If you are an RC car enthusiast, you might very well know that in an Electric RC car, DC motors are used to convert the electrical energy into mechanical energy. Similarly, you might also have heard a lot about Brushed & Brushless DC motors. So what are they essentially?
Brushed and Brushless motors are two configurations of a DC motor that is used in RC vehicles and cars. The fundamental working principles of both are similar, the only difference between these two motors lies in the way they are constructed. The major difference between brushed and brushless motor is, as the name suggests, the latter does not use a brush to convert electricity in the motor. Essentially, this makes the brushless motor more efficient than its equivalent brushed motor.
For those who are not familiar with radio-controlled cars, it can be difficult to understand technical terms and jargon, before making a purchase. One of the commonly misunderstood terms – brushed and brushless RC cars.
In this article, we will have an in-depth look into the differences between a Brushed and Brushless motor in an RC car
How does a motor work in an RC car?
Before we discuss the difference between a Brushed & Brushless RC motor, it is important that we have a clear understanding of how a DC motor works.
When a current-carrying conductor is placed inside a magnetic field, it experiences a mechanical force, torque which turns the conductor.
Similarly, in a DC motor, a current-carrying conductor (Known as the rotor) is kept inside a magnetic field (Stator), which experiences a mechanical force, torque that, in turn, rotates the conductor.
The most important part of a DC motor is the Commutator, which ensures the constant rotation of the motor in a single direction.
Need for Commutators
As mentioned in the previous section, a commutator is an important component of any DC motor. Without a commutator, it will not be possible to keep the electric motor constantly running in a single direction.
The reason for this phenomenon is beyond the scope of this article. Keep in mind that the fundamental difference between a Brushed and a Brushless motor in an RC car lies in how the commutator is constructed.
Technical Differences: Brushed vs Brushless RC Motors
Brushed DC Motors
Brushes are usually made of copper, graphite, or silver, and these are used to energize the commutator to ensure the rotation of the rotor in a single direction.
In a Brushed DC motor, these carbon brushes along with the commutator ring to switch the electrical polarity of the armature (The stator). This switching of the polarity in the coils maintains the armature’s rotation in one direction.
Brushless DC motors
DC Brushless Motors are constructed differently and are sometimes also referred to as Electrically Commutated Motors (ECM).
Unlike with the brushed motors, in this case, the windings are located on the stator while the permanent magnets are on the rotor, and it is due to this unique design that removes the need for brushes.
These motors also use three phases of driving coils and additional sensors to determine the position of the rotor and electronics.
Brushless motors also create the magnetic field inside the rotor with the use of an amplifier, which is triggered by an electronic device. So unlike a Brushed DC motor that uses brushes seven commutator rings to switch the polarity of the electromagnet, a Brushless DC motor uses position sensors instead of mechanical rotary switches.
Also, there are two types of brushless DC motors, sensored and sensorless. Sensored brushless motors contain the sensors within the motor, this eases the process of transmission of information back to the ESC. The speed controller gets the position of the rotor and spontaneous synchronization is established straight from zero RPM.
Advantages of Brushed Motors
One of the key advantages of a brushed motor radio-controlled car is that they are significantly cheaper than a brushless motor. That is, when two similarly powered motors are compared, the brushed motor is cheaper than its brushless counterpart.
Another advantage of brushed motors is that the system is simpler than a brushless motor. The wiring and other aspects that form the system make it a lower-priced option when compared to a similarly sized brushless motor. Due to this, a potential buyer of radio-controlled cars would find that cheaper electric RC cars will have brushed motors in them.
Advantages of Brushless Motors
As explained earlier in this article, the fact that the brushless motor has no brush to convert electricity, this, in turn, ensures that less maintenance is required on a brushless motor. In a brushed motor, a driver would need to clean the various parts more often, whereas this is not the case with brushless motors.
Time can also be converted to money, therefore with a brushless motor, a driver of the radio-controlled car would not need to spend money on the replacement of a brush, as is the case with brushed motor radio-controlled cars.
One of the key advantages and reasons that many people opt for brushless motor radio-controlled cars is that they are significantly faster than brushed motors counterparts. The fact that efficiency drops in brushed motors (along with power), means that brushless motor RC Cars are much faster than their brushed equivalents.
A factor derived from high efficiency and lower maintenance is that it also results in higher run times for brushless motor radio-controlled cars. Thereby reducing maintenance cost and time invested in parts while increasing fun!
Disadvantages of Brushed Motors
One of the most apparent disadvantages of brushed motors as briefly touched upon earlier, is their low power efficiency. In general, the efficiency of a brushed motor is between 75% and 80%, whereas the efficiency of brushless motors is usually between 85% and 90%.
The reason for lower efficiency is due to the design of the brushed motor and because of the mechanical limitation of the brushes themselves, which results in the motor offering lower speed ranges than its equivalent brushless motor.
In addition, there tends to be more electric and electromagnetic noise due to the shifts of the brushes, shafts, and commuters. While heat loss is also higher and all this adds up to lower efficiency and higher losses in brushed motors.
Finally, as briefly mentioned earlier, brushes will wear out over time and will require repairs and replacements.
Although all these factors may be considered minor when looking at the bigger picture, a potential buyer should be aware before making a decision between Brushed motors vs Brushless motors.
Disadvantages of Brushless Motors
The main con of brushless motors is that they are definitely more expensive than their brushed equivalents. Therefore, a potential buyer should consider all factors before making his decision to buy.
The prices for brushless motors are high due to the components in the motor itself. Without going into too much detail, it can be noted that a brushless motor uses an electronic speed controller (ESC), thereby costing more to produce. However, one must keep in mind that a brushless motor provides more value for money because they require fewer repairs and replacements of parts.
Another disadvantage of brushless motors is that they offer less speed control. This translates to difficulty in driving a brushless motor radio-controlled car over rougher terrains when compared to brushed motor radio-controlled cars.
Summary: Brushed vs Brushless RC Motors
So the question comes down to how a buyer chooses between a brushless motor RC Car and a brushed motor RC Car?
This can be summarized by saying that, if you don’t require higher speeds and greater power from the motor, then a brushed motor RC car would be sufficient.
That is to say, if you plan to do drive the car relatively slowly and only occasionally require speed bursts, a brushed motor RC car would be more than enough. These cars are also easier for beginners who want some power but at a lower price.
However, if you want to be able to drive your radio controlled car faster than 15 mph and want to have better power efficiency, the brushless motor radio-controlled car is definitely better suited. These cars are definitely better options for experienced drivers who require speed.
Another option for those who already have a brushed motor radio-controlled car is to modify and upgrade the car to brushless motors.
In addition to upgrading the motor to brushless, you would also need to get a brushless electronic speed controller, a LiPo Battery, and a new battery charger along with certain safety accessories.
Some examples of brushless electric RC Cars would be:
- Traxxas Desert Racer 4×4
- Traxxas Velineon
- JLB Racing J3Speed, which is a four-wheel-drive brushless off-road vehicle.
Similarly brushed radio-controlled car examples would be:
- Traxxas Bigfoot Brushed 1:10 which is a rear-wheel-drive monster truck
- Tamiya Blackfoot Brushed Monster truck, which is also rear-wheel drive.