UPS NOT WORKING ON BATTERY MODE WHEN BLACKOUT | BATTERY FAILURE FULL GUIDE
I just want to share my idea, UPS working on AC but not working on battery mode when the AC power off automatically UPS power off no battery back up troubleshooting check battery voltage and fuse or recharge battery
if battery become 0 voltage it will not charge replace with new one
if you getting 5 to 6 voltage then recharge battery and if battery not getting charging voltage 14 volt check battery charging section in UPS.