Running 8 motors, but 4 ESC's. Possible?

According to Mission Planner my quad only draws about 13A maximum. Each ESC can handle in the 50A range.

This is all just me wondering. I don’t plan on doing this because of the current weight limits I have.

What will happen if I have a motor above and below an arm and have both motors run from one ESC and still have the drone configured as a quad according to the firmware?

I am pretty sure that won’t work.
When the ESC drives a motor, only 2 of the 3 coils are energized. The magnet moving past the 3rd coil induces a current in the coil which creates back EMF and this is used by the ESC to synchronize. When you have two motors on the same ESC this back EMF would not always be at the same time and the ESC will de-synchronise. I guess if you are lucky it could work when there is no load on the motors but as soon as it gets loaded my guess is that they would stop or start shuttering.

Aah OK. Makes sense. Didn’t think of the feedback.

So since my drone can only work with motors on the aux ports that means I can only go up to a 6 motor drone if I ever want to go in that direction.

Esc in aux ports

With Dshot. With any other protocol 14 are available.

The dshot seems like a good idea looking at its pros/cons.

I imagine I will need a bigger car to carry something with 14 motors :slight_smile:

No disputing that just clarifying your statement.

Good to know this info. Thank you. I am learning so much at the moment.

Do you think it will ever be possible to run 8 motors with dshot?

Which other protocol would you use if you built something with 8?

It’s been possible for quite some time with a Flight Controller that supports it. With your Pixhawk, no. Just use PWM over 6 channels with that. You could use Oneshot125 also.

What would you do for ultra safety around people?

Build with quality components. Build robustly and fly responsibly.

With my first crash I had too much power. 10% throttle made the drone shoot up.

What are the settings that would change if you have 6 or 8 motors to allow you to lift with 50% throttle or would you only fly such a powerful drone fully loaded?

FETtec OneWire ESCs only require a single serial port to operate. All PWM and AUX ports would be free. :wink:

Have you used it with a Pixhawk? I see it has a speed that is the same as dshot600. Not sure my dshot speed.

They say you can use 24 ESC’s. How would you connect two of the 4 in 1? Daisy chain?

The full documentation is available: ardupilot_wiki/common-fettec-onewire.rst at 42c58c60f944ea12ab33461077feeea0b4907485 · ArduPilot/ardupilot_wiki · GitHub

Looks great.

When I am done with a design that works I was planning on going back to a 4 in 1 to reduce weight. I might get one of these ESC’s.

I will go through the documentation to see if they can handle hi voltage lipo. That would be an extra bonus.

I don’t know enough to know of this will be a problem but the pads on the esc look very small to be able to solder motor wires to.

I see the documentation talks about beta flight but will the blheli_32 pass through work?

It will not work. You need a separate ESC for each motor.

You can use 8 motors with only 4 outputs by sharing one output between two ESCs - you still need 8 separate ESCs though. Just make sure the direction of rotation is the same for each corner pair, equipment used is the same all round, and ESCs are calibrated properly.

That will give you the lifting power and redundancy of an octo, but with the control stability of a quad (which is still pretty good as the video shows).

Using 8 motors with 4 ESCs would only work if the shafts of each motor pair were somehow clamped or welded together so that they could only rotate in unison, and even then only if the phase positions were matched up too. Not even worth trying imo.

Very cool. Thank you. This is all just dreaming at the moment but great to see things like this.