FIELD OF INVENTION [001] The present invention relates generally to the field of batteries and specifically relates to system and methods for temperature regulations in battery pack system comprising plurality of battery cells.
BACKGROUND [002] A battery pack system includes multiple modules comprising plurality of battery cells. Battery pack systems are widely used in various power storage devices, vehicles, etc. Vehicles using electric power for all or a portion of their motive power (e.g., Battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like, collectively referred to as “electric vehicles”), may provide a number of advantages as compared to more traditional gas-powered vehicles using internal combustion engines. Over the rising concerns of oil costs, climate change and energy security, efforts to promote energy efficient electric vehicles have grown. Energy efficient electric vehicles provide overall reduced air emissions compared to conventional combustion vehicles.
[003] The performance of power storage devices and electric vehicles depend on a battery pack system. It is known that temperature has an influence over life and safety of a battery pack system. For power storage and electric vehicle applications, a battery pack system experiences high charge and discharge rates and the internal chemical reactions of the battery cell generates heat.
[004] The battery pack system needs to be charged and discharged at a suitable temperature range to minimize the battery cell life degradation. Thus, it becomes necessary to precondition the battery pack system before charging and discharging.
[005] Thus, a thermal management system for a battery pack system is required to keep the battery cell temperature within an optimum range to achieve desired performance in varied climate conditions before and during charging as well as discharging the battery pack system.

[006] The battery cells are closely arranged in the battery modules to get maximum packing efficiency and are electrically connected in series or parallel. Thermal management systems known in the art feature heat conducting tubes in different configurations, for example, passing from top to bottom in a module. An alternative arrangement is desirable that eliminates welding or adhesive bonding of such heat conducting tubes with coolant collector section. Further, it is also desirable to avoid the additional power requirements for pumping the coolant through heat conducting tubes.
BRIEF DESCRIPTION [007] In order to solve at least some of the above mentioned problems, there exists a need for an improved battery pack system that is configured for efficient thermal regulation at a lesser cost.
[008] In one embodiment, a battery pack system is disclosed. The battery pack system comprises at least one battery module having at least one battery cell and supported by at least one supporting structure. Further, the battery pack system provides an inlet for coolant entrance into the battery pack system, the inlet is coupled to at least one coolant compartment, wherein the coolant compartment is coupled to an outlet provided for coolant exit from the battery pack system. Furthermore, at least one heat pipe is provided which is in thermal contact with at least one battery cell through at least one thermally conductive and electrically insulative (TCEI) material, wherein at least a portion of the heat pipe is immersed inside the coolant compartment. The TCEI material is configured to contact an outer wall of at least one heat pipe and an outer wall of at least one of the battery cell such that the TCEI material transfers the heat between the one or more battery cells and the one or more heat pipes.
[009] The battery cells are electrically connected according to the voltage and current requirements from the battery pack system and any number of such electrical connections are possible.
[0010] In accordance with second embodiment of the present invention, a method for maintaining temperatures of the battery cells equal in a battery pack system is provided.
[0011] In accordance with third embodiment of the present invention, a thermal management system is provided for the heating and cooling of the battery pack system.

[0012] The summary above is illustrative only and is not intended to be in any way limiting. Further aspects, exemplary embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF DRAWINGS
[0013] Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:
[0014] Fig. 1(a) is a perspective view of the battery pack system with single coolant compartment, in accordance with a first embodiment of the present invention.
[0015] Fig. 1(b) is a perspective view of internal structure of the battery pack system with single coolant compartment, in accordance with the first embodiment of the present invention.
[0016] Fig. 1(c) is a perspective view of internal structure of the battery pack system with single coolant compartment excluding battery modules, in accordance with the first embodiment of the present invention.
[0017] Fig. 1(d) is a sectioned view of the internal structure of the battery pack system with single coolant compartment showing coolant flow from left to right, in accordance with a second embodiment of the present invention.
[0018] Fig. 1(e) is a sectioned view of the internal structure of the battery pack system with single coolant compartment showing coolant flow from right to left, in accordance with the second embodiment of the present invention.
[0019] Fig. 2(a) is a perspective view of the battery pack system with coolant compartments in series, in accordance with the first embodiment of the present invention.
[0020] Fig. 2(b) is a perspective view of internal structure of the battery pack system with coolant compartments in series, in accordance with the first embodiment of the present invention.
[0021] Fig. 2(c) is a perspective view of internal structure of the battery pack system with coolant compartments in series excluding battery modules, in accordance with the first embodiment of the present invention.

[0022] Fig. 2(d) is a sectioned view of the internal structure of the battery pack system with coolant compartments in series, showing coolant flow from bottom to top, in accordance with the second embodiment of the present invention.
[0023] Fig. 2(e) is a sectioned view of the internal structure of the battery pack system with coolant compartments in series, showing coolant flow from top to bottom, in accordance with the second embodiment of the present invention.
[0024] Fig. 3(a) is a perspective view of the battery pack system with coolant compartments in parallel, in accordance with the first embodiment of the present invention.
[0025] Fig. 3(b) is a perspective view of internal structure of the battery pack system with coolant compartments in parallel, in accordance with the first embodiment of the present invention.
[0026] Fig. 3(c) is a perspective view of internal structure of the battery pack system with coolant compartments in parallel excluding battery modules, in accordance with the first embodiment of the present invention.
[0027] Fig. 3(d) is a sectioned view of the internal structure of the battery pack system with coolant compartments in parallel, showing coolant flow from left to right, in accordance with the second embodiment of the present invention.
[0028] Fig. 3(e) is a sectioned view of the internal structure of the battery pack system with coolant compartments in parallel, showing coolant flow from right to left, in accordance with the second embodiment of the present invention.
[0029] Fig. 4(a) is a cross section view of the battery cells in a triangular arrangement having a heat pipe with thermally conductive electrically insulative (TCEI) material on outer walls of heat pipe.
[0030] Fig. 4(b) is a cross section view of the battery cells in a square arrangement having a heat pipe with TCEI material on outer walls of heat pipe.
[0031] Fig. 4(c) is a cross section view of the battery cells in a hexagonal arrangement having a heat pipe with TCEI material on outer walls of heat pipe.

[0032] Fig. 4(d) is a cross section view of the battery cells in a square arrangement having a heat pipe with TCEI material on outer walls of battery cells. ?? same as 4b?
[0033] Fig. 5 is a schematic of the battery pack system with a thermal management system in accordance with the third embodiment of the present invention.
[0034] Further, persons skilled in the art to which this disclosure belongs will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION [0035] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications to the disclosure, and such further applications of the principles of the disclosure as described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates are deemed to be a part of this disclosure.
[0036] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.
[0037] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or a method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, other subsystems, other elements, other structures, other

components, additional devices, additional sub-systems, additional elements, additional structures, or additional components. Appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
[0039] Embodiments of the present disclosure will be described below in detail with reference to the accompanying figures.
[0040] For exemplary and simplicity purpose, the present disclosure and the corresponding drawings explain a battery pack system comprising “cylindrical battery cells”. However, it is to be noted that the various embodiments of the present disclosure are applicable for battery cells having different geometries in the battery pack system. Other types of battery cell geometries include prismatic cell geometry, pouch cell geometry, etc.
[0041] Referring to Fig.1(a), Fig.1(b) and Fig.1(c) a battery pack system 100 provided for the temperature regulation of the battery cells 141 comprises of two battery modules 140 is disclosed. As used herein, a battery module is a group of electrically connected battery cells arranged together with supporting structure. Each battery module 140 comprises of battery cells 141 arranged adjacent to each other held together with the supporting structures 142. The battery casing 130 encloses and holds the battery modules 140 together. One or more such battery modules constitute the battery pack system 100.
[0042] The present invention does not intend to limit the number of battery modules 140 in a battery pack system 100. One or more battery modules 140 may be used by extending the casing structure 130 of the battery pack system 100. The battery modules 140 may be arranged upon one another or adjacent to each other, i.e. in a horizontal or a vertical structure.
[0043] The arrangement pattern of the battery cells 140 may be staggered or inline. Moreover, the battery cells may be in a triangular, square, pentagonal, hexagonal arrangement or any possible geometry. The present invention does not intend to limit the arrangement pattern of the battery

cells 141 inside the battery modules 140 or the arrangement of the battery modules 140 inside the casing 130.
[0044] Further, the battery pack system 100 comprise openings for coolant to flow in and out of the system. The openings are now onwards referred to as “inlet-outlet pair”. The inlet-outlet pair is numbered 111 and 112. The battery pack system 100 further comprises of a coolant compartment 120, wherein the compartment 120 is coupled to the inlet-outlet pair 111 and 112.
[0045] Furthermore, heat pipes 150 are used for heat conduction between the battery cell 141 and the coolant through a thermally conductive and electrically insulative (TCEI) material 160. As shown in the figures, at least a portion of the heat pipes 150 is immersed inside the coolant compartment 120, such that coolant is in contact with the heat pipes 150. As used herein, a “heat pipe” is a closed container in which a continuing cycle of evaporation and condensation of a fluid takes place with the heat being given off at the condenser end and which is more effective in transferring heat than a metallic conductor. The heat pipes 150 shown for exemplary purpose in the embodiments are circular type of heat pipes. The heat pipes 150 are further in contact with the TCEI material 160. The TCEI material 160 thermally connects the heat pipes 150 to the battery cells 141. The TCEI material prevents any electrical contact of the battery cells 141 with the heat pipes 150 while allowing the heat to be conducted between the battery cells 141 and the heat pipes 150. The TCEI material may be silicone rubbers, thermal epoxies, thermal foam or other such materials known in the art.
[0046] Coolant having lower temperature than battery cell 141 temperature is supplied for cooling the battery cell 141. Herein, the TCEI material 160 absorbs the heat from the battery cells 141 and discharges it to the heat pipes 150, further the heat from the heat pipes 150 is taken away from the coolant at lower temperature inside the compartment 120. Similarly, when heating of the battery cell 141 is required, coolant having higher temperature than battery cell 141 is supplied. Herein, the TCEI material 160 discharges the heat to the battery cells 141 from the heat pipes 150, the heat pipes 150 are heated by the coolant at higher temperature.
[0047] In accordance to another exemplary configuration of the first embodiment, as illustrated in Fig.2(a), Fig.2(b) and Fig.2(c), multiple coolant compartments 120 are used and are connected

in series. The flow of coolant through the series of compartments 120 ensure increased surface area for heat transfer between the coolant and the heat pipes 150.
[0048] In accordance to another exemplary configuration of the first embodiment, as illustrated in Fig.3(a), Fig.3(b) and Fig.3(c), multiple coolant compartments 120 are used and are connected in parallel. The flow of coolant through the parallel compartments 120 ensure increased surface area for heat transfer between the coolant and the heat pipes 150.
[0049] The drawback of circulating the coolant in only one direction is a gradual increase in the coolant temperature as it goes from one compartment to the next, which leads to higher battery cell 141 temperature placed downstream with respect to the direction of coolant flow.
[0050] To counter the drawback of having unequal battery cell temperature, as stated in paragraph [0047], the coolant is circulated inside the battery pack system in a to and fro manner (may also be referred as “forward and backward manner”), in accordance with the second embodiment of the present invention. As illustrated in Fig.1(d), 111 acts as a coolant inlet for battery pack system 100, the coolant gets inside the compartment 120 and exits from the outlet 112. As illustrated in Fig.1(e), 112 acts as a coolant inlet for battery pack system 100, the coolant gets inside the compartment 120 and exits from the outlet 111. The time interval of the forward and backward motion of the coolant may be predetermined by a controller or manually set by an operator and may change according to conditions. The to and fro motion of the coolant ensures equal battery cell 141 temperatures throughout the battery pack system. Similarly, Fig. 2(d) and Fig. 2(e) illustrate the to and fro motion of the coolant in series of coolant compartments 120 and Fig. 3(d) and Fig. 3(e) illustrate the to and fro motion of the coolant in parallel coolant compartments 120.
[0051] The battery cell 141 may be arranged in different arrangements along with the heat pipe 150 and TCEI material 160. Moreover, the geometries of the heat pipe 150 may be of any possible shape. Moreover, TCEI material 160 may be attached on outer walls of the outer tubes 150 or outer walls of the battery cells 141. Also, TCEI 160 may be of any possible shape as long as it facilitates heat conduction between the battery cells 141 and the heat pipes 150.

[0052] As illustrated in Fig. 4(a), one arrangement of the battery cells 141 with heat pipe 150 and TCEI 160 is shown. The battery cells 141 are arranged in a triangular arrangement having a heat pipe 150 with TCEI material 160 on outer walls of heat pipe 150.
[0053] As illustrated in Fig. 4(b), another arrangement of the battery cells 141 with heat pipe 150 and TCEI 160 is shown. The battery cells 141 are arranged in a square arrangement having a heat pipe 150 with TCEI material 160 on outer walls of heat pipe 150. As illustrated in Fig. 4(d), yet another arrangement of the battery cells 141 with heat pipes 150 and TCEI material 160 is shown. The battery cells 141 are arranged in a square arrangement having a circular inner tube 151 and a circular outer tube 152 with TCEI material 160 on outer walls of the battery cell 141 is shown.
[0054] As illustrated in Fig. 4(c), another arrangement of the battery cells 141 with heat pipe 150 and TCEI 160 is shown. The battery cells 141 are arranged in a hexagonal arrangement having a heat pipe 150 with TCEI material 160 on outer walls of heat pipe 150.
[0055] In accordance with the third embodiment of the present invention, a thermal management system 500 is provided for the battery pack system as illustrated in Fig.5. The thermal management system 500 comprises of a battery pack system 570, a heater 572, a pump 573, a heat exchanger 574, a two-way valve 575, and a coolant reservoir 571. Piping connections and the coolant is not shown in the illustration.
[0056] The present disclosure does not intend to limit the type and quantity of components mentioned in paragraph [0042]. For example, the heat exchanger 574 may be either of an air cooled radiator, liquid to liquid heat exchanger, etc. Similarly, the pump 573, the valve 575, the heater 572, and the coolant reservoir 571 may be of different types. The coolant used may be of any type and either in liquid or gaseous state.
[0057] If multiple battery pack systems 570 are used, these battery pack systems 570 may be thermally connected in series or parallel. But connecting the battery pack systems 570 in parallel gives an advantage of having equal battery pack system temperatures. One or more pumps 573, heaters 572, heat exchangers 574, valves 575 and reservoirs 571 may be connected in any possible combination Moreover, the order of components may be different than illustrated.

[0058] The thermal management system 500 operates in accordance to the climate conditions. For example, if the outside temperature is higher than 40 degree Celsius, the battery cells inside the battery pack system 570 may be at higher temperature than the desired operating temperature. Thus, it becomes necessary to lower the battery cell temperature to a desired level before operation. The two-way valve 575 diverts the coolant flow through heat exchanger 574 and the heater 572 is switched off. Thus, heat from battery cell in the battery pack system 570 is absorbed by the coolant and is discharged to the heat exchanger 574. Once the desired operating temperature of the battery cells is achieved, the battery pack system 570 is allowed to operate and the coolant continues to flow through the heat exchanger 574 to dissipate heat generated from the operation of battery pack system 570. The flow rate of the pump 573 is adjusted to maintain the desired operating temperature of the battery pack system 570.
[0059] The switching and control operations of the two-way valve 575, the heater 572, or the pump
573 may be controlled by a controller or may be manually set by an operator.
[0060] For example, if the outside temperature is lower than 10 degree Celsius, the battery cell inside the battery pack system 570 may be at lower temperature than the desired operating temperature. Thus, it becomes necessary to raise the battery cell temperature to a desired level before operation. The two-way valve 575 diverts the coolant flow to bypass the heat exchanger
574 and the heater 572 is switched on. The heating of the battery cells is obtained. Once the
desired operating temperature is achieved, the heater 572 is switched off and the battery pack
system 570 is allowed to operate. Now, the two-way valve 575 diverts the coolant flow through
the heat exchanger 574 to dissipate heat generated from the operation of battery pack system
570. The flow rate of the pump 573 is adjusted to maintain the desired operating temperature
of the battery pack system 100.
[0061] As can be understood from the foregoing description, the present invention provides a battery pack system which can be assembled faster. Yet another advantage of the present invention is that lesser pressure drop is experienced in current invention due to shorter path of coolant through bigger cross section area, thus, the coolant pump operates at lower power levels in the battery pack system of the present disclosure as compared to the battery pack systems comprising coolant carrying tubes.

[0062] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

1. A battery pack system 100 comprising:
at least one battery module 140, comprising at least one battery cell 141; at least one supporting structure 142, configured for providing structural support to at least one battery cell 141;
an inlet 111 for coolant entrance into the battery pack system 100, the inlet 111 coupled to at least one coolant compartment 120, wherein the coolant compartment 120 is coupled an outlet 112 for coolant exit from the battery pack system 100; at least one heat pipe 150, the heat pipe 150 has some portion immersed in the coolant compartment 120, wherein the coolant is in contact with the heat pipe 150; a thermally conductive and electrically insulative (TCEI) material 160 configured to contact an outer wall of at least one heat pipe 150 and an outer wall of at least one of the battery cell 141;
wherein, the battery pack system 100 regulates the temperature of at least one battery cell 141 by circulating the coolant such that the TCEI material 160 transfers the heat between the one or more battery cells 141 and the coolant through the one or more heat pipes 150.
2. The battery pack system 100 as claimed in claim 1, wherein the battery cells 141 are arranged in a triangular, a rectangular, a pentagonal, a hexagonal, a heptagonal, a octagonal or a circular arrangement.
3. The battery pack system 100 as claimed in claim 1, wherein the battery cells 141 are arranged in a staggered or inline arrangement.
4. The battery pack system 100 as claimed in claim 1, wherein the battery modules 140 are arranged adjacent to each other.

5. The battery pack system 100 as claimed in claim 1, wherein the battery modules 140 are stacked upon one another.
6. The battery pack system 100 as claimed in claim 1, wherein the TCEI material 160 has more than one layers.
7. The battery pack system 100 as claimed in claim 1, wherein one or more heat pipes 150 are enclosed in at least one TCEI material 160.
8. The battery pack system 100 as claimed in claim 1, wherein the circulation of the coolant in the battery pack system is in one of a clockwise and anti-clockwise direction for a predetermined time period.
9. A thermal management system 500 for the temperature regulation of the battery pack system 100 as claimed in claim 1 comprising:
at least one battery pack system 570, wherein the battery pack system 570 is
operatively coupled to at least one heat exchanger 574;
a pump 573, the pump 573 is operatively coupled to a heater 572, the heater 572 is
operatively coupled to a reservoir 571, wherein the reservoir 571 is operatively
coupled to the battery pack system 570;
a coolant, wherein the coolant is used for heat transfer between the battery pack
system 570, the heater 572 and the heat exchanger 574, the coolant is filled into the
system 500 through the reservoir 571;
a two-way valve 575, the two-way valve 575 is operatively coupled to the heat
exchanger 574, wherein the two-way valve 575 is used for letting the coolant flow
through the heat exchanger 574 or bypassing the heat exchanger 574.