We have established a two-step strategy for the modeling of cell cultures in suspension and applied it to Escherichia coli cultures. Cell concentration, pH, and sugar consumption (glucose) were involved. In the first step, graphical analysis of the experimental kinetic data allowed an approach to the kinetic cell behavior and led to the mathematical dynamic model. An approximation of the corresponding parameters was thus obtained. Then, a more precise estimation of these parameters was obtained using a numerical simulation, including a general modeling of pH effects in acid fermentations. The results show that a simple graphical analysis is able to give a very good estimation for most parameters characterizing the culture at a macroscopic level.