Lithium-ion batteries are widely used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) today, these batteries advantageous compared to other forms of energy storage due to their high energy density and long cycle life. The object of this thesis is to develop the model based on the internal electrochemical states of the battery for battery monitoring and control in advanced battery management systems (BMSs). The investigated battery is 2.5Ah LiFePO4 cylindrical 26650 type from company A123. Pseudo-two-dimensional (P2D) model developed by John Newman and his colleagues is probably the most widely used Physics based lithium-ion battery model in the world, however, the complexity of P2D model makes on-line simulation difficult in automotive applications.