How to connect BEC to the servo rail?

In the hardware setup there is the following:

Power module does not provide power to servos. To provide power to servos connect BEC to the servo rail. BEC would also serve as back-up power supply to Navio2.

I’ve got a DYS D800 quad:

I’ve connected 1 ESC to the Navio2 (channel 1) with all the 3 wires. There is a servo on the channel 7. The issue is, that servo is not doing anything, only if I connect it directly to the X8R receiver’s channel 7.

What am I doing wrong?

DYS HV40A ESC seems to be OPTO, so it does not have built-in BEC.

Thanks for the answer!
then what do you recommend to me, please ?

I am not completely sure about that, you can use a multimeter to check the voltage on the servo rail. Otherwise use a separate BEC, there are plenty of them in any RC shop.

After some investigation I can confirm that the ESC has no BEC. So I need to power the servo rail somehow else … Am I guessing wrong all it needs is some power (making sure the voltage is the same - 5v?) from the big red cable coming from the PM?

No, please do not power it from the big red cable, it has your battery voltage (12V for 3S li-po). You will need a 5V BEC, they are available almost in any shop.

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I’ve got this:
So, just to make it sure I understand … I need another BEC more, just for the servo rail?

Yes, because it is right to separate power of sensitive electronics (RPi, Navio) and servos, which can draw high current and cause spikes on the power rails.


I see now, thanks a lot.