This paper introduced Equivalent Consumption Minimization Strategy (ECMS), and presents simulation results on how the ECMS penalty factor effects Lithium ion battery aging based on Matlab simulations. The vehicles simulated are the Honda Civic Hybrid and the Michigan Technological University developed Plug-in Hybrid Electric Vehicle (MTU-HEV). The battery data was used from A123 systems 20Ah Prismatic Pouch Cell for MTU-HEV, and A123 systems ANR26650 for Honda Civic Hybrid. Both vehicles are simulated using multiple combinations of highway and city drive cycles. For each combination of drive cycles, six ECMS penalty factor values are used. Battery aging is evaluated using the semiempirical model combined with accumulated Ah-throughput method which uses, as an input, the battery state of charge trajectory from the vehicle simulations. The tradeoff between fuel cost and battery aging cost is explicitly displayed. In addition, the results provide insight into how driving behavior effects battery aging. The paper concludes with a discussion of the optimal balance between fuel cost and battery aging.