Detailed thermal modeling of liquid-cooled vehicle traction battery assemblies using Computational Fluid Dynamics (CFD) analysis techniques usually involves large models to accurately resolve small cooling channel details. For large battery packs, some of these meshes may exceed current computational capabilities or result in long and expensive computational efforts. Moreover, only steady-state thermal predictions are usually performed, as drive-cycle transient simulations become impractical due to the exceedingly long solving times. To tackle this problem, an innovative segregated method has been developed for thermal analysis of liquid-cooled traction batteries, where battery cells and their active cooling system are divided into three parts: the cell, the cold plate and the interface between them. Each of the three parts can be separated and thermally characterized and then mathematically combined to predict the overall system thermal behavior for both steady-state and transient operating conditions. The method largely simplifies battery thermal analysis to overcome the limitations of using large 3D CFD models especially for pack level dynamic drive cycle simulations. The proposed approach greatly improves analysis capabilities for predicting battery operating temperature and heat discharge during design and concept development by yielding more time efficient solutions that can successfully support the tight timing requirements of the product design process.