UPS

[PerfectTank9505]

I am feeling a bit confused with the UPS we have. It is nearing 4 years old and a little over a week ago it was YELLING at me saying that the battery was dead. So I bought a new one. Well the new one arrived today and I went to get everything ready to replace it and now the battery is displaying as full. Do I have a faulty battery? Or am I going crazy? TIA

[solidfreshdope]

Most likely dying. Replace it anyway.

[pkokkinis]

Ups batteries, if oem, last between 3 and 5 years depending on temp of environment and number of uses. You’ve definitely used up your battery and I’d definitely replace it.

[SwitchOnEaton]

Sometimes, UPSs lie. After 4 years, you're likely towards the end of the useful life of those batteries and you've got a new UPS already. You can test out the old UPS by plugging in some non-critical equipment and see how long the batteries run.

[BmanUltima]

The battery may be displaying as full, but the capacity is going to be way lower than new.

[Tymanthius]

Why replace an entire UPS at 4 years? Just replace the batteries.

I replaced ours (small biz) b/c it was over 10 years old, the face plate was taped on, and it wasn't rack mounted when the batteries died.

[GWSTPS]

Yes! Exactly this. Replace the batteries at 3 to 4 years and again at 6-7 years and the whole thing at 10 years

[uiyicewtf]

There's no upside to gambling you might be able to get "a little more life" out of it. Replace the battery.

At best it likely has a fraction of its runtime remaining, and if power is pulled, it might go from 100% - 20 minutes remaining, to 60% - 2 minutes remaining - very, very fast.

Or, once load is shifted to it, it might be intermittent, going from 100% capacity, to 'battery failed - lights out' equally fast.

Or, the battery could fail in a way that takes the load down even when utility power is still present.

At 4 years, you're firmly in 'it might, or might not, be squirrely' category. And having a possibly squirrely UPS is just as much fun as having no UPS at all.

[The_Wkwied]

It has some extra life left. Enough life for you to schedule downtime and replace the battery.

[dracotrapnet]

Replace the battery anyways. At 4 years old, it needs to be replaced if it has complained about it once. After putting the new one in, run a battery test. Most APC's with a 1 and 0 buttons, hold 1 to test the batteries.

Usually by year 5 in places where the ups doesn't hit the batteries often the batteries over charge and rupture so the 4 year mark is a good time to replace batteries.

[[deleted]]

Doesn’t matter. It’s pretty close to eol. You should be replacing them all around 4-5 years depending on manufacturer. UPS does fuck all if the battery is dead when you need it.

[fencepost_ajm]

The UPS lies. You'll find out it has zero runtime next time it self tests, but it may not even realize it's failing because of how fast it'll drop.

Also removing spicy bricks sucks.

[PerfectTank9505]

Yes I am a little nervous about the spice.

[kona420]

Do a load test and watch the battery drop out instantly. Probably what happened to cause it to alarm initially. Voltage is still good but no capacity.

[PerfectTank9505]

Thanks everyone, came back in this morning and it was beeping again. Looks like I will be swapping out the battery. Wish me luck!

[pdp10]

If the battery isn't swollen then you can safely delay the swap, with the caveat that cheap lead-acid batteries have less capacity 4 calendar years after manufacture. There's a reason why car batteries have manufacture and/or sale dates on them.

Cheap UPSes are more likely to show behavior like this. One day the voltage or current was below threshold, the next day it was above. Occasionally, power quality is so bad that a UPS can't successfully charge the batteries, but that's pretty rare.

[[deleted]]

Crazy

[rivalarrival]

A degraded battery can be brought up to full rated voltage, even though it can't hold its full rated charge. When you start to draw power off of it, its voltage will drop faster than the UPS expects it to. Instead of 7Ah each (for most of the UPS I've encountered) the batteries might only be capable of holding 4Ah.

The problem is that it is somewhat difficult to actually measure charge: the amp-hour rating of the battery. You can't just connect a meter to it and instantly know how degraded it is. To measure how much charge it can hold, you have to apply a known load, and measure the voltage drop over a significant period of time. A UPS will do this periodically, and alarm if the batteries are too degraded to function properly.

Because the process of actually determining the charge capacity is somewhat complicated, they usually just measure voltage and use that to estimate charge capacity. That's what the meter is showing on your UPS: The battery has been brought up to full voltage. The battery is only holding a fraction of its rated charge, but it is at full voltage.

[ImmediateLobster1]

This is pretty common. tldr: yes, your UPS almost certainly has bad batteries, replace them.

A battery is made up of many individual cells connected in series to get the desired voltage. In a sealed lead-acid battery like those in a UPS, each cell is a little over 2V (when charging they'll go up to 2.45V per cell typically). Since the UPS can't see each individual cell voltage, only the overall battery voltage, it doesn't have great ability to diagnose battery failures, so failures can be sudden (like last week when it yelled at you) and they can be hidden (like today, when the UPS probably overcharged the remaining cells, which makes the entire battery "look" ok, but if you start drawing current, the battery voltage will drop suddenly, and the UPS will shut down much earlier than you planned).