Skrud wrote:
What is the correct type of diode (p/n) to put across a garden-variety
battery contactor to prevent the inductive spike?
It's also a good idea to have the diode at the load, rather than at the
switch. This keeps the diode current circulating only at the load, and
not through the wiring, where it can induce transients in nearby
wiring. This, especially, if the wiring is not twisted pair, but
instead uses the airframe as one of the conductors. With this, there is
only one wire carrying the current, so it acts as an antenna, radiating
into nearby wiring both electromagnetically and electrostatically.
Twisted pair wiring minimizes these effects, since the magnetic fields
from the opposite-direction currents cancels.