Strange ESC sounds

Hi there,

Im getting strange ESC sounds when I reboot my ROV(sometimes). It calibrates always at the end but Im not sure if this is a problem or not. I uploaded the sound file below:

Do you have any clue that what is going on? Can it be harmful for ESCs or Motors?

Thanks for your answers in advance.

Hi @elchinaslanli,

I’m not certain what’s going on there. From looking at the firmware manual for the BLHeli_S firmware used on our Basic ESC the only repeated high-pitched beeps are for the maximum throttle zone of the calibration procedure, but that procedure should not occur when connected to a flight controller, and those beeps seem to be too fast to match the diagram.

I’m also not certain if our Basic ESC 500 uses the same firmware version as our original Basic ESC, so I’ve asked internally in case there’s some more relevant information we can provide.

Even if it is doing a calibration it shouldn’t immediately cause harm to the ESCs or motors, but it may result in control ranges that aren’t what you expect, and could potentially allow higher values through than your configured gain or throttle limits are intended to permit.

Following up on this, apparently the Basic ESC 500 does not use the same BLHeli firmware as the standard Basic ESC, and instead uses a proprietary firmware that we currently don’t have extensive information about (we’ll need to ask the supplier).

At this stage we know that the motor is made to beep if the ESC detects issues with the input signal, but don’t yet have a detailed understanding of exactly when that is. In this case I would presume it’s not detecting a stable/correct “neutral” signal, so if the generated signal is in fact correct then there may be some issue with the ESC’s clock chip or electrical noise on the signal wires.

If you experience issues with operation I suggest you contact our support email (, in case they have additional ideas and/or to start the RMA process.