The optimal concentration of nanoparticles in nanofluids for battery cooling depends on the trade-off between the enhanced heat transfer and the increased pumping power required to circulate the nanofluid. Generally, higher concentrations of nanoparticles result in higher heat transfer coefficients, but also higher pressure drops and pumping power. Therefore, it is important to choose a suitable concentration that can achieve a balance between these factors. Concentrations ranging from 0.5% to 5% volume fraction can provide significant improvements in heat transfer without excessive penalties in pumping power for battery cooling applications