The scope of the present research is the reduction of cost and time related to the design, prototyping and testing of a Li-ion battery pack, which is used in commercial full electric vehicles using tools for rapid product configuration and simulation. This objective is particularly important for small companies that produce many different batteries in small lots. To develop the product design support system, a preliminary study was necessary. A 3D model was analyzed to simulate real thermal behavior, reproducing a real electric load using a standard ECE-15 cycle. Experimental tests have been conducted on the vehicle and battery to validate the model. An analytical thermal model was developed to evaluate the heat generated by electrochemical reactions inside a Li-ion cell. The outcome of this analytical model was used as the boundary condition in the CFD simulation of the battery model to evaluate the cooling behavior. The rules and results deduced from these studies have allowed the implementation of an easy-to-use knowledge-based configuration tool that supports the designer in the definition of the layout of the battery pack to save time and evaluate costs. As a test case, the battery for an urban freight vehicle was designed using the proposed approach. The achieved results show good performance and robustness of the simplified approach in terms of temperature distribution evaluation and design process efficiency.