# Sensored and Sensorless Motors



## fkl1 (May 23, 2013)

Came across a useful tips for those beginners out there.
Experienced drivers should read what is good about having a sensored motor!
took this from Asiatees. 

Sensored Motors uses the “Hall Effect” (named after Edwin Hall, an American Physics scientist) to detect the rotor (magnetic poles with different polarity) inside the motor and transmit the data to the ESC through a sensor wire. It allows the ESC to control the rotation and the speed of the motors precisely. In general, it is smoother compared to a Sensorless motor with the wire connected, and the signals are sent and received correctly. It is noticeable that Sensored motors are smoother especially in the lower end of the motors operations. 

However, there are lags between the signal arrival time and the received time, it is hardly noticeable, but one should bear that in mind. Since it has the extra wire, it is also more vulnerable to damage if abused, and it also takes up space and add weight to the motor. Sensored motors are connected with wires, it means that there’s contact friction. When there’s friction, there’s heat produced, so it would need a better cooling system. Sensored motors usually have room or space open up for ventilation, but it would also mean that dirt or small particles can be stuck or get into the motor, therefore it would need to be cleaned after using for a while.

On the other hand, Sensorless Motors uses back/counter EMF (Electromotive Force) that detects the rotor position by receiving and interpreting feedback current that was generated by motor as the rotor spins. Basically, it is a contact-less system that is similar to Sensored motors, but uses magnetic field force. In addition, Sensorless motors are more efficient when running at a high RPM (revolution per minute) than Sensored motors. It would have no friction without the contact and have no heat produced. Unlike Sensored motors that need open space for ventilation, Sensorless motors do not need that so it is usually sealed to prevent dirt or small particles to get in.

Despite the fact that a lot of advantages of a Sensorless motor is that it has nothing connected, however, it is also a disadvantage that it is hard for the ESC to actually detect where the rotors are. It depends a lot on the quality of the firmware. Also, when the motor is running at low speed, it would occasionally causes cogging, because there isn’t enough EMF (Electromotive Force) to send out for the ESC to receive.


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## nutz4rc (Oct 14, 2003)

Sounds scientifically correct; however, I have had more heat issues with sensorless than sensored motors.


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## ta_man (Apr 10, 2005)

This makes no sense:


fkl1 said:


> Sensored motors are connected with wires, it means that there’s contact friction.


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## RPM (Dec 20, 2004)

.......


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