UPC designed for a desktop computer
I wasn’t really aware of this until a few years ago, but UPSes aren’t really generally designed to keep computers running through power outages. Even today, most still have lead-acid batteries (which have limited energy density and don’t deal well with being deeply discharged many times).
They were really designed to solve two problems:
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In a power outage, being able to shut a computer down cleanly. That means time to save documents and — back in the 1980s and 1990s — shut down cleanly, to avoid filesystem corruption, when commonly-used filesystems could become corrupt through not shutting down cleanly. They also often came with functionality to automatically shut down the computer cleanly when the UPS’s battery was getting low, if a human had not yet done so.
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If a generator that automatically comes online in an outage is present, keeping the computer running until the generate giving it time to come online.
This means that UPSes tend to have a pretty decent inverter, can put out a lot of power…but generally can’t store a whole lot of power. They also are guaranteed to come online quickly; I believe that it’s typically in under 20 ms, a blip that a computer power supply can handle.
To grab a random UPS:
https://www.amazon.com/APC-SmartConnect-Interactive-Uninterruptible-SMC1500C/dp/B077Y62GSJ
That runs $529. It has a 900W inverter.
It uses this battery, which is lead-acid 11Ah 12Vdc (so 132 Wh).
To grab a random power station of about the same price:
https://www.amazon.com/BLUETTI-Portable-Station-Generator-Off-grid/dp/B095Y6ZTR1
That’s $500, has an 800W inverter, but has 716Wh of battery storage, about 5.4 times what the UPS does. It also has an LiFePo4 battery, which will last a lot longer in terms of cycles and dealing with deep discharge than a lead-acid battery.
https://homegrail.com/how-many-watts-does-a-cpap-use/