The constant contact of the brushes with the power terminals of a brushed motor is necessary for it to maintain its rotation. However, the friction that this creates means that a huge portion of the energy generated by the rotational motion is wasted as heat. Generally, the efficiency of brushed motors is limited within the range of 75% to 80%.
Brushed motors are notorious for having parts that get worn out after a while, requiring frequent dismantling and parts replacement. This is because the brushes of the commutator need to maintain almost constant contact with the terminals of the power source, even as the commutator rotates rapidly. When brushes get worn out and can no longer maintain contact, a brushed DC motor basically becomes useless.
This is less of a problem with brushless motors. In fact, there is essentially no contact between the rotor and stator of a brushless motor, so wear and tear are greatly reduced.
LONGER LIFE EXPECTANCY
The accelerated wear and tear due to constant contact of the brushes and the energy generated as heat means that brushed motors are expected to break down much sooner than brushless motors. It is generally not recommended to operate a brushed motors for longer than several minutes continuously. Without a chance to cool down, heat buildup in brushed motors can easily compromise the integrity of its coils or brushes.
Although in brushless motors there is still some heat generation due to air friction, this is kept at a manageable level. Brushless motors can typically run from 30 minutes to an hour continuously with no problems.
THREE DIFFERENT SPEEDS AVAILABLE
ULTRA HIGH SPEED VERSION
35,000 RPM at 7.4v - 52,000 RPM at 11.1v
HIGH SPEED VERSION
25,000 RPM at 7.4v - 36K RPM at 11.1v
STANDARD SPEED VERSION
20,000 RPM at 7.4V - 30,000RPM at 11.1
