Development of a Computational Algorithm for Estimation of Lead Acid Battery Life

The performance and durability of the lead acid battery is highly dependent on the internal battery temperature. The changes in internal battery temperatures are caused by several factors including internal heat generation and external heat transfer from the vehicle under-hood environment. Internal heat generation depends on the battery charging strategy and electric loading. External heat transfer effects are caused by customer duty cycle, vehicle under-hood components and under-hood ambient air. During soak conditions, the ambient temperature can have significant effect on battery temperature after a long drive for example. Therefore, the temperature rise in a lead-acid battery must be controlled to improve its performance and durability. In this paper a thermal model for lead-acid battery is developed which integrates both internal and external factors along with customer duty cycle to predict battery temperature at various driving conditions. The model is fully integrated into the vehicle environment. Therefore, all interactions with under-hood components and air flow are considered. Based on estimated battery temperature, a battery thermal degradation model is applied to predict battery life for a variety of duty cycles. Therefore, appropriate thermal protection and battery charging strategy can be investigated in order to improve battery life and reduce potential warranty costs.