Description:A. TECHNICAL FIELD OF THE INVENTION
[001] The present invention relates to the field of electric vehicle (EV) technology and retrofitting systems. More specifically, the invention pertains to a modular retrofit kit for converting conventional internal combustion engine (ICE) two-wheelers into fully electric two-wheelers, and for upgrading existing electric two-wheelers, without structural modifications to the original vehicle frame.

B. BACKGROUND
[002] With the growing demand for sustainable and environmentally friendly modes of transportation, there is a global shift toward electric mobility. A significant portion of the vehicle population, especially in developing countries like India, comprises two-wheelers powered by internal combustion engines (ICE). Retrofitting such vehicles with electric powertrains offers a cost-effective and scalable approach to reduce vehicular emissions and promote clean mobility.
[003] Various retrofit solutions for ICE two-wheelers have been proposed in the prior art. However, most of these existing systems suffer from limitations that hinder their widespread adoption. For instance, several known solutions require invasive structural modifications to the vehicle chassis, such as welding, cutting, or drilling. These methods compromise the structural integrity and safety of the vehicle, and also limit standardization across different models. Examples include the conversion kits disclosed in Patent numbers 202121030969, 201921043415, and 202241010868, which describe methods for converting petrol-powered two-wheelers into electric vehicles but fail to provide a truly modular or non-invasive architecture. The installation processes in these systems are often time-consuming and model-specific, which restricts scalability and ease of deployment.
[004] Some inventions, such as those disclosed in Patent numbers 202141018487 and 201741042314, propose retrofittable electric hub motor kits for rear or front wheels. While these designs simplify drive integration, they often interfere with the Original Equipment Manufacturer (OEM) suspension geometry, introduce weight imbalance, or affect vehicle dynamics and safety. Moreover, they typically lack accommodation for existing utility features such as under-seat storage or accessory space.
[005] Other prior art documents, like Patent numbers 202111055463 and 202331057289, focus on specialized or hybrid retrofit kits, including tri-cycles or dual-powered vehicles. These solutions are either limited to specific vehicle formats or introduce mechanical complexity that makes them unsuitable for standard two-wheeler applications. Additionally, software-based systems such as the one disclosed in Patent No. 202311019374 concentrate on optimizing vehicle parameters post-retrofit but do not offer a comprehensive physical retrofit solution with modular hardware.
[006] While Patent No. 202317038509 discusses a general-purpose two-wheeler retrofit kit, it lacks detailed provisions for structural modularity, preservation of OEM vehicle features, or plug-and-play subsystem integration, making it difficult to implement across diverse vehicle platforms in a cost-effective and user-friendly manner.
[007] In view of the aforementioned limitations in the existing art, there remains a pressing need for a retrofit solution that enables the conversion of ICE two-wheelers into electric vehicles without requiring structural modifications to the chassis. The market demands a truly modular, non-invasive, and plug-and-play system that can be easily adapted to a wide range of two-wheeler models without compromising safety, reliability, or utility. Additionally, existing kits often overlook user-centric features such as maintaining under-seat storage, standardizing component placement, and allowing for easy maintenance or future upgrades. These gaps highlight the necessity for a retrofit approach that is not only technically sound and scalable but also practical for real-world deployment, particularly in cost-sensitive and infrastructure-constrained environments such as those.

C. OBJECTIVE OF THE INVENTION
[008] A principal objective of the present invention is to provide a modular retrofit kit for converting ICE-powered two-wheelers into electric two-wheelers.
[009] Another objective of the invention is to ensure that the retrofit kit can be installed without requiring structural modifications such as cutting, welding, or drilling of the existing chassis.
[010] Another objective of the invention is to upgrade the existing electric two-wheelers into superior electric two-wheelers.
[011] A further objective of the invention is to provide a plug-and-play system using Original Equipment Manufacturer (OEM) - compatible mounting points and standardized electrical connectors.
[012] Yet another objective of the present invention is to allow independent upgradation, replacement, or servicing of one or more subsystems such as the motor, battery, or controller.
[013] A still further objective is to preserve the original utility space (e.g., under-seat storage, boot space) and exterior aesthetics of the vehicle.
[014] Another objective of the invention is to offer a scalable architecture compatible across different two-wheeler makes and models.
[015] It is also an objective of the invention to provide the conversion kit which is cost effective.
[016] The objectives of the present invention are centered on advancing modular retrofit technologies through the development of a scalable, interoperable system capable of converting internal combustion engine (ICE) two-wheelers to electric powertrains, as well as upgrading existing electric two-wheelers. Key objectives include enabling seamless integration with diverse vehicle architectures, enhancing user accessibility through simplified installation and maintenance, and broadening the applicability of the system across varied use cases and operational environments. The invention seeks to overcome limitations of existing retrofit solutions by delivering a technically robust, adaptable, and future-ready platform.
[017] These and other objectives and advantages of the embodiments herein will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D. SUMMARY OF THE INVENTION
[018] The present invention relates to the field of electric vehicle technology, and more particularly to a modular retrofit kit for converting internal combustion engine (ICE) two-wheelers into electric vehicles or upgrading existing electric two-wheelers. At the core of the invention is a plug-and-play architecture that eliminates the need for structural modifications to the original chassis, thereby simplifying installation and ensuring compatibility across a wide range of two-wheeler models. The system integrates multiple modular subsystems—including a structural mounting frame, battery housing system, swing arm assembly, controller unit, and retains the under-seat storage space—all designed to function cohesively. By leveraging state-of-the-art technologies, the invention enhances safety, efficiency, and operational autonomy. Furthermore, the system is designed to be cost-efficient and scalable, making it widely accessible without compromising on performance, reliability, or regulatory compliance.
[019] The modular retrofit kit comprises:
[020] A structural mounting frame designed for secure and adaptable integration onto a wide range of two-wheeler chassis types by utilizing existing engine mount points, thereby eliminating the need for structural modifications;
[021] A modular battery housing system with an adaptable base plate and one or more battery modules of varying sizes and energy capacities;
[022] The said modular battery housing system is secured using quick-release U-shaped clamps, facilitating ease of maintenance and battery swapping;
[023] A swing arm assembly configured to house a high-torque in-wheel electric motor while maintaining compatibility with the OEM suspension geometry, thereby ensuring optimal ride stability and seamless integration of the electric drive system;
[024] A controller assembly unit, positioned at the original fuel tank location, comprising a motor controller, DC-DC converter, and an active cooling system, configured to manage power delivery, regulate system operation, and ensure thermal stability during vehicle use;
[025] A universal wiring harness enabling tool-less interconnection of components with standardized connectors.
[026] An under-seat storage space, thereby maximizing space utilization and functionality.
[027] A method for retrofitting ICE two-wheelers using the modular kit is also disclosed, requiring only standard tools and minimal mechanical intervention. The installation of the modular retrofit kit involves:
[028] Securely affixing the structural mounting frame onto the existing chassis of the two-wheeler without requiring any welding, cutting, or irreversible modifications.
[029] The battery housing system, comprising the adaptable base plate and modular battery units, is mounted onto the structural frame using quick-release clamps, allowing for tool-less battery replacement and maintenance.
[030] The swing arm assembly, integrated with the electric motor and drivetrain components, is attached in place of or in conjunction with the existing rear wheel assembly.
[031] The controller assembly unit is electrically connected to the battery modules and the motor to regulate power flow, manage regenerative braking, and facilitate system diagnostics.
[032] Additionally, the system provides a dedicated under-seat storage space to house auxiliary electronics or user storage needs.
[033] Once installed, the kit enables seamless electric operation of the vehicle with features such as regenerative braking, remote diagnostics, and modular component replacement, thereby ensuring user-friendly operation, maintainability, and upgrade potential.
[034] The invention enables the modular and independent replacement, servicing, or upgradation of its subsystems. It preserves vehicle utility space and aesthetics and supports standardization across different vehicle platforms.
[035] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating the preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

E. BRIEF DESCRIPTION OF DRAWINGS
[036] The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings in which:
[037] FIG. 1 illustrates a perspective view of the modular retrofit kit (100) installed on a two-wheeler chassis (500), showing the overall placement of the modular subsystems including the structural mounting frame (200), swing arm assembly (300), controller assembly unit (400), and an under-seat storage space (600), according to an embodiment of the present invention.
[038] FIG. 2A illustrates a side view of the modular retrofit kit (100) showing the overall placement of the modular subsystems including the structural mounting frame (200), swing arm assembly (300), controller assembly unit (400), without the under-seat storage space (600) and without the vehicle chassis (500), according to an embodiment of the present invention.
[039] FIG. 2B depicts a detailed view of the structural mounting frame (200) including the modular battery housing system (201), adaptable battery base plate (202) and one or more battery modules (203) secured using quick-release U-shaped clamps (207, 208a, 208b) and under-seat storage space (600) according to an embodiment of the present invention; It illustrates an upward perspective view of the structural mounting frame (200), indicating the airflow path for passive thermal dissipation and the integration with the swing arm mounting interface (301) according to an embodiment of the present invention;
[040] FIG. 3A illustrates the structural mounting frame (200) designed to attach to the existing ICE engine mounting points of the chassis (500) without any structural modifications such as cutting, welding, or drilling according to an embodiment of the present invention;
[041] FIG. 3B presents an exploded view of the said structural mounting frame (200) and battery housing system (201), highlighting modular assembly according to an embodiment of the present invention;
[042] FIG. 4A displays the swing arm assembly (300) with the integrated in-wheel electric motor (303), inner fender mounting slots (308a, 308b), and the shock absorber mounting provision (302), according to an embodiment of the present invention;
[043] FIG. 4B provides a rear perspective view of the swing arm (301), emphasizing OEM-compatible suspension geometry and provisions for mudguard or accessory attachments (308a, 308b), according to an embodiment of the present invention;
[044] FIG. 5A shows the controller assembly unit (400) mounted at the original fuel tank position, comprising the base plate (401), controller (403), DC-DC converter (404), and Charging Connector Mounting Plate (402), according to an embodiment of the present invention;
[045] FIG. 5B illustrates the wiring integration of the controller unit (400) with the modular wiring harness, showing plug-and-play connector configurations for the motor (303), battery (203), and converter (404), and an active cooling fan (405), according to an embodiment of the present invention;
[046] FIG. 6 is a flowchart that demonstrates the full system integration layout of the modular retrofit kit (100), with all major components assembled and interconnected on a standard two-wheeler platform, retaining the under-seat storage compartment and preserving chassis symmetry according to an embodiment of the present invention.

[047] REFERENCE NUMERALS FOR DRAWINGS
100: Modular Retrofit Kit
200 : Structural Mounting Frame
201: Modular battery housing system
202 : Adaptable Battery Base Plate
203 : Battery Pack
204 (a) & (b) : Battery Base Connecting rods (Supporting rods)
205 (a) & (b) : Connecting rods mounting / mounting clamp for support rods / connecting rods
206 (a), (b), (c) & (d): U bolt clamp for supporting / connecting rods
207 : U shaped clamp for Battery locking
208 (a) & (b) : Left and Right Mountings for U shaped clamp to secure the battery pack
209 : Battery Pack Handle (for easy removing of battery for service)
300 : Swing Arm Assembly Unit
301 : Swing Arm Frame (Swing Arm)
302 : Shock Absorber Mounting
303 : High Torque In-Wheel Electric Motor
304 : Shock Absorber
305 a & b, 306 a & b: Left and Right Mountings for Swing Arm Cover
307 : Swing Arm Support bar
308 a & b : Left and Right Mountings for Mud guard
400 : Controller and Electronics Assembly unit
401: Controller Base Plate (Has the mountings to hold the controller, cooling fan and other components such as DC-DC Converter)
402 : Charging Connector Mounting Plate
403 : Controller
404 : DC-DC Converter
405 : Cooling Fan
500 : Chassis of the existing Two-Wheeler
600: Storage space

F. DETAILED DESCRIPTION OF THE INVENTION
[048] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced are shown by way of illustration. The embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical, electronic, and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[049] As used in this specification, the singular forms “a” and “an” shall be construed to include “at least one” unless the context clearly indicates otherwise. The term “plurality” shall be interpreted to mean “one or more.” Furthermore, terms such as “comprising,” “including,” “having,” “containing,” and “involving,” and their grammatical variations, are intended to be open-ended and non-limiting. These terms are meant to include the listed elements as well as their equivalents and other unlisted elements, whether or not expressly stated.
[050] It is to be understood that the terms used herein are for descriptive purposes only and are not intended to limit the scope of the invention in any manner.
[051] Any references to background documents, materials, systems, methods, or known practices are intended solely to provide contextual understanding and should not be construed as an admission that such references constitute prior art or form part of the common general knowledge in the field relevant to the present invention under the Indian Patents Act, 1970.
[052] The embodiments described herein are exemplary and are not intended to limit the scope of the invention as claimed. Numerical values and ranges mentioned are for illustrative purposes only and do not restrict the scope of the claims, which shall be interpreted in accordance with the broadest reasonable construction under the applicable provisions of Indian patent law.
[053] The present invention with its various embodiments, pertains to a system and a method for a compact, modular retrofit kit (100) designed to convert an internal combustion engine (ICE) two-wheeler into a fully electric two-wheeler, or to upgrade an existing electric two-wheeler. The kit comprises a pre-assembled electric powertrain package—typically including a motor, battery, and controller—engineered for compatibility with the existing vehicle chassis and engine mounting points, thereby eliminating the need for structural modifications such as cutting, welding, or drilling.
[054] The present invention leverages modular design principles, advanced powertrain integration techniques, and intelligent control systems, including innovations in battery management systems (BMS), motor controller interfaces, and vehicle telematics, to ensure seamless conversion, improved performance, and enhanced diagnostic capabilities, while preserving the integrity, safety, and aesthetics of the original vehicle.
[055] The present invention offers a cost-effective and practical alternative to purchasing a new electric vehicle by enabling the reuse of the original vehicle structure. Unlike conventional conversions, the kit retains the under-seat storage space and preserves the vehicle’s original handling characteristics by adhering to OEM suspension geometry. A key feature of this invention is the optimal utilization of space vacated by the removed engine. Additionally, the unique placement of components within a custom casing simplifies installation, reduces conversion time and cost, and ensures a seamless transition from petrol to electric mobility.
[056] One or more advantages of the prior art are overcome, and additional advantages are provided through the invention. Additional features are realized through the technique of the invention. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the invention.
[057] The retrofit kit (100) comprises a plurality of modular subsystems including a structural mounting frame (200), a modular battery housing system (201), a swing arm assembly (300) incorporating a high torque in-wheel electric motor (303), a controller assembly unit (400), and a universal wiring harness with plug-and-play connectors. Each subsystem is designed for compatibility with a range of two-wheeler geometries and is capable of being independently installed, upgraded, or replaced.
[058] FIG. 1 shows the modular retrofit kit (100) installed on a two-wheeler chassis (500), showing the overall placement of the modular subsystems according to an embodiment of the present invention. FIG. 2A showcases the structural mounting frame (200), battery housing system (201), swing arm assembly (300), and controller assembly unit (400). Fig 2B. shows the modular retrofit kit (100) showing the overall placement of the modular subsystems: a battery housing system (201), an adaptable Battery Base Plate (202), a Battery Pack (203), Battery Base Connecting rods -Supporting rods (204 b), a Swing Arm Frame (301), Shock Absorber mounting (302), a high torque in-wheel electric motor (303), a Controller Base Plate (401), a Charging Connector Mounting Plate (402), a Controller (403), a DC-DC Converter (404), and a cooling fan (405) according to an embodiment of the present invention;
[059] 1. Structural mounting frame (200):
[060] FIG. 3A and 3B depict a detailed view of the Structural mounting frame (200) according to an embodiment of the present invention. The Structural mounting frame (200) includes a modular battery housing system (201) with an adaptable battery base plate (202) designed to accommodate battery modules (203) of varying dimensions and energy capacities, typically in the range of 1.5 kWh to 4 kWh according to an embodiment of the present invention. The said base plate (202) includes mounting slots to support batteries of diverse shapes and incorporates quick-release locking mechanisms, such as U-shaped clamps (207, 208a, 208b), to facilitate secure and rapid installation or replacement according to an embodiment of the present invention.
[061] In a further embodiment, the battery housing system (201) may accommodate dual or modular battery packs (203) for extended range. Battery modules may be either:
[062] Removable/swappable, suitable for fleet operations or rental applications, or
[063] Permanently mounted, with integrated battery management system (BMS) and thermal monitoring for private EVs.
[064] The battery capacity can range from 1.5 kWh to 4.0 kWh, depending on vehicle class and regulatory approvals.
[065] The said mounting frame (200) is structurally mounted below the seat and forward of the rear axle, and is aligned symmetrically with the vehicle’s longitudinal centerline according to an embodiment of the present invention. This configuration lowers the overall center of gravity of the vehicle, enhances traction and stability during cornering, and contributes to optimal weight distribution. Furthermore, the exposed placement of the battery module allows for passive ambient cooling during vehicle operation.
[066] The said structural mounting frame (200) forms the backbone of the retrofit kit (Fig 3A and 3B) and interfaces directly with the existing engine mounting points of the original chassis (500) according to an embodiment of the present invention. This frame is dimensioned and reinforced to securely support the battery housing (201), swing arm (300), and controller assemblies (400), without requiring any alterations to the chassis.
[067] The said mounting frame (200) provides plug-and-play fitment using standard bolts or fasteners, enabling rapid installation according to an embodiment of the present invention. It also functions as a structural link between the battery module (203) and the swing arm (301), enhancing rigidity and vehicle stability during motion or under dynamic load conditions.
[068] 2. Swing Arm Assembly (300):
[069] FIG. 4A and 4B display front and back views of the the swing arm assembly (300) according to an embodiment of the present invention. The swing arm assembly (300) comprises a custom-designed swing arm (301) configured to house a high torque in-wheel electric motor (303). The swing arm is constructed to match the OEM suspension geometry and includes a shock absorber mounting provision (302) aligned with factory specifications according to an embodiment of the present invention.
[070] Additionally, the swing arm features integrated mounting slots (308a, 308b) for inner fenders or mudguards according to an embodiment of the present invention. These mountings reduce vibration-induced wear and enhance environmental protection of internal components from mud, water, and debris.
[071] The said swing arm (301) is engineered for modular attachment to the chassis (500) and includes optional covers (305, 306) to protect motor terminals and add to the overall aesthetic integration with the vehicle, according to an embodiment of the present invention.
[072] 3. Controller Assembly Unit (400) :
[073] FIG. 2A shows the controller assembly unit (400) mounted at the original fuel tank position according to an embodiment of the present invention. The controller assembly unit (400) is mounted at the original petrol tank position, utilizing a base plate (401) to support an electric motor controller (403), a DC-DC converter (404), and an active cooling system (405) such as a fan according to an embodiment of the present invention as seen in Fig. 5A and Fig. 5B. The design maintains optimal thermal performance under continuous load by directing forced airflow across heat-generating components.
[074] In another embodiment of the present invention, depending on the application and climate conditions, the active cooling system (405) may be implemented as:
[075] A forced air system using ducted airflow and fans,
[076] A liquid-cooled loop with a compact radiator and coolant lines,
[077] Or a hybrid system incorporating both.
[078] The cooling configuration may be automatically or manually controlled based on temperature thresholds recorded by thermal sensors within the controller enclosure.
[079] The assembly further comprises a Charging Connector Mounting Plate (402) positioned at the location of the original fuel inlet as a further embodiment, allowing intuitive access for the end user without altering the exterior look or usability of the vehicle.
[080] Protective enclosures and shock-dampening features are provided as further embodiments to safeguard sensitive electronics from mechanical vibration, shock, and environmental exposure.
[081] In another embodiment of the present invention, the controller unit (400) may optionally include a telematics unit or IoT communication module, configured to:
[082] Monitor real-time battery health and usage statistics,
[083] Enable over-the-air (OTA) firmware updates,
[084] Support vehicle tracking, theft alerts, and usage analytics.
[085] These modules may be housed within the same enclosure as the controller (403) or mounted separately on the chassis.
[086] 4. Universal Wiring Harness:
[087] FIG. 5B illustrates the wiring integration of the controller unit (400) with the modular wiring harness according to an embodiment of the present invention A universal wiring harness with standardized, color-coded electrical connectors interconnects all subsystems including the motor (303), battery (203), controller (403), and DC-DC converter (404). This system ensures error-minimized and tool-less installation, facilitating rapid deployment, testing, and maintenance. The wiring is routed such that it avoids interference with the moving parts and is compliant with automotive safety standards.
[088] The retrofit kit (100) may optionally be provided with:
[089] Integrated fuse blocks or circuit breakers,
[090] Isolation monitoring systems,
[091] Compliance with AIS-156, AIS-038, and other applicable EV retrofit guidelines in India.
[092] These elements can be housed within the wiring harness enclosure or as part of the controller system as another embodiment of the present invention.
[093] 5. Modular Architecture and Upgradeability:
[094] The entire kit (100) is designed with a modular and future-proof architecture, allowing any subsystem — said battery, said motor, said controller, or said telematics unit — to be upgraded or replaced independently. This allows users to incrementally enhance performance or replace failed modules without disturbing the overall system, reducing lifecycle costs and improving maintainability.
[095] In another embodiment of the present invention, the structural mounting frame (200), swing arm assembly (300), and controller mount (401) may be modified in dimension and strength to support two-wheeler platforms with higher gross vehicle weights (GVW) and top speeds exceeding 80 km/h. Reinforcements and shock-damping features may be added to accommodate higher dynamic loads.
[096] 6. Installation and Operation:
[097] FIG. 6 is a flowchart that demonstrates the full system integration layout of the modular retrofit kit (100), with all major components assembled and interconnected on a standard two-wheeler according to an embodiment of the present invention;
[098] The installation method involves the removal of original ICE components (engine, fuel tank, air filter, etc.) and replacing them with the retrofit subsystems as described above. All components are secured using OEM-compatible mounting points, and no invasive procedures such as cutting or welding are required. The storage or boot space (600) under the seat is retained, and the vehicle handling characteristics are preserved due to adherence to OEM suspension and geometry parameters. The steps involved were tailored to the overall goal of the invention.
[099] Once all components are mechanically installed and electrically connected, a calibration process is optionally executed via software or hardware interface. This includes configuring the controller (403) and motor (303) for desired torque characteristics, regenerative braking strength, and load-balancing parameters tailored to the specific chassis used.
[100] In yet another embodiment, the controller (403) may include selectable performance profiles (e.g., eco, city, sport) that can be toggled via a mobile app, display module, or physical switch. These modes regulate power delivery, regenerative braking strength, and acceleration curves to suit different rider preferences.
[101] These various strategies not only minimize development and implementation costs but also ensure that the system remains accessible to a broad user base. The modular architecture further allows for future integration of additional components, such as GPS modules for navigation or IoT devices for enhanced functionality. The design is scalable to accommodate future advancements and enhanced performance.
[102] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the claims presented in the complete specification or non-provisional application.
[103] Experimental results:
[104] To demonstrate the practical implementation and validate the efficacy of the proposed system, a series of experimental setups were carried out. The following non-limiting illustrative examples and accompanying photographs present various embodiments of the modular retrofit kit (100). Commonly known components and processes have been omitted for clarity and to avoid obscuring the invention. These examples are intended solely to aid understanding and practice of the invention by those skilled in the art and are not to be interpreted as limiting the scope of the disclosure.
[105] The working of the said invention is illustrated by the following non-limiting illustrative examples.
[106] 1. Structural Mounting Frame:
[107] Image 1a and 1b show the Structural Mounting Frame (200) comprising modular battery housing system (201), Adaptable Battery Base Plate (202) and associated supporting rods (204a, 204b) and mounting clamps (205) according to an embodiment of the invention.
The battery is secured using U-shaped clamp (207) and side mounting points (208a, 208b). Image 1c depicts the mounting frame interfacing with the original engine mounting points on the existing chassis (500) according to an embodiment of the invention.
[108] Image 1a: Structural Mounting Frame (200): (Example 1)

[109] Image 1b: Structural Mounting Frame (200) after being fixed on the vehicle: (Example 2)

[110] Image 1c: A section view of the Structural Mounting Frame (200) fixed on vehicle chassis (example 3)

[111] The modular setup facilitated battery upgrades of varying capacity (e.g., 1.5 kWh to 4 kWh) and enabled passive cooling due to exposed mounting according to an embodiment of the invention.
[112] It was also found that the arrangement confirmed the ease of battery integration using OEM mounting points and demonstrated tool-less locking features according to an embodiment of the invention.
[113] There was no structural modifications required during installation. The frame was found to enhance the rigidity and provided seamless mechanical integration between subsystems, ensuring safety and stability under load according to an embodiment of the invention.
[114] 2. Swing Arm Assembly Unit:
[115] The Image 2 shows the swing arm frame (301) fitted with a high torque in-wheel electric motor (303), shock absorber mounting (302), and motor protection covers (305a, 305b). Also visible are the mudguard mounting brackets (308a, 308b).
[116] Image 2: Swing Arm Assembly Unit (300): (example 4)

[117] It was observed that the swing arm (300) matched the OEM suspension geometry, thereby retaining factory ride dynamics. Further, it was found that the integrated mountings reduced vibration and protected the internal components from environmental exposure according to an embodiment of the invention.
[118] 3. Controller and Electronics Assembly Unit:
[119] Image 3 highlights the controller assembly unit (400) mounted using a base plate (401). It includes the motor controller (403), DC-DC converter (404), and cooling fan (405). The Charging Connector Mounting Plate (402) is mounted where the original fuel inlet was located, according to an embodiment of the invention.
[120] Image 3:Controller and Electronics Assembly Unit (example 5)

[121] It was observed that the assembly ensured optimal thermal performance and system compactness. The placement of the charging port at the original fuel inlet enhanced user familiarity and ease of use without compromising vehicle aesthetics.
[122] 4. Universal Wiring Harness Integration:
[123] Image 4 shows the routing of the universal wiring harness interconnecting the controller (403), motor (303), battery pack (203), and DC-DC converter (404) according to an embodiment of the invention. The connectors are color-coded and plug-and-play. The battery is secured using U-shaped clamp (207) and side mounting points (208a, 208b) .
[124] Image 4: Universal Wiring Harness Integration (example 6)

[125] The Image 4 demonstrates clean, interference-free wiring layout complying with safety standards according to an embodiment of the present invention. This configuration supports quick installation and error minimization during assembly or maintenance.
[126] 5: Fully Integrated Retrofit Kit on Two-Wheeler Chassis :
[127] Image 5 shows a complete view of the modular retrofit kit (100) installed on the original chassis (500). Visible components include the structural mounting frame (200), modular battery housing system (201), swing arm assembly (300), and controller unit (400) according to an embodiment of the present invention.
[128] Image 5: Fully Integrated Retrofit Kit on a Two-Wheeler Chassis (example 7)


[129] It was observed that the retrofit kit preserved the original chassis geometry, avoided any cutting or welding, and retained the under-seat boot space according to an embodiment of the invention.
[130] This modular design also allows for scalability and easy upgrades in the future.
[131] 6. Performance evaluation:
[132] To evaluate the on-road energy efficiency and functional performance of the modular retrofit kit of the present invention, a series of test rides were conducted on a two-wheeler retrofitted with the proposed system architecture. The objective was to assess real-world energy consumption under varying payloads and riding conditions, and to validate the functional benefits of key subsystems, in accordance with the objectives outlined in the present invention.
[133] The test procedure involved six ride cycles with payloads ranging between 115 kg and 150 kg, simulating typical commuter usage conditions. The results are summarized in the table below:
[134] Table 1: On-Road Efficiency Validation (example 8):
Ride No. Pay Load (kgs) Distance (km) Average Speed (kmph) Top Speed (kmph) Wh/km
1 115 31 27 49 23.48
2 115 29.5 26 51 23.38
3 150 14.3 30 47 31.83
4 150 32 29 55 31.06
5 150 32 30 54 31.52
6 150 49.2 32 55 31.46

[135] The test results revealed that the energy consumption ranged from 23.38 Wh/km to 31.83 Wh/km, with an average performance well within the standard OEM benchmark of 20–35 Wh/km for production-grade electric two-wheelers. Importantly, even under maximum design payload conditions (150 kg) and sustained speeds of up to 55 km/h, the retrofit kit (100) consistently delivered energy efficiency below 32 Wh/km.
[136] These results corroborate the effectiveness of multiple subsystems claimed in the invention:
[137] The structural mounting frame (200) ensured integration without altering the OEM chassis, thereby maintaining vehicle balance and geometry.
[138] The battery housing system (201), with its low center-of-gravity design, contributed to optimal weight distribution, improving ride stability and reducing energy demand during acceleration.
[139] The swing arm assembly (300) with integrated in-wheel motor minimized mechanical transmission losses by eliminating intermediate drivetrain components.
[140] The controller assembly unit (400), with integrated motor control, DC-DC conversion, and active thermal management, ensured efficient power delivery even at peak loads.
[141] The overall modular plug-and-play architecture enabled repeatable and consistent system behavior across test cycles, with energy consumption deviation within ±5%, affirming performance reliability.
[142] Furthermore, the retention of OEM aerodynamic characteristics—achieved by housing retrofit components within original vehicle contours—minimized wind resistance, further enhancing efficiency, particularly at higher speeds.
[143] These test validations affirm that the objectives of the present invention—namely, energy-efficient, structurally non-invasive, and modular electric two-wheeler conversion—have been successfully met under real-world usage conditions.
G. ADVANTAGES OF THE INVENTION
[144] The present invention provides several distinct advantages over conventional retrofitting systems and existing prior art in the field of electric vehicle (EV) conversions for two-wheelers.
[145] Key advantages include:
[146] No Structural Modification Required: The modular retrofit kit (100) is designed to be installed without requiring any cutting, welding, or drilling of the original two-wheeler chassis. This preserves the structural integrity, safety, and certification compliance of the base vehicle.
[147] Rapid and Simplified Installation: The plug-and-play nature of the subsystems, along with tool-less connectors and standardized mounting points, enables installation of the retrofit kit in approximately 1.5 hours using standard tools by a small team of mechanics, significantly reducing labor and service costs.
[148] Preservation of OEM Ride Dynamics: The invention retains original suspension geometry and uses factory shock absorber mounting points. This ensures that the vehicle’s handling, stability, and ride comfort remain unaltered post-conversion.
[149] Modular and Upgradeable Architecture: Each subsystem—including the battery, motor, controller, and optional telematics unit—is independently upgradeable or replaceable, allowing future scalability and reducing lifecycle costs for fleet operators and individual users.
[150] Universal Compatibility Across Vehicle Models: The kit includes adjustable mounting structures and a universal wiring harness, enabling integration across a wide range of ICE and legacy electric two-wheeler platforms with minimal customization.
[151] Preservation of Under-Seat Storage: The design ensures that the under-seat boot space typically used in scooters is retained, enhancing end-user convenience and avoiding functional compromise.
[152] Enhanced Thermal Management: The controller assembly unit is provided with an active cooling system including a fan, leading to a temperature reduction of up to 20°C under sustained load conditions. This feature ensures operational reliability in tropical and high-temperature environments.
[153] Improved Vehicle Stability and Center of Gravity: Strategic placement of the modular battery housing system below the rider’s seat and ahead of the rear axle results in a 15% reduction in center of gravity compared to standard ICE configurations, improving handling and traction.
[154] Protection from Vibration and Environmental Exposure: Integrated mounting slots for mudguards and enclosed covers reduce wear from road vibrations and shield key components from dust, water, and debris, especially under rough usage conditions.
[155] Fleet Readiness and Maintenance Optimization: The quick-release mechanism for battery modules supports rapid swapping and servicing, making the system ideal for shared mobility platforms, logistics fleets, and high-usage delivery vehicles.
[156] Sustainable and Cost-Effective Mobility: By reusing the existing vehicle platform, the invention minimizes electronic waste and manufacturing overhead, offering an affordable and eco-conscious alternative to complete vehicle replacement.
[157] Cost-Feasible Design: The invention is designed to be affordable and scalable, making it accessible to a broader user base while maintaining high accuracy and performance.
, Claims:We Claim:
1. A modular retrofit kit (100) for converting an internal combustion engine (ICE) two-wheeler into a full electric two-wheeler or for upgrading an existing electric two-wheeler, the kit comprising:
a) a structural mounting frame (200), including a modular battery housing system (201), an adaptable battery base plate (202) configured to accommodate battery modules (203) of varying dimensions and energy capacities, with quick-release mounting provisions enabling rapid battery replacement, and mounted in a position that preserves the vehicle’s under-seat storage space (600);
b) a structural mounting frame (200) associated with the battery housing system (201), designed for plug-and-play installation using the existing engine mounting points of the two-wheeler chassis (500) without requiring any structural modification including cutting, drilling, or welding;
c) a swing arm assembly (300) including a high torque in-wheel electric motor (303) coupled to a custom swing arm (301), wherein the swing arm is configured for modular attachment to the vehicle frame and incorporates provisions for shock absorber mounting (302), Original Equipment Manufacturer (OEM) compatible suspension geometry, and plurality of optional fender or mudguard mounts (308a, 308b);
d) a controller assembly unit (400) including a base plate (401) adapted to be mounted at the original fuel tank position, the base plate supporting an electric motor controller (403), DC-DC converter (404), and a cooling system (405), with a Charging Connector Mounting Plate (402) positioned to align with the original fuel inlet of the vehicle;
e) a universal wiring harness with standardized electrical connectors enabling tool-less and error-minimized interconnection between the kit's motor, battery, controller, and other subsystems;

wherein the said retrofit kit (100) is further configured to support independent upgradation or replacement of at least one of its modular subsystems — motor, battery, or controller — and provides a scalable architecture compatible across different vehicle models without compromising structural integrity or utility space.

2. The retrofit kit as claimed in claim 1, wherein the said structural mounting frame (200) comprises said battery housing system (201) with an adaptable battery base plate (202) with mounting slots configured to accommodate battery modules (203) of varying sizes and shapes, supporting energy capacities ranging from 1.5 kWh to 4 kWh.

3. The retrofit kit as claimed in claim 2, wherein the said battery housing system (201) is positioned below the seat and ahead of the rear axle of the vehicle, and is mounted symmetrically with respect to the vehicle’s longitudinal centerline.

4. The retrofit kit as claimed in claim 3, wherein the said battery housing system (201) is exposed to ambient airflow during vehicle operation and is structurally configured to interface between the chassis (500) and the swing arm assembly (300).

5. The retrofit kit as claimed in claim 1, wherein the said swing arm assembly (300) comprises plurality of integrated mounting slots (308a, 308b) for an inner fender or mudguard, and includes a shock absorber mounting (302) aligned with the original suspension geometry of the two-wheeler.

6. The retrofit kit as claimed in claim 1, wherein the said controller assembly unit (400) comprises:

a. said Charging Connector Mounting Plate (402) positioned at the location corresponding to the original fuel inlet of the two-wheeler, allowing intuitive access without altering the vehicle’s exterior aesthetics;
b. said base plate (401) supporting said electric motor controller (403), said DC-DC converter (404), and said active cooling system such as but not limited to a fan (405), wherein the cooling system includes a forced airflow design facilitating thermal dissipation during operation; and
c. protective enclosures and shock-dampening features to safeguard electronic components during vehicular motion.

7. The retrofit kit as claimed in claim 1, wherein the modular construction enables independent upgrading, replacement, or serviceability of any one or more of the following subsystems:
a) the said high Torque In-wheel electric motor (303) within the said swing arm (301);
b) the said modular battery pack (203) mounted on the said adaptable battery base plate (202);
c) the said controller (403) and said DC-DC converter (404);
d) an optional telematics unit or IoT communication module;

wherein said modularity enables rapid customization, maintenance, or performance enhancement of the two-wheeler without requiring re-engineering of the entire retrofit system.

8. The retrofit kit as claimed in claim 1, wherein the said modular battery housing system (201) includes quick-release mounting provisions configured to enable rapid removal and replacement of the battery modules (203).
9. A method for retrofitting an internal combustion engine (ICE) two-wheeler into an electric two-wheeler using a modular retrofit kit (100), the method comprising:
a) removing existing ICE components including the engine, fuel tank, air filter, and mechanical throttle components from the two-wheeler chassis (500);
b) mounting a structural mounting frame (200) with a modular battery housing system (201), the latter comprising an adaptable battery base plate (202) configured to accommodate battery modules (203) of varying dimensions and capacities, onto the existing engine mounting points of the chassis (500) without structural modification such as welding, cutting, or drilling;
c) installing a controller assembly unit (400) at the location originally occupied by the fuel tank, the unit comprising a base plate (401) supporting a motor controller (403), a DC-DC converter (404), and a cooling system (405), and aligning a Charging Connector Mounting Plate (402) with the original fuel inlet opening;
d) attaching a swing arm assembly (300), comprising a swing arm (301) housing a high torque in-wheel electric motor (303), a shock absorber mounting point (302), and plurality of provisions for mounting a mudguard (308a, 308b), to the original suspension mounting points of the chassis (500);
e) securing at least one battery module (203) into the said battery housing system (201) using a U-shaped clamp assembly with plurality of provisions (207, 208a, 208b);
f) electrically interconnecting all components — including the said battery module (203), said motor (303), said controller (403), and said DC-DC converter (404) — using a universal wiring harness with standardized connectors; and
g) conducting a system check to verify electrical continuity, component integration, and overall operational readiness.

10. The method as claimed in claim 9, further comprising the step of calibrating the motor controller (403) and the said high torque In-Wheel electric motor (303) after installation, using a software or hardware interface, in order to optimize torque response, regenerative braking behavior, and electrical power delivery parameters based on the specific chassis geometry and load distribution of the retrofitted two-wheeler (500).