One of my favorite 120 volt tools is my Kill-A-Watt meter. it's about a thousand dollars worth of meters.. in a thirty dollar, give or take, box
You read the WATTS draw and divide by 10 (yes I know that's not the battery voltage but by the time you factor in the conversion loss in the inverter 10 works real good) so if the fridge draws 100 watts running the inverter draws 10 amps
Or you can read the amps draw. the Power factor (you can do things to improve that) and other stuff... Power factor is zero to one (one means you are using 100% of the power) and is the cosine of the relationship between voltage and current... Ideally it's ONE. It's also the difference between VOLT-Amps and Watts. It's possible to have something drawing say 150 Volt-Amps (Which is what you pay for) and only using 100 Watts. (PF .6666666)
Kill-a-watt on Amazon
