[0001] The present invention relates to power storage devices. In particular, the present invention relates to a multi-utility high capacity power storage device capable of catering to power requirement of various electrical devices.
BACKGROUND OF THE INVENTION
[0002] Lithium-ion batteries are preferred over other types of rechargeable batteries such as nickel-cadmium batteries and nickel metal-hydride batteries for portable electronics applications because of their light weight and high energy density. However, lithium-ion batteries are very sensitive to overcharging, and safety is a major concern with their use. Another safety concern is the venting of noxious fumes when the temperature of the battery cell becomes too high. Furthermore, in an over-discharge condition, voltage across a lithium-ion battery cell falls below an under-voltage limit, resulting in a change in the chemical composition of the electrolyte in the battery cell. Consequently, life of the battery cell may be significantly shortened. Therefore, it is important to have a battery management system that accurately monitors the lithium-ion batteries and ensures that they operate within their safe operating areas.
[0003] Power storage devices find application in fulfilling power requirement of electrical machineries/appliances. However, power input required by various electrical appliances can vary according to their specifications, thereby limiting the usage of power storage device that are capable of generating a single-port power output. Also, electrical equipments located in remote and/or inaccessible areas face harsh climate conditions and require a ruggedized source of power since such as are not connected to a reliable electrical grid and may face power outages for long durations. Thus, there is a need for multi-output and ruggedized power storage devices capable of sustaining harsh climate and extreme terrain conditions.

[0004] Efforts have been made in the past to develop devices that can provide a multi-output power supply. However, such devices are typically prone to breakdowns due to overheating and short-circuiting, and usually depend on a single source of energy, i.e., fossil fuel to cater power requirements of electrical devices.
[0005] There is therefore a need in the art to provide a ruggedized and high capacity power storage device capable of overcoming deficiencies of the conventional power storage devices by providing a means for catering to electrical devices having varying power requirements while at the same time ensuring safe and efficient supply of power to the electrical devices.
OBJECTS OF THE INVENTION
[0006] It is an obj ect of the present invention to provide a high capacity power storage device capable of supplying power output to electrical devices having varying power requirements.
[0007] It is another object of the present invention to provide a ruggedized power storage device capable of withstanding harsh climate conditions and rough terrains.
[0008] It is another object of the present invention to provide a highly reliable and efficient power storage device that ensures safe and efficient supply of power to the electrical devices.
SUMMARY OF THE INVENTION
[0009] An aspect of the present invention relates to a power storage device capable of supplying multi-port 5V DC, 12V DC, 24V DC and 220-230V AC power output to electrical devices, thereby meeting power requirement of a wide range of electrical devices. The power storage device includes a battery bank comprising a plurality of 24 V Lithium-ion battery cells with 50 Ah capacity, a control unit configured to monitor

current, voltage and temperature of the battery bank to regulate flow of current to and from the battery bank in case any of the current, the voltage and the temperature of the battery bank crosses a pre-defined threshold value, and an input-output interface adapted to supply multi-port DC and AC power output to one or more electrical appliances. The control unit is also adapted to control temperature of one or more components of the power storage device to regulate flow of current to and from the battery bank in case the temperature of any of the one or more components of the power storage device crosses a pre-defined threshold value.
[0010] According to an embodiment of the present invention, the input-output interface includes an input terminal adapted to receive any or a combination of solar power, fuel cell power, AC power supply and fossil fuel power as input power to charge the plurality of battery cells of the battery bank.
[0011] According to an embodiment of the present invention, the control unit includes a microcontroller in communication with a plurality of temperature sensors configured to detect temperature of the one or more components, and a fan adapted to regulate the temperature of the one or more components in case the temperature of any of the one or more components crosses the pre-defined threshold value.
[0012] According to an embodiment of the present invention, the control unit includes a set of Field Effect Transistors (FET) operatively connected to an FET driver to control flow of current through the input terminal of the input-output interface.
[0013] Another aspect of the present invention relates to a method for controlling charging and discharging of a plurality of battery cells of a power storage device. The method includes the steps of (i) receiving, from at least one external power source, power supply into an input terminal of an input-output interface of the power storage device, (ii) monitoring current, voltage and temperature of any or a combination of the plurality of battery cells and one or more components of the power storage device, (iii)

controlling charging and discharging of the plurality of battery cells in case any of current, voltage and temperature of any or a combination of the plurality of battery cells and one or more components crosses a pre-defined threshold value, and (iv) supplying multi-port DC and AC power output to one or more electrical appliances.
[0014] According to an embodiment of the present invention, the method further includes a step of controlling flow of current through the input terminal when the at least one external power source is connected to the input terminal.
[0015] According to an embodiment of the present invention, the method further includes a step of regulating temperature of any or a combination of the plurality of battery cells and the one or more components in case the temperature of any of the plurality of battery cells and the one or more components crosses the pre-defined threshold value.
[0016] According to an embodiment of the present invention, the one or more components are selected from a group consisting of a plurality of relays, at least one DC-to-DC converter and at least one DC-to-AC inverter.
[0017] According to an embodiment of the present invention, the at least one external power source is any or a combination of a solar power source, a fuel cell power source, an AC power supply and a fossil fuel power source.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

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[0019] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description 5 is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0020] Fig. 1 illustrates an exemplary schematic representation of various units/modules of a power storage device in accordance with an embodiment of the present invention;
10 [0021] Figs. 2A and 2B illustrate exemplary schematic representations of various units/modules involved in charging of a battery bank of the power storage device in accordance with an embodiment of the present invention;
[0022] Fig. 3 illustrates an exemplary schematic representation of battery management system of control unit of the power storage device in accordance with an 15 embodiment of the present invention;
[0023] Fig. 4 illustrates an exemplary representation of multi-port configuration of the power storage device in accordance with an embodiment of the present invention;
[0024] Fig. 5A illustrates an exemplary representation of circuit diagram of overheat protection and temperature control circuitry of the power storage device in accordance 20 with an embodiment of the present invention;
[0025] Fig. 5B illustrates an exemplary representation of circuit diagram of the power storage device in accordance with an embodiment of the present invention;

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[0026] Fig. 6 illustrates an exemplary representation of harness between input terminal of the power storage device and a solar array in accordance with an embodiment of the present invention;
[0027] Fig. 7 illustrates an exemplary representation of an enclosure of the power 5 storage device in accordance with an embodiment of the present invention; and
[0028] Fig. 8 illustrates an exemplary flowchart representation of a method for controlling charging and discharging of the battery bank of the power storage device in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
10 [0029] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0030] Exemplary embodiments will now be described more fully hereinafter with 15 reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements 20 herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future.
[0031] The present invention relates to a ruggedized power storage device capable of 25 supplying power output to electrical devices having varying power requirements, and

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withstanding harsh climate conditions and rough terrains. The power storage device has a high capacity of, say, 50 Ah and is highly reliable and efficient in terms of ensuring safe and efficient supply of power to the electrical devices.
[0032] Figs. 1, 2A and 2B illustrate exemplary schematic representations of various 5 units/modules of the power storage device (100). The power storage device (100) may include a high capacity battery bank (102) having a plurality of 24 V Lithium-ion battery cells. The battery bank (102) may have a capacity of 50 Ah to provide power output to multiple electrical appliances/machines having varying power requirements. The power storage device (100) includes a control unit (104) for regulating the flow of 10 current to and from the battery bank (102) in case any of current, voltage and temperature of the battery bank (102) or any other component of the power storage device (100) crosses a pre-defined threshold value. Further, the power storage device (100) includes an input-output interface including an input terminal (110) for receiving power input from various sources of electrical energy.
15 [0033] According to an embodiment of the present invention, the input terminal (110) may receive power input from any of a solar power source, a fuel cell power source, a fossil fuel power source and an AC power supply. According to an embodiment of the present invention, the input terminal (110) may receive power input from a combination of the solar power source, the fuel cell power source, the fossil fuel power
20 source and the AC power supply to enable charging of the battery bank (102).
[0034] According to an embodiment of the present invention, the input-output interface may include an output terminal (210) having multiple ports (210-1, 210-2, 210-3 and 210-4) for providing varying power output. For instance, the output terminal (210) may have four ports for supplying 5V DC, 12V DC, 24V DC, and 220-230V AC 25 power output to electrical devices. According to an embodiment of the present invention, the input-output control circuitry (214) may control power output from each

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of the ports of the output terminal (210) to provide a desired power output having specific power requirement.
[0035] According to an embodiment of the present invention, the control unit (104) may include an input-output control circuitry (214) including a set of Field Effect 5 Transistors (FET) operatively connected to an FET driver (302) (as clearly shown in Fig. 3) to control flow of current through the input terminal (110) of the input-output interface when an external power source is connected to the input terminal (110). According to an embodiment of the present invention, the external power source may be powered by any or a combination of solar power, fuel cell power, fossil fuel power 10 and AC power supply.
[0036] According to an embodiment of the present invention, a Maximum Power Point Tracking (MPPT) (112) charge controller may be embedded to provide optimized solar power to charge the battery. The MPPT (112) may be configured to continuously check status of solar availability and track the maximum point for production of voltage 15 and current to provide maximum power.
[0037] According to an embodiment of the present invention, the control unit (104) may further include a battery level GUI converter (204) for displaying instantaneous capacity of the battery bank (102). Further, the control unit (104) may include a power interface unit (202) for interfacing communication between various modules/units of 20 the control unit (104). The power interface unit (202) may interface the BMS (106) to the DC-DC/DC-AC converters (206, 208), the MPPT (112) and the battery level GUI indicator (204).
[0038] According to an embodiment of the present invention, the control unit (104)
may include a battery management system (BMS (106)) for controlling charging and
25 discharging of the plurality of battery cells of the battery bank (102) by regulating the
flow of current to and from the battery bank (102). According to an embodiment of the

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present invention, the BMS (106) continuously monitors charging current, voltage and temperature of the battery bank (102), and restricts/stops the flow of current to and from the battery bank (102) in case any of the charging current, voltage and temperature of the battery bank (102) exceeds or falls below a pre-defined threshold value. Thus, 5 the BMS (106) protects the battery bank (102) from adverse conditions such as over¬charging or short-circuiting during the charging process.
[0039] According to an embodiment of the present invention, the control unit (104) may further include a safety control unit (108) to facilitate regulation of flow of current by the BMS (106) to control charging and discharging of the plurality of battery cells 10 of the battery bank (102). The safety control unit (108) may include an overheat protection and temperature control circuitry (212) for protecting one or more components of the power storage device (100) from overheating.
[0040] According to an embodiment of the present invention, the overheat protection and temperature control circuitry (212) may include a microcontroller (502) (as shown 15 in Fig. 5) in communication with a plurality of current and temperature sensors (304) (as shown in Fig. 3), each positioned at pre-determined positions inside an enclosure (702) (as shown in Fig. 7) of the power storage device (100). The temperature sensors (304) may detect temperature variation of various components of the power storage device (100) such as, but not limited to, the battery bank (102), relays/switches, DC-20 to-DC converters (206-1, 206-2), DC-to-AC converters (208), Field Effect Transistors (FET), and the likes. The current sensors may detect the amperage of current flowing across various terminals and components. The microcontroller (502) can trigger a signal indicating overheating of one or more components of the power storage device (100) in case temperature of any of the components exceeds or falls below a pre-25 defined threshold value. The overheat protection and temperature control circuitry (212) can stop the flow of current to and from the battery bank (102) based on

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triggering of the signal indicating overheating of one or more components of the power storage device (100) by the microcontroller (502).
[0041] According to an embodiment of the present invention, the overheat protection and temperature control circuitry (212) of the safety control unit (108) may include a 5 fan (504) (as shown in Fig. 5) to regulate the temperature of the one or more components in case the temperature of any of the one or more components crosses the pre-defined threshold value.
[0042] As shown in Fig. 2B, the input terminal (110) and the output terminal (210) may be accommodated/housed within a power distribution box (216). In an
10 embodiment, the power storage device (100) may include a power distribution circuit (218) for controlling the distribution of electrical power to the DC-DC converters, DC-AC converters and output ports of the output terminal (210). A plurality of temperature sensors (304) may be appropriately positioned to detect change in temperature of battery (102), the enclosure (702), and the output ports of the output terminal (210).
15 For instance, as shown in Fig. 2B, sensor 304-1 may detect temperature of the 24 V DC regulator (24V DC to 24V DC converter), sensor 304-2 may detect temperature of the DC-DC converter, sensor 304-3 may detect temperature of the DC-AC inverter, sensor 304-4 may detect internal temperature of the enclosure (702) and sensor 304-5 may detect temperature of the battery (102).
20 [0043] According to an embodiment of the present invention, the power distribution circuit (218) may detect status of the battery (102), and may display the battery health status on a display (220) in communication with the power distribution circuit (218). The MPPT (112) may match between the solar array and the battery (102) to efficiently convert a higher voltage DC output from solar panels down to the lower voltage needed
25 to charge the battery (102).

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[0044] Fig. 3 illustrates an exemplary schematic representation of battery management system of control unit (104) of the power storage device (100). According to an embodiment of the present invention, the BMS (106) continuously monitor current and voltage parameters of the battery bank (102) such that when any external 5 power source gets connected with the PACK+ and PACK- terminal of the BMS (106), the coupled FETs array (J1, J2, J3) control the charging current flowing from the external power source to the battery bank (102). Current conductivity of the FETs may be controlled through an FET driver (302) which is further controlled by a self-inbuilt controller unit (MCU). According to an embodiment of the present invention, the MCU 10 continuously monitors voltage state of the battery bank (102) and accordingly sends Pulse Width Modulation (PWM) signal to the FET driver (302) to control the charging current of the battery bank (102).
[0045] According to an embodiment of the present invention, the MCU sends a stop signal to the FET driver (302) in case any of the current and voltage parameters of the
15 battery bank (102) crosses the pre-defined threshold limit to enable the FETs to stop the charging current to the battery bank (102). For instance, if temperature of the battery bank (102) exceeds above +70˚ C or below -10˚C, the MCU can send the stop signal to the FET driver (302) to stop flow of the charging current into the battery bank (102). Also, in case when the current flowing into the battery bank (102) exceeds 100A, the
20 MCU can send the stop signal to the FET driver (302) to stop flow of the charging current into the battery bank (102). In another instance, if voltage of a battery cell of the battery bank (102) gets out of range from a prescribed threshold value, the MCU can send the stop signal to the FET driver (302) to stop flow of the charging or discharging current.
25 [0046] Referring now to Fig. 4, where an exemplary schematic representation of multi-port configuration of the power storage device (100) is illustrated, the electrical

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power stored in the battery bank (102) can be utilized to operates electrical devices operating in 24V DC/12V DC/ 5V DC voltage level and 230V AC level.
[0047] According to an embodiment of the present invention, the control unit (104) may include DC-to-DC converters (206-1, 206-2) as well as DC-to-AC converters 5 (208) to facilitate the BMS (106) in generating multi-port power supply having varying voltage ratings. The BMS (106) and the safety control unit (108) protect the battery bank (102) from over-charging, deep-discharging, short-circuit and overheating by continuous monitoring the voltage, current and temperature of the battery bank (102). Apart from this, the safety control unit (108) can also monitor the temperature of the 10 DC-to-DC converters (206-1, 206-2) and DC-to-AC inverters (208) to prevent these components from overheating, thereby providing controlled multi-port output having varying voltage ratings, i.e., 5V DC, 24V DC, 12VDC, 230V AC.
[0048] Figs. 5A and 5B illustrates an exemplary representation of circuit diagram of the overheat protection and temperature control circuitry (212) and the power storage
15 device (100). According to an embodiment of the present invention, the FET driver (302) drives current from the battery bank (102) to the overheat protection and temperature control circuitry (212) through the Pack+ and Pack- terminal if the current, voltage and temperature parameters of the battery bank (102) are in the prescribed range. The overheat protection and temperature control circuitry (212) continuously
20 monitors temperature of components of the power storage device (100) for instance, the DC-to-DC converters (206-1, 206-2) and DC-to-AC inverters (208), and ambient temperature inside the enclosure (702) of the power storage device (100) such that if the temperature of any of the components falls below -10˚C, the microcontroller (502) stops flow of current from the battery bank (102), thereby switch OFF the discharging
25 process, and if ambient temperature of the enclosure (702) exceeds 60˚C, relay U1 get switch OFF and the fan (504) automatically starts to lower the temperature of the

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overheated component. This process continues till temperature of the enclosure (702) falls back to the ambient temperature.
[0049] According to an embodiment of the present invention, the overheat protection and temperature control circuitry (212) monitors temperature of the 12V DC-DC 5 converter (206-1) such that if its temperature is in the range of -10˚C to 60˚C, the relays U1 and U2 work normally as NC modes so that the 12V DC-DC converter (206-1) is powered ON, otherwise in case temperature of the 12V DC-DC converter (206-1) falls out of the prescribed range, the 12V DC-DC converter (206-1) is switched OFF by the microcontroller (502). The overheat protection and temperature control circuitry (212) 10 may also monitor temperature of the 5V DC-DC (206-2) converter such that if its temperature is in the range of -10˚C to 60˚C, the relay U1 and U2 work normally as NC modes so that the 5V DC-DC converter (206-2) is powered ON, otherwise if temperature of the 5V DC-DC converter (206-2) falls out of the prescribed range, the 5V DC-DC converter (206-2) is switched OFF by the microcontroller (502).
15 [0050] According to an embodiment of the present invention, the overheat protection and temperature control circuitry (212) monitors temperature of the 230V DC-AC inverter (208) such that if its temperature is in the range of -10˚C to 60˚C, the relays U1 and U2 work normally as NC modes so that the 230V DC-AC inverter (208) is powered ON, otherwise in case temperature of the 230V DC-AC inverter (208) falls
20 out of the prescribed range, the it is switched OFF by the microcontroller (502). Thus, the power output available at the multi-port output terminal (210) of the power storage device (100) is any or a combination of 24V DC, 12V DC, 5V DC, and 230V AC. This power output can be utilized either individually or simultaneously with the help of switch S1, S2, S3, and S4 dedicated to each port of the output terminal (210).
25 [0051] Referring to Fig. 6, where harness between input terminal (110) of the power storage device (100) and a solar array (602) is shown, a solar connector (604) connected to the solar array (602) may be adapted to operatively connect with a connector (606)

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in communication with 24V DC port of the input terminal (110) of the power storage device (100). The 24V DC port of the input terminal (110) may also be adapted to receive electrical power from a fuel cell, thereby allowing the power storage device (100) to receive both solar power as well as fuel cell power. In an embodiment, the 5 24V DC port of the input terminal (110) is a 6Pin-15A-Mil port.
[0052] Fig. 7 illustrates an exemplary representation of an enclosure (702) of the power storage device (100). According to an embodiment of the present invention, the enclosure (702) may be made up of Acrylonitrile butadiene styrene (ABS plastic) which makes the enclosure (702) lightweight, ruggedized and robust with an ability to
10 operate in harsh climate conditions, such as hilly areas and sub-zero temperatures. The enclosure (702) may be treated with a heat reflective coating on its outer surface to enhance its temperature tolerance. The enclosure (702) may include military grade cables and connectors for connecting various components. The input-output interface of the power storage device (100) provides a plug and play interface for improving
15 comfortability of a user.
[0053] The ruggedized and robust nature of the proposed power storage device (100) makes it suitable for applications which require high portability and mobility, such as military expeditions, long range patrols, and isolated communication applications.
[0054] Fig. 8 illustrates an exemplary flowchart representation of a method (800) for 20 controlling charging and discharging of the battery bank (102) of the power storage device (100) in accordance with an embodiment of the present invention. The method (800) includes at step (802), receiving, from at least one external power source, power supply into an input terminal (110) of an input-output interface of the power storage device (100), at step (804), monitoring current, voltage and temperature of any or a 25 combination of the plurality of battery cells and one or more components of the power storage device (100), at step (806), controlling charging and discharging of the plurality of battery cells in case any of current, voltage and temperature of any or a combination

of the plurality of battery cells and one or more components crosses a pre-defined threshold value, and at step (808) supplying multi-port 5V-24V DC and 220-230V AC power output to one or more electrical appliances.
[0055] According to an embodiment of the present invention, the method (800) may further include the steps of controlling flow of current through the input terminal (110) when the at least one external power source is connected to the input terminal (110), and regulating temperature of any or a combination of the plurality of battery cells and the one or more components in case the temperature of any of the plurality of battery cells and the one or more components crosses the pre-defined threshold value.
[0056] Various modifications to these embodiments are apparent to those skilled in the art from the description and drawings herein. The principles associated with the various embodiment defined herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be provided broadest scope consistent with the principles and novel and inventive features describe/disclosed or suggested herein. Any modifications, equivalent substitutions, improvements etc. within the principle of the present invention shall all be included in the scope of protection of the present invention.

We Claim:

A power storage device (100) comprising:
a high capacity battery bank (102) comprising a plurality of Lithium-ion battery cells;
a control unit (104) configured to monitor current, voltage and temperature of the battery bank (102) to regulate flow of current to and from the battery bank (102) in case any of the current, the voltage and the temperature of the battery bank (102) crosses a pre-defined threshold value; and
an input-output interface adapted to supply multi-port DC and AC power output to one or more electrical appliances,
wherein the control unit (104) is adapted to control temperature of one or more components of the power storage device (100) to regulate flow of current to and from the battery bank (102) in case the temperature of any of the one or more components of the power storage device (100) crosses a pre-defined threshold value.
2. The power storage device (100) as claimed in claim 1, wherein the input-output interface comprises an input terminal (110) adapted to receive any or a combination of solar power, fuel cell power, AC power supply and fossil fuel power as input power to charge the plurality of battery cells of the battery bank (102).
3. The power storage device (100) as claimed in claim 1, wherein the one or more components are selected from a group consisting of a plurality of relays, at least one DC-to-DC converter (206-1, 206-2) and at least one DC-to-AC inverter (208).
4. The power storage device (100) as claimed in claim 1, wherein the control unit (104) comprises a microcontroller (502) in communication with a plurality of temperature sensors (304) configured to detect temperature of the one or more

components, and a fan (504) adapted to regulate the temperature of the one or more components in case the temperature of any of the one or more components crosses the pre-defined threshold value.
5. The power storage device (100) as claimed in claim 1, wherein the control unit (104) comprises a set of Field Effect Transistors (FET) operatively connected to an FET driver (302) to control flow of current through the input terminal (110) of the input-output interface.
6. A method for controlling charging and discharging of a plurality of battery cells of a power storage device (100), the method comprising the steps of:
receiving, from at least one external power source, power supply into an input terminal (110) of an input-output interface of the power storage device (100);
monitoring current, voltage and temperature of any or a combination of the plurality of battery cells and one or more components of the power storage device (100);
controlling charging and discharging of the plurality of battery cells in case any of current, voltage and temperature of any or a combination of the plurality of battery cells and one or more components crosses a pre-defined threshold value; and
supplying multi-port DC and AC power output to one or more electrical appliances.
7. The method as claimed in claim 6, further comprising a step of controlling flow of current through the input terminal (110) when the at least one external power source is connected to the input terminal (110).
8. The method as claimed in claim 6, further comprising a step of regulating temperature of any or a combination of the plurality of battery cells and the one or more

components in case the temperature of any of the plurality of battery cells and the one or more components crosses the pre-defined threshold value.
9. The method as claimed in claim 6, wherein the one or more components are selected from a group consisting of a plurality of relays, at least one DC-to-DC converter (206-1, 206-2) and at least one DC-to-AC inverter (208).
10. The method as claimed in claim 6, wherein the at least one external power source is any or a combination of a solar power source, a fuel cell power source, an AC power supply and a fossil fuel power source.