Battery management system with state of charge indicator for electric vehicles

On the basis of analyzing the electro-chemical characteristics of lead-acid battery, the state of charge indicator for lead-acid battery was developed by means of an algorithm based on combination of ampere-hour, Peukert's equation and open-voltage method with the compensation of temperature, aging, self-discharging, etc. The BMS based on this method can attain an accurate surplus capacity which error is less than 5% in static experiments. It is proved by experiments that the BMS is reliable and can give the driver an accurate surplus capacity, precisely monitor the individual battery modules as the same time, even detect and warn the problems early. A BMS can make the energy of the storage batteries used efficiently, develop the batteries cycle life and increase the driving distance of electric vehicles.