I have an APC SmartUPS 1000 for my servers.

It was good for over 2 years, its capacity is always 5/5. One day I saw a red light illuminated. I searched for the reference it is either "Replace" Battery" or "Battery Disconnected". If that was battery disconnected, there should be a beep sound with it and it didn't beep, so I assume it is battery replace.

Battery should hold for 5 years from what I heard. This building has suffered electricity suspension and the server didn't shutdown in time so the battery is completely used once.

So I was curious what is going on, because the load is 1/5 and the capacity is 5/5. So I think the battery is still good until I pressed the "Self Test" button. Then the capacity suddenly dropped to 2/5 and the load is dropped to 0/5. And then I pressed it again, now the capacity is dropped to 1/5.

Why does it drop this much? Is the battery damaged or it is time to replace (i.e. The APC UPS is telling the truth)? Or, the APC UPS has a problem? The APC UPS is quite old though, over 7 years.

2 Answers 2


A battery can hold between 1 and 10 years. This depends on many factors like: battery lot, storage conditions, usage conditions.

If the capacity suddenly dropped to a very low value, it means the batteries need replacement.

Just order replacements and you should be fine.

  • 2
    I agree. I'm not sure why this is even a question: if your UPS says it needs fresh batteries, just give it fresh batteries.
    – MadHatter
    May 15, 2018 at 7:48
  • @MadHatter Why it isn't? Let me give you an example. If your iPhone suddenly shutdown while your battery status is 100%? And then you turn it on again and it says 3% left. What's in your mind? The battery? iOS or something else? Would you go to Apple store and find out? Similar to my situation. That's what I was thinking and then I post a question here. The APC itself is suspicious so I would like to clear up my mind. Question doesn't always needed to be "difficult to answer".
    – AkiEru
    May 15, 2018 at 13:35
  • 1
    Because an iphone is a consumer product, and a UPS is business-critical infrastructure. The two are not the same; you don't take the same risks with one as the other, and you don't use "home-brewed" investigative techniques with the latter. If the UPS thinks it needs a new battery, start by assuming it's correct, and give it one. If that doesn't cheer it up, get a properly-qualified technician in to service it. Behave like a professional.
    – MadHatter
    May 15, 2018 at 13:48
  • AkiEru, that's a classic case of bad battery. Also note that in the case of Li-Ion batteries, they may actually show a correct charge percentage (which is valid) but it may not provide sufficient current to power the device it was designed for, therefore causing it to shutdown even if the battery load is still high.
    – Overmind
    May 16, 2018 at 6:29

A damaged or worn-out battery may sometimes provide a good-looking voltage when idle, but be unable to provide anything like the specified amperage, so the voltage will drop as soon as the battery is placed under any significant load. The self-test does just that, very briefly.

Even though UPS batteries should be designed to handle deep discharges, a full discharge to exhaustion is going to be hard on them.

This battery will clearly fail if it's required to provide power again. Just replace it, and if the failed battery was still under warranty, perhaps it could be handled as a warranty replacement?

  • 2
    They are also a danger to the UPS. I had situation where due to faulty battery, the UPS fried. Someone insisted of using older batteries from a broken UPS.
    – Overmind
    May 15, 2018 at 8:05

Not the answer you're looking for? Browse other questions tagged .