On December 20, 2009, the public airport in Anchorage, Alaska, lost their radar and guidance systems. The cause was tracked to the UPS system that was designed to provide "hot" backup in the event of a power failure until a generator could be brought on line. However, because the batteries were old, the charge gave out and shut down the system before the generator could be turned on. To compound the matter, the generator shut down when it ran out of fuel, causing a second outage to the unprotected systems. Fortunately, it was a Sunday morning and traffic was light.
This incident is an excellent reminder that any UPS is only as good as the batteries that back it up. In a business environment failure costs time and money. In government or public applications, it may literally be a matter of life and death.
Most UPS batteries are designed to function for 3-5 years, but many factors can affect optimal charging and performance. Extremes of temperature or frequent use (discharging and recharging) can shorten the useful lifespan of batteries, and older batteries typically will have shorter runtimes than new fresh cells.
Generally speaking it's a good idea to test your batteries at least once per month. Some UPS units will do this automatically and create an alarm, others require a manual test. In any case, being sure you have good batteries means you can rely on your UPS in an emergency. |
