How To Tell If A Brushless Motor Is Bad

2 Methods On How To Tell If A Brushless Motor Is Bad?


Do you have a brushless motor you’re not satisfied with? Maybe something’s wrong with it. Often people don’t understand when a brushless motor has gone bad. But not anymore, we’re here to help you!

So, how to tell if a brushless motor is bad?

Well, You can tell if your brushless motor has gone bad by observing some signs. The motor will overheat, make loud noises. The motor will vibrate extremely while running. If you look inside, you’ll notice burnt windings and loose magnets. All these signs are indicators of a bad motor.

This was just a short briefing. You have to understand a bad brush motor’s sign to the depth. We have provided detailed information on this. 

To find out more, you have to keep reading!

How to Tell If Your Brushless Motor is Bad?

A bad brushless motor does not work efficiently like a good one. It shows indicators that the motor’s components may be damaged.

There are different methods to indicate the problems in the motor. Go through methods to know the possible ways.

Method 1: Check the Brushless Motor Parts Individually

Open up your brushless motor and check each part for problems. Use screwdrivers to unscrew the different motor parts.

After unscrewing, you have to carefully observe every motor part individually. Once you notice the faulty motor parts, change them.

Let’s go to the steps now-

Step 1: Check the Motor Fan

If your motor fans don’t function, the motor will get extremely hot. Check to see if it’s clogged with dirt and grime.

Always keep the cooling fan unclogged and clean.

Step 1: Check the RC Bearings 

The bearings of a motor are the parts that work the most. So they tend to get worn out faster than the other parts. If you continue using damaged bearings, it’ll slow your brushless motor.

If you can’t turn the shafts swiftly, that means the bearings are damaged. They need to be removed and replaced with new bearings soon.

Step 3: Check the Windings

If you see the bearing is burnt and has black marks, you need to change it. Also, the cracks in the windings can hamper the operating of your motor.

Here’s a list of the best quality windings for your brushless motor, in case you need it-

Product 1
Product 2

These are efficient windings within a reasonable price range. 

Method 2: Dry Test the Brushless Motor 

Dry testing means you have to check the failure of the motor parts by testing them. Then compare the result with the ideal state. 

This method is very effective to find out the problems in a brushless motor.

Step 1: Check the Voltage

Use a voltmeter or multimeter to take the reading of the voltage of each wire separately. 

If the motor is good, all the readings will be the same. 

The voltage range will be within 0.3 – 0.8 ohms. If they are different, the motor wire is damaged. Replace the wires immediately.

Step 2: Spin the Motor Shaft

Disconnect the motor and separate all three wires from each other. Connect the motor shaft to a constant speed drill and spin the motor up to 1000rpm.

The motor will start spinning easily and there will be no noise. Spin the motor for 2-3 minutes. 

Observe if the temperature rises quickly. If the motor gets extremely heated up, it means something is wrong. 

Check the magnets inside the brushless motor. If they are loose, fix them with glue. Use a jb weld or gorilla glue of your choice to do the job.

How To Prevent a Brushless Motor From Going Bad?

Proper maintenance can give your brushless motor a very long life. For the motor, you don’t even need to use any expensive cleaning chemicals. Here’s what you can do-

Clean Your Brushless Motor

Always disconnect the motor from  RC before cleaning it. See if the wires are okay. Wipe the dust and dirt from the motor with a cleaning cloth. 

Unscrew and open the motor to clean all the parts individually. Clean any dirt around the magnets with a tiny brush. Clean the small areas out by spraying compressed air. 

Lubricate the Brushless Motors Bearings

Remove the screws from the bearing caps to gain access to the bearings. Turn the bearing with a drop of oil on it. It’ll keep the shaft movement smooth.

But don’t put too much oil there. It can make the bearings very loose.

Keep the Motor Cool

Prevent the motor from overheating using heatsinks and cooling fans. Keeping your brushless motor cool ensures a long motor life.

Your motor can still go bad after taking good care of it. It’s better to replace a bad motor rather than keep using it.


Question: Can a brushless motor work without a controller?

Answer: In simple words, no a BLDC doesn’t work without a controller. It needs a control circuit and a regulated power supply. You can say, a brushless motor is totally dependent on its controller. The controller circuit regulates the speed and torque of the BDLC. It can accelerate, terminate, and reverse the rotation of the motor.

Question: What are the disadvantages of a brushless motor?

Answer: The magnet used in a brushless motor is very expensive. It can generate limited constant power. So, it will never reach a speed twice its base speed.

Question: Is it possible to reverse the direction of a brushless motor?

Answer: Yes it’s possible to reverse the direction of a brushless motor. If you see it spinning in the wrong direction you can fix it. Interchange any two of the wires connecting the motor to its ESC. The spinning direction will immediately change. 


Now you’ll understand better how to tell if a brushless motor is bad. Take proper care of your brushless motor to give it a long life. 

Don’t forget to share your experience with us.

Hope you have a wonderful day ahead!

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