Coulomb counting method is a convenient and straightforward approach for estimating the state-of-charge (SOC) of lithium-ion batteries. Without interrupting the power supply, the remaining capacities of them in an electric vehicle (EV) can be calculated by integrating the current leaving and entering the batteries. The main drawbacks of this method are the cumulative errors and the time-varying coulombic efficiency, which always lead to inaccurate estimations. To deal with this problem, a least-squares based coulomb counting method is proposed. With the proposed method, the coulombic losses can be compensated by charging/discharging coulombic efficiency η and the measurement drift can be amended with a morbid efficiency matrix. The experimental results demonstrated that the proposed method is effective and convenient.
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Zhao et al. (2016) studied this question.