It looks like the purpose is kill any power through the car when the ignition is off and the master disconnect is off. But its a complicated way of doing it.
2 wire alt battery relocation to trunk { not a race car }
- Thread starter Denis Breland
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Crackedback
Well-Known Member
The minimum NHRA standard for a race car leaves the cable from alternator to battery hot at all times. When you watch a car burn to the ground because that charge cable remained hot AFTER the cut off switch is thrown, changes your perspective on leaving hot wires anywhere in the car. Once thrown, nothing outside about a 2' cube is hot in any of my cars. That is a freshened up, cleaner version of my wiring schematic up I've used for 20+ years in race cars with a cut off switch.
To answer a different question of why the ford solenoid, I prefer that the starter load never see the cut off switch. Running the load through the cut off then to the ford relay, nope, not on my stuff.
You may create a loop if you aren't careful with feeding everything at the ford solenoid as your buspoint.
Depends on what you are doing and trying to accomplish.
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In your initial statment, you mentioned that this was not a race car, and I was just trying to rationalize all the changes proposed. Now, you note NHRA standard.....if you're building to that standard.....great.....but if not racing to any sanctioning body, why go to the effort? There is a cleaner way to accomplish isolation, especially not disconnecting the alternator output, as the diodes could be damaged. But, it's your vehicle.....do what you wish......
BOB RENTON
Crackedback
Well-Known Member
You asked why the CD relay, that is the answer.
Initial statement? Do you have me mixed up with the OP. OP found my schematic and asked about the CD relay and whether it was "required".
Please post a schematic of how you would do it with a single cut off switch. I'm open to all viewpoints and approaches.
As a side note.... the footnote on your post is how the schematic came about.
Initial statement? Do you have me mixed up with the OP. OP found my schematic and asked about the CD relay and whether it was "required".
Please post a schematic of how you would do it with a single cut off switch. I'm open to all viewpoints and approaches.
As a side note.... the footnote on your post is how the schematic came about.
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99 out of 100 race cars run starter current through the master cut-off switch
This makes sense to me but I still don't see the point of the continuous duty relay, why not run the alternator output to the other side of the master disconnect?
Crackedback
Well-Known Member
I hope you never have a car burn to the ground because the alt charge line was hot AFTER the cut off was thrown.
Not sure what you mean by the other side of the cutoff. Charge line needs to be on the battery side of the cutoff, if battery side it is always hot. If it's on the downstream side, it will continue to power the car if the OEM wiring for regulator is in place.
I understand.
In most "street" applications the mater disconnect is used as an ant-theft device and for safe storage. The switch is generally located in the trunk and not accessible without opening the trunk. In this case it would be fine and safe to eliminate the continuous duty relay and run the alternator charge cable to the output side of the master disconnect. Yes, the master won't shut down a running car but that's not the objective but it will still shut off all power once the switch is thrown.
In a race car where the master disconnect is operated from the exterior to enable shutting off a running car I fully understand your method.
In most "street" applications the mater disconnect is used as an ant-theft device and for safe storage. The switch is generally located in the trunk and not accessible without opening the trunk. In this case it would be fine and safe to eliminate the continuous duty relay and run the alternator charge cable to the output side of the master disconnect. Yes, the master won't shut down a running car but that's not the objective but it will still shut off all power once the switch is thrown.
In a race car where the master disconnect is operated from the exterior to enable shutting off a running car I fully understand your method.
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Crackedback
Well-Known Member
I think the "you don't need it" commentary was covered earlier for the OP's approach.
My schematic was set up for a RACE car where safety exceeds the minimum requirement. Want to use it for a different end objective, have at it.
That horse is dead now.
My schematic was set up for a RACE car where safety exceeds the minimum requirement. Want to use it for a different end objective, have at it.
That horse is dead now.
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