Title: Battery capacity design in EV conversion using the urban dynamometer driving schedule

Authors: Chedthawut Poompipatpong; Warit Thammasiriroj; Puchong Khumpunja

Addresses: Automotive Eco-Energy and Industrial Product Standard Research Center, Science and Technology Research Institute, Thailand; Department of Power Engineering Technology, College of Industrial Technology, King Mongkut's University of Technology North Bangkok, Bangkok, 10800, Thailand ' Automotive Eco-Energy and Industrial Product Standard Research Center, Science and Technology Research Institute, Thailand; Department of Power Engineering Technology, College of Industrial Technology, King Mongkut's University of Technology North Bangkok, Bangkok, 10800, Thailand ' Thailand Institute of Scientific and Technological Research, Pathum Thani, 12120, Thailand

Abstract: Retrofitting old or classic internal combustion engine vehicles into EV conversions is becoming an important approach to reduce urban pollution, reduce fossil fuel dependence, and improve the quality of life in urban areas, especially in Southeast Asia, where many old vehicles are in use. However, determining the right battery and drive system size for practical use remains a major challenge. This research proposes an approach to determine the right battery size based on urban dynamometer driving schedule (UDDS), which reflect urban driving behaviour with frequent acceleration, stop-start, and speed changes. The driving simulation using UDDS clearly identifies the relevant forces such as air resistance, rolling resistance, and acceleration, resulting in accurate calculation of energy requirements. The results show that using UDDS can calculate the battery size of a modified EV based on a standard driving cycle, compared to the conventional calculation method that assumes the motor is continuously running at full power. This result reflects the potential to reduce system size, lower costs, and optimise the design of modified EVs. In addition, this approach is suitable for use in regions with limited driving data and supports the development of sustainable vehicle solutions in the future.

Keywords: urban dynamometer driving schedule; UDDS; energy consumption; battery capacity; EV conversion.

DOI: 10.1504/IJVP.2026.152836

International Journal of Vehicle Performance, 2026 Vol.12 No.2, pp.239 - 255

Received: 07 May 2025
Accepted: 16 Oct 2025
Published online: 13 Apr 2026 *

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