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amlutoyesterday at 8:21 PM1 replyview on HN

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.


Replies

kube-systemyesterday at 9:44 PM

> > 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.

Yeah, but that doesn't mean you want to expose them to brownout conditions when your UPS is depleted. If the power is continuing to flip on and off, it's better to just leave it off if you don't have the battery to prevent even short interruptions. A good UPS can do this automatically for you. A cheap one will just stay off and let you respond to the outage.

> This is such a weird presumption.

It wasn't a presumption I was making for all users -- but an example of why some users might not want auto-restart as a feature. Of course, if you want auto-restart as a feature, you can buy a UPS that has it as a feature and turn it on.

> they don’t apply to most users, and I’m talking about smaller UPSes.

Yeah, I know the situation: Someone has a network closet on a budget with a UPS they've sized to get them a few minutes of runtime. They put a UPS on the BOM because it checks a box. So they buy a low-end UPS that either doesn't have the feature, or it doesn't work right.

The solution is just to buy the right UPS for the thing they were trying to do... and test it.