The main objective of this study is to investigate heat transfer inside and around a supercapacitor stack. The crossflow staggered arrangement with five rows was also studied for different transverse and longitudinal pitches. The mathematical model governing the problem is numerically solved in a three-dimensional computational domain using the commercial computational fluid dynamic package Fluent 6.3. The model is elliptic and takes into account orthotropic thermal conductivity in the active zone. The average Nusselt number and friction factor results of the present model are in good agreement with previously published experimental data of different authors for flow across tube banks. The results include evolution of the maximum temperature of each supercapacitor and contours of temperature distribution. For a definite ventilation power, the arrangement with the lowest spacing provides maximum cooling performance. Inside the supercapacitor the temperature distribution is not concentric around the axis and the maximum temperature is downstream. In the axial direction the temperature variation can be neglected.