Sometimes the UPS shutdown for no reason.  No power outage.

cat /var/log/syslog |grep ups

Mar 16 02:09:28 pihole upsmon[390]: UPS qnapups@localhost on battery
Mar 16 02:09:28 pihole upsd[381]: Client upsmon@127.0.0.1 set FSD on UPS [qnapups]
Mar 16 02:09:36 pihole upsmon[390]: Executing automatic power-fail shutdown
Mar 16 02:09:36 pihole upsmon[390]: Auto logout and shutdown proceeding
Mar 16 03:10:07 pihole kernel: [    0.000000] ftrace: allocated 60 pages with 4 groups
Mar 16 03:10:07 pihole dbus-daemon[275]: [system] Activating systemd to hand-off: service name='org.freedesktop.ColorManager' unit='colord.service' requested by ':1.1' (uid=0 pid=252 comm="/usr/sbin/cupsd -l ")
Mar 16 03:10:10 pihole upsdrvctl[342]: Using subdriver: APC HID 0.96
Mar 16 03:10:10 pihole upsdrvctl[342]: Network UPS Tools - Generic HID driver 0.41 (2.7.4)
Mar 16 03:10:10 pihole upsdrvctl[342]: USB communication driver 0.33
Mar 16 03:10:10 pihole upsdrvctl[342]: Network UPS Tools - UPS driver controller 2.7.4
Mar 16 03:10:10 pihole usbhid-ups[368]: Startup successful
Mar 16 03:10:11 pihole upsd[374]: fopen /var/run/nut/upsd.pid: No such file or directory
Mar 16 03:10:11 pihole upsd[374]: listening on 0.0.0.0 port 3493
Mar 16 03:10:11 pihole upsd[374]: listening on 0.0.0.0 port 3493
Mar 16 03:10:11 pihole upsd[374]: Connected to UPS [qnapups]: usbhid-ups-qnapups
Mar 16 03:10:11 pihole upsd[374]: Connected to UPS [qnapups]: usbhid-ups-qnapups
Mar 16 03:10:12 pihole upsd[381]: Startup successful
Mar 16 03:10:14 pihole upsmon[389]: fopen /var/run/nut/upsmon.pid: No such file or directory
Mar 16 03:10:14 pihole upsmon[389]: UPS: qnapups@localhost (master) (power value 1)
Mar 16 03:10:14 pihole upsmon[391]: Startup successful
Mar 16 03:10:14 pihole systemd[1]: nut-monitor.service: Can't open PID file /run/nut/upsmon.pid (yet?) after start: No such file or directory
Mar 16 03:10:14 pihole upsmon[392]: Init SSL without certificate database
Mar 16 03:10:14 pihole upsd[381]: User upsmon@127.0.0.1 logged into UPS [qnapups]
Mar 16 03:10:14 pihole upsmon[392]: UPS qnapups@localhost battery is low