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Motor Temperatures

Discussion in 'General Discussion' started by gecarey, May 14, 2014.

  1. gecarey

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    There seem to be a lot of people who have taken temperature measurements on the phantom motors. Everyone says they are warm to the touch or not too hot or stuff like that, myself included. Has anyone actually taken the temperatures of the motors ? I have a IR thermometer and have been trying to isolate a possible bad bearing or something. There does not seem to be much of a difference between the motors, say a degree or two at most. After three consecutive batteries, I usually get readings in the 65-70 degree range. As the airflow stops(props) the temp does rise, but usually no higher than 80 degrees. I am curious what other people are getting temperature wise.....
     
  2. Karl666

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    Hi,

    I wouldn't worry too much trying to get a temp reading. Just keep an eye for differences between the motor readings (delta-T).
    The IR thermometer you are using has a fixed emissivity ( usually 0.95 ). This means that unless you are pointing it at a fairly emissive and (thermally) non-reflective surface the temperature you measure can not be relied upon to be 100% accurate. Its good for ball park figures but for more accurate readings you need to be able to compensate for T-Ref and dial in the correct emissivity value. For Non contact measurements a thermal imager would be better or a thermometer with a probe. I have a FLIR P640 thermal imager and have been meaning to shoot some thermal pictures and videos of my P2 but haven't had the time.
     
  3. ElGuano

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    I've never had the motors NOT have a "cool metal heatsink" feel to them, even after a 30-minute flight. I'm also not flying in 100 degree desert temps though.

    I think motor temps is something you can effectively "eyeball" or "guesstimate" based on feel. You'll know if it's too hot.

    But there are some pics folks have taken of running models with FLIR cameras, I can't find them atm.
     
  4. N017RW

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    One advantage of an 'outrunner' BLDC is cooler running temps as compared to a similar 'inrunner'.
     
  5. BruceTS

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    Agree the easiest way to tell, just grip each motor after every flight, if one is getting hot you will easily tell the difference. At that point you'll probably have to lubricate the bearings.
     
  6. KG4MXV

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    OK there are some hits and misses here.

    Using a infrared thermometer is a good start but the detection area is too big to get an accurate reading
    of the important parts.
    That being the windings and the bearings.

    Reading the out motor housing that has the permanent magnets will not give you a 100% clear picture
    of the state of the motor.

    And reading it with a IR "gun" is almost pointless since its reflective surface will only read the temps of the things around it.

    Other than using a infra red imager with a some what decent resolution you will have real fun getting accurate temps
    of the windings and bearings.
    You might be able to get a very small TC contact tip probe but a decent one will cost almost as much as a low end IR imager.

    Using your hand to feel the temp of the outer housing will give you a general idea but you are depending on the thermal conductivity of the metal of the center rod that passes though the bearings.

    The best way to test bearings for wear is to check for "slop" the amount of movement in the bearing. The less the movement
    with out binding the better.

    Also listing to the sound when manually rotating the motor is also a goo indicator of bearing wear.

    Tomorrow when the rain stops I will take out my P2V for a solid run and use my thermal imager to take some readings.

    I have also modified my lower shell to give me access to the bottom of the motor with out removing the top cover or the motor screws. At the moment I am using electrical tape to cover the access holes but I have some rubber grommets on order to do the job.
    Good night, hope my house doesn't float away, My weather station has recorded 4.5 inches of rain in the last 5hrs. and more to come.