Originally Posted by
glennhl
OK, I really like this forum because of people willing to share their knowledge. Even at my age, I keep learning new things. So could you electrical guys give us the equations you would use to determine the power output of a brushless motor. When it comes to electric power, I've always depended upon Ohm's law and it doesn't work in this case. And to gigaplex, you have always been one of my favorites on here. However, I have always considered an order of magnitude to be exactly 10 times. So normally if it's not exactly 10 times, I would always say approximately an order of magnitude. For whatever that's worth.
EDIT: Oh, one more thing. Wolfie was off on the absolute numbers by approximately an order of magnitude, but were the numbers close for comparison purposes? Is his statement correct? "that a 25.5 on 2s is closer in speed to a 17.5 on 1s than a 13.5 on 1s.
See my post earlier where I quoted the Hobbywing spec sheet for the actual power outputs, and then approximated the 13.5 on 1S power by dividing Hobbywings number by 4 (power is proportional to voltage squared). The 25.5 on 2S had more power than 13.5 on 1S. Wolfie's statement was not correct.
There is no calculation for the power output of a brushless motor that only considers the stator resistance. There's so much more to a motor, such as rotor strength, rotor diameter and length, Y vs Delta configuration, how many poles the rotor has, stator length, endbell timing etc.
Order of magnitude is a bit more complex than "exactly 10 times". Of the numbers they quoted, some were just under a factor of 10 while some were just over a factor of 10. Order of magnitude is always a ballpark.
https://en.m.wikipedia.org/wiki/Order_of_magnitude