I just received my AC200P and it showed 64% charge. I hooked up my tv to test it and it’s using 145 watts. Drained down to 40% battery left in 2 hours. This doesn’t seem right. I sure hope this thing performs after spending $1700 on it.
The inverter is about 80% efficient and has about 20W baseline draw. So 145W AC output would mean it is drawing about 180W from the battery, add the baseline 20W draw, that is about 200W. 200W for 2 hours would be 400Wh which is 20% of the AC200P capacity, so your figure from 64% down to 40% isn’t too far off.
Now, the battery meter isn’t perfectly accurate and may needs to be calibrated if you only operate your battery in a narrow range of state of charge. You can calibrate it by charging it to 100% and draining it down to 0% so it learns what is the full range. Do that once a year or so would keep your battery capacity meter accurate
If you have a watt hour meter, you can do a capacity test by charging it fully then draining it to 0%. If you get 80%-85% of rated capacity (>1600wh), then everything is good.