I am putting together a quadcopter, and one of the things I've stumbled across that I don't quite understand is Battery Elimination Circuits (BECs).
The Flight Controller on my quadcopter is a modded Arduino board with some motor pins and other sensors integrated into it. The Flight Controller is capable of being fed anything from 12V to 5V. I have been feeding it 12V straight out of my LiPo battery, which it regulates down to 5V and continues merrily on its way.
Now, the Electronic Speed Controllers (ESCs) that drive the motors each contain an integrated BEC. From a post on this site under the "Discussions" tab, one guy claims that the most common thing to do is use the BEC to power the Flight Controller.
So it seems to me like the BEC is kicking 5V back to the flight controller. Is that good enough? Do I need to worry about low current or low voltage conditions? It's pretty important the Flight Controller say running.
I have read a few links about BEC's:
From this link, I think I understand that the voltage regulators in BEC's are generally linear, which is going to use more power than a switching power supply, but then in the comments, the guy who asked the question said "thanks… I'll go with a BEC." I'm not sure what I'm missing there.
So I currently have four ESCs, each with three pins (Signal, V, GND) connecting to my Flight Controller. I also have 12V straight from the battery connecting to my Flight Controller board, which is regulated down to 5V.
Is this wasteful? Wise? Should I remove the (V, GND) pins to the ESCs and only keep the signal pins? I'm spinning my wheels here because I'm obviously missing something.
What is best power and weight-wise?
Any advice is appreciated. I didn't know BECs existed in the not-too-distant past.
Best Answer
If your flight controller already have its own DC/DC converter you should go for it, because it is probably designed for this particular use.
Most speed controllers with BEC are based on linear regulators. Basically these regulators turn excess voltage into heat, the more current you will draw the hotter they will be. If, for some reason, they become too hot they will go into protection mode, and stop to work.
To disable a speed controller BEC just disconnect the red wire from the from servo plug, unless your flight controller board already have a system allowing to choose the power source.