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Alternator/generator


shinrich's Avatar
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09-19-03, 09:37 AM   #1  
Alternator/generator

What is the difference between a generator and an alternator? When did they stop using generators in cars? Why do they use alternators instead of generators?

 
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bigguy05641's Avatar
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09-19-03, 09:55 AM   #2  
NOWADAYS, THEY ARE THE SAME THING, JUST CALLED DIFFERENT NAMES.
YEARS AGO, THEY USED GENERATORS, WHICH PRODUCED DC CURRENT. THEN THEY STARTED USING ALTERNATORS, WHICH PRODUCED AC CURRENT, BUT CHANGED IT TO DC CURRENT BEFORE IT LEAVES THE OUTPUT POST ANYWAY, SO THE END RESULT IS THE SAME-DC CURRENT OUTPUT.
SOMEBODY CORRECT ME IF I AM WRONG, I CAN HAPPILY ADMIT, GENERATORS WERE BEFORE MY TIME

 
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09-19-03, 11:14 AM   #3  
Joe_F
WAY before me, but you are right .

Correct, GM calls an alternator a generator, or in the past a "Delcotron".

 
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09-19-03, 06:01 PM   #4  
mike from nj
every car sold today has a generator.

it's the new politically correct name, around 2001-2002ish, when they started using similiar names across the board(every manufacturer) they renamed the alternator a generator.

now every car has a pcm, tcm, bcm, iac, egr, mic, generator, etc.
gone are the ecu, eatx, ais, alternator, etc.

it's just a different name for the same part

 
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09-19-03, 09:11 PM   #5  
Generators did generate straight DC current that is needed for an autumotive battery system. The current was carried from the armature (the rotating portion) through heavy brushes to the voltage regulator and then to the battery. The armature windings had to be made of heavy wire to carry the amount of amperage generated. They did not gererate much current at idle and they could not stand very high rpms without danger of throwing the heavy windings off the armature. They had the advantage in that they used magnets in the field windings (in the outer non rotating housing). So you could push start a car with a totaly dead battery and it will start. You cannot do this with an alternator as an alternator has no magnets and needs a small amount of current from the battery to craete a magnetic field necessary to generete current.

Alternators have the heavy current carrying wire in the non rotating housing and only need small brushes to carry enough amperage to excite the rotor. The wire on the rotor is smaller & lighter so it can with stand much higher rpms than a generator. Also they will make much more current than a generator at idle.

The next time you look at an old car with a generator you will see they have a larger pulley than what is found on an alternator, so for the same engine speed the generator turns slower than an alternator producing less current. This is particularly important in vehicles like a police car or taxi that may idle a lot. It is important in modern cars because we now have many more electrical accessories than older cars did. A weak battery can actualy run down and go dead when the car is idling if many accessories are being used as a generator at idle does not make much current.

Generators were less complicated and more trouble free. Unless the wiring had a short which was not common, the only things to go bad were the bearings and the brushes would wear out. And they did not last nearly as long as alternator brushes.

The bearings in an alternator can wear out but the brushes eventhough smaller last much longer. But to be able to change the alternating current (AC) an alternator creates into direct current (DC) it uses a rectifier and a set of diodes.

Generators had seprate voltage regulators as did early alternators. But alternators now use internal regulators. I believe they are called current regulators instead of voltage regulators. My memory has faded a little on this.

There will be a test tomorrow.

 
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09-20-03, 07:10 AM   #6  
darrell McCoy
Carnut: A very good detailed description.

 
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09-20-03, 07:17 AM   #7  
Joe_F
I agree, good job.

The regulator is still called a voltage regulator in Delco literature .

 
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09-20-03, 08:37 AM   #8  
Nice!

 
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09-20-03, 12:04 PM   #9  
good post

That is why I like this Fourm people like car nut make it great I learn something everytime I read the fourms.This has to be the best fourm in the world that is my 2 cents.

 
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