When trying to decide what kind of car to purchase, it’s important to understand what’s going on underneath the hood of your new vehicle and whether the motor is worth the cost of the car. Many cars are described as having either a brushless motor or a brushed motor. For a beginning RC car enthusiast, these terms can be confusing.
What is the difference between brushless and brushed for RC Cars? Brushless cars work using electromagnets and do not contain brushes, while brushed cars have brushes that cause friction and wear down over time. Brushless cars are faster and better for experienced drivers. Brushed cars cost much less and are good beginner cars.
Knowing how the motor actually works and the advantages and disadvantages of each kind of car can help you know which kind of car will be best for you. In the following article, we’d like to explain in more detail what the differences are between these two kinds of motors.
Brushless Motor Components
The brushless motor is made up of two parts. The stator, a cylindrical component, is ringed either internally or externally by electromagnets. Electromagnets are essentially magnets that can be turned on and off by electricity, which, in this case, can change the polarity of the magnets from positive to negative.
There are two kinds of brushless motors, out-runners and in-runners. There isn’t a difference of quality between the two. The only difference is placement, whether the rotor is place inside or outside of the stator.
The rotor, true to its name, rotates, and has regular magnets mounted all around it radially. These magnets alternate between positive and negative charges and never change.
When the power is turned on, electricity begins to flow into the electromagnets. The electricity alternates the polarity of each electromagnet on the stator between positive and negative.
This simultaneously draws the regular magnets on the rotor to the electromagnets with the opposite charge and pushes them away from the ones with the same polarity. This shifting push and pull causes the rotation of the motor and generates the necessary power and torque.
Brushed Motor Components
Brushed motors actually work on a very similar principle to brushless motors. They also have a stator which generates a continuous magnetic charge. The stator is divided in half and has the negative charge at one end and the positive charge at the other end. Instead of a rotor, however, the brushed motor has an armature, which is a coil of wire that electricity is pumped through.
The coil is connected to the battery by a split-ring device known as a commutator ring that is connected to the battery. As the electricity enters the wire from the commutator, the wire begins to rotate, causing the commuter to rotate as well.
The commutator is split so that as the coil rotates, the commuter pair is exposed to first one and then the other end of the battery, causing the coil of wire to shift polarity as it rotates within the stator. This gives the rotor the necessary push and pull against the magnets in the stator.
This process is repeated and provides the push and pull to keep the armature rotating. Unfortunately, as the armature becomes perpendicular to the magnetic flux it enters a space with no magnetism. As a result, the torque drops nearly to zero, which causes irregular motion from the rotor.
This can be resolved by adding more wire coils and separate commutator pairs, which cause flux to always be propelling the rotor forward at a steady pace.
The electrical contacts that connect with the rotating ring are called “brushes” because, originally, copper brush contacts were used. Now we have spring-loaded carbon contacts, but the original name has persisted. These points of contact are the weak points of the brushed motor.
Advantages and Disadvantages of Brushless Motors
Brushless motors have many advantages over the brushed system. For starters, because the electromagnets can be switched simply by using electricity, the motor does not have the commutator rings that rotate through the points of contact.
This eliminates friction and increases the speed and torque at which the rotor can turn. This, in turn, makes your RC car run at speeds that are unrivaled. It also means that you will have to do very little maintenance over the course of your motor’s life.
Brushless motors very rarely breakdown or need to be replaced. You might eventually wear down your bearings, but those can be easily replaced and you shouldn’t need to worry about that for a long time.
Brushless motors have a few disadvantages though, especially for beginner RC car drivers. For one thing, because they are capable of much faster speeds, the companies who produce them often assume that those who are purchasing them are already capable drivers.
Thus, there are fewer stabilizers, and the controls can be more difficult for an inexperienced driver. They are also more expensive initially, though the low upkeep costs can help balance that out. It is suggested that brushless motors use lithium ion polymer (Li-Po) batteries because they are more powerful and they provide a longer charge.
These batteries are usually found within the brushless motors. However, Li-Po batteries come with their own advantages and disadvantages, including the possibility of exploding if improperly cared for.
Advantages and Disadvantages of Brushed Motors
Brushed motors are a bit outdated, but they produce a good vehicle for a beginner driver and for children. They are cheaper to buy and easier to control. They also tend to go a little slower, so they cause less damage to themselves and their surroundings when they crash.
Unfortunately, because the commutator pairs are constantly rotating, the brushes that they rotate against get worn down from a combination of mechanical friction and electrical corrosion. They can be rebuilt in some cases, but often it isn’t worth the time or cost.
In many cases, it’s cheaper to buy a new vehicle. They also waste more power, so the batteries will die much more quickly. In addition, they run off of nickel-metal hydride (Ni-MH) batteries which, while they are cheap and safe, also have less power and have to be recharged and replaced much more often.
What are the differences between Li-Po and Ni-MH batteries and should this affect which kind of motor I buy? Li-Po batteries are definitely the superior choice. They last longer, they don’t lose their ability to recharge over time, and their output is far better than the Ni-MH battery. Due to their impressive power output, they can also increase the speed of the vehicle they are powering, and some have been known to drive as fast as 200 mph. They only have a couple of problems.
First, of all, they are more expensive. The charger and batteries can run from $30 for a cheaper set to over $100, and with Li-Pos, it might be worth it to pay the extra money.
Second, if Li-Po batteries are punctured or damaged, they can either heat up so hot that they will set fire to anything flammable around them, or they can explode. It is recommended that you bring a fire extinguisher with you when driving an RC car that contains a Li-Po battery. Happily, combustion rarely happens, and with the proper care your Li-Po battery can last you for years, providing you with a superior driving experience.
Ni-MH batteries, on the other hand, are about as safe and stable as they come. They are inexpensive, but they lose their charge fairly quickly and don’t produce as much power. They can be used in brushless vehicles, and many brushless RC cars come with Ni-MH batteries. They won’t have the same kind of capabilities for speed, but they will still allow your car to drive well, if for a shorter period of time.
If I’ve already purchased a vehicle, can I switch to a brushless motor? If you already have a car that you’ve put a lot of love into and you want to switch the type of motor that is powering your car, this is an option. Most RC car stores sell brushless motors that can replace brushed motors. You can ask the employees at the store or you can look online to find out what model of motor you need for your vehicle. There are tons of YouTube videos online or instructional articles that can show you how to replace your motor with a different one, as well, if you want to try and do it yourself.
Upgrading an already purchased vehicle can be a satisfying experience, and you’ll be amazed what your car can do with a new motor. There are other upgrades you can make as well, but when you upgrade to a brushless, it is also recommended that you switch to a Li-Po battery.
If I’m new to racing, should I go straight to a brushless motor? Getting a brushless motor right away is a personal choice. Starting with a brushed motor might be a good idea while you figure out how to handle an RC car. They move a little slower and have simpler controllers. They respond quickly and handle abuse well. Also, if they get damaged during the initial learning phase, it won’t be as much money out of your pocket to fix or replace them. However, if you want to learn on a more difficult vehicle, that is up to you. It might take a little longer to master, but they are a delight to drive.