Alternator Upgrade Related Questions (was One-Wire Alternator Questions)

[dirtymac]

It is time to replace my 1G 40amp alternator with something more powerful for future plans.  I have my eye on some 100+ amp one-wire alternators.  I know a lot of people are more behind the 3G upgrade, but I think the one-wire is a better option for me.  I wouldn't mind keeping the old harness in place but it is in really bad shape.

I have read through the 3G Conversion page and several threads about the 3G conversions and One-wire conversions.  Most seem to pertain to newer EFI motors, whereas I have an older carburetor engine with electric choke.  Which leads to my first issue.  I'm not sure how I can get the power needed for the electric choke.  Based on the diagram's I have found, there should be a wire coming off the alternator that directly feeds the choke.  I do not think I can just hook my choke directly to the alternator.

I am planning to do the ammeter/volt meter conversion, but that is a little bit off.  In the mean time, is there an easy way to disconnect the ammeter so it is not damaged by the higher output alternator?  I'd rather not take the instrument cluster apart (again).

Below are some of the threads I have read through:

https://forum.garysgaragemahal.com/One-wire-alternator-tp112799.html

https://forum.garysgaragemahal.com/Help-On-3G-Page-tp86569.html

https://forum.garysgaragemahal.com/GM-one-wire-alternator-tp65069.html

[Gary Lewis]

Your carb's choke needs power from the stator winding of the alternator, which is a half-wave rectified DC.  My limited understanding of 1-wire alternators is that they are based on a GM unit, and I don't know if they provide that output.  However Ford's 1G, 2G, and 3G alternators do.

Back to the 1-wire, if you are thinking about a Powermaster then I'm not your guy.  I wouldn't run one if you gave it to me, for two reasons:

1. You cannot buy parts for them.  Instead you have to send them back for repair when they fail.

 

2.  When they fail, and they will, you can't go to a salvage or a parts store and get one off the shelf. You are stranded until you get a replacement.

Instead I'll run something I can replace easily or get parts for when it fails.  And that's a 1G or 3G alternator.

As for the ammeter, you could disconnect it.  But my worry is more with the shunt than the meter.  The shunt is probably sized to handle a max of 60 or 70 amps, which is all the alternators of the day would put out.  But if you put an alternator on that has a lot more capacity you could burn the shunt up, depending on how you wire it.

If you leave the wiring stock then you'll be trying to charge the battery through the shunt.  And if your battery should get low, when you start the truck the alternator will kick in hard and give you all it has, which could burn up the shunt.

Instead you need to wire the output of the alternator as shown below.  Don't use the factory BK/O wire that goes up to S202 as that feeds through the shunt to the battery.  Instead wire the alternator's output to the battery's positive side on the starter relay.  That way the alternator's output doesn't go through the shunt and you won't burn it up.

And, having done that you won't hurt the ammeter either since the only current it'll be measuring is that going into the cab, which isn't enough to hurt anything - if you haven't installed a killer sound system.

[ArdWrknTrk]

Unplug connector 610.
Bring wire 37 (Y) from S101 to the battery + stud of the fender mounted starter relay.
Bring the fused output of your 1-wire alt to the battery + stud of the fender mounted starter relay.
Toss everything shown below.

The problem with 1 wire alternators is that they are self-exciting, so no matter how high their ultimate output is they provide useless output at idle and low rpms.

[ArdWrknTrk]

Gary you need a Megafuse or fuselink in the blue 'new charge cable' shown.

The ammeter is worthless.
If converted to a RCCI voltmeter then state as such and feed from the LG/R key on power and ground the other side of the new/converted instrument.

[Gary Lewis]

I'm beginning to think that we need to have three or four different scenarios.  Something like:

Quick & Dirty: This would be for those that want a 3G but don't want to do any other work.  So it'd be pretty much as I said, meaning take the alternator output to the starter relay.  Then we'd list the advantages and disadvantages.  One disadvantage would be that there's no protection, meaning no megafuse, and your truck could burn down.  Some would argue that Ford didn't put one on the 1G or 2G trucks, but the counter would be that they did when they went to the 3G.  Another disadvantage would be that the ammeter would only show discharge, so would be worthless.  But an advantage would be that everything would be there in case you wanted to go back with a 1 or 2G, like you put in a 1-wire and got stranded in the back of beyond.

Bare Minimum: As above with a megafuse.

Cleaned Up: As you described with all of the extraneous stuff removed.  But you'd still have an ammeter that was worthless as now it'll never move.  But a disadvantage is that you then can't easily go back to a 1 or 2G.

Done Right: This is the one we've been describing for years, with a megafuse, voltmeter, etc.  The advantage over Cleaned Up is that you can tell that the alternator is working because of the voltmeter. But a disadvantage is that you've now altered the wiring so going back would be difficult.

Maybe we don't need Quick & Dirty and just go with Bare Minimum as we can't recommend doing it w/o a fuse.  But I wanted to get that out there in light of your comment.

If we had three or four options, with schematics and advantages/disadvantages, then we would be able to answer the questions we get of "but why can't we" do this or that.  We'd have thought through solutions that take into account "this or that", at least for the most part.  And then people could chose their poison.

Oh yes, about the "why not a 1-wire".  I don't see enough of an advantage of a 1-wire over a 3G to make it worth doing, so don't want to go to the trouble of drawing up the schematic or doing the writeup.  So maybe I write up my thoughts and bounce it around on here to get something we can agree on and put it on the site.  Then if people ask we can point to that and be done.  Am I wrong, folks?

[ArdWrknTrk]

I'm going to have to get back to this.
I'm trying to keep up with the mail and get parts + a shop lined up right now.

[Gary Lewis]

Don't think there's a hurry as we are just talking about how and what to recommend in the future.  And this thread is probably not the best place to do it anyway.

I'll start a new thread and ask for opinions.

[Gary Lewis]

The new thread is here: https://forum.garysgaragemahal.com/Rethinking-The-3G-Conversion-Pages-Process-td144886.html

[dirtymac]

I think I need more information about the last line of your reply.  Useless at idle and low rpm?  Since this is a work-in-progress truck, and since I live in a high-traffic area, the truck tends to idle a lot.  Can you tell me more about what you mean?

[dirtymac]

I'm still trying to digest all of this so bare with me.

It sounds like I can feed the electric choke from a 3G alternator.  It also sounds like I can connect it up to the starter relay (with a megafuse) the same way I would a one-wire alternator.  That leaves the entire harness out of the picture and makes it removable, right?

I still have to deal with the ammeter-to-volt meter conversion.  I actually have two functioning ammeters and I am shipping one off today for the RCC conversion.

My existing wiring is all in bad shape, so losing that entire harness would be a benefit for me.  I also have no plans of going back to a 1G or 2G.  However, having an alternator that I can easily swap or work on, is a plus.

[Gary Lewis]

I'm in no hurry and happy to answer questions.

Yes, you can power the choke off a 3G since it has a stator connection just like the 1 & 2G.

As for removing the whole harness, yes you can.  But you'll then have to do some wiring.  Let me do some more work to explain that in another post.

[ArdWrknTrk]

1-wire alternators have to be self exciting, because there is no key on power going to the field.
This means they can't energize the windings until the unit is spinning and that there is a threshold rpm to produce any output, and that output is somewhat proportional to rpm.

Now, once spun up  they can be wound to put out a good amount of power.
But remember that regardless of stated Max power they will only provide what's needed to keep the trucks electrical system at the set point (usually 14.3-14.5V)

A 1, 2 or 3G alternator has a sense wire (y/w)
A stator wire (w/b)... also used for choke, or in the case of a 351H.O. to trip a choke relay
An exciter wire (lg/r) that provides key on power to kickstart the alternator output.... rather than relying on it to bootstrap itself.
An output wire or* cable, usually bk/or

[Gary Lewis]

Ok, let's try this.  Here are three schematics in a fairly quick and dirty fashion.  Obviously the next step would be to add the voltmeter and the associated key-on relay, but let's hold off on it for a bit.

Does this help?

1: The original schematic straight from the EVTM

2: The EVTM schematic without C610 and its associated wiring that you can remove

3: The EVTM schematic with a 3G added and how to connect it, but w/o the voltmeter

[ArdWrknTrk]

Looks good!
Thank you for adding the Megafuse.  

[Gary Lewis]

Having slept on it, I think the megafuse needs to move up in the drawing so one of its lugs can be used as the terminal for the Y wire and the wire going to the starter relay.  Just to make things as easy as is possible.

And, I should redraw the wires so they have some color.  That way we can refer to "the red wire" or the "yellow wire".

Just things to fine tune as we revise the approaches, plural, to 3G conversions.

[ArdWrknTrk]

I might eliminate "130A"..
ETA: I would simply put "appropriate Megafuse" as well.
Most people don't need the big alternator in these trucks.
They got by for the entire production life with 40 or 60A

There are plenty of people who would just like a nice 95A, 135mm case 3G just for simpler wiring and low RPM delivery.

The small case 95 fits better on these trucks.

[Gary Lewis]

Good point.  And also eliminate the "150A" on the megafuse.  Or maybe make that "Sized in accordance to the alternator output"?

[ArdWrknTrk]

Yeah
I was editing while you were posting

[mat in tn]

this sure is starting to look easy on paper. I really like that you are taking the time on this. such a valuable option. I do wiring a lot yet I still struggle with explaining something like electricity that cannot be seen until it's too late. never an engineer but many years servicing in the field and everyone's thought process can be a little different.    

[dirtymac]

Having all three of these in one place does make it a lot easier to understand what is going on.  I agree that having the actual colors marked on the schematic would help.  It definitely looks easier on paper but in my case that could just be due to the rats nest of a mess I have under the hood.

I appreciate all of the work you all are doing on this and I know the community does as well.