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Alternator Amperage?

gr8scott

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You said the wiring is easy for this? Mind sharing the necessary wire changes I would need to make to support this amp?
Cheers, B

Super easy. One big charge wire is all you need. I made my own, and went a little overkill with 2 gauge wire.
In the middle I bolted a 175A AMG fuse directly to the cable, wrapped it with self-fusing silicone tape, and put
a piece of loom over it. Love my 3G. Picked it up from WH in 2011 and still going strong.

EDIT: There's different ways to wire a 3G. Mine has the "self-exciting" voltage regulator, so it only needed one big charge wire.
 

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Dinger

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Super easy. One big charge wire is all you need. I made my own, and went a little overkill with 2 gauge wire.
In the middle I bolted a 175A AMG fuse directly to the cable, wrapped it with self-fusing silicone tape, and put
a piece of loom over it. Love my 3G. Picked it up from WH in 2011 and still going strong.

EDIT: There's different ways to wire a 3G. Mine has the "self-exciting" voltage regulator, so it only needed one big charge wire.

Thank you for this! Very helpful! I haven't yet unravel the mysteries of schematic drawings, so a picture is worth a thousand symbols!
 

DirtDonk

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Can you describe (or post another pic of...;) ) the back of the alternator?
Just trying to decide if that's a large-case or not. Seems like it might be.
From some manufacturers, that part number actually does come up as a large-case 1G unit, so I wanted to confirm.

And so then back to an earlier question. What is wrong with this alternator? Did you have it tested to see if it had failed, or was failing?

Paul
 

blubuckaroo

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Super easy. One big charge wire is all you need. I made my own, and went a little overkill with 2 gauge wire.
In the middle I bolted a 175A AMG fuse directly to the cable, wrapped it with self-fusing silicone tape, and put
a piece of loom over it. Love my 3G. Picked it up from WH in 2011 and still going strong.

EDIT: There's different ways to wire a 3G. Mine has the "self-exciting" voltage regulator, so it only needed one big charge wire.

Jeese that's a big wire!
And why did you need that much amperage?
 

gr8scott

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Jeese that's a big wire!

Like I said, went a little overkill. Just thought 4 gauge was a little small, so went one size bigger.

And why did you need that much amperage?

Got tired of turning down my stereo when I came to a stop. The stock alternator just couldn't keep up.
 

DirtDonk

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...Whatever wattage is used by that electric fan will be made up with alternator load.

This may be true, but the additional load from the alternator is less than the loss of turning a big mechanical fan.
Or is that what you were saying?

Either way, there should still be a potential gain from going from mechanical to electric.
It still comes down to can it cool the rig, but only time will tell in that regard.

Paul
 

blubuckaroo

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This may be true, but the additional load from the alternator is less than the loss of turning a big mechanical fan.
Or is that what you were saying?

Paul

Maybe you could explain this. This concept goes against all my mechanical training.
It's going to take the same amount of energy to move the same amount of air, no matter what drives the fan.

After thinking about this though, both an electric and clutch type fan would eliminate the load when the coolant temperature was cool. But when the heat is on, both should be the same.
 
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Dinger

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Can you describe (or post another pic of...;) ) the back of the alternator?
Just trying to decide if that's a large-case or not. Seems like it might be.
From some manufacturers, that part number actually does come up as a large-case 1G unit, so I wanted to confirm.

And so then back to an earlier question. What is wrong with this alternator? Did you have it tested to see if it had failed, or was failing?

Paul

Here's that pic. Nothing is wrong with it that I know of. But, because of other things I have found on this rig, especially electrical, I am suspect of everything. Didn't think it was stock, nor was I sure it could perform as I would need it to, so I checked in with the forum to get some feedback.
imag1156.jpg
[/IMG]
 

DirtDonk

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Maybe you could explain this. This concept goes against all my mechanical training.
It's going to take the same amount of energy to move the same amount of air, no matter what drives the fan.

After thinking about this though, both an electric and clutch type fan would eliminate the load when the coolant temperature was cool. But when the heat is on, both should be the same.

I hear ya. But I think the electric fans basically do NOT flow as much air. Maybe I'm wrong when it comes to the big boys like the Mark VIII and Taurus fans, but I don't really know.
When testing was done on a dyno, I don't think they were playing apples against apples because there were too many variables. I believe they were only comparing a mechanical fan to an alternator under load. But don't remember if they said how much load there was.

Now I have to find that info to see if I'm remembering it wrong....

Paul
 

DirtDonk

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Here's that pic. Nothing is wrong with it that I know of. But, because of other things I have found on this rig, especially electrical, I am suspect of everything. Didn't think it was stock, nor was I sure it could perform as I would need it to, so I checked in with the forum to get some feedback.
imag1156.jpg
[/IMG]

From your stories, I'm not surprised you'd be suspicious!;)

I would keep it, unless you're ready to upgrade one step further.
It's a large-case 1G alternator and was considered one of the best, if not the best performing alternator back in the day.
Good low-rpm output, higher overall output than the stock ones, easy and cheap to find, long-lasting bearings, etc.

So in and of itself, it's a great alternator option for early Broncos.
Now however, as you've heard here, we have the 3G to choose as well. And while there's nothing wrong with the performance of your existing one, and you can keep the stock charge wire, there's no arguing that an internally regulated 3G cleans up the wiring under the hood and is generally considered at least as reliable, if not more so than the one you have.

Your wiring was indeed changed slightly to fit the different connector orientation of the large-case vs the original, but that was minor. It still uses an external regulator, and worked fine on many heavy duty cars and trucks for years.

So it's still good then? Well, the decision to change to a 3G would then come down to simplicity and cleaner wiring. Doesn't sound like you need to have the higher 95 or 130 amp output at this stage, but the cleaner wiring is a bonus.

With either one though, a dual-groove pulley is helpful to keep the squealing belt syndrome at bay. Any large, higher output alternator is tasking a single v-belt to it's max. Which is one reason all new vehicles have had wider and more full wrap serpentine belt systems starting in the late seventies.
But it's not an insurmountable task. So not enough to keep us from running them.
I would never replace your existing one with a lower powered stock original style however. If you change, go newer.

I'm running Explorer serpentine setups on mine, so by necessity have to run an Explorer 4G alternator. But my '71 had your exact alternator on it (with dual belts) for many, many happy years.

Paul
 
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Dinger

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Paul and everyone,

Thank you for all the help! We are lucky to have a cool group with great diversity of ideas, knowledge of options, and experience of installation and maintenance! After hearing the options available with both pros and cons, and given I am upgrading all the wiring anyway, I am inclined to go a higher output 3G that offers the side benefit of a cleaner bay. Given the short list of accessories I want to run (in addition to all the standard running items), guessing a 95A is more than enough for me, is there a pretty standard alternator out there everyone is using as the "go to" option? And, are all alternators created equal, or are there some to stay away from?
 

DirtDonk

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There is a list floating around the forum here that I'm sure someone has saved, that shows all the potential donor vehicles you can use as a source for a 95 or 130 3G unit. This allows you to either source one from the junkyard or your local auto parts store.
Basically you just want one with the standard mounting scheme. Looks very similar to what you have now, with one through-hole (the pivot point) and one threaded hole (the anchor point) that will mount directly to your engine with the current brackets.

For the wiring, you'll want to use at least a 6ga battery cable and Mega-fuse, Midi-fuse, or circuit breaker for protection. You can make your own or buy a kit like the one we sell: Charge Cable and Fuse

We also sell a "1-wire" version of the 130a 3G for those that want the absolute minimum of wiring. It's the same externally and performance-wise, but has a self-exciting regulator to eliminate the need even for the old Green w/red wire from your old body mounted regulator. 130a 1-wire Alternator
It's certainly not a necessity, but is popular with those looking for more simplified wiring than even a stock one needs.

I'm sure someone will post up the donor list. It's been around for a long time and I stopped saving it after the fourth hard drive failure. Plenty of members around with better link-saving kung fu than I have!

Good luck.

Paul
 
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Dinger

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Paul, whatever they're paying you, it's not enough! ;) Cheers, mate! Appreciate all the guidance. I am checking out your site now...
 

DirtDonk

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Hah! Thanks. Ain't it the truth, ain't it the truth.... As Snaggle Tooth would say.

One other thing if you decide to go with the upgrade. You can offset your cost a little bit by selling your still-good alternator to someone that's more interested in that style. It's a very good unit for the right person.

Paul
 

Steve83

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...don't really want to derail this thread...
%) Too late. :D
But, I am looking forward to trying an efan for two reasons: more CFM at idle, and a modest boost in performance (maybe...).
1) How many CFM at idle do you need? How exactly do you know you don't have enough already?
2) E-fans use more engine power than mechanical fans (for the same CFM), so there will be a modest loss. The higher the CFM, the higher the waste.
Mind sharing the necessary wire changes I would need to make to support this amp?
The wiring change (there's really only 1 significant one) for the ALT (I'm not sure what "amp" you're asking about) is shown in that first diagram I posted, which is colored to match the wires you should find on your truck.

This shows (generally) how to add various types of electrical accessories, including a stereo amplifier:


(phone app link)
...there is no free performance. Whatever wattage is used by that electric fan will be made up with alternator load.
...PLUS the losses from each time the energy is converted from one form to another (mechanical to electrical, and back to mechanical). So there will be MORE load from the alternator than the mech. fan had been applying to the belt.
...the additional load from the alternator is less than the loss of turning a big mechanical fan.
That's backward, when comparing fans that move the same air.
It's going to take the same amount of energy to move the same amount of air, no matter what drives the fan.
No, there are 1,000 ways to move air, and some are more efficient than others. If they were all the same, you'd see every conceivable design of fan on all the various vehicles. But everyone started off with stamped steel blades (back when that was cheap & good enough), and now everyone has converted to curved-blade molded plastic. No one ever used centrifugal (squirrel-cage) blowers, or pinwheels, or Japanese folding bamboo fans, or bellows, or... Why not? Because each of those would require MUCH more energy to move the same amount of air as the conventional fan.
But I think the electric fans basically do NOT flow as much air.
Only because it's so expensive to build a big fan motor, and keep a big plastic fan blade balanced; and it's so much more dangerous if a big piece of plastic cracks at those speeds & loads. So big engines (like industrial diesels) that need gargantuan airflow still rely on old-style metal mechanical fans. But plastic fans are slightly more-efficient at moving air, so for light engines like these, an e-fan can be smaller & move the same air as a comparable mechanical fan.

It's just not enough to balance out all the OTHER losses of using an e-fan, unless the fan motor is controlled by the PCM in a very specific way to bring the total system efficiency up slightly above a mechanical fan. That's why modern vehicles come with e-fans (and SEVERAL additional sensors, and a PCM programmed to monitor & control them all). But retrofitting an e-fan to an antique won't work (for efficiency) unless you swap the COMPLETE modern engine & its management system in, along with the e-fan.

So the only reason to put an e-fan on an antique 4WD is so you can turn it off before fording deep water. In all other situations, a mechanical clutch fan is superior: cost, simplicity, reliability, MPG...
 
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Dinger

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Steve83, thanks for walking me (us all) through your logic! I am totally tracking your how’s and why’s that both fan types have merit, specific applications and are also part of a complete ecosystem. Admittedly, I will not be able to create the ideal ecosystem for my rig in that I cannot harvest a PCM, but nor will my vehicle ever see dirt, so my hope is that A) I will have slightly higher cfm at idle, and B) I will have slightly less mechanical resistance off the line. These are literally my only two objectives (other than sufficient cooling during typical street conditions), so wondering your thoughts if I have a chance of achieving them. Thanks!
 

Steve83

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You never said why you think you need "more CFM at idle", or how much more. Whether or not you get it from an e-fan depends entirely on what size e-fan you use. But the e-fan won't change CFM as the temperature increases, or the engine RPM increases, or the temperature DROPS... It'll always be the same, whenever the fan is on. So if you need more CFM at high RPM than you get at idle, you won't get it from that fan. And if the fan stays on after the engine temp falls, the engine will be running TOO cool for proper operation (fuel evaporation & PCV).

If the e-fan moves as much or more air than the mech. fan did, and you understand that the e-fan motor is LESS-efficient at converting engine torque to fan torque, then you have to know that you'll have LESS available torque at all times. The mechanical resistance at the WP pulley (what drove the mech. fan) will move to the alternator, but it will more-than-double (probably closer to quadruple). So you'll certainly have MORE mechanical resistance on the belt with an e-fan.
 

DirtDonk

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I think he said he doesn't really "need" it, and has not had any trouble so far. But likes the whole electric fan concept. That's all I ever wanted one for to.
And just like you said, one of the main reasons wasn't for cooling (I never had a problem in traffic, or anywhere else except on slow trails under high load in hot weather) but like the idea of turning it off for river crossings.

I'm guessing he's just having fun with it and want's to play around with his ideas.
All the talk about the lack of efficiency and bad results with electric fans over the many years has not dissuaded me from it either.

Not that I'm going to change out my Explorer fan for an electric anytime soon of course...
But I might play around with the steel and plastic versions, just for the sheer heck of it.%)
So I can't answer for the OP of course, but that's the feeling I got from what has been said already.

Paul
 
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Dinger

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You never said why you think you need "more CFM at idle", or how much more. Whether or not you get it from an e-fan depends entirely on what size e-fan you use. But the e-fan won't change CFM as the temperature increases, or the engine RPM increases, or the temperature DROPS... It'll always be the same, whenever the fan is on. So if you need more CFM at high RPM than you get at idle, you won't get it from that fan. And if the fan stays on after the engine temp falls, the engine will be running TOO cool for proper operation (fuel evaporation & PCV).

If the e-fan moves as much or more air than the mech. fan did, and you understand that the e-fan motor is LESS-efficient at converting engine torque to fan torque, then you have to know that you'll have LESS available torque at all times. The mechanical resistance at the WP pulley (what drove the mech. fan) will move to the alternator, but it will more-than-double (probably closer to quadruple). So you'll certainly have MORE mechanical resistance on the belt with an e-fan.

Just to be clear, you contend that the alternator resistance will necessarily go up by the addition of an electric fan. Not following the logic, but this may be me just hitting the limit of my understanding. The alternator's resistance is, to my understanding, relatively constant. Even adding a larger alternator (possibly more resistance, but also possibly more efficiency and amperage) this would still be a constant. Assuming I am close to correct, and ALSO subtracting any resistance that the original mechanical fan (variable resistance based on revs, fan style, shroud, balance, etc...), I just don't understand the loss the way you do. And, more importantly for my purposes, any loss in efficiency I may have, would now be constant, not variable. Right?

To my understanding the only purpose of the radiator and fan is to cool radiator fluid. The value of this, a by-product, is a cooler running engine, but its specific function is to cool radiator fluid only (unless it is tasked with cooling other fluids too). So, I come at this problem trying to understand when the radiator is taxed the most, and has the least available cool fresh air freely available. And, to my untrained mind, idle is when our radiators are at the greatest risk of heat accumulation. To improve this inherent vulnerability (weakness) in our system, I plan to experiment with an aluminum radiator (better material for heat transfer, and higher idling cfm of fresh air. Unfortunately, don't think anyone has solved exhausted heated air off the radiator out of the engine compartment in our Broncos yet.

As to you your question about my "why". Broncos run hot, I live in Florida, I ride on the street only. So, theoretically, my engine (and compartment) should be hottest in the summer, while idling. This is the exact, and only condition I am really trying to improve radiator cooling in. Once running (usually on back roads) I am up to speed and passive ventilation, I'm betting, takes on the bulk of the radiator and engine compartment cooling task, the fan itself doing comparably little. And, my guess is, like most vehicles, Broncos are bottom feeders anyway, when it comes to engine compartment breathing. So, again if I am right, at any speed above zero my fan is doing some, but little, and diminishing as vehicle speed increases) work to cool the radiator fluid, which really is it's only task, not engine compartment cooling anyway.

Actually, I bet a few side vents behind the front wheels might create some negative pressure in the engine compartment at speed (or at the very least improve/direct hot air flow out) would do more to cool the compartment than all the fans in the world. Well, okay that was an exaggeration... Anyone experimented with passive (or active) hot air exhaust ventilation?

DirtDonk, you are spot on in your assessment of my intentions. I am not doing this because I have a problem; I am doing this because the exploration is worth the cost, time, and negligible risks to my project. And, if in the end my motor stays cool enough, it was not a loss unless of course, I sacrificed noticeable power to achieve this mediocre result.

Steve83, I hope I explained my reasoning and limited physics justification well enough to keep the conversation going. I like learning about this stufff!

Thanks again all!
 
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Steve83

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The alternator's resistance is, to my understanding, relatively constant.
That's the biggest fallacy that prevents people from understanding this issue.

Like all other energy, electrical energy is NOT FREE. The more you want, the more engine power is used. As your electrical demand drops, so does the alternator's draw from the belt. Next time you're bored, clamp a working alternator into a bench vise, wire its VR (NOT its output) up to a fully-charged 12V battery (a brick-sized one from a UPS is big enough), wrap a high-friction pull-rope around its pulley, pull it like you're starting a chainsaw, and see how long it keeps spinning when it's doing nothing (no wire on the output). Then add a jumper wire (like 12-8ga) from its output stud to its case (where it's clamped in the vise, for good contact), and try pulling the same rope the same way. It will be MUCH harder to get it up to speed, and it will stop instantly because of the higher load.
Even adding a larger alternator (possibly more resistance, but also possibly more efficiency and amperage) this would still be a constant.
Another common fallacy. The typical load on the engine will not change with a larger alternator - it will only increase when the LOAD increases above what the previous alt could put out. But during normal driving (when the load is ~50A), the load a 130A alt puts on the engine is virtually the same as the load from a 60A alt (assuming they use comparable technology & materials).
...any loss in efficiency I may have, would now be constant, not variable. Right?
Wrong. The load from the alt fluctuates with the electrical load of the vehicle. The efficiency itself (I'm guessing ~20% ) is set by the whole system's configuration; but the quantity of lost energy changes with the amount of energy passing through the inefficient system. To get 1hp to the mech fan, it takes almost exactly 1hp off the belt (from the engine). But to get 1hp to the e-fan, it would take closer to 5hp off the belt. The other 4hp are wasted in the alternator & fan motor, as heat. Pull more current through the alt (to do things previously done directly off the belt), and you'll waste more energy.
...a by-product, is a cooler running engine, but its specific function is to cool radiator fluid only...
I'm not sure what you mean, but the purpose of the cooling system is to keep the ENGINE at the correct temp (NOT the lowest temp possible).
http://www.fourdoorbronco.com/board/showthread.php?t=5230
...idle is when our radiators are at the greatest risk of heat accumulation.
No, it would be low-speed high-load, like crawling over rocks or towing up a steep, rough grade, when the engine is burning the most gas to make the most torque, but at low vehicle speed.
...don't think anyone has solved exhausted heated air off the radiator out of the engine compartment in our Broncos yet.
Again - I'm not sure I understand what you mean, but it's "solved" with the open bottom of the engine bay, where all that air is free to dump out & blow away.
Broncos run hot...
Only if there's something wrong. Otherwise, the engine doesn't know if it's in a Bronco, a Mustang, or an F150. So they should all run the same temps.
...hottest in the summer, while idling.
While producing the most torque at the lowest air- (ground-) speed. Idle or high-RPM doesn't really matter. But the concept of an engine being "idle" is that it's not doing much work, burning much gas, or (therefore) producing much waste heat. If you coast down a steep hill in-gear with your foot off the gas, the engine is idle, but the RPM might be screaming. In that situation, it wouldn't be burning much (if any) more gas than idling in Neutral, and it would be cooler (because it's moving air through the radiator faster).
...at any speed above zero my fan is doing some, but little, and diminishing as vehicle speed increases...
Right! ;D
 
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