Configure UPS to shut off power if load is below a threshold while on battery

CyberShadow · ‎2022-11-02

Hi,

I think this is a common problem for home servers. We want a combination of these two:

1. Computer shuts down safely when the AC goes out

2. Computer turns back online when AC comes back on

For 1 the solution is simple - connect USB, install and configure software/OS.

2 is mostly accomplished by configuring power in BIOS to "Always On".

However, there is a problem. If the AC power comes back before the UPS discharges completely, the PC stays off! From its perspective, the power never went away, so it doesn't know when it's OK to turn back on.

I'm thinking one simple way to do this is to tell the UPS that if load is below some threshold (e.g. < 20W) and there is no AC power then to turn it off completely. The PC motherboard will then completely lose power after shutting down gracefully. When the AC comes back online, the UPS will start providing power to the PC again, and it will turn on according to the BIOS setting.

So, I'm wondering if there's a way to tell the UPS: "If you're on battery power, and the load is below 20W, then turn off output power until AC comes back on". Is it possible?

Another way would be to maybe send a delayed command to the UPS right before the PC shuts down. Something like "After 30 seconds, turn output power off completely, and only turn it back on when the AC power comes online". Is it possible?

Thanks!

JonPro · ‎2022-11-04

Hi @CyberShadow

Thank you for reaching out to the SE Community, my name is Jon and I will assist you with this query. Most of our customers would shut down their servers using these criteria.

When the UPS has reached a low battery.
When the UPS has been on battery for X seconds or minutes.
When the UPS runtime falls below the set threshold.

If our software is installed on the servers, it will shut down the PC and depending on the settings would then turn off the UPS thus cutting power to the BIOS/motherboard and when power returns it will then turn on the UPS and if the BIOS is configured correctly, it will detect that there was a change of state.