path towards said bottom casing of said casing assembly. The predetermined shape being formed by a plurality of substantially arc-shaped guide members, one or more substantially U-shaped guide members, and one or more substantially T-shaped guide members.

[00050] As per embodiment of the present invention, said baffle structure being attached to said connecting member using adhesives.

[00051] As per embodiment of the present invention, said baffle structure being made up of foam.

[00052] As per embodiment of the present invention, one or more electronic component being mounted on an outer surface of said top casing of casing assembly. [00053] The present subject matter is further described with reference to the accompanying figures. It should be noted that the description and figures merely illustrate the 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.

[00054] The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. As such, it is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Having thus described embodiments of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Thus, the present disclosure is limited only by the claims.

[00055] In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as one skilled in the art will appreciate, various embodiments disclosed herein can be modified or otherwise implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosure. It is to be understood that the forms of the disclosure herein shown and described are to be taken as representative embodiments. Equivalent elements, materials, processes or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of’, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a nonexclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

[00056] Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, etc.) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.

[00057] Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.

[00058] It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. Additionally, any signal hatches in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically specified.

[00059] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[00060] Figure la illustrates a top-side perspective view of a battery pack (101), as per embodiment, in accordance with one example of the present subject matter. Figure lb illustrates a bottom side perspective of the battery pack (101), as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure la, and Figure lb will be discussed together. The battery pack (101) comprising of a casing assembly (102). The casing assembly (102) includes a top casing (102A), an intermediate casing (102B), and a bottom casing (102C). An outer surface (102CA) of the bottom casing (102C) being configured to have a plurality of fins (103). The bottom casing (102C) being configured to have side flanges (102CB), wherein said side flanges (102CB) are provided with one or more mounting holes (102CC). The top casing (102A) being configured to have a recess or dip portion (102AA) to reliably mount a plurality of electronics components (not shown). Further, the top casing (102A) being configured to have a cut-out (102AB) to accommodate a plurality of electronic components (not shown). As per one embodiment, the battery pack (101) can be mounted on a chassis frame structure (not shown) of a vehicle (not shown). As per another implementation, the battery pack (101) can be used in consumer electronics or power plants.

[00061] Figure 2a illustrates a cut section of the battery pack (101) across an A-A’ axis as shown in figure lb, as per embodiment, in accordance with one example of the present subject matter. Figure 2b illustrates an exploded view of the battery pack (101), as per embodiment with few parts omitted for clarity, in accordance with one example of the present subject matter. For sake of brevity, Figure 2a and Figure 2b will be discussed together. The battery pack (101) comprises a plurality of battery modules (201) enclosed within said casing assembly (102). Each battery module (201) includes a plurality of electrochemical cells (202). The battery modules are surrounded by a supporting assembly structure (204). As per one embodiment, the electrochemical cells (202) are of a cylindrical cross-section. As per alternative embodiment, the electrochemical cells (202) can be of different shapes including a prismatic or pouch type. Further, the bottom casing (102C) acts as a foundation covering the bottom portion of the battery modules (201). A plurality of cushioning members (203) being disposed between the battery modules (201) and the inner surface of the bottom casing (102C). As per one implementation, the length and width of the bottom casing (102C) is substantially higher than the intermediate casing (102B) and the top casing (102A). [00062] Figure 3a illustrates side perspective views of the battery pack (101) where few parts are omitted from figure la or figure lb, as per embodiment, in accordance with one example of the present subject matter. Figure 3b illustrates an exploded view of the battery pack (101), where few parts are omitted from figure 2b as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 3a and Figure 3b will be discussed together. As per one embodiment, the battery pack (101) includes a horizontal air flow channel (301), a plurality of vertical air flow channels (302), and a blower (303). As per the preferred embodiment, the horizontal air flow channel (301) being integrated with a plurality of vertical air flow channels (302). The horizontal air flow channel (301) is provided with an inlet duct (301A) connected with the blower (303) with a sealed joint. As per one implementation, the blower (303) is located on the support assembly structure (204). The support assembly structure (204) includes a left side support member (204A), a right-side support member (204B), a front side support member (204C), a rear side support member (204D), and a top side support member (204E). The left side support member (204A), right side support member (204B), front side support member (204C), and rear side support member (204D) substantially cover all four side portions of said plurality of battery modules (201). Further, the top side support member (204E) covers a top portion of said plurality of battery modules (201). More specifically, the blower (303) is located above the battery modules (201) and mounted on the top side support member (204E).

[00063] Figure 4a illustrates an exploded view of the battery pack (101) where few parts are omitted from figure 3b, as per embodiment, in accordance with one example of the present subject matter. Figure 4b illustrates an exploded view of the battery pack (101), where few parts are omitted from figure 3b as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 4a and Figure 4b will be discussed together. Each battery module (201) comprises a plurality of electrochemical cells (202), a cell holder assembly (401), and at least one connecting member (402). The cell holder assembly (401) includes a securing cell holder (401A) and a receiving cell holder (401B), wherein the plurality of electrochemical cells (202) being disposed in said cell holder assembly (401). The connecting member (402) being configured to have a substantially U-shaped crosssection. More specifically, the connecting member (402) includes an upper flange (402A), and a lower flange (402B). A baffle structure (403) being connected to the connecting member (402) of each battery module (201). The baffle structure (403) is made up of foam. The baffle structure (403) is joined to a portion of the said connecting member (402) using adhesives. As per alternative embodiment, the baffle structure (403) can be joined using double-sided tape.

[00064] Figure 5 illustrates a localized view of a portion of the battery pack (101) wherein baffle structure (403) is omitted from the figure, as per embodiment, in accordance with one example of the present subject matter. The battery modules (201) being connected through the connecting members (402) facing each other at some separation connected at the upper flanges (402A), and the lower flanges (402B). The upper flanges (402A), and the lower flanges (402A) being welded together forming a predetermined gap. The baffle structure (403) being disposed of between said predetermined gap formed between the battery modules (201) when assembled. Further, the baffle structure (403) being disposed of in said predetermined gap between said left side support member (204A) and said connecting member (402) of said battery module (201) located at the left of the battery pack (101). Similarly, the baffle structure (403) being disposed of in said predetermined gap between said right side support member (204B), and the connecting member (402) of said battery module (201) located at a right side of the battery pack (101). As per a preferred embodiment, the predetermined gap ranges between 7 millimeters to 15 millimeters.

[00065] Figure 6a illustrates a perspective view of the battery pack (101), wherein a few parts are omitted from figure 5, as per embodiment, in accordance with one example of the present subject matter. Figure 6b illustrates a side view of the battery pack (101), wherein a few parts are omitted from figure 5, as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 6a, and figure 6b will be discussed together. The baffle structure (403) is attached to the connecting member (402). The baffle structure (403) being configured to have a predetermined shape to guide the air in a serpentine flow towards said bottom casing (102C) (as shown in figure 1), and proper sealing between the battery modules (201). The predetermined shape includes a plurality of substantially arc-shaped guide members (403A), one or more U-shaped guide members (403B), and one or more T- shaped guide members (403C). [00066] Figure 7a illustrates a perspective view of the battery pack, wherein the top casing (102A) and the intermediate casing (102B) are omitted from the figure la to show the airflow in the battery pack (101), and a localized view of the horizontal air flow channel (301) integrated to the vertical air flow channels (302) as per embodiment, in accordance with one example of the present subject matter. Figure 7b illustrates a cut section view of the battery pack (101) across a B-B’ axis shown in figure la, as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 7a, and figure 7b will be discussed together. The blower (303) sucks air and creates a spiral flow of air thereby creating a dynamic pressure that forces the air to flow through a curved path and out of the blower (303) towards the horizontal air flow channel (301) (as shown by arrows). The air from the horizontal air flow channel (301) flows towards the plurality of vertical air flow air flow channels (302) (as shown by arrows). Each one of said vertical air flow channels (302) being provided with an opening (302A) of varying dimensions for achieving a uniform flow of air being circulated in the battery pack (101). As per alternative embodiment, the horizontal air flow channel (301) being integrated to the plurality of vertical air flow channels (302) forming a unified structure. The air from the plurality of the vertical air flow channels (302) flows between the battery modules (201) in a serpentine path formed by the baffle structure (403). The air from the baffle structure (403) reaches the bottom casing (102C) where it dissipates heat due to convection through the plurality of fins (103). The blower (303) circulates the same air over and over again thereby controlling the temperature within the battery pack (101).

[00067] Figure 8a illustrates air flow velocity distribution between the battery modules (201) in the battery pack (101), as per embodiment, in accordance with one example of the present subject matter. Figure 8b illustrates a graphical representation of temperature in the conventional battery pack and improved battery pack, as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 8a, and Figure 8b, will be discussed together. Figure 8a depicts the uniform flow rate between the battery modules as the air flows in a serpentine path. After flowing the serpentine path, the air velocity reduces. The low flow rate aids in the effective cooling of air due to natural convection through fins on the bottom casing before it being re-circulated. This phenomenon effectively reduces the temperature of recirculated air. With reference to Figure 8b, curve B showing a low and uniform average temperature of the modules in the battery pack. Further, curve A showing a conventional battery pack wherein the average temperature is higher than the proposed battery pack, and the average temperature of each module drastically varies within the battery pack which affects the longevity of the battery modules. The primary reason for a large variation in average temperature is due to the uncontrolled flow of air in the battery pack as the air tends to flow towards the least resistance path. As per one embodiment, the number of battery modules are twelve in number. However, the number of modules can vary depending upon the application of the battery pack.

[00068] According to the present invention, the thermal management system provides a controlled or throttled recirculation of air through the opening in vertical channels which is connected to the plurality of baffle structures. The baffle structure provides a serpentine path of recirculated air between the battery modules to provide uniform and steady cooling in the battery pack.

[00069] According to the present invention, the exit air is configured to pass through the bottom casing, the casing having the plurality of fins on its outer surface to dissipate the heat through convection, thereby reducing the temperature of recirculated air.

[00070] According to the present invention, the baffle structure being made up of foam dampens the vibration being transmitted to the battery modules thereby eliminates the failure of weld joints.

[00071] According to an embodiment of the present invention, the horizontal and vertical channels being made of plastic is lighter in weight thereby reduces the overall weight of the battery pack.

[00072] The above-described embodiments, and particularly any “preferred” embodiments, are possible examples of implementations and merely set forth for a clear understanding of the principles of the invention. It will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention. List of Reference

204C Front side support member

101 Battery pack 204D Rear side support member

102 Casing assembly 204E Top side support member

102A Top casing 301 Horizontal air flow channel

102AA Dip portion 25 301 A Inlet duct

102AB Cut out 302 Vertical air flow channels

102B Intermediate casing 302A Openings

102C Bottom casing 303 Blowers

102CA Outer surface of bottom 401 Cell holder assembly casing

30 401 A Securing cell holder

103 Fins

40 IB Receiving cell holder

102CB Side flanges

402 Connecting member

102CC Mounting holes

402A Upper flange

201 Battery modules

402B Lower flange

202 Electrochemical cells

35 403 Baffle structure

203 Cushioning members

403A Arc shaped guide members

204 Supporting assembly structure

403B U shaped guide member

204A Left side support member

403 C T shaped guide member

204B Right side support member

Claims

We Claim:

1. A batery pack (101), said batery pack (101) comprising: a plurality of batery modules (201), said plurality of batery modules (201) being stacked adjacently, one or more of each said batery modules (201) includes one or more electrochemical cells (202); a casing assembly (102), said casing assembly (102) being configured to accommodate said plurality of batery modules (201) a plurality of baffle structures (403), said each baffle structure (403) being attached between said batery module (201) and being disposed between each set of adjacent batery modules (201), and said baffle structure (403) being configured to achieve a serpentine flow of cooling air therein; said flow of air being at a controlled flow rate for achieving effective cooling of said batery pack (101).

2. The batery pack (101) as claimed in claim 1, wherein each of said plurality of batery modules (201) includes one or more connecting members (402), each of said connecting members (402) being disposed on opposite sides of a plurality of electrochemical cells (202) for electrically connecting said plurality of electrochemical cells (202), wherein said each baffle structure (403) being atached to a portion of each said connecting member (402) wherein said baffle structure (403) being disposed between said batery modules (201) in an assembled condition of said batery pack (101).

3. The batery pack (101) as claimed in claim 2, wherein said connecting member (402) being configured to have a substantially U-shaped crosssection, and being made up of conductive material.

4. The batery pack (101) as claimed in claim 2 or claim 3, wherein said connecting member (402) being configured to have an upper flange (402A) and a lower flange (402B).

5. The batery pack (101) as claimed in claim 1, wherein said batery pack (101) includes a supporting assembly structure (204), wherein said supporting assembly structure (204) comprising a left side support member (204A), a right side support member (204B), a front side support member (204C), a rear side support member (204D), and a top side support member (204E), wherein said top side support member (204E) being configured to cover a top portion of said plurality of batery modules (201).

6. The batery pack (101) as claimed in claim 1, wherein said batery pack (101) includes a blower (303), one or more horizontal air flow channels (301), and a plurality of vertical air flow channels (302), wherein said plurality of vertical air flow channels (302) being connected to said horizontal air flow channel (301) and said baffle structure (403).

7. The batery pack (101) as claimed in claim 6, wherein each one of said vertical air flow channels (302) being provided with an opening (302A) of varying dimensions for achieving uniform flow of air being circulated in said batery pack (101).

8. The batery pack (101) as claimed in claim 6, wherein said horizontal air flow channel (301) being integrated to said plurality of vertical air flow channels (302) forming a unified structure.

9. The batery pack (101) as claimed in claim 6, wherein said horizontal air flow channel (301) and said vertical air flow channels (302) being made up of plastic.

10. The batery pack (101) as claimed in claim 1, wherein said casing assembly (102) includes atop casing (102A), an intermediate casing (102B), and a botom casing (102C), wherein said botom casing (102C) being configured to have a plurality of external fins (103) for effectively dissipating heat and for cooling air being recirculated in said batery pack (101).

11. The batery pack (101) as claimed in claim 2, wherein said adjacent batery modules (201) being connected through said connecting member (402), said each connecting member (402) having an upper flange (402A), and a lower flange (402B), said connection being through said upper flange (402A) and said lower flange (402B) together forming a predetermined gap therein.

12. The batery pack (101) as claimed in claim 11, wherein said baffle structure (403) being disposed between said predetermined gap formed between batery modules (201) when assembled.

13. The batery pack (101) as claimed in claim 12 and claim 5 wherein said baffle structure (403) being disposed in a predetermined gap formed between said left side support member (204A) located at a left side of the batery pack (101) and said connecting member (402) of said batery module (201). The batery pack (101) as claimed in claim 12 and claim 5, wherein said baffle structure (403) being disposed in a predetermined gap formed between said right side support member (204B) located at a right side of the batery pack (101) and said connecting member (402) of said batery module (201). The batery pack (101) as claimed in claim 11, wherein said predetermined gap ranges between 7 millimeters to 15 millimeters. The batery pack (101) as claimed in claim 1, wherein said baffle structure (403) being configured to have a predetermined shape for guiding said air in a serpentine flow path towards said botom casing (102C) of said casing assembly (102), wherein said predetermined shape being formed by a plurality of substantially arc-shaped guide members (403A), one or more substantially U-shaped guide members (403B), and one or more substantially T-shaped guide members (403C). The batery pack (101) as claimed in claim 2, wherein said baffle structure (403) being atached to said connecting member (402) using adhesives. The batery pack (101) as claimed in claim 1, wherein said baffle structure (403) being made up of foam. The batery pack (101) as claimed in claim 1, wherein a one or more electronic component being mounted on an outer surface of said top casing (102A) of said casing assembly (102).