What are the most common UPS faults?

Most faults share a common root: temperature and battery wear. Lead-acid batteries are a consumable part and usually need replacing every 3–5 years, depending on temperature and use. In a hot room their life is significantly shorter. Signs of wear include reduced runtime, a failed self-test, a replace-battery alarm or a swollen battery case.

Poor cooling is usually caused by dust in the fans, blocked vents or installation in a closed cabinet. OverloadGlossary · Protection and installationOverloadA condition where the connected load exceeds the UPS’s rated output in VA or W. often happens when devices that do not need protection and draw high current, such as laser printers or heaters, are plugged into the UPS. Out-of-spec input voltage, from surges or an unstable grid, stresses the electronics and forces the UPS to switch to battery often. Fans and capacitors also wear out over the years.

Practical tip: many of these faults can be prevented with regular checks, a clean and cool room, and a load that does not permanently exceed 80% of the rated capacity. A common mistake is ignoring audible alarms, which usually warn of the problem before it turns into a failure.