That sure doesn't sound right, but I don't have any idea of what you could do about it. If you're within a return period, I'd take it back to the store, or contact the manufacturer if it's under warranty. I get the impression that inverter units (boards) themselves are typically just replaced if something goes wrong, and that trying to repair them may be difficult.
A long shot, but: if your load had a really bad/low Power Factor (0.5), you could be putting out 800W, but the actual load on the generator would be 1600VA. And they are really rated in VA, not Watts.
On the Kill-A-Watt, run your load again, and change to the VA display, see what that's showing before it cuts out. That's what the generator cares about, not Watts. For an electric heater, hair dryer, etc, Power Factor=1.0, so VA=Watts. But other loads will have a PF<1, so VA>Watts.
Thanks for the suggestion.
I did the tests checking the VA as suggested with various appliances connected. Most times the Watts was essentially equal to VA.
That said, it may have been one appliance (A small, 1500Watt portable heater) that was causing the problem after all. Without that particular appliance connected the generator was able to run a 1550Watt / VA load.
With one caveat ......I'll mention below.
To clarify - I'm not a Predator, but one of my Generators IS
HarborFreight Predator 3500 Inverter
Last edited by Predator; 07-27-2019 at 10:37 AM.