Numerical modelling is the method by virtually testing and verifying the functionality of a specific product or component. The primary goal is to get approximate results of how the system behaves in a given time and environment. This paper deals with a possibility of the use the numerical simulation for system simulation in the unconventional power sources of electrical energy. This method is useful in application where the complex environment is necessary to use, e.g. electro-mobility, solar power station, etc. It is possible to simulate electro-chemical reactions, current fields, temperature fields, electric potentials, concentrations, charging and discharging cycle, electromagnetism, etc. In this case, it will be presented the multiphysical approach of system simulation of short circuit in the lithium ion battery.