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Hub motor testing

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    Hub motor testing

    Can anyone tell me how to test a hub motor with only a multimeter? And can anyone tell me how to program this LCD? And why it says 82v? I have 52 going to it. ThanksClick image for larger version

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    Hi Jholma,
    And welcome to the forum! :-)

    Testing electrical components of a typical hub motor with a digital multi meter.

    Two major electrical systems need to be checked out in a typical BLDC hub motor. Take a few minuets and look over the wiring going into the motor for cuts, scrapes, missing insulation and other wiring issues that should be resolved first.

    1) The motor's 3 windings. (high voltage components)
    2) The motor's 3 hall sensors, (low voltage components) if present. If not, you will need a "sensor less" capable controller and skip these tests.

    Motor Winding Testing.

    With the phase wire leads (heavy winding wires) disconnected from everything. Test resistance (ohms)between two phases at a time, and comparing all three phase combination's resistances.
    All three readings should match. Note that this is just a general check with a DMM. As the resistance readings are very low to be real accurate. It's not so much the reading, but if they all are comparable. Very easily can be much less that 1 ohm.
    Then check resistance between each phase wire at a time and a metal part of the motor. It should read infinity or open circuit. (nothing shorted to ground)

    Then tie two phase wires together in different combinations at a time for a total of three tests. At each combination, a similar magnetic resistance (also known a "cogging ') should be felt while trying to turn the wheel. With no resistance present when all wires are separated.
    Note: on a geared hub motor, wheel will have to be turned in reverse to engage the motor.

    Motor Hall Sensor Testing.

    In a BLDC motor that has hall sensors. The hall sensors are used to determine the position of the rotor for accurate sensor type controller operation. Each hall sensor has three wires and requires a voltage input (typically 5vdc) , 0vdc, (batt negative, or ground), with the last wire being output. This will bring the harness wires to a total of 5. (Typically, RED=5vdc+ ,BLACK=0vdc, and each of the last three are the outputs of there respective circuits.) When effected by the motor's magnet's gauss (positive and negative) passing by the sensor will switch output voltage from 5vdc to 0vdc. This voltage switching, at the correct time, and in the correct order is used by the controller.

    1) Testing when connected to a working controller.

    See this tutorial...

    2) Bench testing not using a controller.

    As a controller provides a "pull up" resistor to the hall sensor circuit for proper switching between the two typical values. (5vdc and 0vdc) One will have to be added when testing motor by itself.

    See this tutorial...

    And this...

    This is just an overall down and dirty with basic testing. Any questions on specifics, please let me know...

    EDIT: I used my posts in this thread as a template for a BLDC motor testing thread. To see the updated thread that includes even more information, please use the link below...

    Testing BLDC motor's Phase Wiring - Hall Sensors and Wiring.

    Last edited by Tommycat; 05-23-2021, 07:18 AM. Reason: Added "Testing BLDC motor's Phase Wiring - Hall Sensors and Wiring." thread link...
    See my completed Magic Pie V5 rear hub motor E-Bike build HERE.


      Any other particulars on the display? Make, model, brand, kit,ETC?
      See my completed Magic Pie V5 rear hub motor E-Bike build HERE.


        The kit was a pallet return from Amazon. I cant find anything like it, on line. The lcd hasn't any numbers or wording. Not a thing. I've tried image searches and nothing close to it. My motor passed all the tests except the first one. I could get my meter read anything but all zeros. Thanks so much for your help. I just spent alot of time and money, making a battery. And then it wouldn't work. It makes a kind of a banging noise when you engage the throttle.


          Well, depending on your meter's resolution and accuracy. Not picking up the low resistance values may be possible. If it passed the "cogging tests" it may be OK.

          From your description it sounds like your motor is indeed one with hall sensors. If this is the case the hall sensors must be matched with the correct phase wiring in order for the motor to run correctly.

          If you have a controller with "learning wires" or "auto configuration" by all means put it to use. As the controller will magically configure itself. If not, use this chart to successfully pair the hall sensors to their respective phase windings...

          Take it easy on the throttle till better results are obtained! (see Testing Recommendation box.) Good luck.

          See my completed Magic Pie V5 rear hub motor E-Bike build HERE.


            Thank you so much! Reversing the blue and green, did it! Runs great! I still dont know why it thinks I have 82v, though.


              That's just terrific! Glad to hear you solved the motor problem. Well done, and your certainly welcome.

              Alas, as far as the display... I've never seen one with voltage sensing adjustments (calibration) and as it's typically a direct feed from the battery. I suspect it's a bad display.

              Does the reading go down as you use up battery charge? Perhaps a resistor in series with the incoming voltage sense wire to skew the voltage read-out lower....

              I didn't have any luck on finding a manual either, let alone the display itself! :-(
              See my completed Magic Pie V5 rear hub motor E-Bike build HERE.


                Through a multimeter set to low ohms (usually 200), test amongst each winding terminal then the metal casing of the motor. If there is any interpretation on any of these then the motor is bad, do not use it. You might find that when it runs ungrounded that the covering becomes live at up to supply voltage.