Factors That Contribute to UPS Battery Failure

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Although the Uninterruptible Power Supply (UPS) is designed to help keep your systems running even after a power cut, lack of proper servicing can cause them to fail – this increases the risk of data loss, among others. UPS battery failure is one of the most common problems everyone needs to watch out for. Unknown to many, even a new UPS battery can fail several months after installation. Understanding the factors that cause the UPS battery to fail can, however, help you take the proper measures to prevent the same. Feel free to contact us for more information on this or on data centre design.

Open circuit (due to cell dry out) is the most common failure modes for VRLA Batteries. Many UPS systems have batteries connected in SERIES to help provide HIGH current to the System’s DC bus line. Should one of these batteries fail, the current string is broken, compromising the UPS systems integrity.


Temperature variation contributes greatly to battery failure. A lead-acid UPS battery, for example, can only perform optimally at around 22 to 25 degrees Celsius. Anything higher or lower than that only reduces its performance as well as its battery life. Temperatures below 22 degrees, for example, will cause the battery to underperform while higher than 25 degrees lead to increased battery capacity but reduced life. It is also worth noting that every 8 degrees Celsius rise in temperature cuts the battery life by half. To help you understand this better, UPS batteries running at 35 degrees Celsius are doomed to only last half the expected life.

Empty Batteries

Batteries, like everything else, can only last so long. Your UPS batteries will continue losing their ability to store and deliver the desired amount of power with time, hence ultimately require replacing.

UPS Battery Discharge Cycle

The number of discharge and recharge cycles has a direct impact on a battery’s life too. Each recharge and discharge lower the batteries life even farther. That said, discharging your batteries constantly will only cause them to ‘dry out’ even before reaching their life expectancy. Even the shortest UPS bursts when compensating for sags and swells in the line do have an impact on the UPS life.

You can however improve the battery life by scheduling regular preventative maintenance such as voltage testing, visual inspection, retesting the battery terminal connection torque, as well as thermal image scans. Any irregularities with these will help you determine how long the batteries will last, and if it is time for replacements.

Calling for regular preventative maintenance and servicing can help detect issues that could cause the battery to fail. This is in addition to removing corrosion on terminals and ensuring the connections are correctly done.


It is by taking proper care of your UPS batteries that you can squeeze as much life as possible from them. UPS maintenance health checks and preventative maintenance are all that is required to ensure the UPS system is performing optimally, thus reduced risk of battery failure. The batteries provide ‘juice’ to the entire system when there’s a power failure. Ensuring they are in the best condition possible thus reduces the risk of data loss, among other power-related issues.