The chapter focuses on presenting a detailed step-by-step workflow for theoretical and practical approach of Li-ion battery electric parameter identification. Correct and precise information about the electric parameters of the batteries allows defining several types of simulation approaches. Increasing the complexity of these approaches requires more and more identified parameters and by this more complicated hardware to fulfill the identification process itself. However, the level of complexity must be justified by the need of accuracy as well as the compromise of labor, simulation power and time. In this chapter, several simulation complexity levels are presented via theory and then tested via simulations compared with actual measurements. A proper and well-done analysis of these models helps the future reader to decide whether he will use a complex model, function of the need of accuracy, simulation power and time. The compromise will be highlighted by comparing the error of different approaches compared to actual laboratory measurements. Over all, the chapter will be a gathered guideline for identification, modeling and testing of batteries, ready to be implemented both in simulation and in practical experiments.