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Motor rotations failure

Discussion in 'Phantom 2 Vision + Discussion' started by soulboys, Apr 30, 2014.

  1. soulboys

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    Got today my new Phantom Vision+ and when I turned it on I noticed that one motor is "pushing" different then other three and have different sound. The battery level was 2. When I inserted a fully charged battery, the problem disappeared, but I think when it will goes till 30-40% the situation could repeat.

    Didn't fly yet, but is there a fix for this issue?

    Here is the video:

    https://www.youtube.com/watch?v=Zq5QkTmpxzs
     
  2. DBS

    DBS

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    That is normal on low battery while the motors are idling... One motor starts to pulse... When the battery gets lower, two motors will pulse that way... you will also notice the lights directly beneath that motor blink when the pulse is happening... normal stuff bro

    Don't know if dji made this as an audible warning just in case you aren't looking at your flight screen or the battery level indicators maybe? But it's been confirmed by many users in the past couple weeks... :ugeek:
     
  3. soulboys

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    ok, but I sent this video to DJI dealer and here is the official reply:

    "We have received a couple of these reports and are issuing exchanges. Please standby for a return label and authorization. Our new batch of Vision+ units will be here next week.
    It will be a complete replacement. We will need you to ship back the entire unit and controller. A return label will be forthcoming."

    With my old Vision I didn't have such failures, even at 50,40..20%, is this specific only to P2V+ ?

    What to do now?
     
  4. plasmo

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    hmm I remember mine pulsing like this as well, but thought it was normal. It flew fine... I will pay more attention next time I go fly

    EDIT: i watched it again, and see that that particular prop was not spinning as fast as the others (allowing you to stop it easily with your fingers)
     
  5. J Dot

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  6. Tripnman

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    So glad this caught my eye as I just came inside to post a similar message!

    I've been a PV2 operator since the first of the year (50 hours of flight time) and have been happily flying my PV2+ for just over a week. This evening I was flying around my neighborhood and a few people came over to chat. My battery was at 50% so I brought the aircraft down and landed without turning off the motors. I had intended to fly again - but while I was talking with my neighbors my aft starboard engine started doing EXACTLY what is shown in the OP's video.

    So - I rebooted and restarted. Same issue. I pulled the props and applied power and could no longer hear (or see) the twitch. Put the props back on and the problem returned. Thinking that perhaps it was a voltage issue, I put in a fresh battery. The twitch was gone. I lofted the machine and flew (low and slow!) for 10 minutes or so - battery dropped to 70% and when I landed the twitch was there again when the motors were at idle. Grrrrr.

    Plugged the PV2+ into Assistant 3.0 and checked voltages on both of the batteries that were used today - all okay. Thought it prudent to run an IMU calibration but found the button greyed out. Does that no longer work in 3.0 or with the PV2+? Need to look into that. But that's for another post.

    I honestly can't say if I've ever left my PV2 or PV2+ at idle with a less than full battery - so perhaps this is indeed a "feature" that I've never noticed before. Regardless, it is disconcerting that DJI is offering the OP a replacement but another poster says it is normal. Oh my - conflicting information on the interwebs!

    Going to call my dealer (Dave's Motors) tomorrow to see what they say.
     
  7. Venom93corba

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    I had this same issue with my P2V+. DDM told me not to fly it and send it back for an exchange. So I did and my new bird arrives Friday. Exactly the same issue. Once you charge the battery the issue goes away. Weird.
     
  8. JimDE

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    My first P2V was returned for that except I had the light under the motor flashing at the same time with the pulse... was told it was possibly a motor going bad or a bad ESC and to send it back and not fly it. My replacements do not do this no matter how low the battery.
     
  9. amkorp

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    So has anyone confirmed that this is in fact a bad motor?

    My vision+ is doing the same thing. When I turn the motors by hand one of them has a distinctly different feel to it. The other three "snap" to the magnet positions, but one just spins freely.

    Has anybody's dealer gotten back to them regarding this?
     
  10. Dirty Bird

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    Allow me to offer my opinion on this as someone who has been flying electric RC for a long time:

    As long as the motors are operating properly at speed, your Phantom is flying smoothly and responding properly to your commands, and barring any odd noises or elevated temperature from a specific motor, I do not believe this is anything you need worry about. For those who have never built an electric RC, each electric motor is controlled by an ESC unit - an electronic speed controller. The ESC feeds power to the motor, and delivers the throttle position information from the controller. When you build a new aircraft, you calibrate the ESC to the controller, so that the ESC recognizes where the 0% and 100% spots are on the throttle. Every controller is different, so this allows the ESC to learn the positions. There is a procedure specific to each brand ESC for how to enter the calibration mode and complete the procedure.

    In a single-engine aircraft, you have but one ESC to calibrate. The Phantom, however, is a multi-engine aircraft, with four engines and four discrete ESC units. Were I building a multi-engine, manually-controlled, aircraft...say a four-engined B-17 bomber...I would, one-by-one, plug in each ESC/engine combo, enter the programming mode, and calibrate the throttle for each in turn. That way, when I go to 0% throttle, all engines stop. When I go to 100% throttle, all engines are running wide open. This way they are all running at the same speed, so as not to induce any imbalance into the system affecting the aircraft. In some very high-end multi-engine RC aircraft, they have have individual throttles, like in a real plane, so the pilot can balance them manually. In general though, most multi-engine RC aircraft have but a single throttle, so you want the motors all operating at the same speed. Sometimes you can program all of the ESCs at once, but I believe most seasoned pilots would choose to calibrate each motor individually.

    The Phantom, being a multi-engined aircraft, needs its ESCs to be calibrated also. How to enter the calibration mode for a Phantom's ESC I do not know? It may pass on ESC calibration information when you perform the process in the RC Assistant and Assistant software? I doubt this as a usually ESC emits tones indicating it is in a programming mode, and confirming success. But, unlike a fixed-wing aircraft like a B-17, you don't control the Phantom's throttle in the same way. When you issue a full climb command, the NAZA is actually controlling the throttles of each individual engine to keep it oriented to your throttle/stick commands. Thus, even if at idle one ESC is slightly out of calibration, in flight the NAZA will still adjust the speed of each specific motor to make the aircraft conform to your control inputs. As the voltage/current of the battery drops, minute variances will become more apparent in an idle situation. But in flight, the NAZA flight controller will compensate and increase motor speeds as necessary.

    You might want to try re-running the calibration procedure in the RC & Software Assistants. That may help, as many of us probably calibrated before our first flight, and haven't calibrated since. The engines break in after a few flights, and the Phantom 2 engines run a lot more than a typical RC airplane with her long flight times. Unless you notice your Phantom is not responding to commands properly, or flying erratically, I do not believe one engine being slightly faster or slower at idle is anything to worry about.
     
  11. Tripnman

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    I had a great conversation with DDM today. As of now, they have had three clients that are experiencing this same issue. One had additional problems with the aircraft and has been issued a replacement. The tech at DDM is sending the video in the OP to DJI China to get some feedback. DDM also wants to know if this is an undocumented "feature" or if there is something wrong. They suggested that I not fly it until we know and I agree - the last thing I want is the airframe to come tumbling out of the sky at a job site. I mean flying location. Park. Whatever. ;)

    The one thing remaining test I want to run is to see whether or not all four motors start pulsing when battery voltages drop to minimums. Last night I had one motor pulsing at 70% batter and two motors at 45%. Worth checking.

    So, I guess it's back to the PV2 for a few days. Sad.
     
  12. amkorp

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    I can tell you with 99% certainty that this isn't a "feature" of the quad. I left my vision+ on idle until it got to 15% battery and only one of the motors was pulsing and the LED under that arm was going crazy flickering very quickly and the sound that motor and esc were making did not sound "normal" at all. I contacted motionRC and sent them a video or what was going on and Alpha told me to stop flying it immediately.

    This is not normal, it shouldn't be happening and for anyone that has this issue, you have a defective motor and/or esc. Contact your vendor or DJI and get it replaced or repaired.
     
  13. bentwng

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    I second that. I have a Vision+ and before that a Vision. Both came with the problem of one motor being slightly different from the others at idle (you can feel it when you spin them at idle!), but other than that everything is normal and I have never experienced a single problem when flying :lol:

    So, I would also say, keep your bird and its motors and don't even bother to return your Vision+ or swap the motors.
     
  14. soulboys

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    When I noticed first time motor pulsation, it was when I took it out of the box.
    It was only one motor with different sound. The battery wasn't charged.
    I charged the battery and flew around the house. When descended, there are now 2 motors that are pulsing in idle at low battery.
    With all this, the flight process is perfect, but I'm worried, because I never had such situations with my previous P2V.
    DJI dealer says it could be motor or ESC, but I think there is other problem, more general and I will replace it.