Researchers at Penn State University are trying to prolong the life of valve regulated lead-acid batteries by reducing sulfation. The study focussed upon reducing the degradation of the battery caused by the accumulation of suphur during charging and discharging.
The research examined methods to improve the battery management system that would reduce over-charging and discharging. The methods had to be simple, cost effective and non-destructive.
A lead-acid battery was cycled for three months to identify what made it age in real-time. Professor of mechanical engineering Christopher Rahn, who led the study, used electroimpedance spectroscopy as well as charging and discharging to highlight the most common aging mechanisms and identified sulfation in the cells as a cause of problems.
The research team, including mechanical engineering research assistants Ying Shi and Christopher Ferone, designed a charging procedure to reduce sulfation while charging the battery. It also ensured charging was stopped before degradation occurred. This procedure increased cell capacity by 41%, thus improving performance of the whole system.
The team is now developing a model to replace the electroimpedance spectroscopy model for batteries that are not yet subject to sulfation to prevent it from ever developing.
Penn State University works with railway company Norfolk Southern to research and evaluate the use of batteries in railroad motive power applications. This latest study, funded by the DoE, cycled the cells as they would be used in a locomotive.