One of the limits of railway freight market, if compared to road one, is its lower flexibility in the first and in the last connection of the overall delivery chain. In this paper, a battery module is proposed and sized as an innovative solution to replace the diesel engine in the freight locomotives equipped with diesel last mile module currently available on the market. Indeed, nowadays there are well-developed technologies of lithium-ion batteries, coming from road transportation system and some of them are being already tested in railway systems, with promising results. An estimation of the total energy necessary to compose the train and to move it under an energized catenary is carry out using traction diagrams: the sizing of the traction battery, of automotive type made by Lithium Werks, will be based on this estimated value. The economic feasibility of the proposed system is then presented using break-even analysis by presenting three different scenarios: two at the current conditions and one at 2030. Finally, the proposed electrical circuit is simulated in Matlab Simulink environment, to verify its actual stability and to show a start-up cycle.