I'm doing a drone project for my academics. my arm of the drone is a little bit longer. How can extend my ESC? I watched extending a power-ESC cable will make problem, but increase ESC-Motor cable will not affect. If is it true, then which wire can I use to extend my ESC length? will it affect my motor performance?
2 Answers
Extend wires on motor side. That side is expected to deal with voltage spikes due to the high inductance of the motor windings so some extra wire inductance from longer wires isn't a big deal. Not so on the battery side.
DO NOT CUT THE MOTOR WIRES to add on connectors. Those wire strands are directly from the motor windings and are coated in enamel which is tough to remove. Cut the wires on the ESC instead.
DKNguyen is half correct. I will do my best to answer your question. But first, I want to address what DKNguyen said.
"... extra wire inductance from longer wires isn't a big deal. Not so on the battery side."
This is true, however, it's actually the reactance that is our issue. The non-linear current draw reacts to the inductance of the wire and produces a reactance which adds to the impedance of the wire. There is a great curve which explains the reactance of wire with a varying frequency.
Image source: Electronics Tutorials - Inductive Reactance
If you eliminate the need of high frequency current draw, this no longer matters. For example (one of a few methods), if you had a Low ESR Capacitor Up the backside of the ESC. This will reduce the current ripple on the ESC power leads. Inductance is only a issue if we are not pulling a constant current, ie. if we are pulling current in the form of a sine wave.
"DO NOT CUT THE MOTOR WIRES to add on connectors. Those wire strands are directly from the motor winding's and are coated in enamel which is tough to remove"
This is only true in some motors. In fact most quadcopter motors these days are single core copper windings, with enamel coating. They have silicon insulated multi-strand wire soldered to these with heat-shrink and all covered up.
You would ideally need to give some specs as to your setup to get a tailored response, but...
On smaller < 300mm quads, it doesn't matter at all. Extend the Power leads! Extend the motor wires! If you are looking for LEDs as well, look at something like RaceWire. This not only allows you to extend the wires, but you can also get some cool LED lights.
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\$\begingroup\$ "This is only true in some motors." - but isn't true in any ESC, so safer to extend the ESC wires. Also a lot of multirotor ESCs don't come with motor wires, so you have to add them anyway (which is easier than splicing into existing wires). \$\endgroup\$ Commented Mar 2, 2020 at 6:23
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\$\begingroup\$ @BruceAbbott I was not stating which is safer and you have not given any basis as to why you think it is so. My statement was merely stating that I think advising someone to "DO NOT CUT THE MOTOR WIRES" with nearly no information is a ill-informed advice. \$\endgroup\$ Commented Mar 3, 2020 at 6:45
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\$\begingroup\$ It's not ill-informed, it's being safe.You said yourself that most quadcopter motors these days have multi-strand wires - which means some don't. I have seen enough motors destroyed by people cutting the wires to advise newbies not to do it ever (since they won't know what type of wire their motor has). And there are other reasons not to do it too, eg. it voids the warranty, makes the motor non-standard, possibility of bad solder joints etc. Controllers usually come without connectors or even without wires, so extending them is easier and accepted practice. \$\endgroup\$ Commented Mar 3, 2020 at 6:51