Battery relocated in trunk.

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The safety switch kills all power to the car shutting off the ignition (which shuts off the engine) and kills the fuel pump. That is why the alternator goes to the battery side of the master cut-off switch and the main power wire to feed the car goes to the "after" side of the master cut-off switch.
 
67Dart273 said:
Please stop connecting the alternator to the battery This defeats the purpose of a "safety" switch
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Del, Unfortunately, that is absolutely legal by the way of minimum NHRA requirements. When you have a car burn to the ground because that wire remains hot, it changes your perspective on the minimum standard.

@Demonx2

I build the main battery cables for my cars and customers out of 1/0 EPDM welding cable now. Great capacity and flexible. Never had an issue. At the front of the car, MAKE SURE, you have a great ground from engine to frame. I usually weld a nut to the bottom side of the subframe and run a 1/0 cable to the block. Nice solid ground if the car is frame connected.
 
Demonx2 said:
The safety switch kills all power to the car shutting off the ignition (which shuts off the engine) and kills the fuel pump. That is why the alternator goes to the battery side of the master cut-off switch and the main power wire to feed the car goes to the "after" side of the master cut-off switch.
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There is no reason to do that. Read Crackedbacks response above. Use a 4 terminal (proper term double pole) switch and use the small poles to kill the ignition relay, or with EFI the pump relay. That will kill the engine. Then you can run the alternator feed to the dead side of the switch.

And it might not only be the car that burns down. Kill ALL power
 
I prefer a CD relay in charge line energized via a source downstream from the cutoff switch. Keeps the alternator isolated and on the battery side of cutoff. No charge load going through cutoff too.

Lots if ways to do it. Pick one and go.
 
Guys - I appreciate the input as this is precisely why I asked on here! There are a myriad ways to wire these things. While the system I have will work, I still hope I never have to test the overall safety aspect of it but this system will kill the engine via the rear-mounted master switch and it has fuses on anything that runs power forward or rearward from the battery to the front of the car.

@crackedback - your idea of a welded nut for ground attachment and a CD relay powered after the cut-off switch as the link between the alternator and battery is a good one. Like you said, it keeps the alternator isolated for charging and kills it too when you throw the master switch. I like that idea! Likely better for the battery drain too since this is a single-wire alternator car and I've heard they can sometimes have a small continuous draw.
I assume you choose the 1/0 welding cable just due to the better flexibility of it?
 
@Demonx2

Yes, the welding cable you can coil in a 12" circle easily, not so with 1/0 battery cable. It's a really nice alternative as it has many more strands than battery cable. Slightly smaller OD too.

The CD relay is a solid method. If it fails, always carry a jumper wire in the trunk. You can snap it on and be no worse than the NHRA minimum standard at that point. Knock on wood, I've not had a CD relay fail yet.

At the trunk, drop the ground straight down, through the floor/extension panel and weld a nut there too. I use a 3/8 nut, weld all sides and will drill a hole for the bolt to pass into the rail. You could use an existing hole if there is one in the area. If you have any electronics that are ground sensitive, pull a 10-12ga wire from there and go forward to a clean buss stud up front.

oOH8TTk.jpg
 
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crackedback said:
@Demonx2

Yes, the welding cable you can coil in a 12" circle easily, not so with 1/0 battery cable. It's a really nice alternative as it has many more strands than battery cable. Slightly smaller OD too.

The CD relay is a solid method. If it fails, always carry a jumper wire in the trunk. You can snap it on and be no worse than the NHRA minimum standard at that point. Knock on wood, I've not had a CD relay fail yet.

At the trunk, drop the ground straight down, through the floor/extension panel and weld a nut there too. I use a 3/8 nut, weld all sides and will drill a hole for the bolt to pass into the rail. You could use an existing hole if there is one in the area. If you have any electronics that are ground sensitive, pull a 10-12ga wire from there and go forward to a clean buss stud up front.

View attachment 1715500752
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Rob, could you please post the wiring diagram again of how you install the trunk mounted battery? Thanks.
 
So 1/0 welding cable is plenty for a trunk mounted battery with a 100 amp one wire alternator? I'm pretty sure I wont come close to a 100 amp draw. I'm in the middle of a full rewiring with an American Autowire kit right now.
 
I don't like having the main starter cable hot. If you want to run the charge back through it, it's more than sufficient to handle the potential charge load.

If you want to isolate the charge line to the rear, run 4ga wire is what I would choose.
 
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