Development of a test protocol for automotive Lithium-Ion (Li-Ion) battery packs. The thesis consists of the development of a testing procedure to evaluate the State of Health (SOH) of used electric vehicles' battery packs. The final test protocol has been developed by the analysis of the introductory tests performed to determine the behavior of the batteries. The results of the testing protocol, which has been applied to all the modules of three packs of the Nissan Leaf 2011 Edition (24 kWh), have been then analyzed using Matlab and Simulink. From the processing of the data, it has been possible to determine the behavior of the internal parameters of the modules.