A Roadmap to Understand Battery Performance in Electric and Hybrid Vehicle Operation

This chapter presents a roadmap that is rationalized to address the various obstacles faced while understanding the battery performance in practical EHV applications. The first step is the formulation of a systematic approach to analyze the driving and duty cycle data recorded from field testing and classify them according to operating condition and usage. Analyzing the performance characteristics of batteries from laboratory test results and deriving a proper correlation between duty cycles and performance characteristics via the understanding of degradation mechanisms is the second step. Developing an accurate predictive model and simulation tool and methodology to enable prediction of battery performance and life based on both laboratory testing and field operation is the final step. Field testing enables proper data collection and analysis to help derive vehicle usage patterns by using a fuzzy-logic pattern recognition (FL-PR) technique as a method to conduct driving cycle and duty cycle analyses. The combination of driving and duty cycle analyses helps in understanding EHV and battery performance in a synergistic manner and assisting the formulation of representative usage patterns that depict the average use of the vehicle and battery in real-life situations. The process of utilizing incremental capacity analysis to extract battery degradation information and thus identify degradation mechanisms and quantify the effects is also presented. The integral understanding of different aspects in battery behavior and performance also helps to develop a suite of diagnostic tools to control and manage the battery pack.