Because the battery capacity, internal resistance, voltage and other parameter values are not completely consistent,this difference causes the battery with the smallest capacity to be easily overcharged and discharged during charging, and the smallest battery capacity becomes smaller after damage, entering a vicious cycle. The performance of single battery directly affects the charge and discharge characteristics of the whole battery and the reduction of battery capacity.BMS without balance function is just a data collector,which is hardly a management system.The latest BMS active equalization function can realize the maximum continuous 5A equalization current.Transfer the high-energy single battery to the low-energy single battery, or use the whole group of energy to supplement the lowest single battery.During the implementation process,the energy is redistributed through the energy storage link, so as to ensure the battery consistency to the greatest extent, improve the battery life mileage and delay the battery aging.