[Nut-upsuser] permanently setting "battery.charge.low" on APC Back-UPS RS 550G

[Ralf Fassel]

OS Ubuntu 20.04.2 LTS
Network UPS Tools 2.7.4 (Debian Package nut-client 2.7.4-11ubuntu4)

device.mfr: American Power Conversion
device.model: Back-UPS RS 550G

driver.name: usbhid-ups
driver.version: 2.7.4
driver.version.data: APC HID 0.96
driver.version.internal: 0.41

ups.firmware: 857.L7 .I
ups.firmware.aux: L7  
ups.mfr: American Power Conversion
ups.mfr.date: 2019/06/11
ups.model: Back-UPS RS 550G

I can set the battery.charge.low from the command line:

  % upsrw -s battery.charge.low=75 -u ... -p ... UPSNAME
  OK

This works fine until the UPS is shut down after power goes down.
After power is back, UPS comes back online, PC restarts, but now

  % upsc UPSNAME
  ...
  battery.charge.low=10

is back to the default of the device, so I have to repeat the above
command.

Is there a way to permanently set the battery.charge.low in the
device?  Or in some config file (which)?

TNX
R'