unit91

How do you tell the difference?
Which is better? I did some reading that said alternator was the better way to go for my 68 6-cylinder. That true?

MU71L4710N

after reading below guess not.

i always thought what most people call alternators in their car was really a generator...?

and the stator in my motorcycle is more of a representation of an alternator.

JIM5.0

I hit the web and found some info; it seems like alternators would be better than generators.

But for your car, if you are trying to restore it to original, you can look up if your car was originally equipped with an alternator or generator. And from there you can search the PN's to find which alternator or generator is correct for your car.

If you want to retro-fit your car with an alternator (upgrade from a generator), you will have to put in rectifiers or some other circuitry to convert the AC into DC electricity to run your stock stuff.

The way you can tell the differences is to read the labels on the,. Otherwise, you probably would have to open the unit to see if it is an alternator or generator.

Someone more expert than me on this matter, please confirm how to visually distinguish an alternator from a simple generator.

The info on the web I found is as follows (I cannot remember who wrote this, I just read it and copied it to paste here):

"A generator works like this:

There is an armature surrounded by a set of stationary field coils, exactly like a DC motor. The field coils are powered and the regulator controls current to the fields to control the output of the generator. As the armature in the generator turns, current is induced in it's windings, which then travels through the commutator, out through the brushes, through the brush leads, and through the output stud to the battery.

There are advantages and many disadvantages to using a generator. One of the greatest advantages is that generators produced VERY clean electrical output, since it was producing pure DC. The major downside to generators is that all of the output current had to travel through the brushes and brush leads. Not only did this produce a lot of heat and friction, but when the brushes would pass over the bars in the commutator, small electrical arcs would be produced, which significantly shortened the life of the brush through erosion. To counter this, the mixture of copper and carbon in the brushes was changed to make the brush very hard, which had the unfortunate side effect of wearing out the commutator faster. Since the output current traveled through the brushes, most generators were limited to a maximum output of 50 amps.

Generators also needed a cut-out relay to disengage power to the generator when not charging. This was done so that the generator would not try to 'motor' and burn itself out when not being spun by the engine.
Alternators, on the other hand, work like this:

The field coils are not stationary in an alternator. They are wound around a large bobbin and surrounded by two interlocking 'clawfoot' iron shells (extend your fingers and mesh them together to see what I'm talking about). The coil is attached to two copper slip rings which the regulator applies power to through two copper and carbon brushes to control the charging of the alternator. The whole rotating assembly is known as a 'rotor'. When the rotor is energized, the effect produced is that the top shell becomes a magnetic 'north' and the bottom shell becomes a magnetic 'south'. In the alternator, there is a stationary set of windings wrapped around a steel core known as the 'stator'. The rotor spins inside of the stator. As the rotor spins, the alternating between north and south poles (remember the 'clawfoot' design of the rotor!) induces a current in the stator. However, the current induced is alternating current - hence the name 'alternator'. The output current from the stator then passes through a set of six to eight parralel-wired diodes - three or four positive diodes and three of four negative diodes, which polarize (or 'rectify', hence why the assembly which hold the diodes is called a 'rectifier') the AC output into distinct positives and negatives. The negative bridge of the rectifier connects directly to the alternator housing, which is of course grounded to the engine block, while the positive bridge connects to the output stud, which then goes back to the battery.

There are several advantages and disadvantages to alternators. Because of the nature of their design, alternators can produce much higher output than generators - current designs on luxury cars produce upwards of 140 amps. Since the brushes on an alternator only need to carry the current necessary to power the rotor (about 7A maximum) and the slip rings that they ride on are continuous and smooth, they last exponentially longer than generator brushes do - about 120-150,000 miles. There are some disadvantages to alternators, though. The Lundell alternator (the technical name for a clawfoot-rotor alternator) requires two watts of energy(power? my terminology is slipping) to spin it for every one watt that it produces. It is not an incredibly efficient way to produce electricity. Alternators also rely on diodes to rectify their AC output. These diodes only last so many thermal cycles and some of the newer zener ('avalanche') diodes are designed to be self-sacrificial by shunting large output spikes to ground to help save the sophisticated on-board electronics found on today's vehicles. Today's alternators also produce high output from a very small package, which means that there is not a large enough case to act as a heat sink. The high heat helps shorten the life of the diode chips significantly.

There are several new alternator designs out there - General Motors has gone to water-cooled alternators (yes, there are 5/8" hose nipples on the back of the alternator) to keep the diodes cool on the newer model 4.6L Northstar V8s. BMW has designed a combination starter/alternator which is built into the engine's flywheel. The expected switch from 12V to 36V or 42V systems, as well as single-wire multiplexed vehicle systems in the next couple of years also promises to push alternator technology ahead further. "

JIM5.0

That is correct, they are both generators. The difference is the alternator generates AC electricity and a generator can only generate DC electricity.

So the name difference is only done to tell you which kind of electricity is produced

Derf00

Alternators and generators are different.

Alternators are more reliable because their electrical output is phased. This means that the current coming from the alternator is more consistent/continous than a generator which has voltage that can be less continous.

Also a generator has to be polarized after install meaning you have to tell it if your system is a + or - grounding system.

If you need to or want to install anything aftermarket (ignition, radio, etc) you need an alternator. A generator is less reliable for this sensitive equipment.

Ps, easiest way to tell the difference is see if the Windings are rotating or if you have giant mangets rotating. Windings are alternators, magnets are generators.

unit91

Do both alternators and generators have a separate voltage regulator? My voltage regulator is attached at the front of the engine compartment, so I'm assuming I have a generator??.