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One wire alternator upgrade in 86

RangerGoolz

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Thought I would ask before I get into this upgrade if there are any pointers specific to an 86 2.9 ? Looks like I can get rid of the voltage regulator? I am planning a stereo upgrade that includes and amp and sub and thought extra power would be a good call. Thoughts does and donts?
 


RonD

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If you have a AMP gauge instead of a Volt gauge you can still wire that in, but you need to unwrap the current Alternator wiring harness to find the Shunt that's used for AMP gauges

In 1986 the Amp meter wires in engine bay should be red/orange and yellow/green

Running 60-150amps from alternator into the dash and back out would be foolish, expensive, and dangerous, lol
So a Shunt is used, its just wires, no electronics

Electricity always travels on the path of least resistance, like water always runs downhill
A larger wire has less resistance than a smaller wire
So a Shunt takes advantage of these two things

One wire alternator does just have the ONE WIRE to battery positive
These tend to not work too well at lower RPMs, idle, which is why car makers don't use them, so heads up on that

The AMP Meter's red wire goes closest to battery on the one alternator wire, the yellow wire goes closer to alternator end of that wire
For best results these need to be about 3" to 5" apart
The larger wire from alternator to battery carries all the AMPs, but if you add the smaller wire(amp meter wires) some of the AMPs will take that path into the cab and THRU the gauge, and the amount of the AMPs shows as + or Charge on the meter
If alternator was not working then AMPs would be traveling from Battery TO Alternator, and that would show as - or Discharge on the meter

The Shunt is the area/wire between where the two AMP Meter wires are connected to it
The wire size on the Shunt can be reduced to send more AMPs thru the AMP Meter, to make it more sensitive to changes in AMPs coming from alternator, so if you are using a 6gauge wire to battery you can insert an 8gauge wire between the two AMP meter wires
Alternator-----(6gauge)----------yellow wire--(8gauge)--red wire------(6gauge)----------(FUSE)--Battery positive

This would send more AMPs thru the dash gauge

OR you can forget all the above and just install a Volt Gauge, lol, key on volt gauge
Even one of those units that plug in to the cigar lighter works just fine, make sure it has a OFF switch as these will drain the battery if left on all the time, not much but ain't 0 either


The one wire alternator uses an RPM switch inside to "turn on the alternator", an alternator would drain a battery pretty fast if left on with key off
The Voltage Regulator is the ON/OFF switch for regular alternators, that is what 1 of the "extra" wires is for, key on voltage to turn on the alternator
Car makers newer alternators are often just TWO wire now, Main larger wire and the on/off smaller wire

Be sure to FUSE the one wire at the Battery End of the wire, Mega Fuses are the easiest to wire in, match the fuse to alternators AMP rating
 
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RangerGoolz

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After looking in my engine bay I cannot find a alternator voltage regulator. All wires from the alternator seem to trace back towards the drivers side firwall and maybe I am missing it but dont see the regulator. Also RonD yes I have the AMOS gauge so thank you for the advise. This is far outside of my wheelhouse and never done an alternator upgrade like this so I am a bit nervous. I will undoubtedly have more questions. For is it ok to just install the new alternator and leave the AMPS gauge wiring alone for a later date?
 

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Look on the current alternator, if you see a 2 or 3 wire connector then it has an internal voltage regulator so is a 2G or 3G version

If your AMP gauge still works then those 2 wires would still go into the cab and there may be a 3rd wire into the cab for KEY ON 12volts, depends on who did the wiring as there is Key On 12volt wires in the engine bay as well

In newer vehicles the Key on 12v is from the Battery Light in the dash, a green wire at the alternator's 2 or 3 wire plug
 

RangerGoolz

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So by running the positive wire from the new 1-wire alternator to the starter solenoid then it eliminates the keyed on wire from the old alternator to the battery light correct?
 

RonD

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1-wire alternator wire runs to Battery Positive, via a FUSE

On an older vehicle that would be on the Starter Relay(solenoid) post that has the Battery positive cable on it already

So yes.

1-wire Alternator uses an internal RPM switch as the ON/OFF switch, so doesn't need the Key on 12v power
Once alternator reaches a pre-set minimum RPM, the internal switch closes and alternator gets "startup voltage"


Just FYI, alternators can not "create" voltage, so just spinning any alternator will NOT generate any volts, no matter how fast you spin it, lol
An alternator NEEDS the 12volts FIRST before it can start to generate voltage, once it starts generating voltage THEN it no longer needs outside voltage, it can make its own until it stops spinning, then it would need "startup" voltage again

The 1-wire from Battery positive provides the Startup voltage in this setup but ONLY after the RPM switch closes
If there was no switch then alternator would just sit there key off and drain the battery "trying to generate voltage", lol
 
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That the "difference" between an alternator and a generator?
 

RonD

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The word "Generator" is generic term for a device that generates electricity by spinning it with mechanical energy
So alternators and generators are both technically "generators"

An alternator can only "generate" alternating current(AC) and that is converted to DC Volts via diodes for vehicle use
An alternator sends, say 8volts DC, to the spinning rotor which creates a magnetic field around the rotor, and that 8vDC field generates about 13volts DC in the 3 Field Coils in the outside case of the alternator, more voltage out than in from the mechanical energy spinning the rotor
The voltage regular adjusts the "8vDC" in the rotor to increase or decrease the OUTPUT voltage
So alternator's power is generated from the outside case, the 3 fields

A generator usually only generates DC volts but it can generate AC as well
The generator has permanent magnets in its outside case, and they of course have a magnetic field
As the rotor spins inside these magnetic fields the rotor generates the DC voltage out
So its the opposite of an alternator

Alternators are more efficient because a generators max current/voltage output can only be increased by increasing the size of its rotor's windings, the part that spins, and the bigger and heavier it gets means it takes more mechanical power to spin it
Alternators rotor is much lighter, so less power is required to spin it

Generators also have a narrower RPM band that can be used, and a higher minimum RPM

Alternators are best for vehicles
 

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I did a Tuff Stuff on my 88 only complaint is didn’t get the “clocking” right when I ordered it. (Orientation of the positive post) super simple install just modified a SBC upper bracket and done. Quite a few pics of process on my build thread.
 

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Can I expect to have brighter interior light after the alternator upgrade? They all have been very dim since ive had the truck.
 

RangerGoolz

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One other thing before I get into this tomorrow; can I leave the old wiring from the original alternator in the truck?
 

RonD

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No, on the brighter lights

You can test your current battery volts, key off and then engine running
Key off, a good battery will show 12.3v to 12.8volt
Engine running a good alternator will show 13.5v to 14.5volt

Dimming lights at idle means a field in the alternator is bad
Vehicle bulbs, like home light bulbs, can be be found in different wattage, LED bulbs can also be used
Dome light covers can cause dim light as they age, the plastic gets "foggy"

You can leave in old alternator wires, just MAKE SURE they are taped up and can't short to metal
 

RangerGoolz

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Thanks RonD I really appreciate the guidance. Last question, where should I be looking for the appropriate ground in the engine bay for new alternator?
 

RonD

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Alternator is already grounded via its metal case and the bolts that hold it to the bracket, as long as those are clean, bare metal, then its grounded via the engine ground, larger negative battery cable

And if start motor works, then engine ground is OK
Starter motors require 60-75amps instantly, which is why the main battery cables are so large, that's just for the starter motor
Running vehicles use less than 40amps most of the time if ALL the electrics are on, i.e. heater fan on high and headlights on
That why the Alternators "B+" wire(main wire) doesn't need to be as large as the main battery cables, even if alternator is rated at 100+ amps




Voltage FYI
DC Voltage must travel in a "circle", a circuit
If a device need 5amps then the positive wire must pass 5amps and the negative wire must also pass that same 5 amps to complete the circle/circuit

If the negative wire can only pass 2amps then only 2 amps can "pass thru" the device you want to power, so it won't "power up"
That's when wire size matters, also corrosion on connections, dirty connector lowers that connections ability to pass amps

I.e. a poor battery terminal connection will cause the "click, click, click" when you try to activate the starter motor
That's because not enough amps can pass thru the Circle/Circuit, doesn't matter which battery terminal has the bad connection
And if you were to use a Volt meter to test it, it would show 12volts because its not "disconnected" its just a poor connection and the Volt Meter needs maybe 0.01amp but the starter needs 60amps, so "click, click, click"

Electrons are what power electrical devices, and the electrons actually flow from Negative to Positive
When electricity was first being studied the "positive" was thought to be the source of the electron flow so was named "positive", lol, but they were wrong, and it really doesn't matter just one of those things that pops up now and then


AC voltage works by alternating the flow of the electrons thru the device being powered
Still needs 2 wires but each wire switches(alternates) from positive to negative at the opposite time the other wire does
So the electrons "wiggle" back and forth as the polarity changes, powering the device
So AC still needs a "circuit", 2 wires, but its not a "circle" its a Hula, a "shake your booty" power source, lol

AC power is better for higher voltage and long distances since you are not "moving" the electrons from point A to point B, you are just "wiggling" them

DC is better in lower voltage, short distance application
 
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RangerGoolz

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Alternator went in without a hitch. I made a small extension to the original bracket in order to get the clocking right and the belt right. I thought I might have had it too tight at first and loosened it a bit only to hear loud squealing on start up so I tightened back up a bit. .5" in play maybe tad less. just want to say thank you for the help. Such an easy upgrade. next is fuel injectors. I have 6 new ones that badly need to go in. Maybe I should start a new thread or search for an existing one.
 

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