[Nut-upsuser] Low battery unexpected shutdown

[Roger Price]

On Thu, 23 Apr 2020, Marc Franquesa wrote:

> ...this email reports:
> 
> Power ups UPSdevice battery-low notification
> UPS:         UPSdevice at power.srv.l3jane.net
> Notice type: LOWBATT
> Message:     battery-low
> Sun, 19 Apr 2020 12:10:27 +0200
> 
> Charge                    73%
> Charge Low                20%
> Runtime                   15m52s
> ...
> Delay Shutdown            20s
> Delay Start               30s
> Firmware                  02
> Load                      21%
> Power Nominal             1200VA
> Status                    FSD
> ALARM                     OB LB

Assuming the battery is ok, then how long does it take this system to shut down? 
Is a Delay Shutdown of only 20 sec enough?

> So, indeed was in LowBattery and FSD shutdown, however note that the current 
> charge was 73% >> 20% low battery, so why it set LB when there were enough 
> battery to run? Is this a comm problem, device issue, driver ?

System administrators sometimes use the command
  upsrw -s battery.charge.low=75 -u <upsuser> -p <sekret> <myups>
to speed up NUT testing.  Do you have such a command lurking somewhere?

> A) Can upsched introduce some race-conditions making a timer cancel cancel 
> other timers not related ?

The upssched timers operate independently of one another. Unless you have 
strange logic in upssched-cmd the heartbeat timers should not affect any other 
timer.  If you are shutting down on LB, then why do you need timers in upssched 
(apart from the heartbeart)?

Roger