APC “By Schneider Electric” BX1500M model.
Was sitting here dealing with some financial stuff, and the local power goes out. In Florida it worked perfectly. This time however both the PC and the monitor switched off even tho they are hooked up to the thing, and it insists that it has 143 minutes of power available.
???
How old is it? I believe batteries go bad after a few years.
NM, peering at the back there are 2 plug slots, one for “backup” one for “surge” protection-my devices were connected to the latter. Only relevant question remaining is why these two functions aren’t combined into one. 
There are two different plugs so you can prioritize which one gets power so the battery lasts the longest. You should only have your computer attached to the backup plug since that’s the device which you want to stay up the longest. It doesn’t matter if the monitor loses power since there’s no data in it.
What you might want to do is have a power strip go into the backup plug so that you can plug the monitor in there during a power outage if you need it. If you plug your computer straight into the backup plug, you won’t be able to power up your monitor since the backup plug is used by the computer. Normally have the monitor plugged into the surge protection plug. If the power goes out, switch the monitor to the power strip so you can save your work and shut down the computer.
I’ve got a BR1500MS2 by the same company, and it depends on where you plug things into it, as far as what it does is concerned. It’s got two rows of plugs - one is just surge protected, and the other is full UPS power. Maybe you got them mixed up and plugged them into the surge protector side by mistake?
That aside, it’s easy to verify that it works or not- just fire up the PC and monitor and pull the plug to the UPS. That’ll simulate a failover, and your PC/monitor will keep on chugging with the PowerChute software sounding an alarm, or it won’t work.
The battery backup lasts longer if it doesn’t have to work as hard.
If you have a home office set up and have a printer or a desk lamp or some phone chargers plugged in or maybe a 2nd monitor or anything else, you may not care or need to have them on battery power and buy yourself a few more minutes to properly power down your critical gear.
Same principle as backup generators for the house. If you only need it for a space heater or a refrigerator and some lights, you don’t need as big a unit compared to wanting your whole house A/C to stay running.
Said another way, you must a) read the manual, and b) be smarter than your tools.
Failing at either of those basics will result in predictably craptacular performance.
To make it explicit …
All the outlets are surge-protected. Only some are UPS-battery protected. Which is a reasonable compromise between price and capability.
Replace the battery every two years.
I came into our office early and it was filled with a hazy and stinky smoke. I called our public safety office and they came to investigate.
I thought we had a electrical fire. Instead it was the UPS on our server releasing very noxious fumes. The UPS case was hot.
My boss signed a purchase order to replace all the staff UPS batteries. It was quite a job for me to crawl under the desks and write down the model. I looked up compatible batteries. I spent a Saturday installing them. I remember finding two warm batteries that hadn’t spewed gasses yet.
The server UPS worked several more years with its new battery.
We’ve had UPS batteries (the big ones below networking equipment) that started to bulge, so that even removing them to replace them was not easy.
I had that same bulging problem on a large UPS battery pack once. Ended up having to replace the entire UPS unit; that battery was not going to come out without destroying the UPS case.
Kinda scary. Much more so with the latest very high energy-density batteries.
They’re sealed lead-acid batteries, I’m not sure how many new developments are there compared to “sexy” batteries like LiON.
For OP or anyone wanting to replace batteries, make sure you recycle them, and Best Buy or Staples will take them at the customer service desk for free.
Battery failure is an obvious cause for an UPS to fall down at its job, but I found another potential factor.
I have two computers with identical UPSs, but one wasn’t doing the job.
I found a setting in the UPS that controls how sensitive the UPS is. The UPS that was working was set to maximum sensitivy, and the one that wasn’t was set to medium sensitivity. So the power hits we were taking weren’t bad enough for the one UPS to treat seriously and effect a transfer to battery, but serious enough to crash the computer.
I set that UPS’s sensitivity to max and both computers survive the same power failures.
I’ve never heard of a lead acid battery expanding and getting hot. That’s the signature of a lithium ion battery. I wouldn’t want a Lithium battery battery in my house or office.
I’ve had sealed lead-acids swell. As to Li-ion, if you have a phone, tablet, laptop, e-cig, or darn near any modern electric or electronic small gizmo, you have one of those batteries in your house already.
Yes, bigger is potentially worse. But you’re (almost certainly) not a virgin, so we’re just discussing degree of pregnant-ness.
Yes, phones and laptops have Lithium batteries but they generally use better material and are built to a higher standard.
I’ve had numerous bad experiences with Lithium batteries such as motorcycle batteries in just a few years of use. I’m done with them. In 50 years of using lead acid batteries I’ve never had a whisper of an issue and that includes crossing the leads of a car battery and vaporizing a chunk out of the terminal.
For backup batteries for my cpap machine I use lead acid batteries.