Questions about the servo rail power and ESCs

Hi everyone :smile:

I’m a programer and don’t really have any experience with electronics, so I apologize for any noob questions.

So I am trying to build a quadcopter, and I was just wondering if the servo rail needs to be powered by a BEC if I’m just using four Afro Slim 20Amp ESCs?

I understand the adding a BEC to the servo rail is good thing in case the power module fails, but is it necessary for the ESCs I want to use? Could you please explain why the BEC is or isn’t necessary?

Also, I plan to add a BEC whether it is necessary for the ESCs or not; in case the power module fails. Would this BEC do the job? If not or if there is a better one, could you please point me to one?

And finally, would the BEC be connect to a PDB and go directly to the servo rail to power it?

Thank you in advance for your answers!

Hi Ivan,

You would need to provide power to the servo rail in order to power RC receiver. Any 5V BEC will do the job, for example the one you have linked to. Your BEC should be connected to the PDB.

Thanks for the answers :smile:

I just have a few more. From what I understand, the specs for the ESCs say they don’t have any BECs which means I do not have to cut the middle wire of the ESC. Is this correct?

Also, I’m not planning to use a RC receiver, but rather a 3g/4g modem connected to the RPi2, which means I don’t have anything to power on the servo rail (for now). Does this mean that the BEC isn’t necessary for the servo rail? (I’m still planning to use the BEC as a backup in case the power module fails)

Thanks again!

Correct! You only need to cut the wires to prevent power supplies in the ESCs from powering one another (voltage on one will be always lower and current will flow there)

In that case BEC is not required.