Fords had big fender mountain relays aka "solenoids" for their starters on
almost every car/truck until the mid-90's.   This allowed short power cables
from battery to starter and small wires to ignition/starter switches.

You can get them cheap from any FLAPS.

Great for intermittent high current loads (like running a starter).   Not
really designed for continuous use.

The principles of the Ford solenoid are pretty much the same of every relay
out there...a small trigger circuit causes an electromagnet to "switch" a
higher current load.

Good info here on this video;
http://www.youtube.com/watch?v=uGGTaOQkkAk

On Sun, Dec 12, 2010 at 10:30 AM, John Rodgers <inua@charter.net> wrote:

>  The discussion on mega-fues brought this to mine, and I felt it
> appropriate to have a different heading.
>
> I haven't really explored the circuitry so simply don't know much about
> it and am wondering.
>
> Small airplanes - and prol'ly large ones - are wired so that operation
> of the ignition switch  actuates a relay installed between the the
> battery and the starter. Turn the ignition switch to the start position,
> the relay closes, connecting the starter and the battery. As soon as the
> engine starts, the switch is released, the relay opens, and the battery
> is disconnected from the starter.
>
> I take it there is no such circuit in the Vanagon but something
> different. Such heavy relays are always located by the battery box to
> relieve the need for heavy wire strung over long distances. Would there
> be any advantage to have this aircraft type arrangement in the Vanagons?
>
> John
>
> --
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>