An integrated simulation and testing approach is presented to evaluate batteries for electric vehicle (EV) applications. This new approach combines traditional experimental testing with computer simulations to create a cost-effective means to evaluate EV batteries and provide important information that is difficult or impossible to obtain from purely experimental measurements. The present simulators for the lead-acid and nickel-metal hydride (Ni-MH) batteries are developed based on the fundamental principles governing their electrochemical behaviors and are created using an advanced computational fluid dynamics (CFD) technique. Computer simulations are validated by experimental data under the dynamic stress test (DST) procedure for a lead-acid battery module and a Ni-MH cell with good agreement. Moreover, computer simulations reveal that the studied lead-acid battery underutilizes the active material by as much as 70% and the MH electrode of the Ni-MH cell is overdesigned by about 30% under the simulated EV duty. Therefore, there is good potential of increasing the specific energy and reducing the cost if batteries are optimized for EVs using a simulation-based design approach.