Hobotech’s 91% efficiency no. was based on using a device hooked up to the ECOFLOW Delta Pro and running it until all power was used. So, for example, the Delta Pro battery has 3,600 whr. of power. Divide 3,600 by the wattage of the device, say 900 watts. 100% efficiency would give you 4 hrs. of run time. He got 91% efficiency. Perhaps the word “efficiency” is not quite the proper term, but he meant he was able to use 91% of the rated capacity of the battery. The AP200P, I would guess, would be in the 80%+ range (10% reserve plus overhead consumption).