Sniper and Trunk Battery help

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Broke Farmer

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"Working on 69 Dart big block project with my son and have run into some electrical difficulties with the EFI and electrical upgrade. ANY help and opinions would be greatly appreciated. Using the wiring diagram below supplied by "Crackedback" in a previous post I read.

Battery in trunk. I have a Painless Performance High Amp Alt. Shutdown relay that I would like to wire in the system.
Single wire Mopar 100+ amp alternator

Need to wire into disconnect switch BUT the diagram has the feed wire going to the non battery side of the switch.
The Painless relay instructions specifically state to wire the feed to the battery side and has an 18 gauge wire that is supposed to mount on the other side of the switch would surely be fried when the switch is closed ?

THAT means all the feed goes through starter solenoid SO,

I believe I also need a continuous duty starter solenoid that will also support EFI correct? The old style had no diode which could fry my system? Any recommendations on a part?

I have also already bought the wrong disconnect switch as the second pole not rated amperage wise for the alternator output for this application so I could use a recommendation on that as well.

Anybody willing to tell me how you accomplished this or have recommendations?


Thanks
Brian
 

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The 18ga you mentioned fires up the coil to engage the alternator relay, so there should be no danger to it

What are you referring to "diode?"

This always starts a big "thing." I DO NOT generally "like" single wire alternators for a few reasons
1.....Because they are one wire, this means that the SENSING (is almost always) on the main / only wire. THIS means that the charge wire must be somewhat OVER size because voltage drop on the charge wire is going to affect system voltage
2...Because it is one wire, disconnecting it--in an emergency--is going to cause a spike situation. 'I guess' the disconnect solenoid is supposed to prevent this, is it advertised as such?
3...At least some EFI systems (Holley, one) specify the main large power conductors go DIRECT to the battery. If you are racing, IE NHRA you might want to look into this, but I THINK there is now some "leeway" meaning this is considered 'OK' as long as they are properly fused, and that the disconnect actually does kill pretty much everything "else."
4...The Ford like solenoid in the Crackedback scheme only fires the starter......it is not used as a continuous feed

He and I sorta disagree on this, and as he has pointed out, "there is more than one way to skin a cat"
I prefer to simply run a large gauge wire to the Mopar starter, and use that also for the main feed to the rest of the car. No Ford relay. There are certainly arguments to be made both ways

Some "things."

You don't want to create a situation....especially with EFI, where a disconnect involving an alternator will "spike" the system
Many use a dedicated wire from the alternator to the battery. I claim this itself is unsafe, although it would avoid spikes
If you are going to a sanctioned (NHRA) track you need to meet those rules
In my opinion a better way is to use an "non one wire" so you can "break" the regulator/ field circuit--using a relay, which will avoid a system spike.
 
Thanks for the input! Lots for me to chew on and think through.

1. I'm feel I am stuck in the one wire alternator boat as the car sat for 20 years before this "resurrection" and I have already shelled out for the alternator.

2. I e-mailed painless performance about the voltage spike on emergency shutdown. If it doesn't do that I guess I screwed that up as well.

3. The main power wires from the Holley harness have been run directly to the battery terminals. There was nothing in the instructions about fusing them which I thought seemed reasonable as it calls for clean power. The disconnect would kill the battery which would kill the Holley system back on Crackedback's diagram.

4. Perhaps I am using wrong terminology. The ford solenoid would be getting constant current from the alternator on one side of the post. Would that kick the solenoid or is it not enough?

I just like that diagram as it appears to me the starter wire would remain cold after intermittent use in starting the engine.

Sheesh -- my son and I are getting great time together putting this thing back together but it ran 11:20's with the old AVS carb on a cast iron intake and now I am thinking WAY too much about things!
 
Sorry for late addition. I do have a Ford style continuous duty relay PN ST85 to use for the starter.

Can anyone shed light on Cracked backs diagram on the placement of the feed wire from the alternator running through the post on the solenoid when putting in the Alternator shutdown relay solenoid?
Based on the Painless diagram I feel I need to reverse his diagram to the batter side first.

If you are out there CrackedBack your input would be greatly appreciated.
 
Broke Farmer said:
Sorry for late addition. I do have a Ford style continuous duty relay PN ST85 to use for the starter.

Can anyone shed light on Cracked backs diagram on the placement of the feed wire from the alternator running through the post on the solenoid when putting in the Alternator shutdown relay solenoid?
Based on the Painless diagram I feel I need to reverse his diagram to the batter side first.

If you are out there CrackedBack your input would be greatly appreciated.
Click to expand...
You tag a member like this.
@crackedback get yo country *** in here. lol

Also I'm not sure you want a continuous duty solenoid on the started. Del @67Dart273 will confirm if I'm right.
 
Broke Farmer said:
There was nothing in the instructions about fusing them
Click to expand...

The sniper wire harness is fused from Holley. Note the aluminum tube pointer.
20211129_182926.jpg
 
Broke Farmer said:
4. Perhaps I am using wrong terminology. The ford solenoid would be getting constant current from the alternator on one side of the post. Would that kick the solenoid or is it not enough?

I just like that diagram as it appears to me the starter wire would remain cold after intermittent use in starting the engine.

Sheesh -- my son and I are getting great time together putting this thing back together but it ran 11:20's with the old AVS carb on a cast iron intake and now I am thinking WAY too much about things!
Click to expand...

You lost me.......two diagrams. ........the special device you are talking about is to disconnect the alternator. It is basically a specialized solenoid--and you will have to check with the manufacturer---might be a "load" for the alternator upon shutdown. It is basically (otherwise) a continuous duty device. You will have to check DOES IT draw current whenever the disconnect is powered ? If so that is going to be a battery drain anytime the car is not running (charging).

The Ford solenoid AKA Crackedback is triggered by the car "start" wire from the igntiion switch. I'ts only function is to operate the starter. The purpose of this is to keep the large wire from the battery to "up front' DEAD at all times except when the starter is operated.

(Follow crackedbacks diagram, see the relay at top right? That is the stock factory starter relay. The wire going from the "square screw" terminal on the stock relay NORMALLY goes to the starter solenoid, and instead, runs to the rear, to the S terminal on a Ford relay (other end of coil on a Ford relay is the ground /mounting bracket) That relay fires "in start" and feeds the huge cable to the starter. The Mopar starter S terminal must be jumpered to the main battery post at the starter, so when it gets power, it pulls right in and operates
 
WHAT IS the part number and "link" for that alternator relay?
 
The alternator charge line MUST be on the battery side of the cut off switch. If that is what you are asking.

Unless the cutoff has a MONSTER of a duty rating for the small terminals, there is no way I would run the charge line like that diagram. That is a REALLY old diagram and I can't recall running a system that way. I've been using CD relays for 20 years or so.

Running a system to the rear of the car, an 8ga wire is insufficient in sizing. It's a 12-16 foot run from alternator to trunk. I use minimum 4ga on that run.

p8qI1hX.jpg
 
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Would a buffered relay in the power line for your EFI be a spike solution.
 
Wow. Thanks so much for the insight and help! Not calling out Crackedback at all. Been doing lots of research on this topic and I thought he seemed to be the most knowledgeable about it and when I saw his diagram I went with it.
I wasn’t sure about the EFI comparability which is why I am here asking the experts. The Painless relay came with 8 gauge which I thought was suspect. The 18 gauge wire to be placed on the opposite side of the switch seemed sketchy as well.
My ford style relay part number ST85 is a continuous duty.
Is the consensus that I scrap following this diagram if used in conjunction with EFI or move on to something else?
I’m not opposed to changing at all just now I’m not sure how to lay it out?
Thank again to everyone. Learning every day on this
 
Cracked back - just looking at your diagram you recently posted I see you now show a CD prior to the Ford solenoid.
That is how I wired in the painless relay. However
the painless relay is CD but they advise installing it it directly in line with feed wire from alternator it is not powered via switched power?
The ST 85 Ford style relay is rated 80 amps and was listed as a stater solenoid it just happens to be continuous duty.
 
I still think the solution overall is to scrap the one wire. If you break the output at any substantial charge rate, with a Painless/ Moroso relay installed, AND I AM ASSUMING that these have no "load" protection in them, then the alternator itself will spike, and it may just ruin some components in the alternator......like the regulator

You MAY be able to easily "break into" the alternator and modify the field circuit so charge can be stopped in the field / regulator, but that is iffy

I am not at all in favor of a dedicated charge wire to the battery. (No relay). This LEAVES a substantial wire "hot" with the disconnect removed.

My "strategy" is this:
Use a 4 terminal disconnect. Use the small terminals to break a continuous relay FED BY the ignition switch and those terminals in series. Use the contacts of the continous relay to feed your ignition switch switched loads AND break the regulator circuit. This kills the ignition / fuel pumps/ etc as well as the VR circuit. The "3 wire" alternator then hooked to the "loads" side of the disconnect kills the charge wire from the battery

With the above you can also use a dedicated Ford starter relay if you wish.

You seem to be confusing the Ford type relay with continuous duty. The Ford relay is ONLY for a dedicated starter circuit, nothing else.
 
I think I am finally catching up with you. I am using a 4 pole Master disconnect with an amperage rating that meets the alternator output.
I finally spoke with Painless performance and the shutdown relay is designed to be wired into the charge wire and be placed on its own 2 poles on the disconnect. It has load protection built in. It is also designed to work to prevent any surge when flipping the disconnect. I can run the charge wire to the battery side off the relay and through the hot post of the solenoid. The ground goes to the other side of the switch. When the disconnect is open the relay kills all power post relay. I also wired in a 150 am fuse into the charge wire pre-relay.
When the disconnect is open the hot wire coming from the disconnect to the starter solenoid has nowhere to send charge as it is now open and the relay circuit it incomplete.
In theory, there should be no wires left hot when the disconnect is opened on both poles as the power should be shut down to the entire system.
The ford solenoid which is a continuous duty relay is also rated as a starter solenoid. Its the same one I use on my diesel dump truck. It starts a DT466 so I would assume it could start a 440 gasser for intermittent use. But maybe I am wrong?
I really appreciate the tip about the EFI wiring/NHRA regs needing to go to the switched side! I will have to redo that part even thought the holley manual states directly to the battery.
I just don't get why ground kill wouldn't be better but I have had a hard enough time working through this. Ugh
 
OK if that device has a load internally that then changes everything regards the alternator. The only issue with it is that the coil draws current anytime the disconnect is energized. On a race car with the disconnect closed during a race day, that might not be an issue. But on a street car especially, you'd want to pull it whenever parked for any length of time.

You also might contact member here DionQ. He had/ was/ is using a relay / disconnect that is a latching setup IE you give it a shot at the control terminals to turn it on, then another shot to turn it back off. This relay does not draw current when the main circuit is active. I do NOT remember if this can be used for NHRA though. And it may be completely off the track
 
Fantastic! Thanks so much.

Been reading old posts and new posts here. Lots of knowledge to be gotten. Thanks to all!
 
Broke Farmer said:
I think I am finally catching up with you. I am using a 4 pole Master disconnect with an amperage rating that meets the alternator output.
I finally spoke with Painless performance and the shutdown relay is designed to be wired into the charge wire and be placed on its own 2 poles on the disconnect. It has load protection built in. It is also designed to work to prevent any surge when flipping the disconnect. I can run the charge wire to the battery side off the relay and through the hot post of the solenoid. The ground goes to the other side of the switch. When the disconnect is open the relay kills all power post relay. I also wired in a 150 am fuse into the charge wire pre-relay.
When the disconnect is open the hot wire coming from the disconnect to the starter solenoid has nowhere to send charge as it is now open and the relay circuit it incomplete.
In theory, there should be no wires left hot when the disconnect is opened on both poles as the power should be shut down to the entire system.
The ford solenoid which is a continuous duty relay is also rated as a starter solenoid. Its the same one I use on my diesel dump truck. It starts a DT466 so I would assume it could start a 440 gasser for intermittent use. But maybe I am wrong?
I really appreciate the tip about the EFI wiring/NHRA regs needing to go to the switched side! I will have to redo that part even thought the holley manual states directly to the battery.
I just don't get why ground kill wouldn't be better but I have had a hard enough time working through this. Ugh
Click to expand...
Ground kill would OF COURSE be the correct way to go for the master disconnect!! It's hard to believe the NHRA continues to defy logic/sound engineering orinciples and require the disconnect on the positive side which makes everything so complex.

I use a 1-wire alternator and as others have noted, the charge wire to the battery must be sufficiently sized. I use a 4 ga wire that is fused (Maxi-Fuse) in the engine bay and also at the rear by the battery so if a short occurs while the car is on or off, or the short is near the front or rear, it will pop a fuse. And I use a CD contactor to power all of the "veh" things up front. It is fed from a separate fused feed coming from the battery that is after the master disconnect.
As for the battery charging, so far, so good. My voltage gauge is fed off the CD contactor so it truly is the voltage running in the system up front in the car. It runs between 12.5-14 volts depending on loads turned on (2 coolant fans, 1 trans cooler fan, headlights, etc).
A simple welding cable quick-connect (disconnected of course) in the batt ground cable keeps everything dead when the car is parked for extended periods.

Bottom line is you use the Ford relay to start the car and only power the big battery cable when in crank mode, you isolate the charging circuit to go only to the battery, and you have a feed wire to run power for your car through a CD contactor. Thinking of it as 3 legs helped me get my head around it!!
BTW...@crackedback knows what he's doing so you won't go wrong there! I used many of his ideas in my build!!
 
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those painless instructions wire that charge relay in exactly the same way as the one I have it in my schematic. They take a slightly different paths. Mine is direct to battery via CD, then Hot side ford relay, then to battery. Same uninterrupted end point as the painless schematic.

I choose to fire the relay from a switched point within the car (downstream from cutoff, cutoff thrown, switching wire goes dead) instead of direct from cutoff switch. If parked for a long period of time with CO switch in on position, having hot line from cutoff will drain the battery (relay coil amp draw).

Just a different method to skin or in this case, switch the cat on.
 
So I just now got off the "tech" phone with Moroso, Their alternator shutdown solenoid appears to be similar and possibly exactly the same as the Painless one. He told me "there is no load' for shutdown. That means there IS NO spike protection for the alternator with that solenoid.

Frankly for me there is only one solution. That is to ditch the "one wire" alternator, use a 4 terminal disconnect . Use the second set of contacts on a 4 terminal disconnect to break the field/ regulator/ and ignition circuit, and you will be completely protected.

To sum this up in one sentence:

The Moroso/ Painless disconnect solenoids WILL shut down the engine, but THEY MIGHT destroy the alternator/ regulator.
 
Whoa. Looks like I am going to call Painless before the end of the week and get on the tech hold line again to verify. I was advised that it was designed to be built for spike protection upon shutdown and otherwise. That will shift the schematic in dramatic fashion if I was just given the boot to get off the line and go away.

I have already purchased the large 4 pole disconnect to replace the on with the Two large and two small poles.

Damn. That new alternator looks so shiny too...
 
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