In recent years, the thermal management batteries for automotive applications has become a key factor to further improve their performance and ensure their efficiency, durability and safety. As a matter of the fact, an overheat of these devices can result in various issues, including degradation of insulation materials, decreased efficiency, shortened lifespan, and even failure and consequent thermal runaway. In this context, this work aims to improve the comprehension of heat dissipation in batteries and to model the cooling circuit through the integration of CFD, in order to provide guidelines for the optimization of the overall system. To this scope, a novel OpenFOAM solver is introduced, capable of computing electric quantities along with losses inside the battery cells, consequently assessing heat generation across various components. The combined thermodynamic and electric analysis of the battery, which predicts the heat sources and temperature distribution under the effective operating conditions, allows to optimize the cooling system design and the thermal management strategy. The methodology is applied for the simulation of a simplified Lithium-ions battery, to improve the understanding of heat production and guide the development of efficient cooling mechanisms, with the ultimate goal of enhancing both their durability and performance. Additionally, a specific methodology has been developed to model the cooling unit, where the cooling fluid transfers the heat extracted from the battery, plus an eventual contribution from the electric motor, inverter and cabin conditioning system, to the water cooling systems throughout a plate type cooler. The procedure is based on the analysis of the microstructure of the turbulator and its scale up to the macroscale to allow the modeling of the whole cooling unit. At this level optimization procedures can be adopted to design a compact lightweight cooling unit that reduces the impact on the vehicle dynamics.