ORIGINAL: J Strong
You have to be checking pull from one of your 2 packs. Check your wattage, it won't lie, then multiply by voltage. Once you learn it, its very simple and straight forward.
Wattage will tell ya the story. I'm pulling 2900 watts at the 73 amps mentioned.
You should be okay with the Jeti 77. I flew one with the 30-10 EVO for many flights with even larger props. ESCs are normally spec'd at peak continuous current but that assumes adequate cooling. I added a heat sink to my ESC and mounted it right in the air scoop in the chin cowl. In normal flight conditions I seldom went over 75 Amps and the Jeti ESCs can take slightly higher currents for short periods of time. Having said that I'd recommend the Futaba/OS. It seems to run much cooler.
Not sure what you mean about checking the Wattage and multiplying by voltage? Bill was talking about average Amps and 28 is about right for a typical Masters/FAI flight but it is the peak amps times the time you pull it that causes high heat and eventual ESC failure. So the limit the time you are at full throttle, provide adequate cooling and don't use too large a prop and you will be okay.
Jim O