400w Inverter Show Fault with TV Plugged In...

Bill Roosa · Feb 10, 2012

Are the AC outlets wired correctly with hot on the left and neutral on the right and ground below (when looking at them)?
could be the TV has a polarity plug for a reason and the inverter is smart enough to figure that out.
What happens to the fault when you turn the TV on? does it work or not?

Bill Roosa · Feb 10, 2012

Is this thing powered by a 12 volt cigerette lighter plug?
Clearly you have what would be considered "sufficient voltage"
I suspect corrosion at the plug or where you are connecting it to boat power. with the battery charger on it is probably sensing the load and provide 14.4 which is enough to keep the inverter happy iven with the bad connection.
Everything should be clean and bright.
A positive check is to probe the inverter power leads when it is supplying power. That's why multi-meter probes have points on them.

Bill Roosa · Feb 10, 2012

Don't poke your finger when you probe the wires (don't ask). ;-)

tkanzler · Feb 10, 2012

Could it be discharged capacitors in the TV that put a very large but very brief load on the inverter, causing it to trip?

Bill Roosa · Feb 10, 2012

is the 12.9 volts while the inverter is running?

Bill Roosa · Feb 10, 2012

Here is my thinking.
It works with the charger on so having 14+ volts makes it work
it does not work when just 12.9 volts is pressent from the batteries (no load voltage)
A loose or bad connection at the batteries will read 12.9 volts at the clips when no power is being drawn but show enough voltage drop to trip a fault when some load is drawn. At 52 watts for the TV that would be something more than 2 amps which would suggest that running just about anything with the inverter should also cause a fault.
Have you tried other AC appliances to see if it is the TV or the inverter?

mitiempo · Feb 10, 2012

For one thing I doubt the TV likes running on a voltage as low as 91.

SailingHarry · Feb 13, 2012

mitiempo said:
For one thing I doubt the TV likes running on a voltage as low as 91.

I wouldn't place a really high confidence in that number.

Most volt meters, even decent ones, read peak AC volts and derate the nubmer to reflect RMS (Root Mean Square) volts. We use RMS volts for AC, becuase it is a reflection of "apparent voltage," or "useful voltage" and is essentially an "average" of the AC sine curve (which hits zero volts 120 times a second -- but we know "zero" isn't the answer either). What we call 120V is really closer to 200V at the peaks, and the volt meter just scales the peak down to 120V.

Inverters, anything other than "true sine" inverters, give an output that approximates a sine curve. But the curve is a bit choppy and squared off, and so the full peak doesn't show up. Since the top of the curve is more like 180 than 200, the volt meter will scale down to a lower number.

Note that the output of an inverter, while not making the same peak voltage as house current, does make the same RMS voltage. The typical volt meter just doesn't have a computer inside to determine what the RMS voltage output is. Also, the vast majority of devices, even "sensitive" items like computers and TV's, and even rotating machinery like drills, all work just fine with the modified sine wave put out by an inverter. Volt meters are one of the few things that don't work well on modified sine inverters.

You can buy "true RMS volt meters" and they will say it twice -- once on the box, and once on the price sticker!

Harry

Maine Sail · Feb 13, 2012

SailingHarry said:
Also, the vast majority of devices, even "sensitive" items like computers and TV's, and even rotating machinery like drills, all work just fine with the modified sine wave put out by an inverter. Volt meters are one of the few things that don't work well on modified sine inverters.

Harry

With our old Xantrex I had some power tools that would not even start. You physically had to hand spin the drill to get it going. Once going it worked, but the motors sounded "off".

The real danger is that many sensitive items like battery chargers get tricked and they don't know when to turn off. I ruined a few hundred dollars in camera, iPod and tool batteries before wising up and getting a Pure Sine inverter and my batteries no longer cook.

In the first year with our iPod (gen 1 purchased in December 2001) I was plugging it into the inverter for charging as DC charge adapters for iPods were about $80.00 at that time (today they are $3.99 at the Dollar Store). That battery lasted less than a summer. Apple replaced it and in 2012 that battery is STILL working to this day. I suspect because I have not tried to charge it with a mod or square wave inverter since killing it, in a few months..

That MSW Xantrex ate a shaver battery, multiple DeWalt batteries, iPod, and four Nikon batteries for SLR cameras... Xantrex kept telling me it was fine....

tailwind · Feb 13, 2012

I've run a large TV with my rather cheap 300 watt inverter when the power was out at my house last winter. Using the same hookup I had on my boat, it was hardwired to the battery terminals. I don't like the iffy connection alligator clips provide. Remember volts X amps = watts. There's a big draw of amperage off the battery and a little bit of corrosion will cause a fault to be set. I've had it happen to me.

I've read in many places it's not good to charge rechargeable batteries off a square wave inverter. I guess that might even go for laptops, too, although I've haven't had an issue with my 5 year old laptop battery so far.

Bill Roosa · Feb 13, 2012

If the inverter has a standby mode you will most likly not see the full 120 volts on any outlet till you start drawing power from it. The real test is with power flowing from the inverter (tv on) what is the voltage from the outlet?
I suspect that you had the clips to the battery not making a real good contact (now they are) and that caused the inverter to "see" a low voltage fault condition.
or gremlins