1.National Active Distribution Network Technology Research Center，Beijing Jiaotong University，Beijing100044，China;2.Beijing E-power Electronic Co.Ltd.，Beijing100044，China

Based on an analysis of capacity and internal resistance characteristics of the eliminated lithium manganese batteries for the Beijing Olympic Games pure electric bus，more serious battery pack consistency issues due to battery echelon use are discussed in detail.With reference to the battery consistency evaluation method，the battery equilibrium criterion is analyzed based on capacity utilization of the battery pack.And in light of the load shift application of battery energy storage system，an online equilibrium strategy for maximizing the capacity utilization is proposed.The battery pack charging equalization circuit and equalization test platform are built prior to testing and verifying the feasibility and reliability of the online equalization system and its control strategy.