[smolder]

UPSs are never really cheap, since when converting AC to DC to AC you lose a significant amount of power efficiency for your equipment. The funny part is the server PSU then converts back to DC power yet again. My understanding is that well optimized data centers distribute conditioned, battery backed DC power directly to devices to avoid those double conversion losses.

[zrm]

A small UPS will often have the equipment running directly on AC input power and only switch to the battery if the input power fails.

[smolder]

Oh, thanks for the correction. It seems I forgot that type existed or just never knew. Now I'm curious about the relative merits. I'd guess the transition is not as smooth and presents some kind of a risk that's unacceptable for critical infra.

[agapon]

The terms that describe those types are Line-interactive and On-line UPS.

E.g., https://blog.tripplite.com/line-interactive-vs-on-line-ups-s...

[tuatoru]

It'd be good if consumer UPSes had DC output for this reason. If only laptops could be standardized in terms of voltage requirements.

A lot of them are pretty similar; 19V - 21V seems quite common.

Until recently phones were standardized on 5V. Now, it's a mess again. :-(

[smolder]

I vaguely recall seeing someone modify their UPS for this in their "homelab", such that they were running a 12v cable modem, router and WAP off of the UPS battery pack directly somehow. They had dramatically longer run time from a full charge. (Well more than double, I think.)

[yencabulator]

Ooh, imagine a NUC or such small enough machine running off of USB-C Power Delivery. 65 Watt power budget easily. I guess a Raspberry Pi would count as that?

Then a battery pack could provide that, as DC.