[Nut-upsuser] Questions about FSD (Fast Discharge)

Roger Price roger at rogerprice.org
Wed Apr 21 20:10:23 BST 2021

On Wed, 21 Apr 2021, Jey via Nut-upsuser wrote:

> Le 26/02/2021 à 23:29, Roger Price a écrit :
>       On Thu, 25 Feb 2021, Jey via Nut-upsuser wrote:
>             I use NUT on Home Assistant, the version of the add-on is 0.6.2. Home Assistant is installed on a Raspberry Pi 4b.
>             A have a APC 1400, the UPS is connected with USB to the Rasp.
>             I'm working to built an automation, to receive notifications when there is a power cut.
>             So I used OB DISCHRG (On battery discharge) to detect the power cut and trigger the automation.
>       It is sufficient to use OB.  Not all UPS's show DISCHARG
> Ok.
>             Then I use OB CHRG to detect that the power is coming back and the battery is charging.
>       It is better to use OL which says that you are receiving utility power, and therefore charging.
>             Then OL the normal operation, with a full battery.
>       OL should appear before battery.charge = 100%
> Nop, "OL" is coming when the battery is fully charged.

If you can show that the battery is indeed charging while the status is OB then 
you have found a bug in upsd.  I suggest reporting the bug with two upsc reprts 
taken say 10 minutes apart which demonstrate the problem.

>             In the same time I send notification to follow the % of battery (97 > 93 > 90 etc). It's working.
>       I assume you do this by monitoring variable battery.charge.
> Yes.
>             During my real test, the load was to light (3%, only a rasp pi), so it was slow to empty the battery. So I connected and started
>             my main PC, than the load was 18%.
>       If you want faster testing, you could also connect a 60W light bulb.
>             Then the battery fell to 48%, and instead to have OB DISCHRG, I had FSD OB DISCHRG (Fast Shutdown On Battery Discharge).

It is very surprising that there is no LB is the status.  Perhaps this is part 
of the same bug with the APS 1400. (Is this the Back UPS BX1400 ?).

FSD = Final shutdown.  It is set by upsmon to signal to all dependent systems 
that they should shot down.

>       What is the value of battery.charge.low in your setup?  It is surprising to see FSD appear with no LB status.  Do you have upsmon running? 
>       What is your system shutdown criterion in upsmon?  Do you rely on the built-in emergency shutdown on OB LB?
> I use Network UPS Tools, on Home Assistant (HASS.IO) on a Raspberry Pi 4.
> I don't see any "battery.charge.low"
> I don't know for UPSMON.

I don't understand.

What does command upsc <myups> report, where <myups> is the name you have given 
your UPS in file ups.conf.?

Do you have upsmon runnng?  What does command ps -elf | grep nut report?

>             Then I re-plugged the UPS to charge it.
>             And I was surprised to see FSD OL CHRG until the 100%.

So have you seen OL while the UPS was charging?

>       FSD is held fixed in upsd.  upsd does not turn it off, since it is assumed that there will be a system shutdown followed by a system restart
>       which clears ups.status.
>             Then, I had FSD OL, even everything was back and normal, and the battery fully charged.
>             I saw today, few days later, than now it's only OL (Online). I imagine that FSD disappeared after a reboot or when I disconnected
>             some USB cables.
>             So, I have some questions. I didn't find this kind of information on internet.
>              - please, could you explain why FSD is coming ? Is it depending of the load, or the % of battery?
>              - Why FSD didn't disappear when the current was back and the UPS was charging the battery or full?
>             - Is there a list of all "modes" that NUT can show? (because my automation didn't work any more when FSD appeared, so I would like
>             to know all modes).
>       What do you mean by "mode" ?  The possible status symbols, OL, OB, LB, ...?
> Yes, status.

Have a look at http://rogerprice.org/NUT/ConfigExamples.A5.pdf


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