Battery Health Check

Most UPS use sealed lead acid (VRLA) batteries, and their typical service life is three to five years in a room held at 20 to 25 degrees. Lithium batteries commonly last eight to ten years, and flooded cells in large installations can run fifteen years or more. Temperature is the variable that changes the answer most, because every 10 degrees sustained above 25 roughly halves service life. The same batteries in a warm comms cupboard can be finished in half the time the invoice would suggest.

The four clearest signs are a runtime estimate that has dropped from what it used to be, a replace battery warning at any point even if it cleared itself, a failed self test, and an install date more than three years ago. None of them are conclusive on their own, because a UPS reports on the whole battery string rather than on individual blocks. A capacity or impedance test is the only way to confirm what the batteries will actually deliver under load. The battery health check above will tell you whether you are near that point.

Not reliably. A UPS self test puts a brief load on the battery and checks the voltage holds, which a tired battery can pass right up until it is asked for real runtime. That is why batteries are usually found to have failed during the outage rather than before it. The sites that do get a warning are the ones with a battery test on a maintenance schedule, or with the UPS reporting into remote monitoring so alarms land in front of a person instead of blinking in an empty room.

At least once a year for most sites, and every six months once the batteries are past three years old, the room runs warm, or the UPS supports something that cannot be interrupted. A battery test is normally done as part of a preventative maintenance visit rather than as a separate job, which is what makes it inexpensive compared with the failure it prevents.

A capacity test discharges the battery string into a controlled load and measures how long it holds voltage, which gives you the percentage of rated capacity still in it. An impedance test is the faster alternative: it measures the internal resistance of each block and flags the weak ones without taking the batteries offline. Impedance testing is what usually happens during a maintenance visit, because it is quick and non-disruptive. Capacity testing is what proves runtime, so it is the one to ask for when the number actually matters.

20 to 25 degrees. That is the range batteries are rated at and the range their published service life assumes, so it is the number worth designing the room around. Cooler is not better past a point, because low temperatures temporarily reduce the runtime a battery can deliver, but cold does not age the cells the way heat does. If the room cannot hold 25 degrees on a hot afternoon, the fix belongs in the room rather than in the battery budget. See cooling solutions.

Yes. UPS Solutions engineers test and replace batteries in any brand of UPS, including APC, Eaton and Vertiv units as well as our own ranges, across Australia, New Zealand and the Pacific Islands. Tell us the make, model and rating and we will quote the correct cells for it. You can also browse replacement batteries if you already know what you need.

It is driven by the number and type of cells, how they are packaged, how accessible the site is and whether the work happens in hours or after them, rather than by a list price per unit. A rack UPS with hot swap modules sits at one end of the range and a three phase unit with a full battery cabinet sits at the other. Send us the make, model and rating, along with the site, and we will quote it properly rather than give you a figure that changes on the day.

Usually not, but it depends on the unit. Many UPS are designed for battery replacement while the load stays up, either because the battery modules are hot swappable or because the unit can be put on maintenance bypass first. Some smaller single phase units need a short shutdown. Give us the make and model when you enquire and we will confirm which applies before anything is booked, so the answer is known well before anyone is on site.

On small units with hot swap battery modules, often yes, and the manual will say so. On anything larger we would not recommend it. A battery string carries a live DC voltage that is still present when the UPS is switched off, and it can deliver a very high short circuit current, so a dropped tool across two terminals is a serious event rather than a spark. Replacement cells also have to match in chemistry, capacity and age across the string, and mixing them shortens the life of the new set.

They go to a licensed recycler. Lead acid batteries are among the most recycled products in the world and they cannot go into general waste, so ask us to take the old set away when we quote the replacement and it is handled as part of the job. It is worth confirming this on any battery quote you receive, from us or from anyone else, because removal and disposal is sometimes left out of the price.

It costs nothing and it is indicative rather than definitive. The reading is calculated from the answers you give, using battery age adjusted for room temperature against the published service life for that battery type, then weighted for testing history, alarms and how often the UPS has run on battery. That is enough to tell you whether your batteries are healthy, worth watching or worth acting on, which is what most people need. It is not a substitute for an on site capacity or impedance test, which is the only way to confirm what a battery string will deliver under load.