It should not be over 10" ... if yes, it should have low ESR capacitors in middle of leads. You must remember, that unlike DC motor on PWM, we cannot have capacitors on motor leads, and current going via diodes in FETs are CHARGING current on battery leads, while it goes only locally on DC ESC, so long battery leads can lower effectivity in some cases. Capacitors are helpfull, bacause they catch such backwards currents.