12 volt power source?

On Mon, 24 Dec 2007 11:21:58 +1300, I said, "Pick a card, any card"


I don't have it in for you at all, Greg. I feel that there is a need for folk like you who are always wrong. Someday, you will suffer the fate of most Darwin Award winners and do yourself some real harm with all of your wacky notions.
A 12 volt battery will never be at a 13.8 volt potential. Can't happen. Not now or ever. -- Ray
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Ray Haddad wrote:

Even though I cited a manufacturer's data page on their lead acid batteries floating at up to 13.8 volts?
Yeah - well, what do the manufacturers know!?!
Regards, Greg.P.
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On Wed, 26 Dec 2007 07:34:12 +1300, I said, "Pick a card, any card"

The nominal voltage is the one you want.

Greg, do you know what that means? Clearly not. I'll try to explain. That rating means that the battery charge voltage may be floated to 13.8 volts safely for long periods of time for keeping the battery charged. It doesn't mean that the battery itself will ever maintain a potential of 13.8 volts all by itself without an external charger being applied. 12 volt lead-acid batteries under charge do not limit the voltage to 12 volts in the overall circuit when external potential is applied. That's what the "floating" voltage means.
You seem bent on dying in this ditch today, Greg. Press on. -- Ray
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Ray Haddad wrote:

So all the other factual data is meaningless and irrelevant??? I guess they had to fill the page with something?

Go read it again - they said 14.2-14.5 volts.

Well, a small change of tack here - I originally stated that a commonly used circuit for operating a model railway (1930s-60s) was a trickle charger and an automotive battery - giving 13.8 volts. <sheesh> With any electrical/electronics circuit, the _maximum_ voltage is important.

I'm on my 2nd-10th time round with every point - I've given you a manufacturer's cite, I've pointed out your mistakes and flawed thinking. I'm a practical person rather than an theoretical engineer and I know I make the occassional mistake, but you're talking a load of bollocks. The figure that counts is not the nominal voltage, the average voltage, the mean voltage, the minimum voltage, the charging voltage or the static voltage - we were discussing the _maximum_ voltage that could be seen on a model railway from a supply containing an automotive battery at the time when "12 volts DC" was set as the norm (by the NMRA) In an automotive or model railway situation the voltage at the battery terminals and the attached loads cannot be higher than the terminal voltage - the difference between generator/alternator/charger output and battery terminal voltage _MUST_ be lost in the resistance of the circuit. Voltages above 13.8 volts applied to battery terminals will result in high currents which will cause out-gassing and heating of battery plates with consequent distortion and probable destruction of the cells - but what do _I_ know.
Regards and a Merry Christmas to all!
Greg.P.
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On Wed, 26 Dec 2007 10:35:23 +1300, I said, "Pick a card, any card"

It all has its uses, Greg, but not as you believe.

Greg, that's a theoretical maximum and the 13.8 volt charge limit has become a defacto standard. This is a red herring here. The battery itself will not go over 12 volts. You clearly stated that the voltage on train power supplies was 13.8 volts because that is what a battery is. It's not. Quit trying to rearrange your own claim. It's very dishonest, Greg.

For CHARGING, Greg. For CHARGING ONLY. Not for replacement of a 12 volt battery as you originally stated.

For charging, yes. For eliminating a 12 volt battery, no. The voltage that is important is the nominal voltage.

Which you have misinterpreted.

I'm just a lowly electronics design engineer. What would I know?

What, Greg? That a 12 volt lead-acid battery will actually be a 12 volt power source? That's fact, not your brand of fiction. In your world, batteries reach any voltage you want even outside of their physical ability.

That would be 12 volts DC. Or, as pointed out by others here, a maximum of 12.6 volts in an absolutely perfect world. Never will it reach the 13.8 volts you suggested.

So, you can be educated after all. It has to be beaten in, but you can be helped.

The same back at you, Greg. -- Ray
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Greg Procter skriver:

Yes for a very short time, then it will fall down to its idle state, which is 12,6 volts.
If you charge with enough amps and 14 volts, it will hold 14 volts as well.
But I give up, think what you want - It seems that you will not liste to other people.
Klaus
--
Modelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk
Modeltog, internet, gratis spambekmpelse, elektronik og andet:
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B'ichela wrote:

Solenoids work better on AC that DC because the soft iron core can become magnetised under DC current. Depending on the coil winding direction etc the solenoid could become sluggish under DC operation.
I occassionally build batches of hand-held walk-around controllers when I have nothing better to do. Unfortunately I don't expect to have time during 2008, and you'd be better to find a source closer to home.
Regards, Greg.P. NZ.
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Ray Haddad wrote:

Ray, charge an automotive battery to maximum charge and it will hold near enough 13.8 volts, even under a light load.
Greg.P.
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On Sat, 22 Dec 2007 10:06:03 +1300, I said, "Pick a card, any card"

False. -- Ray
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"Klaus D. Mikkelsen" wrote:

Aww Klaus, just apply an expensive piece of equipment that will burn out if more than 12 volts is applied to it - it will detect the higher voltage quicker than you can say "B****R!"
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On 12/21/2007 1:04 PM Greg Procter spake thus:

Isn't that like the old thing about using a $15 transistor to protect a 25-cent fuse?
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Am I the OHMly one that doesn't have AMPle knowledge of WATT this is all about? <g>
Bill
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Bill wrote:

----------------------------------------------------------------------------------------------------------------
That Hertz!
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On Sat, 22 Dec 2007 16:48:40 -0800 (PST), Bill wrote:

Must resist temptation . . . even if it exceeds my capacity
--
Steve

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Am I the OHMly one that doesn't have AMPle knowledge of WATT this is about? <g>
Bill
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"Wolf K." wrote:

One needs 12 volts before applying the load if one needs a precisely regulated power supply!
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Ray Haddad wrote:

Gee, and all these years (50+) when I've needed to charge an automobile, I've grabbed the closest available TRAIN 'Power Supply', checked the polarity, and done the deed!!! (slow, but sure)
Chuck D.

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Charles Davis wrote:

Your train power supply is unregulated, other than the rectifier and rheostat. Even at "12 volts" the output is in pulse form reaching close to 17 volts peak. That difference (17 - 13.8v) allows charging current to flow even when full battery charge is reached. A regulated 12 volt supply would only half charge your car battery.
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On Sat, 22 Dec 2007 10:18:03 +1300, I said, "Pick a card, any card"

Correct. Or, if it's only a 12 volt supply, it will actually drain his battery. -- Ray
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Ray Haddad wrote:

From 12 volts down to 12 volts?
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