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How Do I Choose a Brushless Motor?

Brushless motors are the more efficient and longer-lasting siblings of brushed motors. Both do a great job helping various machines rotate but brushless motors are simply better for various reasons.

But before that, what exactly is a brushless motor?In the simplest term, you know how regular motors have brushes that help them spin? Well, brushless motors are like the high-tech version. They use magnets and some smart electronics to make things spin without any brushes. This makes them super efficient, reliable, and they last longer.

Brushless motors are better at creating lift so they’re often used in drones. Besides drones, you can find brushless motors in PC cooling fans, battery-powered drills, and even CD drives. Here’s a quick rundown of the differences between these two types of motors.

Both brushed and brushless motors have magnets on the outer casing and coils of wire at the center, but brushed motors have carbon blocks also known as brushes that rub against the commutator plates to let electricity circulate through the coils as it rotates.

Brushless motors on the other hand rotate their entire outer casing while the coils remain stationary. Since no brushes are brushing against anything, there’s little friction in brushless motors, there’s also lower maintenance needs, and higher power-to-weight ratios which makes it the more efficient choice.

However, it’s not as simple as buying any brushless motor for your machine. There are several factors at play when it comes to choosing a brushless motor, continue reading as we talk about these factors and so much more.

Brushless Motors

Advantages of Brushless Motors

We’ve already established that brushless motors are better than their brushed counterparts, but let’s talk about this in more detail shall we? Here are all the reasons you should choose brushless motors for your machine(s).


One of the primary benefits is increased efficiency. Since brushless motors eliminate the need for physical brushes to transfer power, there is minimal friction and wear, resulting in less energy loss and heat generation. This efficiency translates to longer battery life and extended operation times, making them ideal for applications where energy conservation is crucial.


Additionally, brushless motors deliver improved reliability due to their streamlined design. The absence of brushes means fewer moving parts can wear out or fail over time. This leads to reduced maintenance requirements and longer operational lifespans, ultimately resulting in cost savings and reduced downtime.

Enhanced Performance

The electronic commutation allows for precise control of the motor’s speed and torque, resulting in smoother acceleration and deceleration. This level of control also allows for more sophisticated control algorithms, which is better in applications that need precise positioning or rapid adjustments.

Key Components of Brushless Motors

Of course, you don’t need to, but understanding the key components of brushless motors will help you make an informed choice when selecting the right motor for your application. Brushless motors have several integral parts that work together to produce motion efficiently and reliably.

  1. Stator. The stator is the stationary part of the motor and contains coils of wire that generate a magnetic field when electric current flows through them. This magnetic field interacts with the rotor to produce rotational movement.
  2. Rotor. The rotor is the moving part of the motor that is connected to the output shaft. It consists of electromagnets that interact with the magnetic field generated by the stator, causing the rotor to spin.
  3. Electronic Speed Controller (ESC). The ESC is a vital component that controls the timing and distribution of electric current to the motor’s coils. It synchronizes the current flow to the rotor’s position, allowing for smooth and precise rotation.
  4. Sensors. Some brushless motors use sensors to detect the rotor’s position. These sensors provide feedback to the ESC, enabling accurate timing and commutation control.
  5. Bearings. High-quality bearings are essential for minimizing friction and ensuring smooth rotation. Bearings support the rotor’s shaft and reduce wear and heat generation.
  6. Housings and Mountings. The motor’s casing and mounting points provide structural support and protection for the internal components. The design of these parts can impact heat dissipation and overall durability.
  7. Wires and Connectors. The wires carry the electric current from the ESC to the motor’s coils. Connectors ensure a reliable and secure connection, allowing easy installation and maintenance.

Now that you understand how these components work together, you are one step closer to choosing a brushless motor that suits your application’s requirements. The type, quality, and arrangement of these components can significantly influence the motor’s performance, efficiency, and longevity.

Brushless Motor

How To Choose the Right Brushless Motor Size

The motor size, or “stator size,” directly impacts the motor’s power output, efficiency, and heat dissipation. Here’s how to avoid making a bad decision.

Power Requirements. Determine the power requirements of your application, considering factors like desired speed, torque, and load. A higher power requirement will require a larger motor size.

Stator Dimensions. The stator dimensions, particularly the diameter and height, determine the motor’s physical size and available space for windings. Larger stators can accommodate more windings, leading to higher power output and efficiency.

Weight Considerations. Larger motors typically weigh more due to increased material and winding content. Consider the weight limitations of your application, especially in cases where weight affects performance, such as drones or portable devices.

Cooling and Heat Dissipation. Larger motors generally have more surface area for heat dissipation, which can be beneficial for applications that run for a long time. Effective cooling ensures optimal performance and extends the motor’s lifespan.

Space Constraints. Some applications have limited space for motor installation. Choose a motor size that fits within the available space while still meeting your performance requirements.

Application Type. Different applications have varying demands. For example, a small drone may require a compact motor for agility, while an electric vehicle might need a larger motor for higher torque.

Manufacturer Specifications. Consult the manufacturer’s specifications and performance curves to understand how the motor size affects performance parameters like efficiency, torque, and current draw.

Ultimately, the goal is to select a motor size that strikes the right balance between power, efficiency, and physical constraints for your specific application. Consider your performance requirements, available space, cooling needs, and any weight limitations to make an informed decision. By doing so, you can ensure that the chosen motor size aligns with your application’s objectives and delivers optimal results.


What To Pay Attention to When Choosing a Brushless Motor

Brushless Motors

The Kv rating, AKA velocity constant, is a specification that helps you gauge the performance of a brushless motor. It indicates how fast the motor will spin when a certain voltage is applied, without any load or resistance. Understanding the Kv rating will help you choose a motor that matches your desired application.

A higher Kv rating means the motor will rotate faster with the same voltage input, making it suitable for applications that require high-speed operation, such as drones or remote-controlled cars. Conversely, a lower Kv rating results in slower rotation, so it’s best for applications that demand higher torque, like heavy-duty robotics.

Something you should note is that the Kv rating is inversely proportional to the motor’s torque. Motors with higher Kv ratings generally have lower torque outputs, while motors with lower Kv ratings offer higher torque capabilities. Selecting the right Kv rating involves finding the right balance between speed and torque to suit your specific application requirements.

When considering the Kv rating, also take into account the voltage of your power source. Multiplying the Kv rating by the voltage gives you the motor’s no-load speed in revolutions per minute (RPM). This calculation helps you estimate the motor’s performance under specific conditions

In summary, by matching the Kv rating to your application’s requirements and considering the voltage, you can select a motor that delivers optimal performance for your specific project. To delve deeper into the world of brushless motors, you might want to explore What are DC brushless motors?

Maintenance of Brushless Motors

Brushless motors may offer reliability and reduced maintenance requirements compared to brushed motors, but proper care is still essential to ensure optimal operation over time. Here are some tips to help you maintain your brushless motors.

  • Periodically inspect the motor for any signs of wear, damage, or debris buildup. Check the bearings, housing, and connectors to identify any issues that could affect performance.
  • Keep the motor and its surrounding area clean to prevent the accumulation of dust, dirt, or foreign particles. Dust and debris can impede cooling and lead to premature wear.
  • Ensure proper ventilation and cooling for the motor, especially during prolonged operation at high power levels. Overheating can degrade performance and reduce the motor’s lifespan.
  • Some brushless motors incorporate bearings that require lubrication. Follow the manufacturer’s recommendations for the appropriate type and frequency of lubrication to prevent friction and wear.
  • Operating the motor beyond its specified limits can lead to excessive heat generation and wear. Stay within the motor’s recommended voltage and current ratings.
  • If the motor will be stored for an extended period, protect it from humidity, temperature extremes, and physical damage. Store the motor in a clean and dry environment.
  • In applications where a motor drives a propeller or load, ensure that the propeller or load is balanced. Imbalances can cause vibrations that stress the motor and its components.
  • Invest in high-quality components such as bearings and connectors. Quality parts can significantly contribute to the motor’s longevity and overall performance.
  • Adhere to the manufacturer’s guidelines for installation, operation, and maintenance. Manufacturers often provide valuable insights into optimizing motor performance and lifespan.

By implementing these maintenance practices, you get the most out of your investment and ensure that your chosen motor continues to meet your application’s requirements over the long term.

Final Thoughts

Whether you’re powering a drone or drill, knowing the right size of brushless motor to choose propels your machine towards success. As you can see there are many things to consider when it comes to choosing the right brushless motor but once you do your research and check all the right boxes, you’ll get your project up and running in no time.

If you want to know more about brushless motors, please pay attention to Donghui Motor.

Related Reading: Brushed DC Motor Vs Brushless DC Motor


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