Remember your love at first sight moment with RC cars? The day your heart skipped that beat? Know that as the heart is to you, is the DC motor is to an RC.
This is why RC enthusiasts must have a good understanding of DC motors and their various types. Especially, if you have plans to upgrade the motor of your RC or build an RC car from scrap, know that choosing the right motor is the key.
When it comes to DC motors in RC cars, there are two main types
- Brushed Motor
- Brushless Motor
This article will discuss in detail both Brushed & Brushless motors, their advantages, disadvantages, and everything you need to know before investing money in one.
What are the different types of RC motors?
As said earlier, RC motors can broadly be classified into two main categories viz;
A thorough understanding of these two terms would be the primary pre-requisite knowledge every RC enthusiast should possess. Before we get into the nitty-gritty of Brushed & Brushless motors, let’s have a quick look into the working of a DC motor.
How does a DC motor work in an RC car?
The fundamental working principle of a DC motor is that, when a current-carrying conductor is placed inside a magnetic field, it experiences a mechanical force which turns the conductor. In a DC motor, a current-carrying conductor (Armature) is kept between a magnetic field and it experiences a mechanical force that in turn, rotates the conductor.
Well, the complete working principle of a DC motor is beyond the scope of this article. It is important to note that for a DC motor to rotate constantly in a single direction, a mechanical device called a commutator has to be used.
The fundamental difference between a Brushed & Brushless DC motor lies in how the motor is made to constantly rotate in a single direction.
- Brushed Motor
Brushed DC motors are the ones with a commutator that keep the motor rotating in the same direction. In a Brushed DC motor, carbon brushes along with the commutator ring switch the electrical polarity of the armature. It is this switching of the polarity in the current-carrying coils that maintains the armature's rotation in one direction.
- Brushless Motor
Brushless motors are a lot different from Brushed motors and are commonly referred to as Electrically Commutated Motors (ECM). The main difference lies in where the armature windings are located.
In Brushless motors, armature windings are located on the stator while the permanent magnets are on the rotor. Because of this unique design, brushless motors do not need brushes. Instead, they use three phases of driving coils and additional sensors to determine the position of the rotor.
So, unlike a Brushed DC motor that uses brushes & commutator rings to switch the polarity, a Brushless DC motor uses position sensors instead of mechanical rotary switches.
Now that you have a basic understanding of the functioning of both brushed & brushless DC motors, let us dig deep into the core of the matter. Which one should you choose? To conclude let us bring them to lights for a one on one comparison.
Brushed motors –advantages
- Controllable torque: Being able to control their torque to speed ratio, they find exclusive markets in automobile and household industries.
- Low manufacturing cost: One of the key selling factors of brushed ones is being cheaper when compared to their brushless counterparts. Choosing a brushed one can significantly trim your budget.
- Prospects of the rebuild: Owing to their simpler design and manufacturing, they can be taken to a custom rebuild once their life is at stake. They could be revamped to extend their serviceability.
- Controller: For the motor to operate at fixed speeds you don’t need one and if necessary, they are simple and inexpensive.
- Operable at extreme climatic conditions: With no electronic components present, they are comfortable operating at extreme climatic conditions. Any repairs are cheap and need comparatively less skilled labor.
Being cheap, they compromise on efficiency which lies somewhere around 75% - 80%. In the meantime, the brushless ones yield around 85% - 90%.
- Speed range: They can offer lower speeds compared to a similar capacity brushless motor. The drop can be attributed to the greater loss of energy.
- Brush shifts, shafts, and commutators: They tend to be less electrical in character and produce noises during shifts in brushes, shafts, and commutators. The result is a further drop in overall efficiency.
- Heat dissipation: The closely wound coils produce excess heat and offer less room for dissipation. Hence causes a loss in torque when running at higher rpm.
- Maintenance cost: The cost of ownership is comparatively higher for frequent maintenance of the RC car.
Brushless motor – advantages
- Maintenance cost: Lack of brushes can significantly broaden the maintenance intervals thereby the maintenance cost of the RC car.
- Efficiency and output: Efficiency and power to weight ratio are high comparatively. It interprets to a higher acceleration and easy overtakes.
- Heat dissipation: They are smaller in size thereby having room for better heat dissipation. They are known for their superior thermal characteristics.
- Speed range: With the rated load they operate effectively at all speeds. They operate at higher speed ranges without any significant electric noise.
- Sensors: The position sensor takes care of handling the electronic communication.
Brushless motor – disadvantages
- Cost: The need for an electronic controller compared to a low-cost mechanical commutator set up can price away from a considerable sum from your pocket.
- Vibrations: There will be considerable vibrations at lower revs but you can see them vanish when the motor reaches its sweet spot.
- Resonance: The inherent natural frequency of the motor can sometimes match with the vibration frequency creating a resonance effect.
- Wiring: An expert can only play with the wiring setup, electronic control, and its link to the electromagnets. Else you may end up burning the currency you have paid for.
So, to wrap it up, we can say it all depends on the buyer’s choice. But for further clarity, if you are a beginner who doesn’t need a punchy motor or swift acceleration you can go with a brushed motor. Of course, it will save you a lot of money and you can take it for granted during your training period with RC cars. Consider visiting our collection of brushed motors made exclusively for you.
If you consider yourself a pro, you will have to go with a brushless motor. But yeah, we would always recommend you to use a brushed DC motor before you move on to using a brushless motor.
Feel free to visit us and select your brushless motor and accessories including ECS and LiPo batteries.