Alternator Harness

Jamie V said:
With everything on...
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Which includes what, exactly?
Jamie V said:
...120amps...
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The alternator would be smoking-hot after just a few minutes.
Jamie V said:
...12.40v at the battery but 12.75v on the back of the alternator.
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That's 0.35V drop. If it's actually pushing 120A through that, you'd have 42W of heat coming off that wire, which should be enough to make it noticeably warm in just a few seconds. What's the battery voltage with NOTHING turned on, but engine idling?

Remove the alternator, and clean its mounting bosses, and those on the engine bracket, down to shiny Aluminum; also the ring terminals from the alt. output, and the starter relay; then apply electrical grease (NOT dielectric, or chassis, or thermal, or battery snot, or antiseize) to each area of contact before reassembly. Also, remove, clean, & grease the battery terminals. While they're off, charge the battery.

(phone app link)


(phone app link)


(phone app link)
 
Steve83 said:
Which includes what, exactly?The alternator would be smoking-hot after just a few minutes.That's 0.35V drop. If it's actually pushing 120A through that, you'd have 42W of heat coming off that wire, which should be enough to make it noticeably warm in just a few seconds. What's the battery voltage with NOTHING turned on, but engine idling?

Remove the alternator, and clean its mounting bosses, and those on the engine bracket, down to shiny Aluminum; also the ring terminals from the alt. output, and the starter relay; then apply electrical grease (NOT dielectric, or chassis, or thermal, or battery snot, or antiseize) to each area of contact before reassembly. Also, remove, clean, & grease the battery terminals. While they're off, charge the battery.

(phone app link)


(phone app link)


(phone app link)
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Let me try and answer these questions in order.

Everything on = Aftermarket PiMPxshift ECU/Trans controller, wideband, aftermarket AEM 340 fuel pump, Mark VIII electric fan, A/C on with blower on high, headlights on with fog lights on (more amps then high beams), radio on, door open with dome light on (but not wipers forgot about them).

Voltage idling with nothing on that doesn’t have to be on is 13.7-13.8v

As far as your links about how I’m suppose to clean and check everything you obviously don’t know me at all. My crap is spotless and clean with no bad connections. My truck has 4,000 miles and is kept in a climate controlled garage and doesn’t see water (not even to wash it)

I have a ton of stuff drawing on the system and a 130amp alternator is NOT big enough and the factory 8ga wire with 12ga fuseable link isn’t large enough. I don’t need anyone to confirm that is just is.

I ordered a new 200amp alternator from PA Performance today and they (along with other manufactures of 200amp alternators) recommend a 4ga wire.

I’m wanting to build a new harness with a 4ga wire and 8ga fuseable link but I don’t want to splice a bunch of new connectors on. I need to find another factory harness that I can remove only the charge wire from and replace so I don’t have to cut mine up. Everything I change on this truck I need to be able to put back to 100% factory.

This post isn’t about trying to diagnose a problem.
 
Your alt is not up to it at 12.7 v at the stud, why don't you just install the new alt with the stock harness and see how it does? That's working fine for me.
 
Because I’m already getting voltage drop and the Alternator manufacturer says it needs to be 4ga.
 
Jamie V said:
...Mark VIII electric fan, A/C on with blower on high, headlights on with fog lights on...
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Those are your big draws, plus maybe the fuel pump. And it's really just the e-fan that pushes it above what the 130A 3G can handle. But you'd make it a little easier on yourself & the alt if you switched to LEDs as those older bulbs burn out. Going back to a mechanical fan would help a LOT because it's much more-efficient.
Jamie V said:
Voltage idling with nothing on that doesn’t have to be on is 13.7-13.8v
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Good - I just wanted to check that the alt is working. But if your ammeter is correct, then you have a rare 130A 3G that can't put out 130A - it drops voltage before it gets to 120A. All the 3Gs I've tested (which is a BUNCH) put out substantially more than nominal.
Jamie V said:
...you obviously don’t know me at all.
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You're absolutely right - I can't see the truck, or anything about it because you have nothing in your signature. So before I can offer useful suggestions, I have to ask a bunch of questions. If you had all that info into your signature, we could have skipped some of this.
Jamie V said:
My crap is spotless and clean with no bad connections. My truck has 4,000 miles and is kept in a climate controlled garage and doesn’t see water (not even to wash it)
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Irrelevant. Aluminum is VERY reactive with Oxygen - even when it's dry and cool. And after 25 years, there IS corrosion on it - apparently enough to keep that alternator from putting out what it could. Remember there's also a mating surface between the bracket & block, and another between the block & negative battery cable ring terminal. They ALL need maintenance & electrical grease - even inside your CC garage. Your voltage drop test proves it.

This bracket was sandblasted & painted with DupliColor Aluminum Cast Coat (DE1650):

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But if you prefer, it also looks good clearcoated (DE1636), like this distributor:

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Jamie V said:
...they (along with other manufactures of 200amp alternators) recommend a 4ga wire.
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That's also what Ford uses for the battery cable, which has to pass ~140A to the starter while also powering the EEC, HEGO, fuel pump, and potentially the headlights & marker lights (in the neighborhood of 200A total).
Jamie V said:
I’m wanting to build a new harness with a 4ga wire and 8ga fuseable link but I don’t want to splice a bunch of new connectors on. I need to find another factory harness that I can remove only the charge wire from and replace so I don’t have to cut mine up.
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Sounds like the Explorer harness would be perfect for your needs. You can even buy a replacement 200A MEGA fuse, in case the 175 blows. But I'd keep the 175 as long as possible - just carry a 13mm wrench in the truck to swap it.
Jamie V said:
This post isn’t about trying to diagnose a problem.
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Not exactly, but you'll still get more & more-useful help if we have all the relevant information. And I still think you'll get better performance from your current alternator if you clean & grease its mounting surfaces. You need to do it anyway before installing the new one, so you could get a jump on that by doing it now. It would also be interesting to find out what effect it has on the current alternator.

BTW
This caption lists the standard fusible link wire colors:

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This is $12 for 24" black with 3/8" ring terminals:
https://www.ebay.com/itm/302709017355
I've bought wire from that seller, and it seems to be high-quality. Most of the wire they sell is made in USA, including that listing. Check the description of how they build those cables.
 
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Jamie V said:
Because I’m already getting voltage drop and the Alternator manufacturer says it needs to be 4ga.
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It needs to be 4ga if you're going to be pulling 200 amps, and you won't be. When the voltage is up where is should be ,the current will go down.
 
Briansshop said:
It needs to be 4ga if you're going to be pulling 200 amps, and you won't be. When the voltage is up where is should be ,the current will go down.
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I’m confused? So your saying I only need a 4ga wire if I’m pulling the full 200 amps?

I think I’m just going to put the alternator on when it gets here and re test everything then go from there.
 
Jamie V said:
I’m confused? So your saying I only need a 4ga wire if I’m pulling the full 200 amps?

I think I’m just going to put the alternator on when it gets here and re test everything then go from there.
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Probably a good idea Jamie, everyone has their favorite calculator, but I used this one quite a bit because it figures in length and voltage drop. Something I was really worried about for the fuel pump way in the back of the truck.

https://www.wirebarn.com/Wire-Calculator-_ep_41.html
 
Ed’s cables are awesome and are plug and play from the best I can remember. I’m running fast xfi 2.0, dual fans with Ed’s fans controller, aeromotive a1000 pump, and much more on the stock alternator and mr Ed’s upgraded alternator and starter wires with no problems so far.
 
I’ve know Ed for over 15 years (He’s even stayed at my home) I know his kits use top quality components. It’s just not what I’m looking to do.
 
this is not directly related to the charging wiring harness being discussed, but is also something to possibly consider when desiring max alt performance. all of the ground points had been cleaned and conductive grease applied on my truck, all cables were in good condition and i thought everything was working as well as possible with the new pa 130 amp alt and their charge wire installed. a 6 ga alt case ground wire was then installed from the alt case to the neg batt post. i immediately noticed that the starter was spinning faster and the engine cranked over and started more quickly. i haven't checked it but i think the case ground wire should also help effective alt ouput some as well since the ground has a much shorter distance to travel.
 
So what is your theory on why the engine cranked over faster by adding a ground to the alternator case?
 
Jamie V said:
So what is your theory on why the engine cranked over faster by adding a ground to the alternator case?
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not really sure. batt cables are oem, maybe it wouldn't hurt if they were a larger gauge (in my example ground cable). long block is stock except for mild cam change. i never have looked into the schematic to try to find out. the improvement in my truck cranking and starting was very obvious so maybe there's a deficiency somewhere i couldn't find. the case ground is still on. couple of friends years ago (elect engineering student and a sharp electronic tech) had the opinions that an alt case ground directly to the batt neg post was a good idea for the "charging system" because the ground path to the batt is shorter and has less connection interfaces to cross.
 
In my case I have a truck with very low mileage and I’m walking the line of modifying some things to make it more enjoyable to drive but at the same time not modifying anything that can’t 100% totally be reversed with no signs of modification.

I’ve considered running an alternator ground from the back of the alternator down to where the stock ground wire mounts to the frame.
 
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