APM2 ESC startup problem and workaround

Both Andreas and I had the same problem... fortunately he had it before I did, and had figured out a workaround.

Problem: when powering up, not all motors will spin.

Workaround:  apply power to the APM2 before attaching the main battery.  You can do this either via USB or by attaching a spare battery/ESC to one of the output lines.  As soon as the board boots up, hook up the main battery and remove the second battery.

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  • Any updates on this ? I am also facing the same issue.

  • Hi,
    I got My ESC calibrate manually because it won't work if calibrate automatically

    all calibration are done, i can arming my esc but when i'm pull the throttle and any stick in my transmitter nothing happen,just beeping rapidly from my ESC

    any suggestion?

  • My apm2.5 and dji f450 kit (30 amp opt ESCs) was making  constant beeping before I tried usb boot up first and then plug in the lipo. Now, ESCs make a brief music sound and stop. However, I cannot get any motor spin by trying everything: reconfig rc with MP, arm/disarm ESCs, move sticks everywhere. Any ideas?

  • Hi Steven,

    Thanks for that. Interesting reading indeed! I'm definitely in the wrong thread though, as this is all about  APM v2.5.

    Yes, It looks more like the second twitch in your video, where one of the 'corners' dips momentarily.

    The effect of the twitches is more pronounced on mine though, probably because having fewer motors than yours.

    My twitching seems to be limited to the pitch and roll axis. Yaw seems stable. But there were times when it just hit the deck because one or more motors had stopped altogether.

    I'll try and get a video of it once I've replaced my cracked motor mount.

  • No Real answers I'm afraid, but you may find the following 2 posts interesting.

    The video I have uploaded, is that what you are experiencing ?

  • Hi All,

    It may not be, but this sounds too much like my quad's issue to keep quiet.
    Apart from mine being an APM 1.4, and the supplied stock ESCs, the symptoms sound similar:-

    Random motor(s) don't spin up after power-up. If they do, and I take off, it hovers perfectly for a while (usually around 20 seconds) before it starts 'twitching' where it looks as if motor(s) are stopping momentarily.
    Sometimes it recovers and goes on to hover perfectly for a while before happening again. Other times it doesn't recover and gravity does the rest.

    So far this has only earned me a broken motor mount, thanks to it being only a few feet off my lawn when it happens.

    It is a new, stock build of the ArduCopter 1.1 full electronics kit bought from BuildYourOwnDrone.
    I was initially using a massive 5000mAh LiPo but now have a much lighter 2200mAh powering it to eliminate a weight problem.
    I have also switched to my best Futaba 35MHz radio gear from the Spektrum 2.4GHz radio I was using before.
    I have not touched the PIDs out of the box. But seeing as it hovers perfectly for a time before literally going belly up without me touching the pitch/roll stick do I really need to?

    ESCs and radio calibration seems to go fine during setup.

    I know you're going to say that it isn't the same issue because I'm on APM 1.4 and the stock speedos. But what else could it be?


  • Hi All,

    First of all, APM 2.5 running latest firmware on HexaCopter.

    I too have an issue where I have calibrated the radio and ESCs a number of times.

    I have then taken the Hexacopter to the field, connected the LiPo, waited for GPS lock and then on throttle up, sometimes only a couple of the motors will spin. I will disconnect the power and try again, sometimes different motors spin up.

    I have then brought it home, done no more than plugged it into USB, tested throttle and all six motors will spin fine.

    Disconnecting USB and running normal LiPo and all 6 will spin without issue.

    The hexacopter is a new build, but it has failed twice in the field powering up, but doesn't when it's on my desk.

    Any suggestions how this can be resolved without stripping the ESCs and reprogramming.

    For information the ESCs are jDrones 30s.

    Many thanks,


  • 3D Robotics

    We've seen this issue with a small number of ESCs (different brands have different firmware, and handle startup sequences differently). We're working on a startup PWM sequence that may handle these outliers better and that patch is currently in the working code and should ship with the next public release. 

    BTW, the reason why these troublesome ESCs would work when you start under USB power, but not LiPo is that when you start with USB power, the ESCs are not powered. So the APM boots up first. By the time you plug in your LiPo and power the ESCs, the APM is outputting regular PWM, and past its own boot sequence. 

  • I have this problem on APM 2.5.  My motors will only spin up if I boot my APM using USB before plugging lipo in.  I can arm/disarm no problem but they just won't spin up unless I pre-boot.

    I've got some different ESCs on the way, hopefully that will resolve the issue.

  • Vernon, the problem only happens when using APM2.  APM1 doesn't seem to care which firmware is on the ESC's.  This tells me that the problem is indeed with the APM board and not to do with the esc's. 

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