The success of hybrid electrical storage systems which combines batteries and supercapacitors is related to the manner how these devices are managed. In this paper, optimal use of the complementarity between batteries and supercapacitors in electric vehicles is studied. First, storage devices are sized based on reduced size specifications of the electric vehicle. Then, power waveforms for each storage device obtained by simulation using the frequency sharing strategy are presented. Different values of filter constant are therefore analyzed to show the variation effect of power sharing strategy on battery current waveforms. The optimal filter constant is finally determined. It offers reduced values of RMS battery current and enhancement of battery service life.