DESC:TECHNICAL FIELD
[0001] The present subject matter described herein generally relates to a battery pack for a vehicle. More specifically, the present disclosure relates to a retrofittable PCM pouring unit for pouring a phase change material (PCM) into the battery pack.
BACKGROUND
[0002] Typically, Lithium-ion battery pack is used as power source in electric vehicles and hybrid vehicles. The battery pack comprises of a plurality of cylindrical cells that are interconnected in series and parallel arrangement to meet current, voltage and capacity requirements. The charging and discharging of plurality of cells are being monitored and controlled by battery management system (BMS). The series and parallel interconnections of the plurality of cylindrical cells present various technical problems. Due to high current charging and discharging, there may be excess heat generation causing melting of components and imbalance among the plurality of cylindrical cells which may cause fire in battery pack. Since, Lithium is highly reactive component, Lithium ion is relatively unstable in nature that poses a safety challenge which requires for specialized handling and operational requirements.
[0003] In general, the battery pack generates significant amount of the heat during functioning, because of which the battery pack temperature can rise significantly. Eventually, the temperature can rise to a value where the battery pack can go into thermal runaway. A good battery pack design should be capable of preventing thermal runaway. The design can be applied to pouch or prismatic cell depending on other requirements like space, current, voltage, weight, cost, and the like.
[0004] Conventionally, to ensure thermal management for battery pack, thermal pads are used. Thermal Pad is a heat-dissipation pad used to control the heat generated in the battery pack. Generally, thermal pad is located between the battery module and a heat sink of outside of the battery pack. It transfers heat generated inside the battery pack to outside of the battery pack. With thermal pads, specialized substrates are provided separately for heat dissipation and insulation. Thermal pads are not advantageous for cylindrical cells as it does not give proper contacts between the plurality of cells. Further, the thermal pads require different layer thickness at different spaces. Hence, the serviceability and assembling of the battery pack is cumbersome. Furthermore, the maximum temperature withstanding capability of the thermal pads is low.
SUMMARY
[0005] The present invention relates to a battery pack comprising a retrofittable assembly for pouring a phase change material (PCM). The retrofittable assembly comprises a lid, a funnel, and a gasket. The lid is configured to hold the funnel. The lid is placed on a top cover of the battery pack with the gasket. The gasket is provided to avoid leakage of the PCM while pouring into the battery pack. The funnel is configured to be placed on a base of the battery pack. The base comprises a PCM filling port. The funnel is attached to the PCM filling port for providing flow of PCM through the funnel into the battery pack.

BRIEF DESCRIPTION OF DRAWINGS
[0006] The detailed description of the present subject matter is described with reference to the accompanying figures. Same reference signs are used throughout the drawings to reference like features and components.
[0007] Figure 1 illustrates a conventional battery pack in accordance with existing art.
[0008] Figure 2 illustrates an exploded view of a conventional battery pack, in accordance with existing art.
[0009] Figure 3 illustrates an exploded view of a conventional battery pack, in accordance with an existing art.
[00010] Figure 4 illustrates an exploded view of a battery pack, in accordance with an embodiment of the present subject matter.
[00011] Figure 5a and 5b illustrates a top view of battery pack, in accordance with an embodiment of the present subject matter.
[00012] Figure 6 illustrates a connection between a funnel and a PCM filling port, in accordance with an embodiment of the present subject matter.
[00013] Figure 7 illustrates a magnified view of the funnel, in accordance with an embodiment of the present subject matter.
[00014] Figure 8 illustrates a method of a attaching a retrofittable PCM pouring unit inside a battery pack, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION OF THE INVENTION
[00015] This invention relates generally to battery power supply and, more particularly, to thermal management in such battery power supply systems. The word “battery” here is meant to include various forms of electrochemical power generation which have chemical energy in common. The chemical energy is in the form of one or more chemical reactants stored in a confined space, which react with each other or with an external reactant in an electrochemical reaction, so as to produce electric power when desired.
[00016] Various uses of battery power supplies have been well established. For example, a plurality of cells are packaged together in a parallel or series configuration to form a battery module or pack for use as a power supply for personal electronic devices such as cell phones, laptop computers, camcorders or the like have become well-known and common. In addition, desirable properties or characteristics of battery power supplies including, for example, the capability of certain battery power supplies to be recharged, makes such battery power supplies potential power sources for vehicle propulsion like electric vehicles (EV). Recently, the concept as well as the application of battery power has been extended to include “fuel batteries” or “fuel cell batteries”, in which, a fuel cell reaction is used to generate electric power similar to conventional rechargeable battery, but in which, one of the reactants (the fuel) must be replenished from time to time.
[00017] In various such applications, it is common that a plurality of cells be packed together in a preselected configuration (e.g., in parallel or in series) to form a battery module. A plurality of such battery modules may, in turn, be combined or joined to form various battery packs as known in the art. During charging and discharging of plurality of cells in battery modules or battery packs, large amount of heat is generated which can significantly impact the performance resulting therefrom. Thus, in-order to maintain desired or optimal performance of plurality of cells or resulting battery modules or battery packs, it is important to maintain temperature of within the plurality of cells, battery module or battery packs within fairly narrow prescribed ranges.
[00018] In practice, temperature variations between individual cells can result from one or more of a variety of different factors including changes in ambient temperature, unequal impedance distribution among cells and differences in heat transfer efficiencies among cells.
[00019] Differences in heat transfer efficiencies among cells can typically primarily be attributed to the cell pack configuration. For example, cell elements at the centre of a cell pack configuration may tend to accumulate heat while those cell elements at the periphery of a cell pack configuration will generally tend to be more easily or freely cooled due to heat transfer to the surrounding environment. Further, such variation in heat transfer efficiencies may lead to further differences in impedance example amplification of capacity differences among the cells. Such capacity imbalances can cause or result in some cells being over-charged or over-discharged which in turn may result in premature failure of the cell pack or specific cell elements thereof. In particular, such failures may take the form of thermal runaway or accelerating capacity fading.
[00020] Thermal management systems based on the use of active cooling (e.g., forced circulation of air, liquid or other selected cooling medium) have been proposed for use in conjunction with such battery power supply systems. However, the incorporation and use of such active cooling regimes may introduce a level of complexity in either or both power supply design and operation such as may hinder or prevent the more widespread use of such power supplies.
[00021] Further, the required or desired size of a battery power supply is generally dependent on the specific application thereof. Thus, certain contemplated or envisioned applications for such power supplies, such as to power electric vehicles, for example, may necessitate the use of such power supplies which have or are of significantly larger physical dimensions that those commonly used or available. As will be appreciated by those skilled in the art, thermal management in power supply systems can become even more critical or significant as the size of such cell, battery module, or battery pack is increased.
[00022] Typically, the Lithium-ion battery construction consists of an outer metal casing and a plastic cell holder in which plurality of cells are placed. The battery pack generally consists of a plurality of cells. The plurality of cells are placed on cell holder. The plurality of cells in the plastic cell holder are placed apart at a typical distance of about 2mm. Further, the outer casing and plastic cell holder are placed apart with minimum of 1mm to 5mm air gap. Depending on the electrical requirement in the vehicle the number of cells in the battery pack may be increased or decreased.
[00023] The lithium-ion battery packs are equipped with battery management system (BMS) to prevent the malfunctioning caused inside the plurality of cells and to ensure that the series and parallel connected cells are operated in desired current, voltage and temperature range. However, in an unfortunate turn of events, when the BMS fails to protect the lithium-ion cells, the cells may undergo thermal runaway causing fire and explosion. Also, in the event of a single cell undergoing failure in a series-parallel arrangement of the plurality of cells, then such an event may lead to a cascading failure on other cells. The conventional battery construction is not equipped to protect from such failures.
[00024] The thermal management for Lithium-ion battery packs is important to avoid thermal runaway. The increased temperature inside the battery pack can cause safety issues and decreases the life of battery pack. To ensure effective thermal management for Lithium-ion battery packs, as per a known art, a Phase Change Material (PCM) is filled inside the battery pack in between the plurality of cells. The phase change material is liquid dispense gap filler material which is used to fill spaces between the plurality of cells, and the heat generated during the thermal runaway is absorbed using the heat absorbing property of the phase change process of the phase change material.
[00025] Generally, the battery pack designers try to use thermal pads or phase changing materials (PCM) to effectively control the temperature in the battery packs. Different PCMs available in the market are used to reduce the temperature rise in the battery pack during charging and discharging operations. However, using PCM in battery pack is more desirable than thermal pads because of the various benefits that PCM provides over thermal pads such as its lower cost. Further, PCM can flow into the microscopic surface roughness due to their liquid nature and better flow leads to lower thermal interfacial impedance at each surface. There is negligible air entrapment issue in PCM whereas in thermal pads, it is a frequent issue. A battery pack using a PCM material provides greater design freedom.
[00026] Generally, a very common issue faced by battery pack designers is while filling PCM in the battery pack, there is spillage in the surrounding areas and over the electrical components within the battery pack. The electrical components getting in touch with PCM may cause damage to electrical components in long run. Hence, the electrical components get degraded overtime due to spillage of PCM while filling it inside the battery pack. Further, filling up of entire battery pack with PCM may lead to increase in weight and cost of the battery pack. Hence, while designing battery, PCM should be provided in a way that it is capable of maintaining battery at desired optimum temperature range thus improving range and life of the battery pack.
[00027] In order to introduce PCM in the battery pack by avoiding above said problems there is a need of a separate assembly to ensure uniform filling and avoiding PCM getting in touch with Battery Management System (BMS) and PCB components of the battery pack. Further, there is a need and a demand for such power supply systems and methods of operation which desirably avoid the potential complications and complexities as mentioned above. Furthermore, there is a need and a demand for a well-designed thermal management system which can better ensure one or more of the performance, safety or capacity of an associated power supply.
[00028] In view of the above, it is an object of the present subject matter to provide an improved design of a battery pack which enables ease of service, is reliable, spillage free and safe for pouring of a phase change material (PCM) into a battery pack thereby protecting electrical components inside the battery pack from undesirable damage during any refurbishing. As per another object of the present invention, the solution needs to be retrofittable on a conventional battery pack for enabling ease of spillage free service of PCM. The PCM being disposed along a thermal pathway within the battery cell assembly that transfers the heat generated by the battery cell away from the battery cell during operation.
[00029] In the present invention, a battery pack includes a battery module, a battery cell assembly that is a component of the battery module, and a battery cell of the battery cell assembly comprising a plurality of battery cells. In an embodiment, each of the plurality of the battery cells is configured to generate heat during operation. The battery cell assembly further comprises a phase change material (PCM) disposed along a thermal pathway within the battery cell assembly that transfers the heat generated by each of the plurality of the battery cells away from the plurality of battery cells during operation. Further, the PCM is configured to absorb the heat generated by the plurality of battery cells to affect a phase change. The PCM material is expected to bring down the temperature considerably during battery operation and prevents thermal runaway due to its ability to hold more heat energy (high latent heat capacity material). The increases the operating temperature band of the battery pack thus improving safety and the range of the vehicle.
[00030] In an embodiment, a known quantity of Phase Change Material is preheated to a temperature where it is completely liquid. The quantity being dependent on the battery pack design which depends on the type of cells, number of cells and other design parameters. Based on the heat generation from the cells, the volume of the required PCM can be determined and accordingly reduced or increased. Then, the liquid PCM is poured into the battery pack through a retrofittable PCM pouring unit which is being provided on the battery pack which enables filling in the empty spaces between the cylindrical / pouch cells.
[00031] As per an aspect of present invention, the PCM pouring unit comprises a lid, a funnel, and a gasket and the PCM pouring unit being retrofittable on a conventional battery pack.
[00032] As per another aspect of present invention, the lid of PCM pouring unit being configured to hold a funnel.
[00033] As per yet another aspect of present invention, the lid being placed on a top cover of the battery pack with the gasket.
[00034] As per another aspect of present invention, the gasket being provided to avoid leakage of the PCM material while being poured into the battery pack.
[00035] As per yet another aspect of present invention, the funnel being configured to be placed on a base of the battery pack where the PCM filling port is available.
[00036] As per another aspect of present invention, the base comprises a PCM filling port. In an embodiment the funnel is attached to the PCM filling port and the funnel provides a directed flow of PCM through the funnel into the thermal pathway of the battery pack.
[00037] As per yet another aspect of present invention, the PCM is gradually filled through the funnel into the battery pack to prevent air bubble formation inside the battery pack.
[00038] As per an aspect of the present subject matter, the funnel is inclined at an obtuse angle to prevent the PCM getting chocked inside the funnel.
[00039] As per an aspect of the present subject matter, the PCM pouring unit is detachably attached to the battery pack.
[00040] As per an aspect of the present subject matter, PCM is a hydrocarbon material with a phase transition temperature in a range of 30°C to 70°C.
[00041] As per an aspect of the present subject matter, the lid is made up of metal and the base is made of plastic.
[00042] As per an aspect of the present subject matter, the PCM being preheated separately to a predetermined temperature before pouring PCM into the battery pack where a predetermined temperature being 5°C to 10°C greater than a phase transition temperature of the PCM but less than 85°C, the predetermined temperature range depends on the battery pack design.
[00043] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present subject matter will be made clearer from the following descriptions made with reference to the accompanying drawings.
[00044] Exemplary embodiments detailing features of the retrofittable PCM pouring unit for the battery pack and its construction, in accordance with the present subject matter will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present subject matter will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the present subject matter. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[00045] The present subject matter along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.
[00046] Figure 1 illustrates a conventional battery pack 100. Typically, a battery pack 100 comprises of a top cover 104, a bottom cover 107, an aluminium casing 106. The top cover 104 has a lid 103. In an embodiment, the metal that is used in the lid 103 is aluminium. A lid holder 102 is also provided in the top cover 104. The lid 103 is provided to pour the phase change material into the battery pack 100. The lid 103 is fastened to the top cover 104 with the help of fasteners. A safety valve 101 is also provided in the top cover 104.
[00047] Figure.2 illustrates an exploded view of a conventional battery pack 100 without the battery cell assembly 111. A battery pack 100 comprises of a top cover 104, interconnectors, interconnector dampers, with plastic cell holder 105, an aluminium casing 106, and a bottom cover 107.
[00048] Figure.3 illustrates an exploded view of a conventional battery pack 100. The top cover 104 is having a lid 103. A PCM filling port 108 is provided on the base member 109. The base member 109 also provides space to hold battery management system (BMS) (not labelled). Further, the base member 109 is also capable of holding a PCB 110. The PCB 110 is used to sense the temperature and voltage inside the battery pack 100. Further, a battery cell assembly 111 which includes the cell holder 105 capable of holding the plurality of battery cells, is also provided inside the aluminium casing 106. A bottom cover 107 is provided to seal the battery pack from the bottom. The battery pack has the lid 103 through which PCM 502 can be poured but it will cause spillage. The spillage of PCM 502 material may cause damage to the electrical components provided nearby inside the battery pack 100.As per the present invention shown in Figure 4 a three component retrofittable PCM pouring unit 411 is provided to enable gradually pouring of PCM inside the battery pack to avoid formation of air bubble and spillage of PCM on nearby electrical components inside the battery pack.
[00049] Figure.4 illustrates an exploded view of a battery pack 400 in the present exemplary embodiment. For ease of explanation, figure 4 and figure 7 are being discussed together. As per an embodiment, the battery pack 400 includes a battery module 409 which comprises of one or more of the battery cell assembly 111, interconnectors (not labelled) and dampers (not shown). The top cover 405 includes the retrofittable PCM pouring unit 411, the retrofittable PCM pouring unit 411 comprises of a lid 401 with a slot 402 to fluidically attach a funnel 404. In an embodiment, the lid 401 is made of aluminium. Hence, the current invention of three component retrofittable PCM pouring unit 411 is capable of avoiding spillage on the electrical components thereby avoiding undesirable contact with PCM 502. The retrofittable PCM pouring unit 411 has a lid 401 combined with gasket 403. Both the lid 401 and the gasket 403 are detachable attached to the slot 405’ provided for the lid 401 in the top cover 405. On the lid 401, a first end 404A of the funnel 404, having an engaging portion 4041, is attached and a second end 404B of the funnel 404 being inserted into a PCM filling port 406 of the plastic base 407 as shown in figure 6. Detailed drawings of the lid 401, gasket 403 and the funnel 404 being connected together is shown in figure 6. The funnel 404 is configured with an engaging portion 4041 having an opening to fluidically engage with the filling slot 402, the engaging portion 4041 is followed downstream by a first conduit portion 4042 extending at a first angle x (shown in Figure 7), said first angle x being with reference to an entry axis AA’ of the engaging portion 4041. As per an embodiment, the angle x can be 180 degrees implying first conduit portion 4042 being substantially parallel to the entry axis AA’. Further the funnel 404 is provided with a second conduit portion 4043 at the downstream side which is oriented at a second angle y (shown in Figure 7) with reference to the entry axis AA’. As per an aspect of the present invention, the second conduit portion 4043 makes an obtuse angle y with the entry axis AA’. Said obtuse angle y being greater than 90° enables smooth flow of the PCM 502 material while filling and avoids any undesirable choking in the funnel 404. As per an alternate embodiment, one or more of the engaging portion 4041, first conduit portion 4042 and the second conduit portion 4043 may be separately formed or integrally formed.
[00050] Figure.5a and 5b illustrates the top view of battery pack 400. The battery pack 400 comprises a plurality of cells 501 in the present exemplary embodiment. The plurality of cells 501 may be cylindrical or pouch cells. The gaps in between the cells 501 are filled with the PCM 502 material to absorb the heat generated in cells during battery operation. The known quantity of PCM 502 is preheated separately to a predetermined temperature. The pre-determined temperature being 5°C to 10°C greater than a phase transition temperature of the PCM but less than 85°C. The quantity of PCM 502 material being poured in the battery pack 400 depends on the battery pack design. The battery pack design further depends on type of cells and other design parameters. Based on heat generated from the cells 501, volume of the required PCM 502 inside the battery pack 400 may be determined and accordingly reduced or increased. Then, PCM 502 is poured into the battery pack 400 and is allowed to fill in the empty spaces between the cylindrical or pouch cells 501. The PCM 502 absorbs heat generated by cells 501 thus increasing the operating range of the battery pack 400. PCM 502does not allow the battery pack 400 to go beyond operating temperatures, thus improving safety in terms of drastically rise in temperature of the battery pack 400.
[00051] Due to lower temperature in the battery pack 400, PCM 502 naturally cools down and solidifies after filling the empty gaps in the pack. The typical duration of PCM 502 getting solidified is around 30 minutes to 1 hours at an ambient temperature between a range of 30 ?C to 35 ?C. The PCM 502 has high latent heat and hence absorbs the heat produced in the cells 501 during charging and discharging operation and thus PCM 502 material helps in bringing down the temperature considerably during battery operation, thus improving life and range of the pack 400.
[00052] Figure.6 illustrates the connection between the funnel 404 and the PCM filling port 406 in the present exemplary embodiment. The retrofittable PCM pouring unit 411 comprises the lid 401 combined with the gasket 403. The retrofittable PCM pouring unit 411is placed in the slot 405’provided in the top cover 405. The funnel 404 is inserted into the PCM filling port 406 of the plastic base 407. The PCM filling port 406 then directs the PCM 502 towards the thermal pathway inside the battery pack 400 where the PCM 502 is filled between the gaps inside the cell 501. The retrofittable PCM pouring unit 411 is detachably attached to the battery pack 400. This avoids the spillage of PCM on the electrical components placed nearby thereby enhancing reliability, safety and ease of service or replacement of the PCM 502. The gradual pouring of PCM also helps in avoiding the bubble formation inside the battery pack 400. This also helps in preventing the air entrapment problem inside the battery pack.
[00053] Figure.7 illustrates the magnified view of funnel 404 in the present exemplary embodiment. The funnel 404 is inclined at an obtuse angle to prevent the PCM getting choked inside the funnel 404. As per an embodiment, the angles x and y should be more than 90 degrees and less than 180 degrees.
[00054] Figure. 8 illustrates a method of attaching the retrofittable PCM pouring unit 411 in the battery pack 400. As per an embodiment of present invention, the retrofittable pouring unit 411 comprises of the lid 401, the gasket 403 and the funnel 404. The lid 401 is attached on the top cover 405 of the battery pack 400 with the help of an adhesive or fasteners (step 801). Further, the gasket 403 is provided between the lid 401 and the funnel 404, to prevent the leakage while pouring the PCM (step 802). Furthermore, attaching the funnel 404 of the retrofittable PCM pouring unit 411 to a PCM filling port 406 (step 803).
[00055] Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.
LIST OF REFERENCE NUMERALS

100: Battery Pack
101: Safety Valve
102: Holder
103: Lid
104: Top Cover
105: Cell holder
106: Outer casing
107: Bottom Cover
108: PCM filling port
109: Base member
110: PCB
111: Battery Cell Assembly
400: Battery pack
401: Lid
402: Slot to hold funnel
403: Gasket
404: Funnel
404A: First end
404B: Second end
4041: Engaging portion
4042: First conduit
4043: Second conduit
405: Top Cover
405’: Slot
406: PCM filling port
407: Base
408: PCB
409: Battery Module
410: Outer Casing
411: Retrofittable PCM pouring unit
501: Cell
502: PCM provided between gaps
,CLAIMS:I/We claim:

1. A battery pack 400 comprising:
a battery module 409, said battery module comprising one or more battery cell assembly 111, interconnectors and dampers,
said battery cell assembly 111 comprising a plurality of battery cells 501, and
a Phase Change Material (PCM) 502, said PCM 502 being capable of transferring heat generated by said plurality of battery cells 501 away from said plurality of battery cells 501 during operation,
wherein,
said battery pack 400 being configured with a retrofittable PCM pouring unit 411, said retrofittable PCM pouring unit 411 being enables spillage free and safe pouring of said PCM 502 into said battery module 409.

2. The battery pack 400 as claimed in claim 1,
wherein said retrofittable PCM pouring unit 411 comprises a lid 401, a funnel 404, and a gasket 403, said lid 401 being provided with a PCM filling slot 402.

3. The battery pack 400 as claimed in claim 2,
wherein said battery pack 400 including a top cover 405, said top cover 405 having a slot 405’,
said lid 401 being configured to hold said funnel 404,
said lid 401 being detachably attached along with said gasket 403 to said slot 405’,
said gasket 403 being provided to avoid leakage of said PCM during pouring.

4. The battery pack 400 as claimed in claim 3,
wherein a second end 404B of said funnel 404 being inserted to a PCM filling port 406,
said PCM filling port 406 being provided on a base member 407 of said battery pack 400.

5. The battery pack 400 as claimed in claim 2,
wherein said funnel 404 being configured with an engaging portion 4041 at a first end 404A,
said engaging portion 4041 having an entry axis AA’, a first conduit portion 4042 and a second conduit portion 4043,
said second conduit portion 4043 forming a second end 404B of said funnel 404.

6. The battery pack 400 as claimed in claim 5,
wherein said engaging portion 4041 having an opening to fluidically engage with said PCM filling slot 402,
said first conduit portion 4042 being provided downstream of said engaging portion 4041,
said first conduit portion 4042 extending at a first angle x,
said first angle x being taken with reference to said entry axis AA’ of said engaging portion 4041.

7. The battery pack 400 as claimed in claim 6,
wherein said angle x can be 180 degrees implying first conduit portion 4042 being substantially parallel to the entry axis AA’.

8. The battery pack 400 as claimed in claim 6,
wherein said second conduit portion 4043 being provided at a downstream side of said first conduit portion 4042,
said second conduit portion 4043 being oriented at a second angle y,
said second angle y being taken with reference to said entry axis AA’.

9. The battery pack 400 as claimed in claim 8,
wherein said second conduit portion 4043 making an obtuse angle y with said entry axis AA’.

10. The battery pack 400 as claimed in claim 5,
wherein said one or more of said engaging portion 4041,
said first conduit portion 4042 and said second conduit portion 4043 being formed separately or integrally.

11. The battery pack 400 as claimed in claim 1,
wherein said PCM being a hydrocarbon material with a phase transition temperature in a range of 30°C to 70°C.

12. The battery pack 400 as claimed in claim 2,
wherein said lid 401 being made up of one of a metal or a plastic.

13. The battery pack 400 as claimed in claim 1,
wherein said PCM being preheated separately to a predetermined temperature before pouring PCM into said battery pack 400,
wherein said predetermined temperature being 5°C to 10°C greater than a phase transition temperature of the PCM but less than 85°C.

14. A method for transferring a phase change material (PCM) in a battery pack 400, said method comprising steps of:
attaching a retrofittable PCM pouring unit 411 to a battery pack 400, said retrofittable PCM pouring unit 411 comprising a lid 401, a funnel 404, and a gasket 403, detachably attaching a lid 401 to a top cover of said battery pack 400,
detachably attaching a gasket 403 between said lid 401 and said funnel 404 to prevent leakage when pouring said PCM inside said battery pack 400,
inserting said funnel 404 into said PCM filling port 406 for smooth flow of the PCM through said funnel 404 into said battery pack 400, said PCM filing port 406 being provided on a base member 407 of said battery pack 400.

15. The method as claimed in claim 14,
wherein preheating of said PCM to a predetermined temperature being done before pouring PCM into said battery pack 400,
wherein said predetermined temperature being 5°C to 10°C greater than a phase transition temperature of the PCM but less than 85°C.

16. The method as claimed in claim 8,
wherein said PCM being a hydrocarbon material with a phase transition temperature in a range of 30°C to 70°C.