Smart charging of electric bus fleet minimizing battery degradation at extreme temperature conditions

This paper presents an optimized control strategy for lithium-ion batteries lifetime used on electric buses at high and low temperatures. In high temperature environments, the main aging mechanism is the formation and growth of the solid electrolyte interface. This mechanism is typically related to calendar aging and amplified at higher state of charge and temperature. On the other hand, at low temperature, the deposition of lithium metal (lithium plating) is predominant only during cycling and battery degradation increases as the temperature drops. All these factors could greatly increase the battery degradation. A novel battery aging model based on Eyring's laws is developed considering different aging mechanisms particularly subject to extreme temperature conditions at rest and charging scenarios. Based on this model, the aging is quantified and optimized through an optimization methodology under several scenarios. The simulation results show that the charging strategy becomes necessary at extreme temperature conditions and is able to save on vehicle operation costs.