SOC Estimation of Power Battery Design on Constant-current Discharge

This paper takes the electric car’s power battery (VRLA battery cell) as the research object, for real-time monitoring problem of power battery's state of charge (SOC) and remaining time, The system adopts micro control unit (MCU) 89S51 and AD974 to control battery discharge in constant current, Through the measurement of a periodic, get Series of working voltage, using phase-slope calculation method at this time calculating the battery's SOC and remaining time. Through the experiment, this estimation method proved the feasibility of the dynamic working point can be mapped to the static working point, and the largest relative error is no more than 7 %. For further improving the measurement accuracy and reducing error, Through the software can realize appropriate correction and compensation of temperature, aging and other interference factors. Error analysis results show that this method has small error, high measurement accuracy.