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Multi-Speed Gearboxes for Battery Electric Vehicles

Project by Polygence alum Shrihan

Multi-Speed Gearboxes for Battery Electric Vehicles

Project's result

Researched and experimented the application of a multi-speed gearboxes in a battery-electric car. Submitted final paper to Polygence and UCIxGATI college credit program.

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Electric Vehicles (EVs) have started to become a significant part of transportation. Battery Electric Vehicles (BEVs) are one type of EV to draw attention towards. Despite their numerous benefits over gas-powered vehicles, they still have the potential for improvement. The performance and energy efficiency aspects of their powertrains are often not optimized, affecting their real-world capabilities. Multi-speed gearboxes could have the potential to improve the powertrains of BEVs. To investigate this hypothesis, an experiment was conducted where a three-speed gearbox was implemented into the powertrain of a Nissan Leaf, an existing battery electric car. The car’s powertrain specifications and its electric motor performance curve were used to generate the initial graphs. By applying the gear ratios from the gearbox on the motor’s initial values, new data plots were generated. The experimental data consisted of torque-speed relationship, energy efficiency, and loss in power graphs. The results of the experiment were then analyzed to evaluate the effects of the gearbox on the car’s powertrain data. The gearbox showed overall improved combinations of performance and energy efficiency figures. Enhanced performance figures meant that the output speeds and accelerations of the car increased. High energy efficiency outputs at various speeds occurred, which was not obtainable by the electric motor. The significance of the experiment’s results was then applied to helpful uses in real-world driving scenarios. Further evaluation was made, speculating on future helpful uses of gearboxes in BEVs.



Polygence mentor

PhD Doctor of Philosophy candidate


Engineering, Computer Science


robotics, mechanical engineering, drawing, computer science - python, computer science - machine learning, engineering design, circuits, PCB design




Hi! My name is Shrihan, currently a Junior at Dougherty Valley High School. My main interest is cars and my intended career path is in the automotive engineering field. This is why I chose to create and my publish my research website, Learn your Car, hope you visit it and enjoy the experience! [learnyourcar.wordpress.com](https://learnyourcar.wordpress.com)


Dougherty Valley High School

Graduation Year


Project review

“My goals for my research paper exceeded my expectations. I was able to conduct experiments on the effects of gearboxes in electric vehicles, in ways that I had not thought were possible when I first proposed my research topic. I was able to narrow my research topic and focus on key aspects of implementing multi-speed gearboxes in electric vehicle powertrains. In the end, I built a complex project paper that compiled all my experiments and research, to show the potential impacts of EV gearboxes that can help electric vehicles in the future.”

About my mentor

“My mentor, Bibit, gave me the right information and resources needed to build a great research paper. Initially, I had a broad foundation on where to start, but my mentor helped me through the processes I could take to test my hypothesis. As gearboxes and electric motors can be confusing topics to understand, I was able to gain important knowledge that played significant roles in my research and experimental data. She taught me how to conduct experiments by plotting data from programming, showcasing useful graphs that can be used to evaluate the effects of gearboxes in electric vehicles. I never imagined that computer programming would be a process for my research paper, yet I was able to generate experimental data through the programming aspects she taught me. Without my mentor, I would have not been able to successfully build a passionate research paper that I would be proud of today.”