UPS reports "battery exhausted" with 39 minutes left

[Rienk]

I recently bought a Back-UPS BX750MI as replacement of an old Smart-UPS. I'm running a Ubuntu server behind this UPS and monitor the UPS via a USB cable and the apcupsd daemon.

When fully charged, the UPS reports 100% battery charge, about 13% load and about 41 minutes runtime left.

Now I noticed that when there is a power failure, after about 3 minutes the server is stopped with the message 'battery exhausted'. Next time, I monitored the process a bit closure and noticed after power failure, the battery charge goes down normally, from 100% to 94% in around 3 minutes. In the same period, the time left goes down from 41 to 38 minutes. Exactly as expected. But around that time, suddenly apcupsd reports 'Battery exhausted' and shuts down the server.

Does anyone have a clue why the battery is reported as exhausted? I would expect it would run for at least another 30 minutes.

Some details from the UPS data attached

[Teken · Accepted solution]

Based on the information you have provided the most likely scenario is the system needs to be calibrated if the option is available.

Using APC Power Chute (PCPE / PCSS) manually initiate a battery calibration with 30% or greater load attached.

Once complete allow the system to recharge the RBC to 100% SOC. Repeat your test and relay the outcome.

I suggest you also compare how Power Chute operates vs APCUPSD in case there’s a problem / conflict.

You may also use NUT which is still being developed and supported vs the other isn’t.

Questions Ask . . . 👍

[Rienk]

Thanks, I'll give nut a try

[Rienk]

Nut is working better indeed. Still need to tune the notifications, but basic functionality is ok, after power failure, the system is stopped after about 40 minutes, leaving a few minutes/percentages in the battery.

[Teken]

That’s great to hear and appreciate the follow up.

Rock On . . . 🤟