12 volt power source?

Ray Haddad wrote:


NOT!!!!!
There is this little thing commonly referred to a 'Voltage Stabilization'
I.E. the "12 Volt Lead Acid Battery" serves as a 'low impedance load for the electrical system' and also a 'medium impedence source for current when the 'Alternator/ Generator' is not supplying power.
Chuck D.

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On Sun, 23 Dec 2007 16:17:51 -0500, I said, "Pick a card, any card"

Yes it is. It also provides stator winding current but never, ever will the battery be a 13.8 volt device.

See the above, Chuck. I realized I left out that important use but it is NOT for running all the accessories. When the alternator is running, the automotive voltage regulator (not to be confused with a real voltage regulator as used in electronics) isolates the battery from accessories in the car. -- Ray
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Ray Haddad skriver:

WHAT ????
Will yo then claim, that the whole eletronic circuit of the car is detached from the battery, when the car is running ?
Klaus
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On Mon, 24 Dec 2007 10:28:44 +0100, I said, "Pick a card, any card"
replied:

Not at all. Go back and read what I wrote. -- Ray
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Ray Haddad skriver:

Okay
I still read it as I understood it. Can you rephrase ?
Klaus
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On Mon, 24 Dec 2007 12:52:52 +0100, I said, "Pick a card, any card"
replied:

Sure.
When a car is started, the battery supplies voltage for turning over the engine and also to the stator coils on the alternator. It does this via the voltage regulator on a car, not to be confused with the kind of regulator we've been discussing on a DC power supply. Once the engine is running, the voltage regulator does other things.
In a car, when the alternator is supplying 13.8 volts, that is what is supplied to the lights, radio and so forth. The battery is a reserve power source, trickle charging merrily and supplying the stator voltage to the alternator. As long as the alternator is working, the battery is not being used for more than the stator windings. If the belt should break, as it has on a few occasions worldwide, the battery will power the car for a short while.
In a car, the voltage regulator keeps the current flow from the source of the highest capacity. That's another reason for the 13.8 volts of the charge circuit versus the 12 volts of a battery. As long as the charge voltage is adequate, the regulator uses that to power all the auto accessories and lights. -- Ray
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Ray Haddad skriver:

And working as the filter capacitor in a normal powersupply.

It depends. Many older cars does not have high enough output from the alternator when the engine is at idle speed.

Yes, a few hours.
Klaus
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On Mon, 24 Dec 2007 23:58:17 +0100, I said, "Pick a card, any card"
replied:

It's a different kind of regulator. It's really misnamed. Normally they're mechanical relays inside of a sealed unit with the ability to switch high currents nearly instantly. They're nothing at all like regulators in power supplies. That regulator is normally built into the alternator inside the rectifier circuitry. In modern computerized autos, they're most often solid state switches. -- Ray
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Ray Haddad wrote:

What component in a car's wiring do you imagine isolates the battery from everything downstream of the regulator???
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Ray Haddad wrote:

Nope, the 'stator' current comes from whatever is available. Witness the FACT, that once a car is started, IF the RPM of the engine is high enough, the 'Battery' may be removed --- WITHOUT killing the engine.
> As long as the alternator is

Depending on the car, hours to days.

Just where is this 'Magical Switch' circuitry or relay. there isn't anything like this available in any of the 'Voltage Regulator' circuits that I have ever worked with. Chuck D.

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Charles Davis wrote:

The "magical switch" is 4 diodes (or more) used both to rectify the alternator's output and to stop the battery-alternator-battery discharge loop. Beyond that, the battery and internal resistances are the voltage regulator. (check the voltages at different rpms without the battery in circuit ! =8^O)
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Greg Procter wrote:

snip
Most (if not all) of the automotive alternators that I've seen are 3 phase units, needing 6 diodes to convert to DC.[4 diodes would work quite well for a 2 phase unit.] The feed/ connection for the 'Stator (Field) control circuitry' being after these diodes (the same connection point as what goes to the battery), the diodes only prevent reverse current flow through the armature windings, nothing else.
Chuck D.

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On Tue, 25 Dec 2007 14:52:44 -0500, I said, "Pick a card, any card"

Without a battery, the stator is not powered.

That's a short while.

Get real. It should be in the engine compartment. Depending on the car, it may also be under the dash. -- Ray
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Ray Haddad wrote:

Spooky!!!
Your cited battery data said that batteries at 13.8 volts will drop to 13.2 volts in a short time - that's days!?!

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On Wed, 26 Dec 2007 10:16:10 +1300, I said, "Pick a card, any card"

I never cited any battery data. Also, I have never stated and never will state that a 12 volt lead-acid battery will ever reach a charge potential above 12 volts by any significant amount.
You must be thinking of someone else. -- Ray
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Ray Haddad wrote:

Right!!! And I'm just hallucinating about the engine still operating. Nice to be told that after all these years.

Yup, strictly a matter of interpretation of 'short'.

Come on now Ray, SHOULD, doesn't cut it. It's easy to say 'Should' and then blame the other person for not being able to find something. If it's there, what are we to look for, a relay?, a circuit board with diodes and other components? I'd really like to know just what this nebulous thing should be made up of.
Chuck D.

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On Tue, 25 Dec 2007 19:55:49 -0500, I said, "Pick a card, any card"

Give it a rest, mate. Go look in your shop manual. Ok? Get back to me when you can help yourself. Are you still in diapers or something? Do you need this much help eating your din-din? -- Ray
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Ray Haddad wrote:

Well gee, you can't tell me what to look for???
Why am I not surprised!!! [Because there ain't no such thing there!!!
Chuck D.
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On Tue, 25 Dec 2007 20:15:48 -0500, I said, "Pick a card, any card"

Good grief, Charles. What kind of moron asks a question like this about something I cannot possibly see? That's a bit like asking you to tell me where my barbecue is standing when you have no idea what my house looks like. I'm sure you believe in barbecues so there shouldn't be any question of fact about that.
Your voltage regulator may be in the engine compartment on your car. It may be under the dashboard. It could be part of your car computer. The fact that it exists doesn't mean that you automatically know about it, Charles. After all, do you know what an FPGA is? They exist but I doubt you could find any of the 30 or so that are more than likely scattered around your house at this very moment. -- Ray
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Ray Haddad wrote:

"Capacity", I think you are referring to Voltage. [Nothing else would make sense.

The 'Regulator" (voltage regulation circuitry of the alternator circuit.) doesn't have anything to do with 'powering accessories and lights', it is only concerned with allowing the necessary current to flow in the 'field windings' to maintain the desired 'output wattage' from the alternator. NOTHING ELSE.
The following exchange shows that you couldn't see the 'forest for the trees' (U.S. idiom) -- I.E. there is no 'Magical Switch' which is why Ray couldn't tell me where to find it.

Sorry Ray, I do know of what you speak of.

I lead a rather circumspect life, so if you exclude the many dead PCs that I have, you would be hard pressed to find more than about a dozen if that many.
Chuck D.

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