Therefore, most hobbyist brushless motors are not limited by how much current you can deliver to the motor, but rather by how much current you can deliver before the motor overheats.

However, the use of extremely large currents will quickly overheat and destroy a motor. This is of course provided you have a big enough motor controller and power source to deliver the required current. 0.1 Ohm) it is possible to deliver extremely large currents to a motor even with a modest supply voltage. Since most brushless motors have a very low winding resistance (i.e. Therefore, more of the supply voltage is available to deliver current to the motor and so the capability of a motor to produce torque will increase as you move further away from its no-load speed. As a motors speed is reduced so too is it's back EMF.

The speed at which you can do useful work with a hobbyist motor and motor controller is always going to be smaller than its no-load speed. With near-zero current flowing through the motor there is near zero torque produced and so it can not spin any faster. The situation is no different with a brushless motor, just that it is now electronically commutated.Īt the no-load speed, the voltage difference between the motor and its power supply approaches zero and so very little current can flow through the motor. If you have ever adjusted the speed of an unloaded brushed DC motor by adjusting its supply voltage then you have already seen the effect of supply voltage on a motors no-load speed. nothing connected to its shaft) is reached when the motor's back EMF is about equal to the supply voltage, such as from a battery.

When using a hobbyist grade motor controllers the maximum speed of an unloaded motor (i.e. This is a brushless motor's back electromotive force (back EMF). When a brushless motor is rotating the motion of the rotor magnets relative to the stationary stator produces a voltage in the windings.

Bldc tool terminal battery voltage