Y6 Hot motors and ESCs

Posted by James A on June 22, 2014 at 5:32am

Hi, just been testing my Y6 with it's new 6000mah 4S pack and noticed the motors are getting hot. This is affecting the bottom motors more where if you touch them on the base, non rotating part, they are too hot to touch for more than a few seconds. The rest of the motor is hot but can be held without issue.

To check I did another flight with a 3S 4400mah setup and the motors were again getting hot, not as hot but the flight time was 5 mins vs 13 mins.

It's also worth noting with the 4S setup the ESCs were also getting hot, again after a 13 min test flight.

The flight itself basically consisted of a 13 minute hover in loiter mode, I was testing battery times, and consumed 5000mah. The weather for the UK was hot, 25 deg C. The Y6 is a new 2014 B version weighing 1900 grams or so, std config plus 600 gram pack, with std 10 inch props and 850 blue motors.

And finally to the question, is this normal of does something sound wrong?

The only thing I can think I haven't done is balance the props, guide for this would be handy, but I have no vibration issues looking at the data log.

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Replies

  • Haygood June 22, 2014 at 12:26pm
    My 2014 with a 4s gets hot, too. I'm not really clear on why it should, but the ESCs get hot even without the motors running. One of mine is melting through the heat shrink a little. Still, they should be able to survive getting so hit you can't touch them for more than a few seconds. That really isn't describing a terribly high temperature as far as circuits and solder go.
  • Greg Kosin June 22, 2014 at 7:51am

    I have had the same experience. I have two 3s packs and I have one 4s pack and found the esc and motors get much warmer on the 4s. I had read some threads in the past about this. Do a google search on diydrones y6 4s and you will find things like this. 

    Over wattage on Motors

    Since everything ran much hotter for me I have only flown with my 3s packs since as I don't want to burn up a esc. I am somewhat confused by this because typically if you can increase your voltage like with a 4s pack your current should be lower therefore cooler but it must have something to do with how the esc works. The calculator used in the link above is show with the 11 inch 4.7 prop and the typically y6 has 3 10" props as well so I wonder what that would look like. I also noticed that a 30A controller was used so I question that as well because my esc have a 20a sticker on them from 3dr so a direct comparison my not work. Sorry this doesn't really answer your question but wanted to add some info to the discussion for you. BTW I have a tarot 2d gimbal with go pro and fly a 3s 5000 pack and I land at 8min with about 70% of the pack used. I like to keep it on the safe margin side. 

    Greg

    • Tim Painter > Greg Kosin July 12, 2015 at 8:55am

      Hi

       I also have noticed hot lower motors ( all props the same 10x4.5) using 4s 6.6mah ms battery's.

      I think the reason may be that the lower motors work in an accelerated and rotating air stream,

      This effectively reduces the angle of attack,

      This would reduce the load , thus the torque would also be lower.

       Therefor power will  be increased ( by the controller ) to the lower and reduced to upper to maintain torque balance ( neutral yaw)

      My proposed solution is to use much higher pitch on the bottom and a smaller diameter to keep it in the slipstream the top motor.

      I believe that the solution  of  using a larger bottom diameter works is that the increase in  torque better balances power between the motors.

       I believe that an increase in pitch and reduction in diameter will better balance power and also increase power available before yaw control is lost

      comments invited

       Tim

    • DG > Tim Painter July 12, 2015 at 2:27pm

      You may wish to read this:

      http://is.gd/eW0JV1

      Since Leonard Hall did much testing, I did not try various props/pitches on my Y6B except for switching to CF. Ultimately, to keep it stock and perform well, I ended up buying 3 gram scales ($7.50 each) from Ebay and made sure the copter was perfectly balanced as possible. Then I switched the stock motor mount plates (blocked air flow from bottom of motors) out for the "+" style steel mounts that come with the motors. This greatly improved the convective heat flow which improved the cooling. It flew well like that for many more flights. One thing about these motors is they should be oiled about every 10-15 flights IMO, which most do not do.

      I don't have the link handy, but the motor mfr. stated in their literature to allow as much cooling as possible. It is odd that a flat motor mount with no cooling holes was used on the 3DR Y6. The bottom line is the motors are at the edge of what they can handle on this copter so cooling is very important IMO.

      Doug Walmsley later in this thread made some radical motor swaps to make the Y6B to his liking, and was successful if I recall.

      I also have a Sky Hero Spy 750 Y6 with KDE 2814XF-515 motors which I really like. On this copter I did experiment greatly with props/pitches. The best configuration for stability attained was using Xoar 15x5 props on top and 14x7 on the bottom. Virtually all flight characteristics were excellent, including high wind and even fast descents.

      However, efficiency did not improve probably because of the added weight of the Xoar props and the fact they have a thicker leading edge. In the end, I went with T-Motor 15x5 top/bottom which work very well; not quite as stable as the Xoar configuration, but 3A+ reduction in current draw gives me more flight time. 

      Throughout all this testing on my quads and coaxials, in my opinion, especially on heavier craft, high quality props are not an option but a necessity. I have quite a collection of cheap CF props that just don't work. On the Spy 750, I tried Tarot 15x5.5 props that are complete junk in my experience. They flex from the hub out, so for example when a gust of wind hits, the props would bend, then the copter would oscillate causing vibration and erratic behavior, even while doing Auto Tune. The PID's were literally maxed out. With the T-Motor props, the difference was night and day.

      Good luck. To me experimenting is half the fun of owning a multirotor.

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    • Tim Painter > DG July 12, 2015 at 2:57pm

      Hi

          I agree that the heat problem is less severe using metal mounts to sink heat into metal arms

      I also use + type adapters directly to the arms.

      I think your choice of propellers is correct for balancing power between motors

      this allows a bigger  reserve overhead for control before the lower motors run out of steam

      this dos not necessarily mean better efficiency,

      only more power  is available before control runs out

      Tim

    • Tim Painter > Tim Painter July 13, 2015 at 1:53am

      Hi  concerning hot lower motors.

      I have just checked outputs to the motors via the data logs (rcout)1-6

      average pwm  in the hover  =approx  1= 1460   2=1520

                                                          3=1520   4=1550

                                                         5=1460    6=1500

      1, 3, 5, are top

      now i am confused the results look like a close balance to me ?

      torque must be equal( no yaw)  and presumably power?

      I think i must find a way to measure the actual current to each motor /esc,

      am i right in thinking that for any given pwm value  a reduction in load will reduce the motor current?

      If so then it all points  to cooling problems.

      I am going to use heat conductive grease (used for transistor to heat sink thermal coupling ) on motor base to metal arms

      and have just received slimmer arms  15mm x 30 mm x1mm thick this should a give better air flow and cooling surface?

      I hope this is of interest and will post results later

      Tim

    • Pektusin > Greg Kosin June 22, 2014 at 5:51pm

      " I am somewhat confused by this because typically if you can increase your voltage like with a 4s pack your current should be lower therefore cooler but it must have something to do with how the esc works."

      Each motor is an inductor. Every real life inductor impedance has two components: active DC and reactive AC resistance. The last depends on inductance and signal frequency and this is what produces magnetic field and therefore does the actual work in your motor. For an ideal inductor that has no DC resistance for some given power increasing voltage leads to decreasing the current. You're right here. However, every real inductor has parasitic DC resistance - this is where power is lost. It is like a resistor: more volts means more amps and hence more watts. 

      By increasing voltage to 4S you increase DC loses in the stator's coil that turn to heat. More volts - more heat. 

      Hopefully it explains this little mystery to you :)

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