Electricity for Dummies

[29er]

So, what's the difference between an alternator and a generator?

[Ed H]

Generator requires rpm to put out voltage that an alt can do at a fast idle. More efficient. i do not know which puts more drag on the eng.

[Mitch]

These are in our technical forums

Generator info by Tom Wesenberg
https://www.vintagefordforum.com/for...tion-repairing

Electricity 101 by Tom Wesenberg
https://www.vintagefordforum.com/for...lectricity-101

Google
http://www.differencebetween.net/obj...and-generator/

[GRutter]

Both Generators and Alternator generate electricity by moving a magnetic field through a coil of wire.
In the case of a Generator, a magnetic field is created by the field windings, and the armature (driven by motor pulley) spins inside of the field, generating an electrical output. The commutator on the armature keeps switching which armature windings are passing through the field, such that a Direct Current output is generated.
In the case of an Alternator, the armature is spinning inside the field windings, generating current. However the lack of a commutator means that the alternator is generating AC (Alternating Current) rather than DC (Direct Current) as was the case in the Generator. To convert the AC output of the alternator to DC required to charge the battery, a diode bridge is used.

[DaWizard]

Hey GRutter, WELCOME to the VFF!!

[MikeK]

Looking from another point of view the difference is authenticity.

[Tom Wesenberg]

One reason the alternator generates more electricity at engine idle is because it's spinning a lot faster due to the smaller pulley. My powerhouse will stay on 0 with the lights on and the engine idle at 500 RPM. That's fine with me. If I lived in a hot climate and added air conditioning, then you need more amps to power the fan and clutch coil. A later generator puts out 35 amps and should handle the A/C, except at idle.

As far as engine power to run each, it would be about the same for the same amps being generated.
The old rule of thumb for home generators was 2 gas engine horsepower for each 1000 watts of power.

[Mitch]

A cogged style belt works best to turn an alternator pulley. It also needs to be adjusted fairly snug which puts stress on the water pump bearing. Those James Ruppert extreme water pumps are designed to withstand those forces. I run them on my generator cars, a superior product IMO

[Mitch]

Both Generators and Alternator generate electricity by moving a magnetic field through a coil of wire.
In the case of a Generator, a magnetic field is created by the field windings, and the armature (driven by motor pulley) spins inside of the field, generating an electrical output. The commutator on the armature keeps switching which armature windings are passing through the field, such that a Direct Current output is generated.
In the case of an Alternator, the armature is spinning inside the field windings, generating current. However the lack of a commutator means that the alternator is generating AC (Alternating Current) rather than DC (Direct Current) as was the case in the Generator. To convert the AC output of the alternator to DC required to charge the battery, a diode bridge is used.

Welcome GRutter!

[plyfor]

A little off topic, but we had an electrical flareup started by a defective repro cut out that locked down. (1970's).No battery cut off switch was thought about then. The gurus at the time were suggesting bolt -on GM alternators with internal voltage regulation and to avoid moving the generator 3rd brush. After that we've not strayed from1 wire alternators on all 6 volt applications for drivers. Our current 12 volt A runs an alternator as well. In our area, we have one decades old remaining small business that rebuilds generators for the car makes we work on, with no apparent business succession plan....

[tbirdtbird]

All good info, #4 has the most concise story. The diode bridge converts the AC of the alternator to DC, which is what cars need. Another reason alternators can pack so much more juice is because the AC current produced is actually what is termed "3-phase"; this is why there are 6 diodes inside, all 3 phases need to be converted to DC. Having 3-phase (3 sine waves) over the same amount of time means when the diodes have done their converting, the DC waveform will be much flatter and smoother than if it were single phase.

https://www.allaboutcircuits.com/tex...ve-alternator/

[CM2]

Consistent voltage with the alternator yields longer bulb and component life. Instead of the cogged belt is the industrial 'B'size belt better? they tend to grip better than automotive style belts,maybe get away with less tension..

[Mitch]

Dave may know the answer to that belt question

[BILL WILLIAMSON]

Why not GOOGLE, A/C & D/C Generators????---Wikapedia offerings are generally quite reliable!
Dad Simple

[Mitch]

I did on post #3 i'm well trained
K-ssoon

[tbirdtbird]

I have found that some of the belts that are in the O'Reilly, etc, books as 5/8 are really not at all, but in fact 9/16, and they are bottoming out in the smaller alt. pulley, which does not have a deep groove. If they bottom out, then the sidewalls cannot grip, and the concept of a V-belt is lost. It took me a long time to figure this out.

I chuckle when I see so many posters all over the place state that the alt. belts have to be way tighter.
Here is what you need to make it work:
1. I totally agree you need a cogged belt since the alt. pulley is such a small diameter.
2. Go to the website of the manufacturer you want to buy from, eg Gates. Find their cogged belts. Look up a full 5/8 width belt YOURSELF and get the part number for the length you need. I have AC so I need a longer belt and my PN will not help most of you here.. Then, since I can seldom get exactly what I want anymore from O'Reilly's, I order it from Amazon, and that way I have speced out the belt myself and obtained exactly what I needed. Stop on over and you will find my belt to be not crazy tight. I was always taught that regarding the water pump, if you are just barely able to turn the fan blade by hand with the motor off, you have the correct tension. You will find that you can turn our fan blades by hand.

I have long given up on relying on counter guys at the FLAPS to properly look up my parts. I look them up on-line myself first, and then order. And in this case, the specs for the belts on-line and in the books are WRONG

CM2, "industrial 'B'size belt", I do not know what that is. Is that the green so-called fractional HP belts? Why they are termed fractional HP belts is beyond me since they are way better quality than traditional automotive fan belts

[Mitch]

Our parts cross reference has some info under MISC.
There is an industrial cog listed along with some others

https://www.vintagefordforum.com/for...ross-reference

[tbirdtbird]

Mitch, in this line should it read 'alternator' instead of 'generator'
"Consider an industrial cog belt if you have a generator as it will fit around the smaller pully better"

[Mitch]

I would think so, good catch
fixed

[BILL WILLIAMSON]

A simple answer would have SUFFICED, like: "A GENERATOR PRODUCES DIRECT CURRENT & AN ALTERNATOR PRODUCES ALTERNATING CURRENT & CONVERTS IT TO DIRECT CURRENT"----That's ALL the Man wanted to know.----Sorta' like, "I only wanted to know what time it is, NOT how your watch works"!
KDad Simple

[CM2]

Ive got a delco pulley same size its no shallower or smaller,other than diameter.Fractional horsepower refers to the capability of the industrial V belt...The industrial V belt comes in a letter designation for the width,a model a uses a Gates BX40,the 40 means total length of the belt B is the width. Industrial belts have a softer rubber compound and less fiber belts,they transmit more horsepower at less tension and will handle smaller sheaves,but they dont last as long as modern automotive belt designs.

you only need enough belt tension so the alternator doesnt slip under max load..turn all the lights on and watch the belt as it goes over the sheave..if it jiggles on both sides of the sheave its slipping on just one side its not..a little whip doesnt hurt a thing,other than maybe belt life,cheaper than water pump bearings.

[CarlG]

BX40 with an alternator
BX50 with an alternator AND A/C

[tbirdtbird]

A man armed with the back story will go further than the man who just memorizes the synopsis. The first guy will be a better trouble shooter

[CM2]

a lazy mechanic is your best mechanic,he goes right to the point.

[29er]

Well, I'm better at trouble MAKING than trouble SHOOTING!

Thanks to all you Road Scholars for all the input.To answer George W's question: Our Children IS learning! I installed an alternator and a new Rupert Extreme Duty water pump last summer. I appreciate the lesson, not only on the difference between generators and alternators, but also on the best belts to use.

When were alternators first put into cars?

Mike
All charged up in Oregun

[Tom Wesenberg]

In the teens, the alternator was tried in at least one car, but the size of the selenium rectifiers made it impractical. MoPar used alternators in 1960, so that's what I consider the first common usage of alternators. GM had them as an option on 1962 Chevrolets, but standard in 1963.

[CM2]

One of the few actual solid improvements,an alternator.I love a period specific parts,like a generator,a model a purist is right about it's amperage and function however the mechanic in the purist sees the benefits of an alternator,like modern chemicals and adhesives its just better....ugly,but better. The further I get back into A's the more I see,make a driver and make a stocker..cant do fine point...but one the way the Rouge produced them? yes...

[29er]

Gee, I didn't know it was that late (1960). Thanks for the lesson!