Battery state-of-charge estimation using polynomial enhanced prediction

A novel polynomial-enhanced open-circuit voltage extrapolation method is presented. It is used to identify a battery's state-of-charge based on the estimation of the corresponding relaxation voltage. The proposed method represents the relaxation process via a polynomial enhanced voltage model, calculated by least squares estimation. Compared to state-of-the-art models, the proposed approach reduces the period of time needed until the state-of-charge can be accurately determined. For the particular cell under test, an open-circuit voltage accuracy of +/- 1 can be reached within the first 11 minutes of the relaxation process. In addition, the reduced estimation time also leads to a lower power consumption of an integrated circuit-based battery identification solution.