Aging Model for Re-used Electric Vehicle Batteries in Second Life Stationary Applications

Energy generation and distribution around the globe expect that micro-grids, renewable and distributed energy services will be key elements in future grid infrastructures. That is why batteries, as storage energy systems, are in the scope of many studies. To counteract the high costs of Li-ion batteries appears the idea of electric vehicle battery reuse or second life for stationary applications. In fact, batteries from electric vehicles are not useful for transportation purposes after they have lost a 20% of its capacity. This study uses an electric equivalent circuit to model battery behavior and aging under five different second life applications: Fast charge of electric vehicles; isolated applications; uninterruptible power systems and Self consumption with and without participation on grid frequency regulation. The battery model takes into account temperature, C-rate, depth of discharge and voltage of the battery to evaluate and calculate battery aging along time and use. This model runs on Matlab and Simulink to determine the battery state of health evolution and, therefore, the rest of useful life, which can be used for future economic analysis and maintenance management.