I see all this on here a lot about the 3g alternators. Can someone please tell me besides the obvious higher output of these are there any other advantages?

I see on LMC they have a 100amp one that bolt rights up no bracket, pulley or wiring issues for $100 wouldn't that serve most of our needs?

 

One advantage of a 3G alternator is that it's internally regulated. This gives a slight improvement in load regulation and transient response. Another advantage is that the 3G's internal regulator is electronic; the original regulator in these trucks was electromechanical. Note however that almost all replacement regulators today are electronic, so if your regulator is not original, there may be less of a step there.

"High output" is an ambiguous term; a high output original-style alternator can be as high as 100 amps as you found, but a 3G alternator can be rated for as high as 130 amps.

Your question about what would serve most of our needs is hard to answer, because everyone's are different. A stock 65 amp alternator can do just fine in an untouched electrical system. The main reason to go higher is when you start installing things like electric fans, plow lights, and other heavy-duty loads.

I will say that about half the threads I see on this forum that have to do with 3G alternators are when someone is having a simple charging system problem, and they're told to "screw it and get a 3G" instead of getting help actually solving the problem. The other half are legitimate situations where someone is adding more electrical demand and needs a cost-effective and reliable way to approach the problem.

 

How about the 'am meter'? As pointless its purpose will it still work with a high output alternator vs the 3g? (it has been stated that this gauge will not work once the 3g installed)

Also, the 3g reference sounds like a cell phone is being installed or something. Just saying.

 

It never "worked" anyway, and it won't "work" after the 3G swap, buy a proper gauge....


Ford Ammeter Gauges: Do They Work? | MILEPOSTS Garage (Tech Tips)

 

Good response. I like things explained. Is the volt meter the suggested replacement?

 

Thanks fmc400 great explanation

 

A voltmeter is a much more useful tool, 3G or not. An ammeter can only give relative charge information (is it charging or discharging), it doesn't tell you how close the battery is to depletion. And because the regulator under the hood monitors voltage, it only makes sense that you also use voltage as a diagnostic tool. Why an ammeter was chosen as the original gauge is beyond me. They are less common nowadays.

 

my question is where do you all find these altonators as cheap as what I read you all post? I just bought one and the F.errrrrr cost me $165 after I gave the core back. beside why go thru that work when a stock alt does just fine. I have 4 210 watt DickCpek off road lights and a tard stero. my alt does just fine. so that being said if I buy a new one I'll do the 100 amp alt in from LMC the 3G is more work & money than it's worth. just my thoughts on the subject

 

Junkyard.

This is true for stock setups.

Have you watched your system's voltage with a voltmeter at idle in gear with all of the lights on (and something like the defroster running)? It's probably not as fine as you think.

 

yeah I'd trust a junk yard alt... NOT!!!!!!!!! It's still a $100 to have one rebuilt so...... yeah I'd still buy the 100 amp from LMC or check with my local rebuilder & see if they can upgrade my internals with the 100 amp goodies and still be cheaper & easyer than useing a alt from Torass

yeah it's fine with the lights on the alt's idk 5/6 years old now at it works just fine with teh heat/defrost on with the lights on or the radio cranked up. if i run the lights & radio then it will dim the lights some.

 

Not looking for a pissing contest here but most of the parts your running are older than whats in the junkyard. To each their own but I have saved a lot of money through routine visits to pick n pull.

Specifically as it pertains to the alternator... What are the chances a car was sent to the j/y because of an alternator failure? Something like none. That means there is a a good chance you will find a good unit. It is smart to take reasonable precautions, as mentioned elsewhere in 3g threads, by getting it tested at a parts store before installing it or anything and making sure the j/y takes returns/exchanges in the event it is bad.

I can't speak to brand new units but I have had worse luck with rebuilt alternators purchased at the parts store not working than with j/y parts not working. I think this has to do with the little Vietnamese kids they force to work in the rebuild factories not knowing what the hell they are doing and the fact that you can usually find OEM parts at the junkyard which are going to be more reliable.

As I previously stated, however, to each their own.

 

I think I'll get the high output from LMC. Looks like it will save me time to do an easy change out then a rework of everything for the 3g. I think 100 amps will be enough output for my needs.

 

Instead of guessing, why don't you calculate the planned loads to figure out how many amps ya really need?

The formula is: Amps x Volts=Watts

Solve for Amps: (Watts/Volts)=Amps

Example:
Headlights (2): 110W
Offroad lights (4): 400W
Heater blower motor(1): 200W
Electric cooling fan (1): 360W
Total: 1,070 Watts

Divide by 12 Volts = about 90 Amps.... allowing 25 percent for ignition, tail lights, and a mild sound system that puts it up to about 112 Amps.... a 3G would be able to keep up with the loads under this assumption.

Of course one or more of the systems above can be switched off (except the engine cooling fan and any system unsafe to do so) to stay within the range.

Add a winch or high-powered sound system? Then an auxiliary battery and "high output" alternator is darn near mandatory... or at least a really, really, really good idea.

 

I've bought four of them on 1/2 price weekends at PYP for $12 each. I look for the newest ones then take them a block away to Autozone and have them tested for free. I've only come up with one dud which I swapped for a good one immeadiately after. After two years I'm still running the first one I used for the swap with three in reserve. Not bad for $48 I figure.

 

2x with Fordworth.

I rebuilt a bad $13 3G for $30 (brushes, regulator, bearings) only cuz I exceeded the time limit on the wrecking yard's exchange policy.

Nonetheless, I am still waaaaaaay ahead of ya.