I spoke of an efficiency curve like a bell that sits in an x-y plot of speed and rpm. Lets say timing is dynamic and always perfect. Your bell would be wide. Lets say timing is not dynamic but its perfect for some arbitrary narrow band of rpms that we will call x. If you add a load you know the torque. Now you can say x=1 and y=2 and see where it sits inside the bell. We dont have 1 efficiency for the motor its a range of efficiency with several bands that are varying degrees of ok, good, better, best and bad. The drive train is designed around the application and the work it does (power requirement) has a mass.

Mass requires torque to move it. Acceleration means you need allot more torque. Torque equals current and acceleration means you need allot more torque for a short amount of time. If a 1hp motor can convert 1amp of current into 1nm all day long how do i help you understand that 100 amps in a motor 30mm in diameter has no relevance in a conversation about power? The numbers i used are common in figures in motors with specifications. i probably pushed a little more current through my 30mm motor but its not that big of a leap. When I explain this inequality my hope is that you see 100 amps is only relevant for acceleration for a very short period of time. Lets say that a 30mm motor is a 1/20hp motor. Do you need 100 amps to do work with a 1/20 motor? No. You needs it to accelerate it. If the motor goes through a band of efficiency that is bad, better, good, best where is all the current going that is the difference between 100% and the band? Its turned into heat. So what is optimal? When you accelerate you want to minimize heat generation and make sure you bypass bad and better and accelerate through good and best most of the time. Less heat and more mechanical conversion happens. If i know i have 5.6 amps (torque) at 18000 rpm do i know how efficient I am? Maybe but i doubt it. you know the motor won’t overheat under some situations but 5.6 amps is allot of current for a 1/20 motor and its certainly not 5.6nm. Its an average power that is not continuous and not peak so what is it? Its a rule of thumb for the motors ability to dissipate heat for an average amount of load, accelerations, and efficiencies. If its on the average 60% efficient all the time while going through the bell curve the motor can dissipate the other 40% as heat without cooking. 5.6 amps times 40 percent is the amount of heat the motor can dissipate into air based on its thermal efficiency. Its a good number to understand to keep things from breaking but you are building a system that wont burn and you should be building a system that accelerates to an rpm first and then narrowing the choices by the motors thermal efficiency. Even if you only have 1 motor. Because the point is to average the efficiency, torque and rpm requirement for a 1450 gram mass accelerating 20 times to 25mph in 12 seconds. Then you use the torque/rpm and efficiency curve to put your track and timing dead center in the middle of the curve. 100 amps at 40% is way different than 100 amps at 80%. You know you can change the mass or the FDR and timing to move the curve to that average requirement and low efficient accelerations are a thing of the past.