12 volt power source?

Sure Ray, stop arguing with me when I agree with you! ;-)

Greg.P.

But you haven't sent me my "Ray Haddad Gold Credit Card" yet. (or do I only get the "Lead" edition at this stage? ;-)

We all know it's only a "nominally" 12 volt device.

It's time you bought a new battery!

How precise/pedantic are we being?

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.

On 12/23/2007 12:41 PM Greg Procter spake thus:

Now, Greg, you've been following my recent battle with Ray here, so you know I'm not one of his fans. He's basically a snot, and one who will never admit he's wrong.

But the fact is that you are spectacularly wrong here, and are apparently competing with Ray for Snot of the Year.

Lead-acid batteries produce about 2 volts per cell. A 12-volt battery is as close to 12 volts as no never mind. (I measured mine and it was 12.5 volts.)

Not 13.8 volts. Time for *you* to admit you're wrong here.

On 12/23/2007 12:41 PM Greg Procter spake thus:

Greg, do us a favor: go out right now (well, assuming it's light outside) and measure your car's battery voltage. Measure a couple if you have more than one. Report your findings back here.

Perhaps you're not reading what I'm writing?

eg: A 13.8 volt battery charged to 13.8 volts will be at 13.8 volts.

and: A nominal 12 volt battery in series with an alternator/generator/trickle charger will be at 13.8 volts ... The point, winding back to the original question, is that the "12 volts DC" of model railways can be as high as 13.8 volts because ... I doubt that there are any model railway components that are designed to cope with 12 volts DC that can't cope with 13.8 volts DC.

I don't want to compete for the 'Snot of the Year' prize, but from the perspective of the above context I don't see that "admitting I'm wrong" would serve any useful purpose.

Regards, Greg.P.

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

David, read the line which I have requoted below:

"If one charges a battery to 13.8 volts it will be at 13.8 volts."

Now before you start with the ifs and buts, think about it. Yes, 24 hours later it will have dropped in voltage to something like

12.5 volts, depending on a whole list of factors; temperature, acid level, ... but it will, if charged to 13.8 volts, stand at 13.8 volts for some time. THAT is the voltage any electrical equipment attached to the battery must be able to withstand.

If you take _your_ battery from your car and power your model railway with it, the voltage available will start at 12.5 volts - not 12 volts - and slowly drop to about 10.5 volts as your train goes round and round. You should have stopped it at 10.8 volts to avoid damaging your battery.

12.5 + 10.5 / 2 = 11.5 volts. You really should get a new stick on label printed for your battery "Exide 11.5 volt battery" rather than the only correct for an instant "Exide 12 volt Battery". (or a whole series of labels with different voltages so you can strip them off one after the other to match the 'Truth in Advertising' requirements)

The safe operating range of a 12 volt car battery is 13.8 - 10.8 volts and the circuit in the car should hold it in a range close at or near to or below 13.8 volts.

It's fun arguing with Ray because he seems to have it in for me, but I'd rather real people like you kept the context in mind when getting involved.

Regards, Greg.P.

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I'm SHOCKED that this subject is still going on. It certainly exceeds my CAPICITOR to understand. Let's let the subject DIODE in peace.

Bill

Well David, you seem to be trying to follow Ray's lead here.

You didn't say what sort of vehicle you measured on, but the recent U.S. models, all have a fair amount of constantly connected electronics.* Which will rapidly drain the 13.8 V level down to 13, or 12.5 depending on the time interval since last charge cycle.

• Electric Clock -- minimal drain, Radio --- memory for station presets (the push button station selection.), and other weird and wonderful 'Bells & Whistles' that 'Marketing has convinced people they just HAVE to have.

Chuck D.

On 12/23/2007 4:16 PM Charles Davis spake thus:

Gawd, I hope not!

Hah. Mine's an '87 Toyota van, and even if it did have anything that would drain the battery it doesn't matter since I disconnect the battery as an anti-theft measure.

12 volt batteries don't get up to 13.8 volts, sorry.

hehehe... right you are!

Ah, but they do. My '87 Ford F250, while running down the road, will 'float out' at 14 or 14.5 After siting for a while 10 or 20 minutes, the 'voltmeter' reads close to 14 before the starter kicks in.

Of course that's an OEM automotive dashboard gauge. Which I wouldn't guarantee the accuracy of.

Chuck D.

On 12/23/2007 5:50 PM Charles Davis spake thus:

I'd be curious to see what a decent multimeter makes of the actual voltage of that battery. And by "sitting", you mean engine turned off, right?

The steady state voltage of a charged battery is that produced by the electrochemical activities in the individual cells, which create a stable voltage (for a given temperature). That stable voltage per cell is of the order of 2.1 volts, giving 12.6 volts for 6 cells in series - which is why one measures about 12.6V by applying a meter across the terminals without other loads.

It isn't 12 volts or 13.8 volts, it is what the laws of physics and chemistry require it to be.

However when the system is NOT steady state, a range of outcomes is observable. The wikipedia article at

some of these situations apparently fairly accurately.

Yeah, well, how do you know what it's doing when you're not looking?