For that short a run of extra wire, you can probably do either one, just use the same size wire or one size larger.

I can see more problems if the motor leads are long.

Do you mean with equipment placing and wire routing, or something else.

Electrically, unless the ESC is specifically designed for it, longer battery wires are worse than longer motor wires.  It's hard to explain if you're not an electrical engineer, but basically longer wires look like inductors in series with the thing on the end of the wires.  Motors are already inductive, because they're made with coils of wire inside, so a bit extra outside doesn't change anything.  Batteries don't natively look like inductors -- with long wires on the battery, when the ESC switches off current to the motor (which it does 10000 times a second) there's a water hammer* effect from the motor wires that tries to force current through the ESC anyway, much to the detriment of the poor thing.

This can be overcome easily by putting capacitors on the inputs to the ESC -- so read the manual: it should have guidance on how long the battery wires can be before they become a problem.

* Cringe, but if you'e not an EE it's the best explanation.

For that short a run of extra wire, you can probably do either one, just use the same size wire or one size larger.

Do you mean with equipment placing and wire routing, or something else.

Electrically, unless the ESC is specifically designed for it, longer battery wires are worse than longer motor wires.  It's hard to explain if you're not an electrical engineer, but basically longer wires look like inductors in series with the thing on the end of the wires.  Motors are already inductive, because they're made with coils of wire inside, so a bit extra outside doesn't change anything.  Batteries don't natively look like inductors -- with long wires on the battery, when the ESC switches off current to the motor (which it does 10000 times a second) there's a water hammer* effect from the motor wires that tries to force current through the ESC anyway, much to the detriment of the poor thing.

This can be overcome easily by putting capacitors on the inputs to the ESC -- so read the manual: it should have guidance on how long the battery wires can be before they become a problem.

* Cringe, but if you'e not an EE it's the best explanation.

Thanks Tim.  I am not an EE but I did stay at a Holiday Inn last night, so I do understand it.  That was the answer I was looking for.  One follow-up.  How long is long?  You imply in your opening comment that 12" may not be that long.  Tell you what.  When I have it all wired, I will take it out of the plane
and post a picture either here or on the build thread, or both.  Jetti ESC's are not cheap!

Ken

Ken,

As a rule of thumb, the 3 wires which run from the ESC to the motor can be extended without much trouble; extending the wires on the battery side of the ESC might result in blown CAPs.  Some companies such as Kontronic would suggest using additional capacitors on the battery side of the ESC if the wires were getting long. The comment about the effect of the inductance of the longer wires is spot on.  They problem is that manufactures normally don't say what too long actually means. On my R/C pattern plane the battery wire, once everything is hooked up, is about 9 inches long and it has worked well for many years.  If trading motor side wire length for battery side wire length is possible it might be a worthwhile compromise.

Good luck,

Teo

The electric twin airplanes with a single centrally located battery have long battery leads to get out to the nacelles.  Doesn't seem to be too detrimental.