The start/stop functionality is widely used as a fuel saving solution for on-highway vehicles, being constantly studied and implemented in new series models. The subject of this work is to demonstrate the same start/stop functionality applied as a retrofit solution for off road vehicles that have high fuel consumption and operate many hours a day. The start/stop retrofit (SSR) solution includes an ECU added in the vehicle acting as the system’s controller, which must be adapted according to its specific application. These interventions are important discussions topics and include electrical modifications, battery monitoring strategies, adapted ways to retrieve the vehicle data and an important safety study to secure all the modifications. The implementation of the start/stop system in a mining truck aims for a reduction on fuel consumption and CO2 emissions.