Advice Needed for UPS setup

If you do a search online for UPS calculator or UPS load calculator you should be able to check times etc, [of course UPS is also a major shipping company so you will have to filter these out ]

example here ... UPS System Load Calculator | Tripp Lite

you may find that the manufacturer of your devices have a bespoke calculator for their products on their sites

I think you have made a mistake on your calculation on the total time you can run the UPS during a power failure.

You seem to have used the sum of the AH of the batteries. usually the batteries are wired in parallel so you still only have 7 AH, not 28 AH.

When the batteries are wired in parallel the current draw is spread over the 4 batteries in this case, so the while the amperage draw may be say 20 amps, one 7 AH battery would flatten fairly quickly, but with 4 the time to flatten them will take in theory 4 times longer. Effectively each battery in this case would have an amperage draw of 5 amps.

To test the TV after you set it up with the UPS etc. Just turn off the power at the wall switch & see how long it go until the UPS shuts down.

A UPS isn't practical for long term power supply; a backup generator is far more practical (and I have thought about getting one). A UPS is primarily for, when the power goes out, keeping something running until there is time to safely shut the equipment down. It can also provide the transition from when the power first goes out and a generator can fire up and start providing replacement power.

I got mine after one summer we had frequent blackouts, often several times a day, over a two or three week period until an elusive, intermittent short in an improperly spliced underground cable was finally found and our el cheapo absentee slumlord could be convinced to shell out the shekels to do a proper repair (replaced the missing section of conduit and pull new cable). I got an oversized UPS, not so I can run a long time after an outage, but to ensure my computer would get properly shut down even if we get multiple outages in a day without time for the batteries to recharge between outages. I also wanted the extra capacity for future expansion (such as the three 24" monitors and powered HDMI splitter that recently replaced the single 22" monitor I had when I got the UPS). Even though I have 1 hr. 44 min. run time showing right now, my UPS is set to automatically shut down my computer five minutes after an outage first starts. That both allows the computer to keep running if I all I get are short power blips and provides enough time to get the computer automatically properly shut down (hibernated, actually, so I don't lose any unsaved work) unless I need a few extra minutes to finish something, in which case I can intervene, then manually shut down.

That picture sure does clear up the issue. Yes it does seem they are wired in pairs so the effective voltage from them would be 24 volts, but the amp hourage is still 7 AH.

As the voltage is now 24 volts the amperage draw will be half what it would be with only 12 volts.

You are correct Lady F. I have a back up generator, needed here because of power outages during storms etc. & I have used it on a number of occasions. I have it wired into the household system so I just change one switch, start the generator & I can run everything in the house very much as I usually do, except I do have to limit how many elements I use on the stove at any one time. It's 240 volt, 7.5 kilowatt petrol engined generator.