So, in my professional life, I've built a brushed motor controller -- basically a 250W ESC with lots of extra features and spread across a 20 square inch board (because we could). I've worked on systems with built-in brushless controllers (including writing the embedded firmware that made one come alive, which is not a trivial portion of the total engineering), and I've worked on systems that have high-power "noisy" wires running in the same enclosure as low power noise sensitive equipment.
There's a few others in the many people on Stunthanger who are professional circuit designers or work in related fields.
The bottom line: unless the ESC design is screwed up, just keep the motor on the motor side of the ESC, and the batteries and timer on the other side of the ESC, and you'll be fine. You could only get in trouble if you laid the timer lead up tight against the motor leads, and even then things may still work. The voltage to the motor is chopped, and that could potentially generate interference, but these things are designed to work with radios; they're certainly not going to mess up a timer without a lot of effort on your part.
But if you'd rather believe the butcher the baker and the candlestick maker on this -- you just go right ahead.
John, just to be clear, you are talking about the battery to ESC leads, not the ESC to Motor?
Ken
ESC to motor is fine; the extra wire length adds inductance, but the motor adds lots of that anyway, so the circuit is designed for it.
Battery to ESC is
not fine, unless you put extra capacitors at the ESC. The analogy that works best if you're not an electrical engineer is a water hammer -- the final drive transistors in the ESC are constantly turning current on and off to the motor. Inductance in the battery leads, plus the electrical current, acts very much like water in a pipe, that generates a pressure pulse when a valve shuts off rapidly. In the case of the ESC, what's generated is a voltage spike. Capacitors absorb that spike (much like a water hammer arrestor), but have to be sized to the length of the motor leads.
(And if there's any circuit designers that want a proper engineering explanation -- go ahead and ask, I'll deliver, with math & circuit diagrams and everything. With credit to Igor Burger who pointed this effect out to me pointedly enough that I actually
thought it through).