I have searched for hours, so here is my question.
I am looking for experience and facts on where is the best location to put esc’s for large (1200+mm) quads.
Options are either,
At the motors.
I get that this option is good for airflow but long power wires create problems?
If you have longer power wires should you add capacitors/bigger capacitors?
There is the downfall of having long signal wires, is there a fix for this other than twisting the wires?
In the center of the frame
Less air flow but the DC power wires are close to the source.
Last question, does adding large capacitors (I am aware that they need to be the high esr type) inline help? Other than weight does adding massive capacitors matter, is their a downside to this? I have some Panasonic 1000uf ones that I want to add vs the 330uf that they call for.
The best place for ESCs is inboard with shorter power wires and long motor wires.
The signal wires can be an issue too if using PWM, DSHOT is better, CAN bus is best.
If ESCs and motors are all operating correctly then ESCs should only get warm (ideally).
If you do need to place them out in the arms or nearer to the motors then extra Low ESR capacitors are required, as close to the ESCs as practical.
I’ve seen where capacitors were required in the arms very near to the ESCs and also capacitor banks at the base of each arm. Even the arms were a some distance from the batteries - this was what we call a big copter
Pay close attention to the wire gauges. I’ve used #16 for the motor wires of about 1m length, instead of the standard #18 or worse that motors come with. Battery wires should be up-rated for lengths of anything more than a few centimetres, without going crazy on the weight - every gram counts too.
In the AWG link below, go to the multicore 7-24 column, or above depending on your wire strands, estimate how much current you’ll need then go across to the left and read off the wire gauge. It’s always a bigger gauge (smaller number) than you expect - this is the gauge you’d need for continuous current and no heating effect in the wire. In reality we can usually go down a size or two.
The trick is the motor wires are carrying a transient square wave kind of current, so 3 wires each good for 7amps DC is probably OK for 5 times that current overall when we talk about running a single BLDC motor.
On the other hand the DC battery wires to the ESC would have to be closer to #12 or even #10
One of the issues with the ESC’s that I purchased is they don’t have a heat sink, I get concerned about heat even though they are rated for 30amps. I sent an inquiry to the company asking if that rating was based on a spec air flow but never received a response.
here is the link…
I know most people want 80+ amp esc’s but with my quad it only pulls 40-50amps total max, hover is 18amps total (5ampish per motor). This quad is a slow flyer.
I am planning on using 14g wires to the motor, will have to see where I end up putting the esc for the gauge of the battery wires.
I like to place the esc 4 in 1 at the rear of the craft next to the battery jack not on the arms. Regarding the Cap I do not use them if under 6S. Be very careful how you install them as the heat wrap can squeeze the thin wire and short.
In case of doubt, air flow. But try it out. Enable ESC telemetry via BDShot and observe the temperatures. Didn’t find the exact MCU spec sheet, but this should be correct:
You won’t get an answer to this. I have these on 2 craft in heat shrink (poor cooling) with no problem to rated current. @Oli1 advice is good if you have a craft flying with $$$ hardware.
