The experience of a UPS company in advanced battery monitoring

Abstract

With the merging of computer telecommunication technologies, and multimedia, uninterruptible power supplies (UPS), already widely used to protect the computer networks and to guarantee service continuity to their users, should certainly be viewed as a reliable and cost effective solution to assure protection and battery back up to telecommunication infrastructure, private, or public. Mission critical applications for battery systems need reliable and accurate measurement of battery capacity particularly with UPS. This paper explores the unique, patented approach used at Merlin Gerin to provide battery monitoring with high accuracy in the standard metering of our newest UPS products. At Merlin Gerin we found that an increasing number of our customers want to know the battery status and time available, and prefer alarms when the autonomy falls below acceptable limits or when batteries need to be changed. When designing our latest generation of UPS products, we recognized these needs, and embarked on designing a system which would provide the answer. Our challenge was not simply to predict battery capacity for a given static load, but to do, so with good accuracy for dynamic loads and different battery temperatures. Further we wanted to take into account the aging effects of the battery and work toward a method of failure detection, and prediction. The result is a unique approach that models internal battery resistance and capacity to predict backup time and life expectancy.