Roadkill Garage FROD wiring?

[451Mopar]

Was watching Roadkill Garage where they were wiring the F-ROD and they were using several relays as part of the battery cutoff system. Is there a link to the actual wiring diagram they were using?
David Freiburger commented that they only wanted the large gauge cable to have power for the starter motor, which I get, but then they run another large but slightly smaller gauge wire to power the car. Anyhow, I think the reasoning is a bit flawed, and the wiring over complicated?

 

[1 Wild R/T]

Was watching Roadkill Garage where they were wiring the F-ROD and they were using several relays as part of the battery cutoff system. Is there a link to the actual wiring diagram they were using?
David Freiburger commented that they only wanted the large gauge cable to have power for the starter motor, which I get, but then they run another large but slightly smaller gauge wire to power the car. Anyhow, I think the reasoning is a bit flawed, and the wiring over complicated?

No idea what they did but the harness I put together for my Falcon has an 8 ga feed to the rear of the car, it's how modern cars are designed, honestly it's how most major power grids are designed, send the bulk of the current out over large conductors, control it with tiny conductors & low current switches that control relays... Relays are cheap, easy to replace if & when they fail, one design of relay can be used to run practically any component.... On our Mopars all those old switches that were never designed to last as long as they have, well those switches are hard to find, expensive to purchase & sometimes difficult to replace.. But if they are just controlling a relay instead of passing say 3-6 amps now they only pass 0.05 amps so a switch that was heating up & only worked intermittently now works find.. And a switch that was fine will still be fine in twenty years cause it's not working very hard.... Instead the relays fail.. But if you mount them all in relay centers then changing one only takes a few seconds & only costs a couple bucks... Most builders leave a space or two for spare relays right in the relay center....

 

[451Mopar]

I found a diagram on For A Bodies, by Crackedback that appears to be what they were using?
https://www.forabodiesonly.com/mopar/threads/questions-about-battery-disconnect-wiring.454312/

Electrically, it is very good.
Physically (as shown in the show), you have three fairly heavy, long runs of wire. The Starter wire, the alternator wire, and the main power feed wire.
The RoadKill show claimed having the large wire going to the starter could cause a fire, although the wire was fused, and the two other wires are just as likely to have short circuits. Having a single large wire from trunk mount battery to engine compartment is an easier way to run the wiring.
If they are concerned about protecting the wiring with fuses, then the Ford starter relay circuit could be placed in parallel across a smaller sized main fuse to by-pass the small fuse when starting the car. The alternator is still an issue, but if using a DPST cuttoff switch, the CD relay could be placed in the engine compartment between the alternator and large starter wire. The second switch of the DPST cuttoff could be used to ground the CD Relay, and that can be done with a small wire like 18 awg.

I was thinking of something closer to what Mattax shows, just with the main power fused at the battery, with the ford relay fuse by-pass while starting.

 

[dvw]

You know I see "fire and shorts" in the starter wire as a reason for this style wiring. Ever look at any factory produced new cars with the battery not under the hood? The positive feed goes to the starter. Think about how many government regulations there are and this isn't one of them.
Doug

 

[Darter6]

I had a Painless shut down relay a few years back on my car. I believe you can get the PDF diagrams on their web site.
dvw has a point.OEM manufactures also have a fused battery cable for the cars that have batteries in the trunk.One time use only and hooked to the air bags system.When it blows the cable has to be replaced.
But in all my years drag racing I can't say I ever seen a car on fire because of the positive cable.Maybe unless it was installed incorrect.

 

[451Mopar]

You know I see "fire and shorts" in the starter wire as a reason for this style wiring. Ever look at any factory produced new cars with the battery not under the hood? The positive feed goes to the starter. Think about how many government regulations there are and this isn't one of them.
Doug

The "fire and shorts" is what got me thinking about the configuration. This is alot easier to just layout the harness to explain than trying to write a description or even look at a schematic.

The Road Kill FROD looked like the starter cable was fused with a 250 Amp mega-fuse, and I think the schematic showed the alternator fused with a 125 amp mega-fuse? I don't know if the cable supplying the main power was fused, or with what size fuse or feed wire?
I wish the show gave a bit more detail, or reference to what they were doing.

 

[Mike67]

I did something similar and a lot of audiophiles do the same thing.
So instead of powering everything off the line side of the solenoid on a fjord, the split happens right after the battery. I have a battery terminal that has several lugs, my main running to the starter, then I have a separately fused #6 feeding another fuse block for my stereo equipment and fuel pump, I also have another 6 that goes to my starter relay which also feeds my main fuse block. There is one more aux fuse block I mounted in the engine bay that has the feeds for my dual fans and my trans cooler and my headlights which run through relays .
My fuse block only controls relays for the most part.
The only