alt Hacker NewsI completely agree with B. But alas, people love buying shitty cheap UPSes.
But A is along the lines of the misconception that I'm referring to... There should be no such thing as "the power being out too long for your UPS". A UPS isn't there to give you a little while to ignore the problem, it's there to give you time to address it. Either by switching to another source of power, or to power off the equipment.
Now, the reason that every UPS that supports auto-restart has it as a configurable option, is because you often don't want to do this for many reasons, e.g.:
* a low SOC battery could not guarantee a minimum runtime for safe shutdown during a repeated outage
* a catastrophic failure (because the battery shouldn't be dead) could be an indication of other issues that need to be addressed before power on
* powering on the equipment may require staggering to prevent inrush current overload
The whole use case of "I'm using the UPS to run my equipment during an outage" is kind of an abuse of their purpose. It's commonly done, and I've done it myself. But it's not what they're for.
But also, if you want a UPS that auto-restarts -- they exist -- but you get what you pay for.
Some of these is IMO a bit silly:
> a low SOC battery could not guarantee a minimum runtime for safe shutdown during a repeated outage
A lot of devices are unconditionally safe to shut down. Think network equipment, signs, exit lights, and well designed computers.
> a catastrophic failure (because the battery shouldn't be dead) could be an indication of other issues that need to be addressed before power on
This is such a weird presumption. Power outages happen. Long power outages happen. Fancy management software that triggers a controlled shutdown when the SOC is low might still leave nonzero remaining load. In fact, if you have a load that uses a UPS to trigger a controlled shutdown, it’s almost definitional that a controlled shutdown is not a catastrophe and that the system should turn back on eventually.
All of your points are valid for serious datacenter gear and even for large server closets, but for small systems I think they don’t apply to most users, and I’m talking about smaller UPSes.