Originally Posted by jabram
You want the cable from Lipo to ESC as short as possible, You want that wiring and the whole power distribution to be as far away from the magnetometer as possible.
Reasons; the wiring from Lipo to ESC carries heavy currents which creates strong varying magnetic fields and will be right under, very close to the magnetometer making the magnetometer/Compass useless AND WORSE if you fly headfree the frame will yaw violently when you apply throttle to lift off as the magnetometer is severely affected by the strong magentic field around the Lipo to ESC wiring right underneath it.
The ESC cannot really tolerate long wires to Lipo, the capacitor on ESC will get hotter, will fail sooner, generally you will have more electrical noise.
Sorry, don't take it personally, but most of this is incorrect.. and anyone who know electronics will confirm...
Magnetic field is generated when current is being switched on/off thru wire - the wires from ESC to motor are the ones which are used for switching the power (only 2 wires from the 3 motor wires are used at once).
Therefore, those wires are the one which generates electro-magnetic field. If you make those wires longer, the bigger the field will be. Also long wires may attenuate the back EMF from motor to ESC (which is used for sensing the motor position) and it may cause misfires (cracking noise in motor).
The wires from ESC to battery are always at the same voltage and not being turned off. Only the current is changing, but the changes are not as fast - the capacitor at the ESC is supposed to help with that.
And the last point is the weight - mounting the ESC close to the motor you have to prolong only 2 wires and not 3. (+1 thin wire for signal)