Electricity Generated

[Rick]

@JFLuvly

And so the next component we find in our charging system is the rectifier which does this job of turning alternating current into direct current. While Yamaha does not describe the restifier in detail, it probably performs in fucntion by simply discarding that half of the alternating current which flows in the wrong direction. The rectifier has six diodes which allow current to flow through them one way, and only the one-half of the alternating current which is going the right way gets through.

Now that we have our direct current, we need to understand that the faster magnetic fields expand and contract through the coils of wire, the more current we get. So as our engine speeds up the electrical power available to us increases. But our battery and electrical components don’t need all this current and voltage all the time, and so a circuit comes into play called the regulator. ** In Viragos, this circuit and its components reside in the same “box” as the rectifier.** It’s main purpose is to keep the battery from overcharging.

The regulator senses voltage and when it sees that the electrical system is getting enough direct current to run all the needed loads (ignition, lights, electric jock strap, etc.) and has enough left over to keep the battery charged, the regulator dumps the excess current (actually alternating current, before it is “rectified”) to ground. In this way the unneeded current is dissipated and never enters the motorcycle’s electrical system to overcharge the battery.

This is an example of what I am talking about.

Well since the first paragraph is factually incorrect, I see no reason to believe the third paragraph is correct. Who ever wrote this does not know how an alternator works. Note the use of the word probably to describe how the diode bridge works.

ETA: Hint: google diode bridge and full wave rectification.

[JFLuvly]

Exactly what is it that is incorrect?

[JFLuvly]

Here is the wiring diagram for a Virago. Look in the top right section.

http://wsamel.fortunecity.com/virago-starter-wiring.jpg

[Kevbo]

JFLuvly is correct in the discription of some motorcycle/scooter charging systems. I’ve also seen similar on outboard boat motors and snomobile engines.

Permanent magnet alternator single or three phase. Rectifier. Series or shunt regulator.

Such systems tend to have short battery life and poor reliability. They have the advantage of being cheap initially, but repair parts are often expensive.

Since the 1960s or so, all automobiles have gone to alternator systems regulated by manipulating the (rotating) field current. I have one modern automotive alternator that uses brushless rotor excitation. It is a large unit rated at 215 amps and intended for use in ambulances.

[Uncommon_Sense]

@Rick

@friedo

So does that mean the chassis is basically connected to a wire somewhere that goes to one of the terminals on the battery? (Or one end of the alternator?)

Yup. go out to your car and find the negative battery cable. follow that cable it will either be bolted to the chassis, and there will be a (heavy) wire connecting the chassis to the engine, or it will connect from the battery to the engine, with the wire going to the chassis, or in some cases it will split and go to both the engine and the chassis.
This is done as a wire saving measure. If you did not use the chassis and body as a ground it would take twice as much wire to wire the car.

And this is why working on boat trailer lights and older cars (with rust and corrosion) can be an absolute nightmare. One of the umpteen ground connections to the rusted chassis is shot. Find it.

[Rick]

@JFLuvly

Exactly what is it that is incorrect?

it probably performs in fucntion by simply discarding that half of the alternating current which flows in the wrong direction. The rectifier has six diodes which allow current to flow through them one way, and only the one-half of the alternating current which is going the right way gets through.

This is 100% incorrect. Using a diode bridge with 6 diodes half the voltage is not discarded. the guy does not understand how electricity and diodes work.
Like I said, Google diode bridge and full wave rectification.
My old starting and charging manuals had some great illustrations on how full wave rectification works, but they are not on line.

[Rick]

Here this should explain it (Chrysler training video)

[JFLuvly]

This is 100% incorrect. Using a diode bridge with 6 diodes half the voltage is not discarded. the guy does not understand how electricity and diodes work.
Like I said, Google diode bridge and full wave rectification.
My old starting and charging manuals had some great illustrations on how full wave rectification works, but they are not on line.

Three-phase full-wave bridge rectifier circuit.

Each three-phase line connects between a pair of diodes: one to route power to the positive (+) side of the load, and the other to route power to the negative (-) side of the load.

From here

Rectifier Circuits | Diodes and Rectifiers | Electronics Textbook

Explain where the negative side of the load is. I think it would be ground, therefore directing the bottom half of the sine wave (-) to ground.

[JFLuvly]

@ rick …smartass…lol I actually watched half of it waiting for the rectifier, lol

[AndrewL]

@JFLuvly

Explain where the negative side of the load is. I think it would be ground, therefore directing the bottom half of the sine wave (-) to ground.

You still don’t understand how rectifiers, and electricity in general, work. Ironically the page you link to actually explains how half-wave and full-wave rectifiers work pretty well. Half-wave rectifiers (which would be a three-diode rectifier for a three-phase AC source) allow current to flow half the time, when the AC voltage is in the positive half of the cycle, and block current the other half of the time, when the AC voltage is in the negative half of the cycle. Full-wave rectifiers, such as the six-diode rectifier on that page, allow current to flow all the time, with the diodes acting to reverse the voltage when the AC source is in the negative half of the cycle. Nothing gets discarded or ‘directed to ground’ as such, the diodes are just acting as one-way gates of current flow to make sure the voltage being applied to the load is always of the right polarity.

[JFLuvly]

Kevbo

JFLuvly is correct in the discription of some motorcycle/scooter charging systems. I’ve also seen similar on outboard boat motors and snomobile engines.

Permanent magnet alternator single or three phase. Rectifier. Series or shunt regulator.

Such systems tend to have short battery life and poor reliability. They have the advantage of being cheap initially, but repair parts are often expensive.

So you are saying that this does not exist?

[JFLuvly]

There are two types of Alternator:

(1) The constant magnet. Here a magnet turns inside a set of charging coils. The output is rpm related, up to a max. When the output is more than what is “used” and the battery can “consume”, the rest is shorted (to “earth” -the frame). A total waste of energy, but cheap to build. That is what the F650 has.

(2) The other alternator type has an electro magnet turning inside the charging coils. Here the charge is controlled by the “power” applied to the magnets. That is what all cars and some other bikes have. (All BMW boxers have this type)

From here

http://faq.f650.com/FAQs/VoltageRectifierFAQ.htm#So%20What%20(Simply%20Explained)%20does%20The%20Voltage%20Rectifier%20do

This is for BMW motorcycles. I don’t think I have argued that you guys are completely wrong, but I know how this system works, and I am saying that I had just assumed that all alternators work the same way. Like I said earlier when we load tested an alternator and it failed we just replaced it. I know a few years ago you could buy a GM rebuild kit, but we rarely bothered. In my youth I worked in a garage that repaired a fleet of taxis and I have been down this road before, the technical details were not important when you are in a hurry. My understanding of electricity is a lot better than you guys think, I’ve got fancy papers to prove it, lol…

[Diver]

@JFLuvly

That is what’s known as ‘sarcasm’.

SNIP

Maybe I am wrong with the new cars but I know how this works without question and have always assumed that the cars were the same way.

There is no excess current/voltage sent to ground. The voltage regulator varies the current into the rotor coil as needed to control the output. Less current required = less current produced. It’s been that way since they started putting alternators on cars.

[JFLuvly]

Did you read the above post? Maybe Yamaha and BMW have it wrong. I have provided the cites to back up what I have said and you guys are still arguing with me. WTF? Even Kevbo agreed with me saying that he has also seen this system ( Thank You by the way ). All I am saying at this point is that this is an alternative configuration, believe what you want.

[Balthisar]

No, he’s right. There is a such a thing as a “shunt regulator.” Apparently they’re used for when no one cares about the excess current going right to ground, and usually for very low current applications. A motorcycle electrical system doesn’t seem particularly “low current” to me, though. The only possible reason I could ever imagine seeing something like this used is due to cost, but he’s talking about pricey bikes.

[JFLuvly]

These are pretty common on a lot of motorcycles.

[Diver]

The OP asked about cars and my answer is correct for cars.

[Kevbo]

@JFLuvly

[

So you are saying that this does not exist?

Which part of "JFLuvly is correct " was not clear?

[JFLuvly]

Sorry for not being clear Kevbo, that was directed at AndrewL’s post. When I replied I did not realize that his post would be the last one for the first page.

Once again I appreciate the lifeline you threw me, Thanks!