# 12 volt power source?

• posted
On 12/21/2007 4:15 PM Ray Haddad spake thus:
They're *all* unregulated, contrary to your observation about how "more than half of those are only partly regulated". No regulation at all.
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Man have you asked the wrong group hehehe...
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Perhaps Australian batteries have a lower voltage than the rest of the world.
BTW - I started in electronics at much the same time you did, built mr controllers in the 1960s, first computer from Electronics Australia 1978/9, electric cars mid 1970s ...
Regards, Greg.P.
• posted
From 12 volts down to 12 volts?
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You'd prefer Wikipedia over the manufacturer's data? 13.8 volts is the level an automotive battery will charge to. 13.2 volts is the voltage it will "quickly" drop to. 12.6 volts is the voltage it will eventually settle to.
The definition of "quickly" and "eventually" will depend upon the age, sulfation and acid percentage, but one could carry the new fully charged battery home from the garage, have tea and then connect it to the layout and still find a voltage between 13.8 and 13.2 volts. The following week, without use it will be at 12.6 volts. If one were to place a 12v car battery between a low amp battery charger and one's rheostat controller, a setup as has often been used in the past, there would be 13.8 volts on the track.
13.8 volts is the _maximum_ but it is the maximum working voltage of an automotive battery.
Regards, Greg.P.
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I've used computers and PCs for layout operation for years.
• posted
On Fri, 21 Dec 2007 16:28:07 -0800, I said, "Pick a card, any card" and David Nebenzahl instead replied:
Then you're wrong. They are mostly regulated. If they aren't, you aren't opening the right ones. -- Ray
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On Sat, 22 Dec 2007 14:36:46 +1300, I said, "Pick a card, any card" and Greg Procter instead replied:
Lead-acid batteries are 2 volts per cell. World wide. Go measure yours again without the car running.
Definitely not the same as I did, Greg. If so, you'd know about lead-acid batteries, chargers and power supplies. -- Ray
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On Sat, 22 Dec 2007 14:38:11 +1300, I said, "Pick a card, any card" and Greg Procter instead replied:
Lead-acid batteries require a minimum of 10% over nominal. That's why 13.8 volts is used to charge a 12 volt lead-acid battery. Applying any less will cause a drain after a very short time. When a battery goes way down, say to 10 volts or so from use, a 12 volt power supply will work up to a point and then become a drain on the battery. At 10% over battery rating, that's 12.0 volts plus 1.2 volts or a minimum of 13.2 volts to sustain a charge and then a trickle. Obviously, 13.8 volts fits that requirement. A unique thing about a lead-acid cell is that you really can't overcharge it unless you are dumb enough to use a constant current charger. The battery presents a smaller and smaller load to the charger as it gets more fully charged. Nature of the beast. -- Ray
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On Sat, 22 Dec 2007 00:42:35 GMT, I said, "Pick a card, any card" and Big Rich Soprano instead replied:
Clear your mind. That was easy. No thoughts. -- Ray
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well, I just measured 4 Australian batteries with 3 different meters, and all measurements were at least 12.5 volts - which is as I would expect from the basic electrochemistry of lead-acid cells.
Tell me, Ray, what do YOU think the exact potential is across a standard individual lead-acid cell? Are you trying to tell us it is exactly 2.00 volts?
You might like to look at some actual data at
you probably wouldn't like to, because it would show you the facts.
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On 12/21/2007 7:03 PM Ray Haddad spake thus:
And how do you know that? Have you cracked any open yourself?
I mean, I've opened literally *dozens* of the little buggers, and never saw a single regulator--78xx or anything similar--in any of them.
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On Fri, 21 Dec 2007 20:20:39 -0800, I said, "Pick a card, any card" and David Nebenzahl instead replied:
And you think that's the only kind of regulator out there? Oh, dear. -- Ray
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On Sat, 22 Dec 2007 15:11:22 +1100, I said, "Pick a card, any card" and Eddie Oliver instead replied:
Yes? And?
I'm not going to quibble over a half volt. I'll leave that to the rivet counters out there. The battery is still a 12 volt battery not a 13.8 volt battery. That's close enough. If you want to continue this, go right ahead.
I'm right. You're right. So what? The point is already lost. There is no such thing as a 13.8 volt lead-acid battery. The difference of half volt variance is silly to argue over. But do press on if it amuses you. Greg will be along to huff and puff and pretend he never stated his batteries were all 13.8 volts. -- Ray
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"_All_" is irrelevant! Where electronics (or Tortoises running too fast) are concerned, the _maximum_ voltage likely to be met is the relevant figure.
I know you have to disprove everything I say, Ray, but this is getting well out of hand.
Regards, Greg.P.
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On 12/21/2007 8:52 PM Ray Haddad spake thus:
No, they can also be made of discrete (i.e., non-IC) components (like transistors). But there has to be *something* there besides a transformer, rectifier and filter capacitors. So what kind of regulators do you think is in those wall warts, eh, Ray?
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Greg Procter skriver:
Wouod yo be so kind to ponit me to a data sheet showing tha at lead-acid battey has a nominal voltage of 13,8 volt at full charge.
Klaus
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On Fri, 21 Dec 2007 22:03:46 -0800, I said, "Pick a card, any card" and David Nebenzahl instead replied:
Even a zener diode is a regulator. Play puffery all you want, David. I do know what I am discussing here while you are just guessing after opening a few wall cubes. Enjoy the game. -- Ray
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On Sat, 22 Dec 2007 18:10:00 +1300, I said, "Pick a card, any card" and Greg Procter instead replied:
None of them are, Greg.
Not everything. Just the wrong stuff. Oh. Wait. -- Ray
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On Sat, 22 Dec 2007 08:20:27 +0100, I said, "Pick a card, any card" and "Klaus D. Mikkelsen" instead replied:
I wasn't going to push him for a reference, Klaus. Cornered beasts can be deadly. As long as he doesn't have to prove anything, he's harmless. -- Ray

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