The aim of this work is to design and implement a bidirectional buck-boost converter prototype to regulate DC voltage in a powertrain of an electric vehicle. To validate the design of the proposed converter start-up transient experiments are realized in open loop for the buck and boost mode. The activation signals of MOSFETS switch are generated using a transition method by hysteresis and are implemented in micro-controller. Experimental results show its works properly in both modes, keeping the criteria design parameters.