Updating battery date on an ancient UPS(like APC Back-UPS NS600, etc)

This may be one of the reasons your UPS can shutdown prematurely even if the battery has been replaced recently and is in a good shape. It's projecting time based on the original battery date. Below are the simple commands to update it. These are for OpenWrt, adjust accordingly if you are on systemd system.

# /etc/init.d/apcupsd stop
# apctest
...
You are using a USB cable type, so I'm entering USB test mode
Hello, this is the apcupsd Cable Test program.
Getting UPS capabilities...SUCCESS

Please select the function you want to perform.

1)  Test kill UPS power
..
4)  View/Change battery date
...
12) View/Change self-test interval
 Q) Quit

Select function number: 4

Current battery date: 04/03/2011
Enter new battery date (MM/DD/YYYY), blank to quit: 03/28/2023

#/etc/init.d/apcupsd start