Whole house "battery" wiring/power...

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On Mon, 28 Sep 2009 08:52:38 -0700, "Bill"

Hmm, I generally use batteries for *PORTABLE* devices. The stuff that sits in one place is all AC operated. I think your idea needs work.
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His idea may need work, but I still have plenty non portable things with battery power or battery backup. Both thermostats have AA cells. My light timer and clock radio use batteries for backup. Telephone memory has 4 cells, a caller ID unit has a 9V. Some of those items have plug in adapters, some don't. I have one smoke/co detector that is battery operated, the others are had wired.
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wrote:

Most have none ;maybe an old clock radio.

Nope. None here. Both powered off the heat pumps. It doesn't take much of a battery to keep a clock going. A button cell should last the life of the clock.

See above. You bought junk.

Wired is a requirement now.
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Bill wrote:

http://www.wirelessmicrocolorcam.com/estore/popup_image.php?pIDG&osCsid e4daf8d5319ed8efaa7a77410624ea
It would be just as cost effective to put the power supplies inside the devices and make them all AC. We are already wired for that. They can still use batteries for portability or back up. I hate those frigging power boxes you get with every god damn thing you buy.
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On Mon, 28 Sep 2009 08:52:38 -0700, "Bill"

    Remember that 9 volts will loose voltage in a short run. By the time you get it trough a wire from one end of the house to another, you might be down to 7 volts and that might not work too well.

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Bill wrote:

http://www.wirelessmicrocolorcam.com/estore/popup_image.php?pIDG&osCsid e4daf8d5319ed8efaa7a77410624ea
My suggestion would be for a 48 volt DC system. Plain old telephone service uses 48 volts DC for battery and PoE, power over Ethernet is usually 48 volts DC. The wire size could be smaller than that for a lower voltage system and the 78xx type regulators are very inexpensive and come in a variety of wattage ratings for stepping down the voltages. The technology to pull it off is not exotic and can be done with all off the shelf parts. Solar and wind power could integrate quite easily with such a system.
TDD
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On Sat, 03 Oct 2009 00:22:41 -0500, The Daring Dufas

Think "transformer".

The maximum "safe" voltage. There is a reason power transmission is in the hundreds of KV. AC.

You really want to waste power, don't you?

Not everyone wants to waste ten times the power they use.
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krw wrote:

Do you have the slightest clue of what the discussion is about? It's a hypothetical discussion about a DC power distribution system for a home. I neither seek to impose a standard or ridicule the ideas of others. I do have about four decades of experience with all things electrical and electronic but sadly, I don't know everything. I wish I did.
TDD
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The Daring Dufas wrote:

I am guessing his point was that linear regulators such as the 78xx series are quite inefficient.
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George wrote:

and have a 35 volt limit on the input voltage. Even if one could handle 48 VDC at the input, a 7805 with a 1 amp load would waste 43 watts as heat just to power a 5 watt load.
--
You can\'t have a sense of humor, if you have no sense!

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Michael A. Terrell wrote:

I was thinking about the 35 volt limit and the fact that the 78xx regulators are linear regulators but for low power needs what's a power resister and a 78xx regulator going to waste? DC to DC converters are a lot cheaper than they used to be and for a heavy load like a laptop I would use something like that. A "greenish" home with things like LED lighting and thermoelectric refrigeration could be an interesting use for a 48 volt DC system in a home. An LCD TV, a surround sound system and all manner of the electronic gizmos that we can't live without these days could be adapted to a 48 volt DC system. I don't remember the part numbers but I remember a line of controllers made by Linear Technology Corporation that have input voltages that can range up to 60 volts DC and provide a constant DC output regardless of the varying DC input. There are some interesting developments with thermo- electric air conditioning and I think that a 48 volt DC power source would be great for that. For someone living off the grid, a 48 volt system could use 12-2 Romex instead of a large wire size needed for a 12 volt system to carry the increased current. I find it an interesting concept.
TDD
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On Sun, 04 Oct 2009 03:31:58 -0500, The Daring Dufas

My house has outlets all around that do not use any power at all unless I attach a device to one, and then it only uses what that device needs to operate.
Your long line, low voltage "idea" is wasteful from the get go, regardless of the regulation device you should choose. Since you are unable to grasp why it is wasteful, you are unable to handle any of the advice you get about it here, and you are ridiculed, by your own hand.
Your "idea" is an old one, and the facts were ironed out decades ago. So take your idea and use it to stuff the obviously vast empty space between your ears.
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On Sun, 04 Oct 2009 03:31:58 -0500, The Daring Dufas

The same as the ratio of the voltages. For a 5V device, you're wasting 7 times as much as you use. Most people don't consider that smart.

Could be <> smart.
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On Sat, 03 Oct 2009 16:51:51 -0500, The Daring Dufas

think so. To answer your question, yes, I can read and understand your post quite well. ...well enough to know you're clueless.

Think before posting in an electrical engineering (science) group.

You clearly haven't and don't.
The short story is that linear regulators waste tremendous power, particularly in this application (large voltage drops), making your idea worthy of ridicule.
There is a very good reason AC is used to transmit power. Thinking that your brainchild throws out a hundred years of practice is another reason it's worthy of ridicule.
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krw wrote:

Well professor, I would only use the damn things for low power applications. For any kind of load, a DC-DC converter would be the way to go. Remember, it's just a discussion about possibilities. Good grief, 78xx regulators are very inexpensive and DC-DC controllers are getting that way too. Ridicule bothers me not because as a small boy I had Irish nuns for teachers. That's also why I have no fear of terrorists. I'll take Tesla's power distribution system over Edison's any day. Darn, now I'm gonna have to go out in the back yard and try to build one of those power transmitting towers that Nikola used to play around with. Do you scream at your TV too?
TDD
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On Sun, 04 Oct 2009 03:51:51 -0500, The Daring Dufas

So you're going to add another level of wiring into homes. Real smart.

Why not stay with the AC distribution we have and use a small power supply for those things that need low power. Oh, that's what we are doing.

They're *very* wasteful too. I don't want my power bills to go up 7x.

IOW, you're simply stupid as a stone.
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In all fairness, DC-DC converters can exceed 95% efficiency, and 85% is common. They're really not too bad.
The class II transformers used to power most small stuff are down around 50%. It's one reason switchmode power supplies have become popular for those applications. A SMPS is nothing but a DC-DC converter that first rectifies the AC line to DC.
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On Sun, 04 Oct 2009 12:44:44 -0700, James Sweet

78xx <> switch mode DC-DC.
95% efficiency is a bit optimistic for the real world. 85%, perhaps. I still don't want to increase my power bill by even 10%, though it's better than 10x.
Most power supplies are more or less the same thing. That said, there is still no advantage to DC distribution and a *LOT* of disadvantages.

You still haven't identified *ONE* reason to go through this crap.
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krw wrote:

You still don't get it, it's only an exercise in what's possible. Look at all the replies on how and why this or that won't work. That's what a discussion is all about. Good grief, you've no idea what the term "thought provoking" means. You get your pointy little head tweaked and result to name calling? You point out what's wrong with an idea and that's a good thing. When I ran a crew on a project, I would deliberately tell them to do something that was wrong. After having to stop them a few times, the really smart ones caught on and challenged me. I told them that if they even had a feeling something was wrong, speak up but be prepared to explain why. A crew like that can save a company a lot of money. I once installed a Halon fire suppression system in a mission control center and the prints I was given made no sense to me. I argued with the HMFIC and was told it's on the print, DO IT. The prints had been prepared by my employer not The Core of Engineers. The cost of a mistake like that falls on those who supply the prints. When the manufacturer's rep arrived, he exclaimed, "These prints are wrong! It's a good thing you didn't go by this!". Even though I saved the company a great deal of money, it put a bug up the tailpipe of the HMFIC. Something about loss of face. Being an agent provocateur is a lot of fun, keep those ideas coming.
TDD
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On Sun, 04 Oct 2009 15:06:45 -0500, The Daring Dufas

No, Dufus, it is you who doesn't "get it". What is possible is irrelevant, if the dream is worse than what is.

Yes, all telling you that your idea is stupid.

I agree. Everyone agrees that your idea is stupid.

You have to have some thoughts before they can be provoking. Try it.

You are what you are. I've simply told you what you are. Grow up and deal with it.

Something that should be immediately obvious to anyone posting in a science/engineering group.

Ah, so you're testing us? You're not just stupid, but a stupid liar.

Do keep the really stupid ones to yourself.
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