Quad power wiring, with BEC and independent on/off switches
Am I doing it right? (What I'm trying to achieve follows the diagram)
[I am a NEWBIE: please do not mock - I already know I don't have a clue!! ;-) ]
I've finished building my first quad and during the early testing I have found myself having to connect and disconnect the motor power and APM power several times. I've installed a BEC to have a completely separate power circuit for the electronics. For safety and convenience, I want to add two on/off switches, and be able to independently power on or off the motors, or the electronics.
Notes and details:
The two LiPo's are plugged in with Deans connectors and are only plugged in when I'm ready to fly or tuning motors and ESCs.
The LiPo's are more powerful than I need, they are in parallel to provide additional capacity (mAh), not current. I may sometimes fly with one and other times with both. I use a T shaped parallel Deans splitter.
The SBEC is powered *even* when both switches are off - this is intentional. The SBEC has a battery indicator light and low battery warning. As soon as the batteries are plugged in, it will light up and let me know if the batteries are ok. It serves as a visual reminder that the batteries are still plugged in, even when the switches are off.
I'm too much of a newbie to be sure about the diagram above, so any recommendations, comments or suggestions are welcome.
Can anyone give me feedback? Am I doing it right?
Replies
Awesome drawing Andy. In what drawing software did you create it? Are you willing to share your source drawing?
I am hearing many reports of some very expensive multi-rotors falling out of the sky due to power distribution wiring issues. Please consider that every set of contacts is a potential failure point. That said, even though you are using an 80A switch, you may want to consider installing your switch temporarily to use during testing and then remove it once you are through to minimize the potential failure points.
You should also consider using some high strand count, silicon insulated wire like this, which is capable of carrying much more current than the wire one typically finds for automotive purposes.
You didn't mention which motors you are using, but they sound similar to the Hacker Style motors I am using for my crash quad, which max out at 15.89A.
The total Amps to hover is 11.89A and 63.55A for maximum power with 11x4.5 props, thus you are well within the capabilities of your 80A switch. You can likely benefit from this calculator.
I am also very new to multi-rotor copters, but I am working with some very seasoned collective pitch helicopter pilots and they have helped me out considerably regarding power distribution issues.
Good luck!
Follow up question:
For the high-amp circuit, I'm keeping the run between the Deans, switch and PDB very short (1-2 inches total). Essentially, the two Dean inputs, the switch and the PDB are mounted right next to each other.
What kind of wire do I need to use? American electrical code says 8 AWG or thicker for 68A. I couldn't even begin to fit that on a Dean's connector and as I understand it that's for longer runs and conservative estimates for continuous load. So, can I get away (*safely) with 9 AWG or even 10 AWG? With a bit of practice, I found I can solder 2 x 10 AWG solidly onto a Deans, but any thicker and it won't fit.
Looks good to me. Of you know that the switch on the battery side is going to have some serious current running through it. It's enough to weld metal. So make sure that it can handle the load.