UPS batteries are critical to the proper operation of an uninterruptible power supply and the continuity of protected loads, yet they are frequently overlooked. Despite the necessity of UPS batteries for delivering runtime and dc power to the inverter in the case of a power outage, periodic tests and maintenance are frequently neglected, which is not a good practise. The UPS battery’s capacity to keep a charge is critical for proper operation when it is needed, and this will be jeopardised if it is not properly maintained.

The UPS battery of today. Modern sealed lead-acid UPS batteries have a design life of five to ten years (depending upon their size). However, UPS battery systems often have built-in automated testing, regardless of the design life. This may be set to happen every 24 hours, triggered by a push-button or keypad on the front panel, or activated remotely through a network connection. The fundamental difference between UPS batteries with differing design lifetimes, aside from performance, is cost.

Controlling the temperature is critical. Because a UPS battery works through a chemical process, its efficiency degrades with age, condition, and environment. Failures are most common between years three and four of a five-year UPS battery. All UPS batteries, regardless of age, should be inspected for corrosion, discharge, and wear on a regular basis.

Temperature is the most essential aspect in extending the life of UPS batteries; the optimum is a constant 20-25 °C (UPS battery life is halved for every five degrees above or below that). A UPS and UPS battery set (especially those used in congested data centres) frequently require an adequate cooling system to sustain this, which is another element to consider during specification.

Electrical load (measured in kW) and the length of backup time necessary during a power loss determine the size of UPS battery. Most UPSs supply roughly 10 minutes of backup power, which is enough to cover most power outages, ride through until the generator kicks in, and securely shut down non-critical loads. Additional battery packs or strings, a backup generator, or a redundant UPS can all be used to extend operating duration.

UPS batteries with flooded cells. Flooded cell UPS batteries placed in open frame racks may be utilised in larger UPS installations (usually above 500kVA). These require authorised and qualified workers to assemble, install, and commission battery racks on-site. Because flooded cell UPS batteries continually release gases, they must be placed in specific UPS battery rooms with spill containment and controlled access. Inspection of the electrolyte and battery plates, as well as measurement and recording of the electrolyte specific gravity and water replenishment, are all required on a regular basis.

For a longer UPS battery life, a good design and frequent maintenance are required. One method a UPS design may preserve its battery set is to make sure the rectifier or charger has low alternating current (AC) ripple, which is an AC element superimposed over a rectifier’s or battery charger’s direct current output waveform. A strong ac ripple can hasten the corrosion of the positive plate and diminish battery life; it can also raise battery temperature, shortening UPS battery life.

Finally, proper design, routine maintenance, and knowledge of battery care concepts can help you get the best performance and service life out of your UPS batteries. Leading UPS manufacturers and resellers, of course, offer this guidance as part of their service.