AX860 on APC BackUPS PRO BR1500, it switch to battery when I power off the PC.

As title.



I had a BR1500GI since years, I never had a problem on my old PSU Enermax Modu87+ 700W.



Now with the new system and the new PSU Corsair AX860i, sometimes, when I power off the PC, I can hear the UPS that it switch on battery for a while and than it return in normal operation.

This happen when the PC switch from the "On state" to "Off state".



What does this means?

Is it something that I should worry about?

AX860 on APC BackUPS PRO BR1500, it switch to battery when I power off the PC.