Charging strategies for VRLA batteries in standby applications

Valve-regulated lead-acid (VRLA) batteries have replaced their flooded analogs in many applications and in fields such as telecom they have allowed for completely new concepts in battery use such as distributed power. Because of their versatility and ruggedness, they have been placed in harsh field environments compared to the traditional battery rooms previously employed by telecom users; similar changes have also occurred in other standby applications such as UPS. In spite of the differences between flooded and VRLA products, charging approaches have been largely unchanged. This causes serious problems for both positive and negative plates in VRLA batteries. This paper explores this situation and ends with a recommendation for radically new approaches to charging VRLA batteries, approaches that address the unique requirements of this new technology.