UPS: What About Batteries?
An uninterruptible power supply can be a lifesaver when a power outage hits and the batteries kick in to help save data and equipment, but the power cells in a UPS arent like the batteries in a flashlight or radio.
Most UPS products on the market use sealed lead acid batteries, according to Falcon Electric Inc., a maker of UPS based in Irwindale, Calif. "These types of batteries can deliver a large amount of current if shorted, and as such can be very dangerous if not handled correctly," the companys Web site notes.
Underwriters Laboratories mandates voltage levels and standards under which U.S. manufacturers may allow end users to replace batteries themselves or have them replaced by trained service personnel, says Falcon. In either case, these batteries are considered toxic waste and their disposal is subject to federal, state and local laws.
How often should batteries be replaced? The answer may depend on what kind of UPS you purchase. According to John N. West, president of Power & Systems Innovations Inc., a power systems contractor based in Orlando, Fla., batteries in higher-priced online UPS typically last twice as long as those in lower-priced units.
"The battery typically lasts five-to-seven years," he explained. "With a standby unit, you get three years if youre lucky; line interactive will give you three-to-five years."
"We have UPS equipment in operating rooms on heart machines," said Michael A. Stout, engineering manager for Falcon Electric. "I tell them the batteries, although sealed, are still lead-acid technology. They can fail at any time, but typically they are good for three-to-five years. In a critical application, though, I would change batteries every two years."
Mr. Stout suggested a testing procedure to provide early warning about possible battery failure in a UPS. The user should develop a consistent test of the battery using something other than the computer system being protected. "Try it and time it on the battery," he noted. "Every month do a test the same way. When you get down below 20 percent of your original run time, replace your batteries."
He noted that some UPS units have battery test and warning indicators built in, but he warned that these may not be absolutely reliable. "Theyre reliable 50-to-75 percent of the time," he said. "The less expensive the UPS, the less reliable the circuit."
Extended battery packs are also available, but often not for less expensive UPS products, said Mr. Stout. "On most line interactive and all offline units, the converters are so cheap you cant use extended battery packs," he said. "The online units support addition of extended battery packs."
Reproduced from National Underwriter Property & Casualty/Risk & Benefits Management Edition, February 20, 2004. Copyright 2004 by The National Underwriter Company in the serial publication. All rights reserved.Copyright in this article as an independent work may be held by the author.
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