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Whole house "battery" wiring/power...

G

George

Jan 1, 1970
0
Bill said:
How about getting rid of all those batteries in various devices in the home
and connecting the battery connections to one central battery?

That is to run separate wires when wiring a home and these would carry say
12 volts DC. There would be a central large battery and battery charger like
the type used in a computer UPS.

Then at each electronic gizmo which needs a battery, use a "battery
eliminator" along with a voltage regulator to supply it with the correct
voltage. And plug this into a nearby 12 volts DC "outlet".

This could provide battery power to smoke detectors, carbon monoxide
detectors, HVAC thermostat, security system, clocks, digital thermometers,
computer UPS, phone answering machine, etc.

Then only ONE battery to worry about...

A 9 volt battery eliminator picture...
http://www.wirelessmicrocolorcam.co...ID=47&osCsid=86e4daf8d5319ed8efaa7a77410624ea
Pretty impractical because there is a single point of failure.

You can consolidate a lot of it for a good start. For example in our
house we have an alarm panel which powers all of the smoke and CO alarms
and of course the security system.

What does a phone answering machine do?
 
G

George

Jan 1, 1970
0
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

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

James Sweet

Jan 1, 1970
0
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



And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.

You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.

Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already have.
 
J

James Sweet

Jan 1, 1970
0
Bill said:
In my case, basically for higher reliability of some electronic gizmos. Also
to have pretty much maintenance free electronic gizmos so far as battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to have the
time reset each time the power goes out. Or other models the batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I have a
wood stove and want to keep an eye on the temperatures when I am in other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It would be
nice to have just one central battery and not worry about it except once
every several years!


How about a whole house UPS? It would be much easier and more efficient.
Get an inverter designed for solar use that can synchronize with the
grid and set up a bank of deep cycle batteries.

Put lithium batteries in the smoke alarms, or get the AC/battery units.
Use rechargeable cells in everything else. Sanyo Eneloop are excellent.

For the answering machine, do what I did and modify it to use a
rechargeable battery. All it takes is a resistor added to trickle charge
the battery at a rate sufficiently low to allow continuous charging.
 
K

krw

Jan 1, 1970
0
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.
DO you have the *slightest* clue about electronics? No, I didn't
think so. To answer your question, yes, I can read and understand
your post quite well. ...well enough to know you're clueless.
I neither seek to impose
a standard or ridicule the ideas of others.

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

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.
 
T

The Daring Dufas

Jan 1, 1970
0
Michael said:
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.

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
 
T

The Daring Dufas

Jan 1, 1970
0
krw said:
DO you have the *slightest* clue about electronics? No, I didn't
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.

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
 
T

The Daring Dufas

Jan 1, 1970
0
James said:
And what would be the advantage? The 78xx series are linear regulators,
they are in effect a regulated resistor that burns up the excess voltage
in the form of heat. On top of that, they max out at 37V input at which
point a substantial heatsink is required to dissipate the heat. The end
result is FAR less efficient than even the lousy iron class II
transformers found in most wall warts and small appliances.

You could use a switchmode regulator to get decent efficiency, but once
you've gone that route, you may as well just use 120V or 240VAC since
the additional components required are trivial.

Solar and wind power can easily integrate with the existing grid, with
the additional advantage of being able to sell excess capacity back to
the utility. The cost of the special inverter is low compared to what
the panels cost, and dropping all the time. This proposed DC system is
just reinventing the wheel with something inferior to what we already have.

I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD
 
S

StickThatInYourPipeAndSmokeIt

Jan 1, 1970
0
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


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.
 
K

krw

Jan 1, 1970
0
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?

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.
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.

Could be <> smart.
 
K

krw

Jan 1, 1970
0
Well professor, I would only use the damn things for low
power applications.

So you're going to add another level of wiring into homes. Real
smart.
For any kind of load, a DC-DC converter
would be the way to go.

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.
Remember, it's just a discussion
about possibilities. Good grief, 78xx regulators are very
inexpensive and DC-DC controllers are getting that way too.

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

IOW, you're simply stupid as a stone.
 
J

James Sweet

Jan 1, 1970
0
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

You can calculate precisely what a 78xx regulator will waste if you know
the input voltage, output voltage, and the current drawn by the load. As
soon as the input voltage is double the output voltage, you are wasting
just as much power as you are using, and it gets worse as the input
voltage increases.

I don't know how you managed to associate thermoelectric cooling with
"green", because it's anything but. It has its place, but it is
extremely inefficient. Once you go above the size of say a portable
cooler big enough for a 6 pack, a standard phase change refrigeration
system is far more efficient. Look at the size of the heatsink you have
to put on the hot side of a Peltier device. The only reason they are
even used on the portable coolers is to achieve compactness and allow
the thing to heat or cool with a simple polarity switch.

Yes, all these gizmos could be adapted to use 48VDC, but like I said,
the DC-DC converter to do that is very nearly as complex as a switchmode
power supply to convert AC line voltage to whatever DC voltage is
required, and economies of scale make those far cheaper.

As myself and others have stated, there are serious flaws with this
idea, and it is a backwards approach to the problem at hand. Some
portions are viable, such as low voltage LED lighting with a central
battery, I've contemplated something of that nature too, but powering
all manner of battery operated devices from a central source is just not
practical outside of a very small niche.
 
J

James Sweet

Jan 1, 1970
0
I was thinking about it as an off the grid system. I would
imagine that a single high current DC to AC converter in the
battery room putting out standard AC power to a home would
be more practical than trying to reinvent all the appliances
and gadgetry. Tesla won the battle for the power distribution
system and I'm glad of it. There are those very high voltage
DC power transmission lines. I'm going to have to read up on
them and find out why they're using DC. It's been 20 years
since I worked on any high voltage power distribution systems.
Have you ever used a wooden hot stick? Make sure it's dry.

TDD



DC has an advantage for high power transmission lines because it
eliminates capacitive losses, which become significant at such a large
scale. Think of the wire as one plate in a giant capacitor, and remember
that a capacitor conducts AC to an extent, but appears as an open
circuit to DC. At a certain point, the losses in converting from AC to
DC and DC to AC at the ends is made up for by the reduction in losses
along the line, and the system becomes practical. Modern semiconductors
capable of handling these power levels have also increased the viability.

I remember touching the neighbor's electric fence with a damp stick when
I was a kid, I nearly peed my pants. Thankfully it did more to make me
curious about electricity than scare me away.
 
J

James Sweet

Jan 1, 1970
0
Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG



I rarely have power outages, but I do keep a deep cycle battery in a box
on a float charger and have a couple of inverters to provide power for
lighting and appliances. Combined with an automotive alternator
connected to a lawnmower engine, both salvaged, it makes a pretty good
system and the only part I paid anything for was the battery.

I got good use out of it during one extended outage we had after a
severe winter storm a few years ago. I used the big inverter during the
day to run higher power stuff, then the little 175W unit with much lower
quiescent draw so I'd have power for the bedroom lamp and cock radio
throughout the night.
 
J

James Sweet

Jan 1, 1970
0
James said:
I rarely have power outages, but I do keep a deep cycle battery in a box
on a float charger and have a couple of inverters to provide power for
lighting and appliances. Combined with an automotive alternator
connected to a lawnmower engine, both salvaged, it makes a pretty good
system and the only part I paid anything for was the battery.

I got good use out of it during one extended outage we had after a
severe winter storm a few years ago. I used the big inverter during the
day to run higher power stuff, then the little 175W unit with much lower
quiescent draw so I'd have power for the bedroom lamp and cock radio
throughout the night.


*CLOCK* radio!
 
J

James Sweet

Jan 1, 1970
0
They're *very* wasteful too. I don't want my power bills to go up 7x.

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.
 
T

The Daring Dufas

Jan 1, 1970
0
krw said:
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.

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
 
K

krw

Jan 1, 1970
0
In all fairness, DC-DC converters can exceed 95% efficiency, and 85% is
common. They're really not too bad.

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.
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.

You still haven't identified *ONE* reason to go through this crap.
 
T

The Daring Dufas

Jan 1, 1970
0
Andy said:
Many items in the home can run off of DC; some can't. The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. At 48 volts the
current draw for any AC device would be more than double. Watts =
volts times amps. If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. Standard
outlets are rated for 15A. Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). An AC
motor can not work on DC. However, many motors in the home are what
are called "universal" motors. These motors work for AC and DC. Most
power tools and small kitchen appliances use universal motors. For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. 100 years ago this country struggled
over the AC/DC concept for the electrical grid. Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank. Many of the
backup generator systems I've installed over the years have not
been designed to take care of the whole electrical load of a
home or business but to supply power to the essentials through
a transfer switch and sub-panel. The same thing can be done with
an inverter system. By the way, Tesla is more of a hero to me
than Edison. I think Edison just had a better publicity machine.

TDD
 
K

krw

Jan 1, 1970
0
You still don't get it, it's only an exercise in what's
possible.

No, Dufus, it is you who doesn't "get it". What is possible is
irrelevant, if the dream is worse than what is.
Look at all the replies on how and why this or
that won't work.

Yes, all telling you that your idea is stupid.
That's what a discussion is all about.

I agree. Everyone agrees that your idea is stupid.
Good grief, you've no idea what the term "thought provoking"
means.

You have to have some thoughts before they can be provoking. Try it.
You get your pointy little head tweaked and result
to name calling?

You are what you are. I've simply told you what you are. Grow up and
deal with it.
You point out what's wrong with an idea
and that's a good thing.

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

Ah, so you're testing us? You're not just stupid, but a stupid liar.
fun, keep those ideas coming.

Do keep the really stupid ones to yourself.
 
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