When designing a small unmanned vehicle, unmanned boat, multi-rotor, and fixed-wing. A problem that must be faced is how to choose a suitable motor, battery, and ESC. The combination of these three is good, the machine can play an excellent performance, otherwise there is a possibility of burning out the equipment. So next, I will introduce how to design the relationship between the motor, ESC, and battery. The battery here refers to the polymer lithium battery, and other types of batteries are not discussed in this article.
First determine the maximum operating current of the motor
When the motor is at its maximum efficiency, the current is: 30A. The no-load current of a general model motor is about 2A, and the maximum load current is different for each motor. If the motor is locked, a high-power ESC and a high-discharge rate battery are used at this time, which will cause the current to rise sharply in a short period of time. If the time is too long, the motor will be burned. If it’s just a 540 motor for a general toy model, don’t choose a high-current ESC. If you choose a high-current ESC, you must match it with a high-power motor so that they cooperate with each other.
Select ESC:
If the maximum efficiency current of the motor is 30A: then the ESC you choose must be at least 30A, but in general, for safety considerations when going out, you should choose a larger ESC! For example: 35A -40A. But it is best not to exceed too much, so as not to affect the service life of the motor.
Battery selection:
Generally, look at the battery capacity first, such as 2200MA, the capacity is confirmed, then it depends on the magnification! For example: 2200MA 10C, then this battery can be: 2.2A (2200MA =2.2A) *10=22A, the maximum discharge current of this battery is 22A, which obviously does not match the above ESC, then you need to choose 15C 2.2*15=33A, this can meet the previous requirements! If it is 20 C battery, then it can be discharged at a current of 2.2*20=44A. When the aircraft is at its maximum power, the current is only 30A. This battery can be discharged at 44A. No doubt, the battery will be easier. The motor is always running at the maximum power! The obtained power will be very satisfactory.
With a 2200MA 20C battery, a motor with a maximum load current of 30A, and an ESC with a maximum output of 45A is a reasonable configuration.
A motor with a maximum current of 30A, a 35A-40A ESC, and a 2200MA 20C battery are the best combinations.
Determine the motor, determine the ESC, and finally determine the battery. Don't ignore the condition of the motor, blindly choose the battery, ESC, it is easy to burn the motor.
Note that if we choose batteries for the four-axis, because the four-axis has four sets of ESCs, if we use 20A ESCs, then we need to use 20A X 4 = 100A batteries. On the four-axis aerial photography, we generally use 5000MA, 20C batteries, which is 5 X 20C = 100A, which has reached the optimal matching relationship between weight and capacity. The four-axis has multiple motors, so a larger battery should be selected.