Battery Power - November/December 2013 - (Page 14)

Feature Understanding When and Why You Need UPS Battery Replacement Gregory Ratcliff, Director of Life Cycle Management Services Emerson Network Power, Liebert Services μOhms seen at installation. In order to capture the true baseline of the replacement battery, a stationary instrument is required. As organizations become increasingly dependent on data center systems, there is a need for greater reliability in the critical power system. For many organizations, the IT infrastructure has evolved into an interdependent business-critical network that includes data, applications, storage, servers and networking. A power failure at any point along the network can impact the entire operation and have serious consequences for the business. In most cases, the ability to keep critical systems running through power outages, sags, brownouts, utility spikes or other unforeseeable power issues is dependent on the reliability of the Uninterruptible Power Supply (UPS) system. However, the UPS system is only as reliable as the batteries that support it. A recent study by Emerson Network Power, Liebert Services on real-world results of Valve-Regulated Lead-Acid (VRLA) batteries in the UPS environment along with the company's field experience, has revealed the following three battery performance realities. 1. Battery life cycles vary far too much to rely on manufacturer's published life spans and initial resistance baseline data. In order to get the most accurate resistance baseline measurements of the thousands of VRLA batteries in the study, Liebert Services chose to use stationary resistance instruments. Battery voltage-type monitors are an alternative popular methodology, as are float-current and temperature-only monitors that may be installed for alarming purposes. However, these systems do not provide an indication of battery health in UPS, highvoltage, high-unit-count implementations. For the study, the alarm-based systems were considered unsuitable for increasing availability, while resistance methods provided an indicator of battery state of health data, particularly when data was compared over the full lifetime of a given unit and compared against an initial baseline. The stationary instruments were a necessity due to inexpensively increase the frequency of measurement and the high degree of repeatability they afforded. It was important to capture very accurate unit-specific, situation-specific baseline resistance and periodic resistance readings. What Liebert Services found during the analysis is that initial baseline consideration should begin 90 days after installation. When a new battery is replaced due to premature failure or cause, often the initial change in resistance will be downward and then remain constant. Figure 1 details an example of a battery change-out occurring after 600 days of life. Note that this battery's initial baseline resistance will likely settle near 5250 μOhms, instead of at 5650 14 Battery Power * November/December 2013 Figure 1. Trending results that are typical for 70 ampere-hour VRLA batteries. This result was seen with many battery units and has caused Liebert Services to reject manufacturer-provided baselines. We found that when a specific unit settles to its running baseline, the initial variance from the manufacturer's baselines could be as much as 25 percent. To effectively alert our customers to imminent battery failure, we recommend they closely monitor

Table of Contents for the Digital Edition of Battery Power - November/December 2013

Solid-State Battery Developed at CU-Boulder Could Double the Range of Electric Cars
GS Yuasa Batteries Help Power Orbital Science’s Cygnus Spacecraft on Mission to ISS
Li-Ion Battery Technology Delivers High Power for Data Center UPS Installations
Battery Demands for Yesterday, Today and Tomorrow
Understanding When and Why You Need UPS Battery Replacement
Charging Forward: A Resurgence of the EV Movement and the Role Charging Infrastructure Plays in Continuing the Momentum
Charging Systems
Testing & Monitoring
ICs & Semiconductors
Industry News

Battery Power - November/December 2013