A new method to follow the evolution of the plates of a battery during the formation processes is proposed and developed. The developed methodology can be used not only in research but also in the factory laboratories due to its simplicity. To exemplify the methodology, results for formation processes of tubular plates are presented using as precursor PbO or Pb3O4. The methodology gives access to the evolution, during its formation process, of the portions of the active material available for the discharge processes, the so called electrochemically active area. At the same time, the proposed technique permits the determination of the whole amount of PbO2 during formation. Through the results it is pointed out what experimental conditions must be used during the application of the method and examples are given of the kinds of interpretation that can be made. Finally, information is presented which was deduced from the results presented.