alternator wiring help

[RHW2]

I've spent quite a bit of time reading through pages of threads that deal with electrical issues and alternators but I can't seem to find a thread that gives the answer I need.

I've got a 64 Belvedere with the stock alternator I will be upgrading to the Powermaster internally regulated 140 amp alternator. I'm running Holley fuel pump and will be adding dual electric fans with a Griffin radiator. The alternator that is currently on the car has 2 wires coming out the back.....a green wire with a spade connector going to the voltage regulator and a black heavier gauge wire with a ringlet connector going inside the car. Looking at the wiring diagram I have the black wire feeds the headlight switch, the ignition switch and runs through the amp gauge. Talking to the tech people at Powermaster they say I should disconnect the black wire and tie/cut it back and run a 4ga wire directly to the battery, which is in the trunk (I know the green wire to the voltage regulator will also not be needed). I've read some threads here that say run a wire to the starter relay AND the battery, some say only to the starter, but none of them say lose the black wire with the ringlet connector..... which is correct? BTW I've taken the amp gauge out of the picture, I sent my gauges out to be rebuilt/refaced and I'm have the amp gauge converted to a volt gauge and I also had the clock converted to a tach with the gauge face font matching the rest of the gauges so it looks factory but that doesn't have anything to do with my question just passing it along. I want to make sure I do this right and not burn down my car.

Not sure if any additional info is needed on my car but I'll give it just in case.....500cid, LARGE bump stick(I have the specs if needed), MSD 6AL box and MSD distributor, cross-ram with 2-750cfm carbs, headers 2" primary 3 1/2 collectors 3"exhaust, 4.10 S60 Dana with Detroit Locker, CalTrac bars, frame connectors, push button trans with 10" 3500 stall converter, manual steering. Not sure I've left anything out.....any help would be appreciated.

I apologize in advance if this has already been covered but I spent the entire day reading through posts with no success.

Thanks, Mike

 

[Shorthorse]

Take a look at the drawing. The large black wire is the output side (for lack of a better word) of the ammeter to the alternator. Power for the rest of the car is tapped off before it gets to the alternator. It's last destination is the alternator. The reason Powermaster says to tape it off is so you don't have to get into the wiring harness. By running the new main lead of your new one wire alternator directly to the battery, you are completing that path of the new charging circuit. If your battery is in the trunk, you might consider maybe a 2 ga. but that's just me. All the different ways you heard are basically correct but Powermaster's suggestion is the easiest.
Good move on the volt gauge vs the ammeter.
http://www.mymopar.com/downloads/1964/64BelvedereFurySavoyA.JPG
http://www.mymopar.com/downloads/1964/64BelvedereFurySavoyB.JPG

 

[RHW2]

thanks Shorthorse, just so I'm clear on this taking the black wire out of the loop won't prevent the car from starting? The reason I ask this is on my wiring diagram the black wire is also hooked up to the ignition switch and since it's the "power wire" won't taking it out prevent the ignition switch from "sending" power to the starter relay? The tech guy at Powermaster says taping back the black wire means the battery is supplying every electrical component on the car and the alternators sole function doing it this way is just keeping the battery charged....is this correct?

Thanks, Mike

 

[Shorthorse]

That is correct. The wires in the harness will continue to have 12V you need with the old main alternator disconnected. Just curious, what model Powermaster did you purchase? Some models are truly internally regulated and some supply a strap that goes from the main post to the field terminal. In effect it just turns the alternator on full time. You can usually tell because the instructions will mention a constant milliamp draw whether the car is running or not.

 

[Crackedback]

The flow of current when the car is running is from the alternator to the battery. The black wire at the alternator is the POWERING side of the system. Note which way the ammeter moves when the engine is off and headlights on.

The tech guy is good on the 4ga wire at a minimum and wrong on disconnecting the black wire at the alternator IMO. You want to keep that wire connected at the alternator if the bulkhead connectors are in good shape. Once you place the 4ga wire, the OEM harness only carries the loads the interior of the car require. It doesn't carry the charge load unless you disconnect the 4ga wire.

There are plenty of ways to do this and mopars are a different animal than other OEM's regarding charging system design. I build the wiring (charging, battery cables, headlight relays, etc) as a sideline to partially support the habit.

 

[RHW2]

That is correct. The wires in the harness will continue to have 12V you need with the old main alternator disconnected. Just curious, what model Powermaster did you purchase? Some models are truly internally regulated and some supply a strap that goes from the main post to the field terminal. In effect it just turns the alternator on full time. You can usually tell because the instructions will mention a constant milliamp draw whether the car is running or not.

Shorthorse,
The alternator is a Powermaster 8-48529-120 I don't have it in my hands yet....should be here in the next couple of days. The tech guy says it's internally regulated.

- - - Updated - - -

The flow of current when the car is running is from the alternator to the battery. The black wire at the alternator is the POWERING side of the system. Note which way the ammeter moves when the engine is off and headlights on.

The tech guy is good on the 4ga wire at a minimum and wrong on disconnecting the black wire at the alternator IMO. You want to keep that wire connected at the alternator if the bulkhead connectors are in good shape. Once you place the 4ga wire, the OEM harness only carries the loads the interior of the car require. It doesn't carry the charge load unless you disconnect the 4ga wire.

There are plenty of ways to do this and mopars are a different animal than other OEM's regarding charging system design. I build the wiring (charging, battery cables, headlight relays, etc) as a sideline to partially support the habit.

Crackedback,

Thanks for your response....but now I have 1 person saying tape the black wire coming off the back of the alternator and 1 saying leave it hooked up. What happens if I leave it hooked up and my electric fans kick on and the alternator throws out 60 amps or more isn't that black wire going to get that same load as the charge wire?

Also, when you say you "build the wiring as a sideline" are offering to put together a charge wire for me....for a fee? If so let me know I may be interested. I'm not sure how to PM on this site so if you want to communicate that way let me know how that's done...thanks

 

[Crackedback]

Electricity and water generally seek the path of least resistance. If you wire the fans properly, the interior/bulkhead wiring will never see the load. The requirements of the items on each line determine what that line sees for loads/current. Battery needs charging, the load goes on that line.

Yes, I build charge wires, battery cables, relay kits for a bunch of items on these older cars.

There are a lot of ways to skin a cat with these deals. You can run a cable from alternator to starter relay, then run cable from starter relay to battery. Or go direct to battery/CD relay and run another cable forward to the starter relay from a cutoff switch if you are installing one. There are many ways to approach this, some safer than others.

My favorite saying about this comes to mind. Pick your parts, pay your money.

Shoot me a PM if you want to talk.

http://www.forbbodiesonly.com/moparforum/showthread.php?107500-Charging-System-Bulkhead-Wire-Around

Those prices are for an underhood set up, not running 13-16ft to the rear of a car.

 

[Shorthorse]

Like Crackedback says, there's lots of ways to do this. I believe Powermaster is just offering the quickest and easiest way to wire the new unit.
Apologies first. I'm going to get in a lot of trouble over this but here is a very oversimplified diagram of what Powermaster is telling you.
With an ammeter it was important to have all the current draw on the same side of the ammeter. Now that you have done the bypass and installed the volt meter it is not necessarily the case. The new alternator is supposed to do the sensing internally and can do that virtually anywhere in the 12V system. You connect it to the battery because it also makes current and has current flow, therefore a larger gauge wire/cable is necessary.

 

[RHW2]

I called Powermaster again today and asked some additional questions based on the information the 2 of you have given me. The tech told me the preferred method of wiring the new alternator to run a 2ga charge wire from the alternator to my battery cut-off switch in the trunk and find another 12v source for the black wire that is currently attached to the back of the stock alternator, he said that I could leave it attached to the back of the new alternator but sometimes attaching 2 connectors to the same terminal can cause them to come loose and arc. So he suggested that I find another 12v source so I was looking at my wiring diagram and thinking that I could attach the black wire to one of the terminals on the starter relay....thoughts ??????

 

[Crackedback]

OK, now that you mention a cutoff switch, that changes a lot. With a cutoff switch, the charge line MUST be isolated from the rest of your electrical system. Keeping the OEM black wire connected will provide a power source and defeat the cutoff switch. I'm not a fan of a hot wire to the alternator all the time. I use a CD relay to kill that line, more work, safer than the minimum acceptable standard. Seeing a car burn because that wire was hot isn't fun...

Best to take that OEM black wire and run it as you suggest, over to the starter relay 5/16 stud, have both the original red and black wires feed the cabin. Similar to the Mad Electric approach.

Here's a basic approach. This one uses a Ford/Jeep starter relay to keep that fat wire cold except when starting.

 

[Shorthorse]

The existing black wire has 12V on it now. That is because it is tied to your red wire of your volt meter bypass (run through the ammeter on your old original wiring). Just look at the wiring diagram. You could take that black wire off the existing alternator and the car will continue to run off the battery. That will assure you that the black wire you are talking about will not take 12V away from the cars electrical system. It would effect absolutely nothing if you taped it off or tied it back into the cars 12V system. Tape it off. Your new one wire alternator and cable to the battery replaces that old black wire.
As for the cutoff switch. Run a short cable from one side of the cutoff switch to the battery and attach the new alternator cable to that same lug. Attach the main feed to the other lug by itself. When that switch is off, there will be no voltage to the cars electrical system.
Another modified, over simplified drawing. Keep it simple!

 

[Crackedback]

I hook the OEM black wire up at starter relay because it provides an additional path for current. Less voltage drop across the runs, everything in the cabin works better.

Same thing happens when people install my headlight relay kit. The interior and cluster lights are brighter because there is less load traveling along the path. Same thing occurs if you increase the current available highway.

Lots of ways to go, pick one and have at it. Don't get killed by "paralysis by analysis".

 

[Shorthorse]

Lots of ways to go, pick one and have at it. Don't get killed by "paralysis by analysis".

Amen to that!