This paper derives simple algorithms for determining parameters of two circuit models for charging/discharging batteries. The problems of identifying parameters for the circuit models are converted into algebraic problems of solving systems of polynomial equations of special structures. A recent algebraic tool is applied to obtain analytical solutions to these polynomial equations and simple algorithms for extracting model parameters from experimental responses. Computational results are obtained for 3 types of batteries: Li-polymer, lead-acid and NiMH. (C) 2013 Elsevier B.V. All rights reserved.