A rechargeable lithium-ion battery or a supercapacitor,which could provide fast and additional power for thePEMFC when the load demand increases rapidly, is addedto build a hybrid power system [4], which can improve theperformance and lifetime of the fuel cell and result in increased reliability in FCV. With the recent development ofhigh-performance lithium-ion battery technology, it makesthe hybrid power system more reliable [5].[6] proposed a power control design of a battery chargerin a hybrid active PV generator for load following applications. This strategy makes it possible to ensure a high stateof charge and overcharge security of the battery. An on-linestrategy based on an optimized fuzzy logic controller wasproposed in [7], which could improve the fuel economy ofa PEMFC hybrid vehicle. [8] described a PEMFC hybridpower supply system with battery energy balancer, whichmodulated the excessive or insufficient power for the loadin order to increase the efficiency of PEMFC in partial loadconditions. But the battery models they chose are very simple and couldn’t present the accurate performance of the battery.