As lithium-ion electric vehicle (EV) batteries are sensitive to the conditions they are exposed to during charging and discharging, operational control has been an important research area. While an understanding of the effects current load and operation temperature has on the ageing stability of a battery has been established, associated control strategies are yet to be fully optimized. Most battery charging studies utilize controlled ambient temperatures and basic defined cycles, which may only apply to a small subset of real-world EV consumers. This leads to control strategies that do not consider electrical grid price fluctuation, user driving habits or local weather conditions.
This paper looks to propose improved smart charging strategies of EVs to reduce consumer costs while also increasing the battery longevity. To accomplish the primary objective, A model has been generated that simulates the standard charge cycle of a battery. To distinguish this model from others, it has inputs for the local weather and electrical grid pricing forecasts. By providing this information, the charging controller can determine when the best time to charge the battery will be to ensure the lowest pricing, while efficiently maintaining an appropriate battery temperature during the charge cycle. Timing of the charge can be crucial as the controller needs to establish whether letting the battery cool after driving, then heating to charge during cheaper hours is more cost effective than charging during peak hours directly after a drive cycle while the battery is still warm.
The methods used to accomplish the primary objective also help for the secondary objective by ensuring the correct battery operating temperature window during charging. During the storage phase of the vehicle, the controller can monitor the battery temperature and forecast to ensure an appropriate temperature. By controlling the temperature and charging cycles this way, battery ageing should be reduced due to the direct correlation between temperature and SEI growth.