CyberPower Setup - Improvements?

i recently had Cyber Power installed for my parents (with 2 Volta batteries: 175 AH). i chose to have one phase of the house connect to CyberPower. Any suggestions/comments to improve ? There is a common ground and the output coming from the inverter is only hot wire. This model of Cyber Power does not have a voltage regulator. Is it recommended to get a stabilizer ?

Also, i have noticed that the fan slows down a bit once running on the batteries. Wapda seems to supply 250V and Cyber Power supplies 220V. Could this explain the slowing down ?

What is the length of the wires (both neg. and pos.) from the battery terminals to inverter. Also what guage of wire are you using for the battery to inverter connection. How are the wires terminated at both ends. During power outages when the inverter is running, are the wires warm to the touch at the normal load.

The wires came with the inverter. They are coming out of the inverter as you can see in the pic below. i would guess the length to be about 3 feet. Don't know what the guage is but they look thick enough. i used the battery clamps on the battery side to fasten the +ve/-ve wire ends.

My CYBERPOWER ups burnt and gave smoke maybe due to short circuit while electrition working in DB.

Can you guys guide me if this is repairable?

The electritian said only fuse needs to be changed in ups and it would start working again

Mere fuse being blown does not cause emission of smoke.

It should be repairable though.