Hey guys - I just wanted to give you a quick insight to the difference between brushed and brushless motors.
Here is your typical brushless motor. This one is from a brand called Hobbywing that you will see a lot in the RC world, and are involved with the majority of other electric motor manufacturers - chances are your non-Hobbywing motor was probably made by the same factory as the Hobbywing range.
Here is your typical brushed motor. This one is the famous Sport Tuned Tamiya upgraded motor from the stock silver brushed motor that used to come with all the classic old Tamiya kits.
They look very different and there are many differences. Let's look at them.
To put it literally in a nutshell, a brushless motor is laid out in the opposite way to a brushed motor. The brushed motor has the windings on the rotor that spin as the motor turns, and the power is supplied to them via the brushes. The inside of the can has permanent magnets.
The brushless motor has its windings on the inside of the can and the rotor has the permanent magnets. The windings do not move, or have any physical contact with the rotor which does not require any power supply. This makes it a far more efficient and simple system.
Ok, so if you know anything about the RC scene nowadays you will know that brushless motors are the way to go. Why is this?
Less friction.
All brushed motors spin by a process of transferring the electrical energy from the battery into a magnetic field. When the brushes supply power to the windings on the rotor, it pushes and pulls on the permanent magnets outside of it causing it to spin. With no charge supplied, there is no electromagnetic field, and no spin.
Because the brushes have to make physical contact with the rotor, it creates a lot of friction, resulting in a lot of energy from the battery being lost in the form of heat and noise.
The brushless motor does not have a physical conductor on the rotor, and does not need brushes to make contact with the rotor in any way. It instead uses the same magnetism from specifically positioned electromagnets on the inside of the case, and a very carefully timed sequence of ‘firing’ to continually make the permanent magnets on the rotor attract and spin.
Essentially it is a similar principle, but far more efficient. This means next to no friction as the rotor never actually makes any physical contact with anything. This is all good news for you RC lovers. It means:
- More Speed. Due to the fact that there is little to no friction between the rotor and external parts, the brushless motor is capable of much greater speed and power. This is because it is losing far less electronic energy as noise and heat.
- Reliability. Brushless motors are more durable and generally have fewer things that can go wrong meaning they last longer despite the big performance differences.
Brushless Motor KV
One last thing to touch on is the KV rating of the brushless motors and what they mean.
The KV rating is the RPM it will spin at (under no load) when 1 volt of direct current is applied. So for example, my Tamiya TT-02 uses a 3300kv motor. This means when I run it on a 2 cell (7.4v) battery, it will be doing 24,420rpm. Higher KV systems achieve higher RPM but have less torque, and get hotter more quickly. My system is a relatively ‘cool’ system, meaning I can get away with gearing it up a lot without overheating the motor.
