14 volt tv and the inverter squealing.

What is the measured voltage input to the inverter?
Also measure the voltage at the battery terminals to compare.

I have a 12vDC tv which functions normally at 9.5vDc input, perhaps even less. Your 14v tv likely can be hooked directly to your 12vdc system bypassing inverter. Worth a try anyway.

My wagan elite 400 psw inverter failed a while back. Bummed.
If you are.plugging the wagan into through a ciggy plug, ciggy plugs are horrid electrical connections with ever increasing resistance until complete failure.

Isn't it always a low voltage problem w/ an inverter.

The fact that the line in is controlled thru a wall switch, would suspect the inverter being too far from the batteries, or the wire being too small.
But a volt meter at the tv when turned on will tell the story.

time2roll,
I measured the battery voltage and the connections at the inverter, both 13.4 volts. I turned on and was running the front Tv off of the house batteries and the house inverter and all was well for a few minutes then the high pitch whine started. I checked the battery voltage and it dropped to 12 volts already. My Trojans T-105 were purchased 8/15. Maybe they have are due to be changed.
One incident i am embarrassed to admit is last spring I checked my batteries and they were almost out of water. I am better than that. I filled with distilled water and they have been performing quite well but I wonder if that was the beginning of their demise.

Landyacht, I may just try that. I would have to come up with a plug similar to what is on the tv now.The inverter is hardwired to a wall switch.

After having a service port failure in my dining area charging my phone ,I reluctantly use those "cigarette lighter" ports or trust them.

If the battery power went from 13.4 to 12.0 basically just powering this item then it would seem the batteries have severely diminished capacity or were not really charged. Although usually these inverters do not complain until you get to 11.0 volts or below. Yes have the batteries checked. Consider a bench test of the inverter with a known solid 12.5+ volt DC supply such as the chassis battery with the engine running.

Few dried up batteries perform properly after refilling. An extended recharge at higher voltages is usually required to get specific gravity back to 1.275 range.

My wagan elite 400w psw when it failed was emitting that high pitched whine that would appear once turned off. Instantly when turning it on. I fond internal fuses blown and on replacement it could not handle over 300 watts. A month later it refused to fire up at all.

Sometimes the easiest way to get the correct barrell plug connector is to buy an inexpensive universal laptop car adapter. Double check polarity before splicing it to 12.x vdc

If inverter powers tv with engine running or.plugged in and converter holding higher voltage then your batteries might have been toasted when you ran them dry.

Which then brings into question the proper function of converter

If you do replace the inverter consider wiring it into the branch circuit you use for the tv. I recommend 300-350 watts from GoPower or Victron as a replacement.

If a battery has only one or two cells that are bad, it will act like wnat you are describing. After charging, it will show full voltage,, but will drop quickly with any load at all, and will output low voltage to a load, because some of the cells are not pulling their part. Especially after having a low water condition. So have a full load test done.

Great ideas, thanks. Going to get a load tester and check the batteries first.

A load tester is hardly necessary in this diagnosis. If 18 watts of tv alaong witth voltage drop on the wiring to inverter are enough to make low voltage alarm on inverter scream. Then turning on all lights and dc loads would similarly drop voltage.

Any load can be considered a test. Bigger loads just reveal more.