Issue about ESC calibration

Hello everyone,

I’m currently using ArduCopter 4.5.7 to control my quadcopter. While calibrating the ESCs, I tried the following two methods, but only the second method (via ground station) worked. I would like to understand why.
My hardware setup is:

  • Flight Controller: CUAV V5+
  • ESCs: Hobbywing Platinum 30A

Method 1: Manual Calibration via RC (as per official documentation)

I followed the official RC-based ESC calibration procedure:

  • I pushed the throttle stick to maximum, then powered on the drone via battery.
  • At this point, the flight controller showed cycling red-blue-yellow LEDs, which matches the documentation.
  • Then I disconnected and reconnected the battery (with throttle still at maximum).
  • However, the ESCs started emitting strange beeping sounds:
    • One beep,
    • Then two beeps,
    • Then three,
    • Then four,
    • Then back to one — repeating in a loop.

I’m sure that the RC signal is properly reaching the flight controller, because once I move the throttle stick to minimum, the tone of the ESC beeps clearly changes.
But even then, the ESCs continue the 4-step repeating beep cycle and ESC calibration does not succeed.

Also, if I randomly move the throttle stick during this state, the ESCs emit strange nonstandard sounds, and eventually the motors start spinning.
But typically 1 or 2 motors don’t spin until the throttle exceeds ~40%, which is abnormal.


Method 2: ESC Calibration via QGroundControl (QGC)

I used QGC’s ESC calibration feature, and this method worked fine:

  • I clicked “ESC Calibration” in QGC;
  • Then disconnected all power (including USB);
  • Connected the battery while QGC was waiting;
  • This time, the ESCs beeped 6 times (my battery is 6S), and
  • After that, the motors spin normally.

Question:

Why did the first (manual RC-based) calibration method fail, while the QGC method worked perfectly?
Thanks for any help!