A retrofit kit serves as a system facilitating the transformation of a traditional internal combustion engine vehicle into a fully electric one. This thesis project aim to enhance a tailored algorithm designed for a vehicle control unit (VCU), an integral part of a conversion kit intended for installation in vintage cars. Specifically, the development of both Powertrain Control Module (PCM) and Battery Management System (BMS) features and how they communicate with each other is addressed. The algorithm is developed within the LabVIEW environment and subjected to testing based on the model-based design approach. The initial section involves a thorough requirements analysis of the PCM and BMS algorithms and presents their preliminary implementation.