For those of you own, utilize, depend on, or are responsible for an Uninterruptible Power Supply (UPS), let me strongly recommend that you either have a vendor check the internal batteries at least once a year.
Why ,you ask? Well despite looking at the indicator lights on the outside of the UPS and seeing that it is properly charging, there is a lot about batteries that you cannot easily detect without visually inspecting the batteries. Most, if not all, UPS systems have the batteries mounted inside a metal housing preventing a casual glance.
Ever paid much attention to a car battery? UPS batteries have a lot in common with automotive batteries in that after many charge cycles, they will begin to fail. One of the external signs you can detect just by looking is that the plastic casing of the battery swells and becomes deformed.
Sorry the picture is not my best, but yes, that battery has a big lump on the top side. And yes, that is one of several the service technician found while performing a visual inspection of the internal batteries in a moderate sized UPS system. A battery that has deformed like that has become unstable and undependable. A more dramatic failure is on the way.
Another item of concern that only a visual inspection will provide is corroded terminals.
Yes, that is one of about 16 batteries inside one external battery cabinet for a UPS system, and that is what the service technician found when he opened the cabinet to visually inspect the batteries. The corrosion was so severe that the battery post had separated from the battery itself but was still bolted tightly to the battery cable.
How much power would that provide in the event utility power was lost and your computer room or dispatch center were to flip over to the UPS system for power?
Leaking battery acid is another item that can be found during a visual inspection of internal batteries. Most UPS systems have a drip tray under the battery racks to prevent battery acid from reaching the floor of an equipment room or computer room, so you will not see it if the cover stays in place.
UPS battery maintenance has to be one of the most overlooked items in the technology arena. For some reason a lot of people have a mistaken notion that they can purchase the UPS, have it installed, and forget about it. We all know that does not work with car batteries. They usually die somewhere between 3 and 5 years. Well, guess what? Yup, UPS batteries have a 3 to 5 yr expected life span as well.
Over the years, I have observed some of the pitfalls of overlooking UPS battery maintenance. A few years ago, I was working in a work room just outside a computer center in a large company's IT department and noticed a strong "rotten egg" smell. I followed the smell to its source, the UPS system. I ran my hand along the metal enclosure and half way along the side found a very warm spot. I called the situation to the attention of the computer room operations staff. They called the UPS service provider who quickly dispatched a technician. When the technician opened the enclosure, he found a battery that had swollen, then cracked its plastic housing and was boiling battery acid across the battery rack where it was located.
I have also heard about a 30-story building that was evacuated because of a very bad "rotten egg" smell on all floors. Another UPS system with some swollen and leaking batteries was really close to an HVAC system's return. The "rotten egg" smell was sucked into the HVAC and pumped to every floor of the building. The Fire Department and Emergency Services were in full force when the UPS technician opened the enclosure to see what he had to clean up.
So, avoid the potential hazards that can result from leaking batteries and avoid the hazard of your UPS system not being ready to keep your equipment up and running should utility power fail. Annual battery inspection/maintenance is the only answer.