[RobertClark]

I agree, I would never put a sump pump on a small inverter. The best rule of thumb is to double your start-up power (IMO). I have a well pump that I run at my cabin that has one heck of a start up draw - fortunately, I don’t use it as a pressurized system (I use it to fill a tank in the beams of my cabin and allow gravity to pressurize my lines).

[JRandomFreeper]

Back around 1998/1999 at the old ham club, we pooled an bought a gadget that you could plug in (like a shunt, with fancy electronics) that would give you detailed information about whatever you were powering, including start-up cycles, all the majikal trig stuff, and average power consumption over time, etc....

We built a gadget that would handle the startup (duplicating the soft-start circuit, but we didn't know that) and decided, to heck with it, go for a bigger hammer.

/johnny