I'm doing a self build camper at the moment and have been setting up the electrics. Everything seems to be working well so far however I've been having some issues with my inverter.
I have two lithium batteries that are 220ah each and have a max continuous current rating of 200a which are connected in parallel. I then have this 3000w (6000w peak) pure sine wave inverter hooked up to the batteries: https://www.photonicuniverse.com/en/catalog/full/380-3000W-12V-pure-sine-wave-power-inverter-230V-AC-output-UK-sockets-with-remote-onoff-switch.html?gclid=Cj0KCQjwnqH7BRDdARIsACTSAdvLhoC0mDJEIrGYIunEEhhWvXBdQ8PC2mB1OBdWCFg_ZRHR-BsYVgYaAjyGEALw_wcB
Lower powered devices are running fine off the inverter however I wanted to run a microwave oven from it, specifically this one: https://ao.com/product/kmqfx33910-kitchenaid-microwave-stainless-steel-63833-50.aspx
It's rated at 900w microwave and 1200w grill so well below the 3000w of my inverter.
I originally had a 250a circuit breaker between the inverter and the battery but when I plugged the oven in and turned it on after about 30 seconds it tripped out. I thought that was a bit odd since 250a x 12v is 3000w so that would indicate the inverter was running at maximum capacity. I changed it for a 300a breaker instead but now when I plug the oven in and turn it on after 30 seconds the inverter trips instead and shuts itself off, presumably the over load protection is kicking in.
So it seems a bit odd to me that a 1200w appliance is maxing out a 3000w inverter. The inverter even says it can handle up to 6000w spikes for a few seconds so I'd have thought it should be more than capable of powering this oven.
I also have a Simarine Pico monitoring system and a shunt on the circuit so I can monitor the power consumption and see exactly what is going on. When the oven is on the draw on the batteries is around 130a so 130a x 12v = 1560w, so the inverter should only be running at about half of its maximum output. And the voltage when the oven is running drops slightly from 13.5v to 12.8v so decent enough voltage.
So I'm just a bit confused about the whole thing really, is my maths or understanding of any of these things wrong or could the inverter be faulty?