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How to Test and Troubleshoot Brushless Motors

Brushless motors, with their efficient design and prolonged lifespan, are integral components in many modern devices, from drones to power tools. As these motors become increasingly common, understanding how to troubleshoot and test them is crucial for both enthusiasts and professionals.

Especially when these motors are often sourced from renowned manufacturers like Brushless Gear Motors Manufacturer. This guide delves into the world of brushless motors, highlighting their basic structure, common faults, and testing methods.

Understand the basic structure of a brushless motor

Grasping the architecture of a brushless motor is the foundation for understanding its operation and potential faults. Unlike their brushed counterparts from Brushed Gear Motors wholesale, brushless motors stand out due to their efficiency and longevity. Their basic structure comprises:


Acting as the stationary part of the motor, the stator contains multiple coils. When these coils are powered, they produce a magnetic field that induces the rotor to turn. The design and winding pattern of the stator play a crucial role in determining the motor’s performance, a feature often highlighted in premium DC Motors.


This is the rotating part of the motor. Generally, it is made up of permanent magnets. The rotor spins when influenced by the stator’s magnetic field, producing the motion that drives whatever device the motor powers.

Electronic Speed Controller (ESC)

The ESC serves as the brain of the operation. By adjusting the voltage and current sequences supplied to the stator, the ESC controls the direction and speed of the rotor. Modern ESCs, often found in motors from leading Gear Motor Factory, also have built-in safety features and diagnostics to protect and assess motor health.

Brushless Motors

Common faults of brushless motors

Brushless motors, although efficient, are not exempt from wear and tear or occasional malfunction. Recognizing these common faults can significantly expedite the troubleshooting process:

Short circuits

This is one of the most frequent issues. A short can cause the motor to halt unexpectedly during its operation. This problem often results from damaged insulation or wire exposure.

Bearing failures

Bearings facilitate the smooth rotation of the rotor. Over time, due to friction or external contaminants, bearings can degrade. When they fail, the motor may emit high-pitched noises or generate excessive heat.

Faulty windings

Windings, the coiled wires on the stator, can sometimes be damaged or worn out, either due to overheating or physical stress. This fault can hinder the motor from starting or reduce its efficiency during operation.

How to test whether the brushless motor is short-circuited

Detecting a short circuit is fundamental to preventing potential damage and maintaining the motor’s functionality. A short circuit can lead to reduced efficiency and even catastrophic failure, rendering the motor useless. For those curious about different motor types, understanding the Applications of DC Motors can offer valuable insights.

Safety First

Before you start the testing process, it’s paramount to prioritize safety. Always disconnect the motor from its power source before performing any tests. This step ensures both personal safety and the prevention of further damage. Keep the work area dry and free from any conductive materials.

Multimeter Setup

Equip yourself with a reliable multimeter, an indispensable tool for anyone working with electronics. Set it to the resistance (or continuity) mode, ensuring that it’s ready to detect any shorts accurately.

Testing Procedure

The brushless motor typically has three wires, corresponding to its three phases. Measure the resistance between each pair of these wires. In a healthy motor, some resistance should be present, indicative of the coils within. A reading of zero resistance or extremely low values is a clear sign of a short circuit, which means that there’s a connection where there shouldn’t be.

Additional Observations

While testing, be on the lookout for any burnt smell or visible damage to the wires or the motor itself. Such signs can often accompany a short circuit and further confirm the diagnosis.

How to Dry Test a Brushless Motor

Dry testing a brushless motor is a preliminary and non-invasive method to gauge its functionality without subjecting it to a full load. If you’re new to motors, considering a read on the Small DC Motors guide can be helpful.

Secure the Motor

Before initiating the test, ensure that the motor is firmly secured to a stable surface, minimizing any risks associated with unexpected movements or vibrations.

Connection to ESC

Every brushless motor requires an Electronic Speed Controller (ESC) to operate. Attach the motor to its designated ESC, ensuring all connections are tight. Be meticulous and make sure there are no exposed or frayed wires, as these can skew the test results.

Power Up

With everything set, power up the motor gradually using the ESC. As the motor begins to spin, keenly observe its behavior. Listen for any hesitations, unusual noises, or vibrations that might suggest underlying issues. A well-functioning motor should exhibit a smooth and consistent spin, free from any anomalies.

Brushless Motors

Post Brushless Motor Test Recommendations

The findings from your tests will determine the next steps: 

Successful Test

Congratulations! If the motor exhibits stellar performance, it’s ready for its intended application. However, always document the results of your tests. Such records become invaluable when you need to diagnose issues or compare the motor’s performance over time.

Check Bearings

Bearings are pivotal in facilitating the motor’s rotation. If you identified excessive noise or if the motor became exceedingly hot during testing, the bearings could be the culprits. Over time, bearings can degrade and may necessitate replacements.

Inspect Windings

The windings are the heart of the motor. If the motor struggled to start or seemed inefficient, it’s possible the windings sustained damage. Physically inspect them for signs of wear, burns, or any other visible anomalies.

Temperature Concerns

Brushless motors do get warm, but an overheated motor is problematic. If yours runs hot consistently, ensure it’s well-ventilated. Consider investing in a dedicated cooling system to alleviate the issue.

Prolonging the Life of a Brushless Motor

Ensuring a long and productive life for your brushless motor hinges on several factors: 

Routine Maintenance

A little effort goes a long way. Schedule regular cleanups for your motor, using a soft brush or compressed air to remove dirt or debris. This prevents foreign particles from impeding its operation or causing undue wear.


With time, bearings can dry out, a situation that hastens their wear and tear. Periodically lubricate them, but always opt for lubricants designed for electronic components to avoid complications.

Operate within Limits

Tempting as it might be to push the boundaries, always stick to the manufacturer’s specifications. Overextending the motor’s voltage or speed thresholds can severely truncate its lifespan.

Protection from Elements

If your motor operates in environments that expose it to dust, moisture, or extreme temperatures, it’s essential to shield it adequately. Protective casings or shields can significantly enhance its durability.


The realm of brushless motors might seem intricate, but armed with the right knowledge and approach, it’s navigable. Regular maintenance, periodic testing, and adherence to best practices will ensure your motor serves you effectively for a long time.

In the dynamic landscape of brushless motor technology, whether you’re an enthusiast or a seasoned professional, staying informed is paramount. For more insights and expertise on motors, consider checking out DongHui Motor.


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