Model-based sizing of battery packs for minimum cost

Lithium ion (Li-ion) battery life and performance significantly depend on operating temperature and usage. There are four battery characteristics that are interlinked: Life, capacity, operating temperature, and usage. The goal of battery pack design is to minimize the battery pack cost or to maximize the battery pack life or both if possible. This paper develops a model based process that selects battery operating temperature and capacity to optimize the life and cost of the battery pack under prescribed usage. Simulations using experimentally validated performance and aging models demonstrate that for a particular application, battery cost can be reduced by 30% if the battery pack is operated at 45° C. Also there exists an optimal battery pack size for a specified battery temperature, and over-sizing the battery pack does not further increase the battery life.