You’re going to do what to that motor? Let the party begin!

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Today, I am going to review the GForce Motor Analyzer tool. When it comes to test equipment, like this, I tend to get excited about these things and my wife will look at me and think I am weird (hey, she did agree to the better or worse part). I don’t know what it is but being able to learn what makes our motors tick is what gets my adrenaline going.

Let the party being!

Let the party being!

Ok, enough of the talk about my weird quirks and let’s review the GForce Motor Analyzer. What does it do? Well, the definition of Analyzer, according to dictionary.com is “to examine critically, so as to bring out the essential elements or give the essence of”. So in other words, it is a Motor Analyzer tool that provides the following measurements, KV value, RPM, Current Draw, Motor Timing, Vibration Noise and checks the Hall Effect Sensor. It will do 2 pole motors up to 36 poles but I will only be using it to test 2 pole motors.

Reusable packaging!

Reusable packaging!

The Motor Analyzer comes in a reusable cardboard box so you don’t have to worry about how you are going to store it. It obviously includes the necessary hookup cables to test motors. What it doesn’t come with is the power source. You will need a DC Source which will have to supply at least 7.4 volts and max out at 8.4 volts. They recommend a 2s 1p Lipo Battery which is what I used during my test.

As with almost all piece of electronic equipment you don’t want to mess up the polarity. If you do, you risk damaging the unit. While the instructions are clear on how to hook up the cables I strongly encourage you to pay attention to what you are doing, i.e. follow the directions. If you don’t, you might end up with a pretty expensive paperweight.

When you first attach the Sensored Motor to the Analyzer you will see red led’s at the top labeled A, B, C. These led’s let you know that the Hall Effect sensors are working.

When active, the sensor led's will light.

When active, the sensor led’s will light.

As you rotate the rotor you will notice the following pattern for a two pole motor, A, AB, B, BC, C, CA, A and so on. If you don’t see this pattern there is a strong possibility that there is something wrong with the sensor unit in your motor. Just to be safe I would recommend you try another motor if you have one just to make sure that the Analyzer is working correctly.

Once you turn the power on you will be greeted with a menu that has the following options:
1. KV RPM U I
2. Motor Timing
3. Noise Level
4. Pole of Motor

Now that you have verified that the Hall Effect Sensors are working it is an easy turn on the dial down to the Motor Timing test. Press the dial to tell the Analyzer that this is the test you want to run. There will be a prompt on the screen and you will be asked to press the dial again. I suggest that before you do you place your hand with pressure on the motor so that it stays in the cradle, it doesn’t require a lot of pressure. Otherwise, the motor will twist itself out of the cradle. The motor will run for approximately 7 seconds. It is during this time that it is identifying the location of the Hall Effect sensors. Once the test is completed you will see the Average Timing and the Timing for each phase, A, B, C.

Which one is not like the others?

Which one is not like the others?

The motor timing test has a tolerance of +/- 4%. So let’s put some actual numbers behind this and figure out what we could experience. When I ran this test my motor had an average of 35 degrees. Phase A, B, and C were 35, 36, 34 degrees respectively. So with a +/- 4% tolerance this means my Phase A could have been 33.6 or 36.4 degrees. Phase B could be 37.44 or 34.56 degrees. Phase C could be 32.64 or 35.36 degrees. In an extreme case, we could experience an almost 5 degree shift. Does this mean the motor is bad? No it does not. What it does mean is that you now have a baseline to test the motor allowing you to detect any changes over the life of the motor or if you disassemble the motor to clean it you know how it was set.

Up next is the KV RPM U I test. I believe KV and RPM acronyms are understood but what might not be clear is the “U” and the “I”. The “U” stands for the input voltage and the “I” stands for current. The input voltage, “U”, is important when testing because whenever you test you want to be able to repeat the steps. By being able to reproduce your test steps is very important when testing. That is why scientists are always writing things down when running an experiment.

KV, RPM, Volt (U), Current (I)

KV, RPM, Volt (U), Current (I)

To access this test you will use the dial to move through the menu until it is displayed on the screen and then push down on the dial button. You will be prompted to push the dial again and then rotate the dial. This is one test where you have control over the RPM of the motor. Similar to pulling back the throttle on your radio to accelerate you will be doing the same thing on the dial until you reached the max speed. I will let the motor run until the readings become somewhat stable but don’t let the motor run forever because you could damage it or the Analyzer.To stop it just push down on the dial and the Analyzer will display the last reading it had and you can now use this as a baseline.

Up next is the noise test. This test could potentially tell you when you might have a bad bearing, improper assembly or an unbalanced rotor.

Noise, can you hear me now?

Noise, can you hear me now?

These things cause vibration in the motor which can affect the performance of the system. I am sorry but I don’t have a magical number to give you for this test but I can tell you that when you run your motor record the number(s) so you can refer back to it later. The motors that I have tested have all be around the 93-95 dB range.

As I mentioned earlier, the Analyzer allows you to test motors up to 36 poles. I only have 2 pole motors so I can’t tell you what I found with a 36 pole motor. But if you did want to change it to 36 poles then all you have to do is rotate the dial until you see “Pole of Motor”, push down on the dial and the number will start to blink. You then rotate the dial until the number of poles your motor has has been reached and then push down on the dial again and you are all set.

The overall operation of the Analyzer is very easy to figure out. It only has one dial that also acts like a button so you can’t mess it up unless you don’t read the screen prompts.

Learn about the sensors in brushless motors.

Learn about the sensors in brushless motors.

The menu is easy to read and with the dial and button combo you can quickly change and start the tests. The manual even includes a good explanation of the Hall Effect sensors in the motor. Most importantly, it also has a nice diagram on how to hook up the motor and power supply correctly.

While it is not exactly a dyno which could tell you if your motor is a rocket or a dud over its life, as long as you have the motor values base lined. If you have a motor that is a rocket on the track you can use it to see what it is producing. Then when the time comes to setup another motor you can use this to take the guess work out hoping that you set the new motor the same way. While the consistency of brushless motors has gotten better it is always nice to have a tool like this setup a motor from the same manufacturer.

Do you have to have one? Most likely not but it won’t hurt you if you have some extra cash burning a hole in your pocket because of what it can do. Heck, you could also split the purchase of the Analyzer with a buddy and you will both benefit from it. Don’t get me wrong because it is a good tool which, like I said previously, will allow you to establish that baseline value to allow you to check the condition of your motor over time.

If you want to read how people are using the Analyzer, check out the G-Force Motor Checker thread.

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About Author

I have been involved in R/C since the early 90’s. I have participated in dirt oval, carpet and paved oval, on-road and off-road racing. I have found ideas that work and ideas that seem to be good on paper but fail for one reason or another. I have been involved in the rules decision process and tech inspection for one of the largest indoor on-road only events held in the U.S.

4 Comments

  1. Pingback: Motor Analyzer - Explained - Local Rc Racing

  2. Interesting, I think one of these would be valuable …i’ve just never wanted to spend the money on one, however this article has got me re-thinking that.
    Curious, I’ve always heard that it is bad to full throttle a car w/ no load? -wouldn’t using this device act the same way? Is it bad for the motor?

  3. Kraig O'Brien on

    It is valuable as long as you use it to baseline a known good motor.

    In regards to the throttle a car with no load, you do have load from the drive train but it most likely isn’t much. Yet I think it is better than no load at all.

    I have only blown up one rotor in my time and that was when I ran the motor at a full 8.4 volts for an extended period of time. That was also a brushless motor that I would consider to be old, over 5 years. Today’s motors seem to be better built and can handle the no load situation better than previous generations. However, I don’t recommend doing it because that is what the manufacturers will tell you so I would follow their recommendation.

    • Thanks for the info on no load of the motor.
      …this does interest me quite a bit as I do want to measure the rpm differences in various motors that all claim to be of the same value.

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