questions about battery disconnect wiring

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MOPARCODY

MOPARCODY

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i relocated the battery to a trunk used a sealed box kit. a 4 post disconnect switch. i have the 10g wire ran to the back but im confused on what to do with the alternator wiring. i have it wired to the 4 post on the small positive lead on the switch then to the positive terminal on the battery but as far as the wiring from alternator to the fuse box im not sure what to do
 
Don't try and use the switch to handle the alternator output. I like the idea of switching a relay in the field circuit. You don't want to create a voltage drop situation whatever you do. What do you have for an alternator/ regulator? That is the first thing. And what is it that we are working on here, model year, and how original is the wiring?
 
alternator and regulator are stock 72 duster. i will admit that i know nothing about wiring
 
Maybe I'm not getting the question, but 10 ga. wire from the battery to the engine is nowhere big enough. You need 1-gauge cables, + and -. There is no need to change any of the alternator wiring if all you're doing is relocating the battery.
 
I need the disconnect switch to function to pass tech inspection. leaving the wiring alone wont allow the vehicle to shut off with the switch
 
This isn't real clear on what you have done and want to do. If you are relocating the battery to the trunk, then look at where the battery is connected in the engine compartment, you will need to run a 0 or 1 gage cable from the battery (now in the trunk) all the way to the front and connect it just like it was before (to the starter). For a cut off switch, you would put that somewhere along the new cable's route and have the new cable go to one side of the switch and then the a cable from the other side of the switch to where you were going (the starter). You will need a battery relay feed (the smaller red wire that normally goes from the battery to the relay); since your battery is all the way in the trunk, you can connect a 10 gage wire from the main stud on the starter where the battery cable is and run it up to the starter relay (thus replicating how it is normally); you will still need the 10 gage wire running from the relay down to the starter as it normally is. If you mount your disconnect on the firewall or inside the engine compartment, you can run the battery relay feed wire from the one side of the disconnect to the relay.

Just google "mopar starter relay wiring diagram" and you will see how all of the wires/cables go, then just imagine that the battery is located in the trunk and thus you will need longer cables. You could run a 10g wire from the battery all the way to the starter relay if you wanted but you do not need to.
 
Ah ok, well then you need to wire it differently so that it cuts off the alternator as well, for this you need a solenoid. I haven't installed one myself as I don't have race cars but I have looked at the diagrams and it isn't that complicated. Got this off the internet, there are a lot of racers here, I am sure someone can jump in with some pointed advice.

5951863-2postfullcutoff.jpg
 
The battery is already relocated switch mounted on back of car. it runs as is. my question is for the alternator wiring. it has to be wired through the disconnect switch to it will turn the car off from the switch. my question is how do i wire the alternator to the switch. wouldnt running the wire from the alternator to the switch directly affect the wiring to the regulator?
 
Here is the problems:

Most of these switches, the second set of contacts are not designed to handle alternator output. Also, dropping the alternator output can cause a voltage spike which can damage/ fail the alternator rectifier diodes. And, a long run of wire can cause voltage drop problems

One way to do this---especially if you have already rounded up enough no 10 wire, is to use the second set of contacts to break the field circuit to the regulator

"Stock 72 duster" This means you have the newer style (70 and later) Mopar regulator some incorrectly called "dual field" and more correctly called "isolated field." Look at the alternator. It should have two small wires connected to "push on" flag terminals. One is blue. This is switched 12V to the field. Break that and wire it to your rear switch, the second set of contacts. You want to use large wire to avoid voltage drop

(A better way is to add a relay but you can do that later)

Here is how this works. If you pull one cable off a battery on a running engine (AND YOU SHOULD NOT DO SO--IT IS HARD ON ELECTRONICS!!!) and if the engine is running fast enough to cause the alternator to charge, the engine will keep on running.

That is why you need the second set of contacts for a disconnect

There is a diagram floating around some place that details a relay/ solenoid............
 
What this is doing

Start at top left the blue "cut" wire. That is the original "ignition run" wire coming out of the firewall/ bulkhead connector from the ignition switch, and out into the engine bay. It originally fed several things "under the hood" depending on the car model, year, and accessories.

At the very least in 72, it feeds the igntion system, the blue alternator field, and the power to the voltage regulator. It may also feed the electric choke and some smog control doo-dad

That original circuit is subject to voltage drop problems which is why the idea of a relay or continuous duty solenoid. The key turns on the solenoid, and the solenoid then feeds the loads thus relieving the wiring.

NOW Notice that in this modification, the "cut blue" coming out of the bulkhead is wire to the rear, to one terminal (small) on the disconnect, and BACK up front to feed the solenoid. The key switch is turning on the solenoid through the disconnect, and allowing the thing to operate. So when you pull the disconnect, this drops out the solenoid and kills BOTH ignition power, and the voltage regulator and field power. It can not run on

ALSO NOTE that you can easily create a sort of anti-theft by hiding an extra toggle switch in the solenoid circuit, OR IF YOU MOUNT the disconnect inside the trunk, and operate it with a push-rod, you can easily create a rod-inside-a sleave set up where the switch can be "pushed" off, but cannot be turned back on with the pushrod. You have to unlock the trunk to re-power the disconnect.
 
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WHAT SOME GUYS DO Some guys like to run the alternator output to the battery direct. This makes the disconnect "work" but IT STILL LEAVES a nice big wire "hot" all the way up to the alternator. I like to claim this does not meet the intent of the rules, NOR IS IT SAFE. If I am the guy, upside down, with fuel dribbling everywhere, I would rather not have that alternator wire "hot"
 
I wired my kill switch up to kill the power to my digital ignition box and electric fuel pump relay. Works as intended and passes tech at the track.
 
Fast340cuda said:
I wired my kill switch up to kill the power to my digital ignition box and electric fuel pump relay. Works as intended and passes tech at the track.
Click to expand...

The diagram above does that and more. Killing the VR/ field circuit SHOULD help to alleviate spikes coming from the alternator The marine industry has "load dump" devices designed to control alternator spiking in battery switching systems. I think one of the race outfits, don't remember who, also offers one now, Moroso? MSD? Don't recall
 
67Dart273 said:
The diagram above does that and more. Killing the VR/ field circuit SHOULD help to alleviate spikes coming from the alternator The marine industry has "load dump" devices designed to control alternator spiking in battery switching systems. I think one of the race outfits, don't remember who, also offers one now, Moroso? MSD? Don't recall
Click to expand...

You could include the voltage regulator/alternator circuit as well. It was easier in my case to just kill power to the ignition box and fuel pump.
 
There is the minimum to pass tech and safer methods. Have to choose your route.

When you see a 25K+ car burn to the ground from a hot alt wire AFTER the kill switch was thrown, it colors your opinion regarding the minimum standard. I always run a ford style starter solenoid and a CD relay (alt wire). From the left side of that plate, forward, NOTHING on my cars is hot when the kill switch is thrown.

6QH5A1Z.jpg


pick your parts, pay your money
 
Properly protect your whole car and electrical system by using fuses! Start at the + battery terminal and put a 200 amp mega fuse between the positive post and the positive cable. Every wire that splits off the + cable should be fused for the size wire it is with a fuse in a fuse block to protect every circuit.
The + output on the alternater on my car has a 50 amp megafuse between the alternater and the #4 welding cable i use for the alternater output. I am going to fuse both ends of that cable since a short could be generated from either end if the alternater is charging. The #4 is big enough that you can run a one wire alternater and there will be no line loss to affect the internal regulater in the alternater, and everything is happy. If this doesn't make sense right away just look at how a house is fuzed. Main fuses protect from total overload, and each circuit starts with the juice going through a breaker sized for the wire it protects. The fuse should never be rated higher than the wire it protects. And lastly, solder all connections.
 
Lots of good information here and I agree on many of the statements above.

All of my additional circuits are fused, have properly sized conductors and have solder connections throughout.

I actually manage a facility that designs and manufactures power distribution boxes that are used in the semi conductor and robotics/automation industries. Our products must be built to some fairly strict UL requirements before being marked with a listing and being released to the market. I have been able to leverage a lot of this knowledge on my own projects.
 
crackedback said:
There is the minimum to pass tech and safer methods. Have to choose your route.

When you see a 25K+ car burn to the ground from a hot alt wire AFTER the kill switch was thrown, it colors your opinion regarding the minimum standard. I always run a ford style starter solenoid and a CD relay (alt wire). From the left side of that plate, forward, NOTHING on my cars is hot when the kill switch is thrown.

View attachment 1715464619

pick your parts, pay your money
Click to expand...

Crackedback, do you have a part# for this CD relay or one that you recommend?
 
Wouldnt running the alt cable to the batt. side of the ford start solenoid also work for keeping the alt cable from being hot after the kill switch it thrown? So using the same power cable from the batt to the solenoid as the recharging line.
 
Matts440 said:
Wouldnt running the alt cable to the batt. side of the ford start solenoid also work for keeping the alt cable from being hot after the kill switch it thrown? So using the same power cable from the batt to the solenoid as the recharging line.
Click to expand...

You don't run the starter cable through the cut off switch when using a ford relay. The idea is for that cable to be hot only when starting the car. Run a separate cable to feed the car. The black wire going to the rear and back forward feeds the car. The black line has a 60 amp maxi fuse inline, going to the switch... in case the switch goes dead ground.

@4mopwr

I use a cole heresee CD relay that is 85 amp IIRC. Don't have a part number off top of my head. 24059 or 24106???
 
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True, I currently have my battery to disconnect, up to the ford solenoid on firewall, then to starter, was just going to run a 0/1 gauge wire off alternator to the batt side on the solenoid which would go back through the shut off to charge the batteries.
 
crackedback said:
There is the minimum to pass tech and safer methods. Have to choose your route.

When you see a 25K+ car burn to the ground from a hot alt wire AFTER the kill switch was thrown, it colors your opinion regarding the minimum standard. I always run a ford style starter solenoid and a CD relay (alt wire). From the left side of that plate, forward, NOTHING on my cars is hot when the kill switch is thrown.

View attachment 1715464619

pick your parts, pay your money
Click to expand...
Can you draw out a wiring diagram of the panel you're using? Just trying to picture how you have it wired in my head and that ain't workin!
I have the same problem in my Dart, but my car is race only. Wiring is basic for a drag car, (IGN, Fuel, Water Pump, Fan & Lights). I've added a one-wire alternator and need to make it work with my trunk mounted disconnect switch to pass tech. I like the idea of what the other gentleman said about wiring the fuel pump and ignition box to be killed with the disconnect.
 
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