Determining battery parameters by simple algebraic method

This paper derives simple and explicit formulas for computing the parameters of the Thevenin´s equivalent circuit model for a discharging battery. The general Thevenin´s equivalent circuit model has n pairs of parallel resistors and capacitors. The main idea behind the new method is to trans form the problem of solving a system of high order polynomial equations into one of solving several linear equations and a single variable nth order polynomial equation, via some change of variables. Experimental and computational results are obtained for 3 types of batteries.