Powertrain Development of a Small Electric Cargo Vehicle

Abstract

This thesis presents the development, manufacturing, testing, and evaluation of an electric drivetrain conversion kit for a Piaggio Ape cargo moped. The project was carried out in collaboration with Mint Engineering with the objective of developing an electric conversion kit for small cargo vehicles while minimizing modifications to the original vehicle. The work included requirement definition, concept generation, component selection, reverse engineering, CAD-based design, manufacturing of custom Components, assembly, and prototype testing. Several drivetrain layouts and transmission concepts were evaluated with respect to packaging, manufacturability, installation complexity, cost, and vehicle performance. The selected concept consisted of a centrally mounted electric motor connected to the original differential through a customdesigned adapter and spline shaft while retaining parts of the original driveline. Reverse engineering methods including 3D scanning, manual measurements, and CAD modeling were used to adapt the drivetrain to the existing vehicle geometry. Multiple custom components were designed and manufactured, including drivetrain interfaces, mountings, battery, and electrical integration into the original vehicle. The electrical architecture incorporated a battery management system, regenerative braking, CAN communication, and both high- and low-voltage systems. Following manufacturing and installation of the developed conversion kit, the vehicle underwent functional testing, initial driving tests and troubleshooting. The testing verified the functionality of the electrical systems, drivetrain integration, regenerative braking, and overall vehicle operation. However, the vehicle exhibited significantly lower torque output than expected, resulting in limited hill climbing capability and failure to meet the specified torque requirement. Extensive troubleshooting, measurements, and analytical calculations were therefore conducted to investigate the source of the performance deficit. The investigation showed that the delivered motor differed from the specified model, as well as a mistake in motor controller selection where a controller with 200A peak amplitude phase current instead of 200A RMS was selected. Despite the torque deficit, the project demonstrates the practical challenges and feasibility of converting lightweight cargo vehicles to electric propulsion using commercially available components combined with custom-designed mechanical interfaces. The work further emphasizes the importance of component verification, iterative testing, and system-level troubleshooting in electric vehicle conversion projects.