How an alternator works!

[97Silverado]

Here is a good explanation of how an alternator works:

Alternator Construction and Operation

• An alternator or A.C. generator creates voltage by rotating a magnetic field inside a looped conductor.

Alternator Components
Rotor

• A multi-pole electromagnet that is rotated by a belt & pulley.

• Usually 4 to 7 pole pairs.

Rotor Components

• Winding & Slip Rings

• Magnetic Pole Pieces

• Shaft With Iron Core

Stator

• A circular laminated iron frame that holds the looped conductor.

• An automotive alternator stator usually has three separate looped conductors.

• Each conductor has as many loops as the rotor has pole pairs.

• The current output is 3-phase (3 over-lapping A.C. currents).

Stator Winding Types

• Wye (Y) - 3 looped conductors connected in series. Higher voltage output at low speeds.

• Delta - 3 looped conductors connected in parallel. Higher current output at low speeds.

Rectifier Bridge

• A set of 6 or more diodes used to rectify the A.C. current in the stator into D.C. current before it leaves the alternator.

• The diodes are mounted in a heat sink.

The Charging System consists of two circuits: Output and Field
-Output Circuit:

• The output circuit consists of the stator windings, rectifier bridge, battery and all electrical loads.

• The stator produces current in two conductors during the same time period.

• As the rotor rotates, the stator windings that produces current change every 120 degrees. This produces 3-phase output.

• As the magnetic poles alternate past the loops they produce A.C. voltage.

• The rectifier bridge consists of positive diodes connected to (B+) and negative diodes connected to (B-) in pairs.

• The stator output goes into the bridge as A.C. and leaves as D.C.

-Field Circuit:

• The field circuit may consist of the rotor winding, slip rings & brushes, voltage regulator, indicator bulb and wiring.

• The field circuit controls the current flow through the rotor winding.

• This current is called the “excitation” current.

• Excitation current is provided by the battery before the stator begins producing current.

• The stator provides excitation current after the alternator starts producing current.

Voltage Regulator

• The voltage regulator is part of the field circuit.

• It limits alternator output voltage by controlling the strength of the rotor field.

• The regulator senses battery voltage and controls system voltage to a safe level by pulsing the rotor current.

• Long pulses result in a stronger field and higher voltage output and vice versa.

• Maximum alternator current output is limited by stator CEMF.

• Output voltage will exceed 16V if not regulated.

Field Circuit Types:
-“A”

• The regulator supplies the ground for the field circuit. The other side of the field is connected directly to battery B(+).

• Both brushes are insulated.

• “A” for after rotor!

-“B”

• The regulator supplies B(+) for the field circuit.

• One brush is insulated, the other is grounded.

• “B” for before rotor!

-Isolated

• The ignition switch supplies B(+) to the field.

• The regulator supplies the ground. Both brushes are insulated.

_________________________________
Alternator Output

• Measure current output at the alternator B(+) wire while loaded to 12V at 2000rpm.

• Should be within 10% of rated output.

• Example: Alternator rating; 120 amps Tested output should be 0.9 x 120 amps = 108 amps minimum

[redsled]

now, can you tell me how to run a pair of internally regulated's together or how to run two externally reg'd units to the same regulator? other than running one of those overwound "hot" units to get an arseload of amperage, how else can i get enough juice to power.... uh, let me add this up...

2x500 watt kc = 1000 watts, in amps (if w=a*v) = 83
4x150 watt kc = 600 watts, in amps = 50
estimated consumption of all stock lighting (dash,park,stop,turn,tail) in amps = 50
estimated consumption of aftermarket ignition in amps = 30
estimated required amperage for alternator field excitation = unknown
forget about front or rear winch

where were we... oh, yeah: so it seems i would need more than 250 amps from my alternator to be able to maintain my battery level while running all of my lights. while its pointless to have upwards of 1800 watts of lighting (including high and low beam) running at any given time, i would like to be able to run a pair of my smaller kc's at the same time as running my winch. even running my lightweight with a doubling block forces me to kill the extra lighting and bump the throttle to at least 1500 rpm. my high idle solenoid only holds it to 1100. i have actually killed the engine by loading up the big warn and having my big kc's on at the same time. i assume it sucked enough power away from the ignition to cause a coil failure, as no other problem could be found. i have since made major upgrades to the ignition and some of the wiring, but have yet to upgrade the alternator. i know that it made a big difference when i went from 4 ga batt cable on the winch to 0 ga welding cable. i upgraded the batt cables to 2 ga welding cable and put on two extra ground straps. the wiring to the alternator is still stock crap from 1975, so its begging for change, but i wanted to wait until i decided something with the alternator. that little 63 amp squeeler needs help.


...sled

[Bobby_Mac]

What year is your truck?
By your post im guessing 1975?
Does your alternator look like this?

If so you can swap in a newer casing alternator which came up to about 94 amps stock. Just put a smaller puller on it to get more amps in lower rpm's.
I put a smaller pulley on my truck and the lights don't dim as much when the bass hits

[redsled]

bass... that's funny. i don't even have a radio. it'd get covered in mud.

the victim here is my 1975 k20 suburban (454/400/203ft/6"sj/4.10/d44ls/c14l/35"bfgmt). i tried an offroad 140 amp unit on my 74 k5 and was sorely disappointed at what the manufacturer deemed weather resistant. took 8 long distance phone calls to get my money back. as for the burb, i have upgraded alot of other stuff, just not the alternator. 94 amps still won't cut it.

[DarkEternal]

I know its a bit off topic but you said you had a 500 watt KC lights? Where did you find those! I have a pair of the 150watt daylighters and thought they were the brightest they made short of HID. Please let me know where you dug those up and a little bit of info on them.

[redsled]

they look like regular kcs with a hoods and finning on the back, only these are about 9 3/4" diameter. i 'aquired' them from a salvage yard after a tornado a couple of years back. they came off a train. to be honest, i have never had them lit, i just think they look cool. i spec'd the rating off of the bulb number on the back. it is an ac assembly so i probably won't ever be able to do anything with them. and no, they aren't for sale. i use my million candle power handheld anytime i need that kind of light. that f'er gets HOT! i can only imagine the heat those big rounds would generate. every once in awhile i see a train when i am on the road at night. my deviant mind wonders what it would take to make those things work. 10 miles of daylight vision at midnight would

[DarkEternal]

Thats awsome, I need to try and find me some of those, imagine driving on a back country road at night, you could see like daytime. With the heat, they should be ok as long as your moving, know my 150 watt ones will meltthe abs plastic stone guards if i leave them on long without moving.

[Tony Denali]

Thats great except for one thing. The DC current is flowing backwards on the diagram. DC current flows from negative to positive. The schematic even proves it. Look at your Diodes. A diode is a current "check valve". The current is shown flowing through the "check"??? Needs some revision.

[TigerEyz3]

97Silverado... Great explanation!!!
redsled...I don't know if you are still looking for an alternator or not, but I just replaced mine - went from 105A to 220A. Call Dominick and tell him what you have and what you are looking for as far as output. He builds a wide output range of alts so at least one will suit your needs.

I would suggest contacting him before you purchase elsewhere. I have been very pleased with my purchase.

phone: 615-287-7991
Click here to email him

[pwm_Z71]

Originally posted by 97Silverado
Here is a good explanation of how an alternator works:

Alternator Construction and Operation

• An alternator or A.C. generator creates voltage by rotating a magnetic field inside a looped conductor.

I think an alternator creates D.C., not A.C.

[redsled]

Originally posted by pwm_Z71


I think an alternator creates D.C., not A.C.

uh, no. alternate - or. get it? rectifiers ultimately distribute a dc charge in the electrical system, but internally, its ac.

[Tony Denali]

Im betting that if you measure the output of the alternator your going to measure DC. They have a built-in rectifier. The diodes in that diagram seem to be in a wheatstone bridge type setup. But, then again, I question whoever drew that diagram's electrical knowledge seeing that the DC current is flowing backwards.

[pwm_Z71]

Originally posted by redsled


uh, no. alternate - or. get it? rectifiers ultimately distribute a dc charge in the electrical system, but internally, its ac.

Allow me to rephrase: the rotor/stator produce AC which is converted to DC by the diodes so the assembly, as a whole, produces DC

[97Silverado]

Originally posted by Tony Denali
Im betting that if you measure the output of the alternator your going to measure DC. They have a built-in rectifier. The diodes in that diagram seem to be in a wheatstone bridge type setup. But, then again, I question whoever drew that diagram's electrical knowledge seeing that the DC current is flowing backwards.

That diagram is only showing excitation current. There were actually 8 diagrams that go along with that explanation. I will see if I can get the others posted.

[Sammy004]

Can I take the alternator I have now and modify it so I get more juice from it. Say my alternator is 60amps and I wanna make it 100 or even more can I do that.

[Bobby_Mac]

It can be done. It all depends on which alternator you have and how much amps you need. Some guys with older vehicles come into my work and have lower amp alternators and we rebuild there alternators with higher amp stators and rotors.
But the parts that are readily available only go so high amprage wise.
If you have a pic of your alternator or specs on your truck i can see what you could get out of it.
It'll only get so much before you will have to go aftermarket.
I think the guys name was Dominick
Tribal vision knows him and how to get a hold of him.
He has after market alternators that can produce LOTS of output.

[Sammy004]

I have a 97 silverado Z71 I dont know what the speck are of the alternator. will this help?

[Bobby_Mac]

Ya its a start.
Sorry i should of said need stuff like engine size, transmission, Air cond or non, 1500/2500/3500.
Stuff like that.
If i showed you pictures could you identify it?
Where do you live?
I don't have the program we use at work on my home computer.
I usually just plug the info in and it tells me which u have.

[Sammy004]

Oh it a 5.7 liter V8 All options Power everything i live in BC canada
1500

[Bobby_Mac]

U live in vancouver?
I think its either a CS130 or CS130D
Can u see if you can see the fan or not?
Edit
Which of these does it look like?


Or



Or does it look like one of these?