Brushless motors are becoming increasingly popular in the RC hobby and other applications. In this article, we’ll cover the top 10 items you need to know and understand about brushless motors. Whether you’re new to the hobby or an experienced user, this information will help you choose the right brushless motor for your needs.
Table of Contents
KV – Velocity Constant
The first item on the list is KV, which is a popular specification that provides information about a brushless motor. KV is a velocity constant that represents the RPM you get from a brushless motor for each volt that is applied to it. This allows you to determine the maximum RPM of a specific combination of battery pack and KV option.
Different KV Options from Motor Manufacturers
The second item is related to the first and deals with the different KV options offered by motor manufacturers. Different battery voltages can be used based on the chemistry of the battery pack, and motor manufacturers offer various KV options to best suit the battery pack you plan to use.
Turns vs. KV
The third item is about the difference between turns and KV. Turns are often seen in radio control car applications, where motor manufacturers will specify a 7.5 turn or 12 turn motor. However, turn counts are not specific enough to provide an absolute performance number. The KV specification is far more superior as it provides more information about the brushless motor’s performance.
Misconception About KV and Torque
The fourth item is a common misconception about KV and torque. Many people believe that a lower KV value will result in more torque, but this is not the case. A lower KV value will result in more torque for every amp applied as current to the brushless motor, but it will also have a lower current capacity.
Power Output of a Brushless Motor
The fifth item deals with the power output of a brushless motor. A larger motor, whether in diameter or length, will have a greater influence on power output. When comparing motors, it’s wise to assume that a smaller motor may underperform compared to a larger one.
OutRunner vs. In-Runner Motors
The sixth item is about the difference between OutRunner and in-runner motors. OutRunner motors have a lower KV value for their size, but this also limits the total RPM that can be extracted from the motor. OutRunner motors can be compared to diesel engines, while in-runner motors can be compared to gas engines.
Advantages of OutRunner Motors
OutRunner motors have several advantages over in-runner motors, including a lower KV value, which means they are more difficult to overheat, and they also have a better torque-to-weight ratio. OutRunner motors are also more efficient and have a longer lifespan.
Advantages of In-Runner Motors
In-runner motors, on the other hand, have a higher KV value, which means they can achieve higher RPM. They are also smaller in size and lighter, making them ideal for smaller applications.
Choosing the Right Brushless Motor
When choosing the right brushless motor, you need to consider several factors, including your battery pack, application, and desired performance. You should also consider the size and weight of the motor, as well as its efficiency and lifespan.
Final Thoughts
In conclusion, understanding brushless motors is essential if you want to get the most out of your RC hobby or other application