Nowadays recognition of the importance of clean fuel has led to increased use of electric vehicles. Despite the researchers’ efforts in this field, still the limitation of the range per battery charge remains as a critical challenge which avoids these vehicles from being extensively used. Furthermore, the battery charge shall be usedwithin a definite amount in order to protect the battery life. Since direct measurement of the battery state of charge is not possible, usually estimation of this quantity is being performed. In this thesis, an efficient filter is designed to estimate the remaining battery charge through a suitable model. Due to the necessity of high energy density in electric vehicles, the lithium ion batteries are used. The model used for such batteries is the reduced order of an electrochemical model called single particle model, in which the output voltage of the battery is a non-linear function of the battery state of charge.Taking into account the importance of the uncertainty of the model, in this thesis it is proposed to combine the switching method with an SDRE non-linear filter structure. For this purpose, first the theoretical development of this filter and its robustness analysis is reviewed and then its implementation on the non-defined lithium ion battery is taken into consideration.The simulation results verifies the efficiency of the recommended filter in comparison to the conventional filters which is quite promising in practical implementations. Furthermore, in order to demonstrate the applicability, performance and effectiveness of the purposed filter, real implementation is reported.