Nick Williard, Wei He, Michael Osterman, and Michael Pecht
Center for Advanced Life Cycle Engineering (CALCE), University of Maryland, College Park, MD 20742, USA
Traditionally, capacity and resistance have been used as the features to determine the state of health of lithium-ion batteries. In the present study, two additional features, the length of time of the constant current and the constant voltage phases of charging were used as additional indicators of state of health. To compare the appropriateness of each state of health feature, batteries were subjected to different discharge profiles and tested to failure. For each cycle, capacity, resistance, length of the constant current charge time and length of the constant voltage charge time were measured and compared based on their usefulness to estimate the state of health. Lastly, all the features were combined to give a fusion result for state of health estimation.
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