APC Smart-UPS 1500 Battery Replacement

I am of the opinion, if you plan to have a desktop computer, and by that I mean a machine without a built in battery, you need to have a UPS or Uninterruptible Power Supply. I am of the belief, go as large as you can reasonably afford. Should you have a power interruption, your computer and equipment will thank you in the best way it knows how, by not turning off unexpectedly and corrupting your data.

I Received this used, APC Smart-UPS 1500 a few years back. They did work when I got them, not for long as the batteries failed. After building my workstation / server / desktop unit that I make do things all the time. I decided, after a power outage, it was time to investigate the failure and fix it. I was 99% sure that the batteries were dead as it was the “Replace Battery” light that was on.

Video montage of repair. It’s not very good…


Like in any repair of mine, I find that disassembling it first is the best way to go about it. I have had countless other projects that have gone wrong because I trusted online documentation and batteries for a UPS are never cheap. The first objective is to open it up. The tools required for this was just a crossed-recess (Phillips) screw driver. I opted for the battery operated driver because I am lazy.

Two screws on the front hold the battery compartment door shut.

After removing the batteries, I was completely certain that they were dead as the multi-meter made that very clear.

Search for Batteries

My initial search for batteries lead me to realize that this was not going to be a cheap repair. My local supplier of batteries had them listed at $54.00 each. Others I found all were comparably as expensive.

Then I stumbled upon a site called BatterySharks.com that had these batteries for sale $48.00… for a pair. For a pair! I double checked the specs from the old batteries to the new batteries and I completed the order.

I can’t guarantee that the prices will stay so low but was certainly a fantastic deal. Shipping wasn’t too bad, another $24.59 which brought the grand total to $72.55. I was thinking, however, I am making a $72 gamble that there isn’t anything else wrong with this UPS.


It didn’t take long for the batteries to arrive. The rather weighty package landing with a thud on my front porch signaled it had arrived. The actual installation was really quite simple. Just a reversal of disassembly. Installing the terminal connections, reinstalling the protective terminal caps, I used a little double sided sticky tape to hold them together like the originals (and thinking about it, totally unnecessary), and screwed it back together. Extremely basic.

I did clean up the corrosion with white vinegar just to be sure that there wouldn’t be any issues from the old battery acid that leaked.


After assembling it, it was time to do the initial “smoke test” to make sure that I didn’t mess anything up. Sure enough, I turned it on and an incredibly uneventful yet thrilling beep followed that meant, all was well and ready to be used. I did want to do some testing.

This included using a laptop hooked up to see that when the grid power was removed from the UPS, that it would continue kicking out uninterrupted power. Upon removal of the power, a clunk with a 60 hz hum sound coupled with an alarming “beep” to signal the loss of power and sure enough, just like its name, the power to my computer was uninterrupted.

I let it sit a while so I could watch to see the battery charge meter climb while it remained plugged into the mains. Since it all seemingly worked well so I shut down my server, router/firewall, access point and switch to plug it into the UPS. The load indicator was fluctuating between 1 and 3 bars out of 5 while I was standing there and monitoring it for a while. That was good news as it is well within the limits of this newly repaired but well aged device.

Power Loss

Within a week of installing this newly finished UPS system, the power went out at my house. The server, and network equipment kept chugging along and the battery charge held surprisingly well. Since I was using my laptop, I could still access all things on the server, wirelessly, though I was unsure as to how long it would hold out. After about 40 minutes or so, I thought I should probably start shutting things down nicely. I checked the display and I still had plenty of battery to go so I left it and within 20 minutes of that, the power was restored.

The timing of this repair couldn’t have been better…

Final Thoughts

This was one of those projects that was well worth the time and effort. I do know that I can connect this UPS up to a computer and have it do things but I really am not sure what. I think I need to start playing with the power awareness features so I can figure out how to safely shut down my server and Firewall safely should power levels get low.

Buying a new UPS can be quite expensive. Repairing a used one is much more affordable and also, a better choice for reducing e-waste. Hopefully, this little writeup and crap-tastic video will give someone just enough courage to try it out themselves.


APC.com UPS manufacturer website

6 thoughts on “APC Smart-UPS 1500 Battery Replacement

  1. Interesting: I’m pretty sure that were I live there was not a single grid-caused power outage last year — at least none that was longer than ~0.5 seconds so that the PSU of my workstation could not handle it. Also, I cannot remember any that was longer than 15 minutes within the last 20 years. I suppose that a too reliable power grid takes some nerdy fun away… 😉

    1. Where I live, we have tall trees and “fun” wind storms from time to time. Generally, a power loss is due to a tree that gave up.

      Thank you for sharing your thoughts!

      1. We also regularly have storms, floods and all the other fun sh**, so the power lines are generally buried or — for most high-voltage lines — trees are cleared around them.

  2. Hello there Nate
    Thanks for your guide!

    One question though – when searching for batteries (locally, not from the USA or Canada myself) – do the terminals have to be like in the video / photos – on each side?
    What if they are both on the same side, can i use a pair or two then?

    Photo of what i mean => https://2.grgs.ro/images/products/1/1409094/1520010/full/hr1234wf2-12v-34w-b586a30983503cec5d9f96ad5d881a8c.jpg

    Thanks for your input

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