Hello,

I wanted to report a potential problem and maybe see what can be done to fix it,  or if it solely my fault,  what I can do to avoid it in the future.

 

I just installed a new receiver (Hitec Optima 9) and calibrated my radio.  Next up was calibrating the ESCs.  I proceeded to plug the signal wires (going to the ESCs) into the APM,  plug in USB,  flipped the APM into CLI mode and hit reset.  Immediately the channel 1 motor began to shake violently and smoke poured out.

 

I recognized this symptom from my reading of the manual,  so I went to read up on what went wrong.  (See http://code.google.com/p/arducopter/wiki/AC2_Troubleshooting ,  Section - One of my motors started shaking and then burned out!)

 

I had heeded the warning and only plugged in the wires for essential testing  (I don't see how this warning would prevent this problem,  as I followed it and the problem occurred).  The description on the troubleshooting page clearly states that this problem only occurs with APM1280certain ESC types, and the older Arduino bootloader.  I am running an APM 2560 provided by jDrones along with jDrones 30A ESCs and jDrones 880kv motors.  So the scope of the problem is clearly not limited to just that hardware.

 

Does anyone have any insight as to what happened?  Can someone provide any technical detail on  what exactly causes this to happen?  If this is a common problem with only certain ESCs,  should the community not adopt different official ESCs?

 

Can anyone tell me what the likely extent of the damage is?  Do I need to replace both the ESC and the motor?

 

Thank You

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  • Developer

    I recommend Castle Creations and use their UBEC's and ESC's too.  

    UBEC is the best I have found, you can set output voltage with CastleLink up to +12v if needed.

    Great for Video Tx power supply!

    Dimension Engineering has great stuff too.

     

    I connect / disconnect AP USB many times daily and on all AP units sold here and several others.

    I follow these guide lines all the time...so far NO blood or component smoke! (I did melt wire harness on a FPV once, but these rules would not have helped, I had a pinched wire causing a shot to +12v battery. (Replaced harness to fix, no harm done to camera or video TX)

     

    APM Testing and Operation Safety Procedures.  Protects you and the UAS.

     

    1. Do NOT connect Motor lipo's unless you are testing the motors or flying! 

    When bench testing, first test with NO props! if all motors spin OK, then add props to continue your testing.

     

    Additional method for ensured safety with props ON. 

    Remove one of the 3 power lines to all motors, (when power is applied motors will twitch and try to spin but at very low power, you will know it is getting a signal, as it twitches but won't spin up.

    Note: ONLY run motors for a second or two, I don't know if prolonged test with 2 power lines  will damage motors or your ESC.    ( I have done this many times with many motors an ESCs.)

     

    2. Do NOT test FailSafe function with props ON!   Motors can go to cruise speed 30% or more when FailSafe is activated and mode automatically goes to RTL.   If radio is turned OFF, or signal fails this will happen, if FailSafe is setup correctly.

     

    3. I usually test with 2 or 3 small servos only and use USB supplied +5v

    If all servos are used,

    Power up APM with a 2 cell lipo battery or a regulated power supply, Set to +6 volts (APM will regulate it down to +5v) with 3 amps, if using more than 4 digital servos, 5 amps or more may be required.

     

    4. Since I have two computers connected to APM when developing OSD integration code, I also connect power to OSD board last, add disconnect it first.

  • Colby,

    I have been down this path like you recently and started with the same ESC's (30A) and 880Kv Motors.  I had an unfortunate brown out on my maiden outside flight, after weeks of bench testing.  i have recently spoken about the various motor issues, but I had a few interesting exchanges with other members including Olivier here on ESC's.  There is some good motor information and also some good ESC's choices to consider.  For me I am looking at a few motor choices at the moment I like the Axi's models made for multicopter use but they come at a price.  Pulso's are a good Axi clone but for precision bearings (they have 3)  its hard to go past Axi.  

     

    I like CC and use their UBEC's. I have no experience with their ESC's, but the posts here have spiked my interest.  Also have a look a using Opto ESC's if you do not mind paying more.  There is a lot to be said about isolating the noise from the ESC from the APM.  I have also recently been looking at YGE who make an opto cable which you can use with any ESC and this is cheaper than say the 40A Platinum Pro ESC's discussed in the forum post link I gave you earlier.

     

    Regarding booting the APM as Jason said there is nothing we can do in software about the CH1.  However given I have the same ESC's and motors as you I do take the following precautions which works for me.

     

    I never power the system using the copter lipo unless I am flying.  If I have to do any reset and radio calibration then I use a Castle UBEC to provide the 5+ regulated power to the APM and Receiver.   I have a separate small lipo or flight pack I use to power the UBEC.  I have the signal wires detached from the ESC's anyway unless I am about to fly with no dramas.  I did this because the constant regular beep from the motors without the Signal from the ESC is really annoying after a while.  Whats more to the point if your doing any calibration the slight twitch from the motor intime with the beep registers on the IMU sensors.  For example have a look at the MP flight view and realtime gauge readings while the motors are beeping away and doing there tiny twitch.  There is no need to send power to the ESC because the external UBEC avoids having to use the internal ESC bec which normally supplies 5+v to the APM and Receiver.

     

    I do all my programing work from the USB and anytime I need to re-calibrate an power the receiver etc.  I just connect the +5V to the APM as I described.  Also calibrate your ESC's manually so again no need to have the risk of the signal noise from the APM affecting your motors.  

     

    Of course I agree with Greg, a good ESC will not cause these motor issues.  

     

    I hope this helps

  • Thanks for the info Greg, I'll try those BECs.

    Regarding the Roxxy motors. My main quad is still a mikrokopter, though I have did have three Ardus (2 quads and a arduplane) until a recent string of bad luck.

    The roxxy are smooth as silk on the Mikrokopter, and I have the same motors on my ardu copter. Out of curiosity I tested the several cheaper quad copter marketed motors in the 750 kv range on both the MK and the ardu and it definitely pays to use better quality motors with good bearings and consistency between motors.

    Al
  • Developer

    I load code and power up the boards probably more than anyone and most combined. I've never had this issue for one reason. I never press that damn reset button. NEVER. And I never have the USB plugged in and Lipos connected at the same time. I don't know that much about the hardware (I'm the polar opposite of an EE,) but I've seen the CH1 output on the scope and nothing can be done about it on the SW side. It's an AVR quirk, I guess.

    Jason

  • Hi Al, I remember you now. I use these BECs. They have always worked for me with 2x9g servos and everything else. They have a 3A one if you need it.

  • Moderator

    It is also my impression that the direct cause of hardware is the ESC behavoir given spurious input, and that this input can be expected during board resets (I do not know if the spurious input could be prevented, I'm sure some EEs here would know.)

     

    I have never seen this with Castle Creations ESCs, and although I have 16 jDrones 20A ESCs, I have also never experienced it myself.  

  • The motor is junk. I wouldn't trust it even if it still works. Your ESCs are all junk IMHO because of what they did to your motor. The ESC is a small computer with one input, 1 or 0 (PWM). Its output is a group of 6 (maybe 12?) MOSFETS that are either 100% on or 100% off. If a valid PWM is not received by the ESC, it has absolutely no business firing any MOSFET!

    Its all in the sequence and timing of the on/offs. If the MOSFETs are not pulsed in the proper sequence, and the moter doesn't spin, then it's just like a dead short, and thus smoke and damage.

    It's like this. Look at one of the windings on your motor. It's maybe what a few inches of solid copper wire. If you unwrapped this wire and connected it across your battery, what happens, smoke. It's the spinning and and electromagnetic magic that limits the current.

    An ESC's firmware should never let this happen, yet apparently some do.

    And don't worry, the APM should be fine.

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