Kudos on your patience to explain this after the prior inappropriate comments. I can confirm that the measurement of capacity required to replacein and out is indeed how many R/C'rs get a handle on the energy requirement of their power systems. Average voltage and time are often not considered (to ultimately calculate power and energy) but this can be estimated or with the right equipment, energy can be measured directly. Is this capacity approach extremely accurate? No. But it is legitimate within it's known limitations...