Skip to Main Content
Ultra-capacitor has the features of high power density, quick charge and long life cycle, which receives great attention in the research and development of electric vehicles. State of charge of battery or ultra-capacitor is the most important parameter in an electric vehicle. In this paper, a state-space state of charge estimation method for ultra-capacitor made of active carbon electrode and aqueous electrolyte is studied based on an equivalent circuit model. The charging and discharging experiment results indicate that the precision of the method is similar with ampere hour method. So state of charge of electric vehicle ultra-capacitor could be estimated accurately.