Ebay title: (about $330)
8000W LF SPLIT PHASE PURE SINE POWER INVERTER DC24V/AC110V&220V 60HZ/Charger/LCD
Made by Power Jack
UPDATE: Be aware that this inverter I have WILL OVERHEAT and shut down at a continuous 2000W after 1 hour. The transformer was at 244F (117.8C) when I pulled the cover. The unit I got only has one toroid transformer in it. Looking at YouTube videos it seems that it should have two. It was sold as a "2016" model. If it did have two transformers it might handle 4000W. The AC fuse installed was a 15A on one side of the 220V only. See other details below.
It is good to know that it could be used for a cheap back up inverter.
BUT.... Being the geek I had to look at the waveform. The Xantrax Prosine 1800W Pure Sine I have is better of course under load the waveform isn't perfect (most aren't) but it is still more of a sine wave looking thing under load.
The PJ at about 1000W starts to look more like a triangle wave (pics below) and the very tops of the wave start to flatten.
The fridge really didn't care and the 1000W microwave was fine with it, also a 600W window A/C but the volts are low like 110V to 115V and I knew that up front since it said 220V. Computers are fine with it of course, they could run off of a square wave. CFL lights are OK too.
Point is for a back up it's great for around $300. I don't know if a well pump would like the triangle wave though at 6000W (motor using a run cap) that flat top part would get worse. I did not test at that power level and I don't know if I want to.
I think they may push a triangle wave into it and since it's a transformer it tries to straighten it up and at low power you can't see it. I am thinking if you keep pulling more and more power that "flat top" would widen to the point that the waveform is more like a square wave.
I don't think mine is bad, like a mosfet crapped out because it's on BOTH sides of the waveform. They simply don't put in a sine wave to start with I am sure.
The nice thing about this inverter is that most of it is repairable and they sell several boards for it, including little mosfet PCBs with all the mosfets mounted and all you do is screw it down with screws, no de-soldering or anything, easy fix and you could keep some spares around.
The DC side mosfets are 30A and there are 6 of them per "H Bridge" side so 180A max but you should run them at half really so 90A at 24V is 2160W if you don't want to poof it.
30N10 N-Channel MOSFET
Drain Current ID=30A TC=25C Drain Source Voltage VDSS= 100V(Min)
Static Drain-Source On-Resistance RDS(on) = 0.77 ohm (Max)
Fast Switching for switching power supplies,converters, AC and DC motor controls
It does seem to regulate the voltage OK, a crap inverter could just keep going down and down as the load goes up. That also means I could someday find the voltage reg circuit and turn it up to 120V !
One other small problem I found is it's low voltage warning beep and shutdown doesn't quite work correctly. It seems to depend on how fast the voltage changes. With large batteries of course it's slow and it will warn at about 21.2V but I took it down to 18.3V and it still did not cut off. So I would not depend on that function.
The manual says you only get 4000W per 110V side of course. Even though it has a big fan, the manual says 165F is the ROOM shutdown temp so if the room is hot it may not take much to reach the shutdown temp.
Youtube: A guy tests the 5000W version of the LF Inverter
http://www.youtube.com/watch?v=ZWsjmMsaIPoPictures of the actual waveforms below, first is no load, then slightly flat tops at 600W then worse at 1000W, and a waveform reference. You can see how the lines to the sides start straightening up for the sine / triangle wave. And the flat top increases of course.
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