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...
If I am not mistaken, at low (12v) voltages, there is substantial
voltage loss in longer cable runs. Also, many DC devices operate on
other voltages, like 9V, 6V, 19V, 20V, etc. There is also not a
universal DC power outlet, unless you think of the car lighter type
plug, but I've seen other outlets in airplanes, etc.
So all in all I don't think it is feasible.
Now lets see - there's my torch, my mobile 'phone, my camera, the remote
controls for our TV, VCR, HDD recorder, CD recorder, digibox....
Not sure I want those hard-wired to a central battery >-|
The only other battery operated devices I can think of are the smoke and
CO2 alarms. Not worth the effort.
feds should mandate a wall wort standard, the wide variety of them
clogging the landfills is very wasteful. all wall wart devices could
be designed to accept a standard voltage.,....... same for a cell
phone charger standard to cut down on trash
That is the way I have been thinking. The green people call all these
wall warts "vampires". These days they are getting standardized to 5v,
simply to have USB port compatibility. I am thinking the same way as
the OP about some DC distribution but it is wall warts I want to get
rid of. I already got rid of several around my PCs by porting out
voltages from the power supply when they would work.
I think if you had 5v and 12v available, you could get rid of a lot of
That is another interesting idea!
Many "wall warts" provide DC to all these electronic gizmos. So perhaps
connect these to the DC system - do away with the "wall warts".
So the central battery would provide battery backup AND DC power to
electronic gizmos (instead of using wall warts).
This could help to solve another problem which is voltage surges. The "whole
house" DC electronic power supply in the home could be well protected from
voltage surges, thus you don't need surge protectors at every outlet where
an electronic device is plugged in.
Also these electronic gizmos would continue to work during power outages.
As to voltage drop, make the main supply 24 volts DC if necessary. That
should give you over 12 volts DC at the end of the line.
One problem whigh you might ecounter when powering devices from
one DC power supply: Ground loop. If you feed everythign with
one power supply, is is very asy to get noise problems to system
if those parts were originally designed t work with their wall warts
what provide isolated power. Then worst case would be if one equipment
would have - side grounded to case and other one + connected to case...
There are whole house surge protectors that plug to main electrical
panel. The DC power distribution system on the other hand could have
it's own surges when things are plugged in and out...
24V distributed around and locally converted to 12V or whatever needed
is a working idea. A suitable switch mode power supply circuit could do
that (and provide isolation if needed). The problem here is that you
need that small converter box near the outlet.. not much different from
small switch mode type wall wart in size. If you plan to hide those
things inside wall electrical box, then it would not be much different
than having the wall warts hidden somewhere inside the wall
(many same problems).
Tomi Engdahl (http://www.iki.fi/then /)
Take a look at my electronics web links and documents at
Indeed. Many things have proprietary wall warts anyway, with ferrite stubs
(like my turntable/RIAA preamp compo, each came with its own 16 V wall
wart;the preamp, a Cambridge Audio (www.cambridgeaudio.com) 540 PP moving
magnet preamp, 16 V with a ferrit stub, the turntable, a Pro-ject
(www.project-audio.com_ )Debut III with a physically (and probably
electrically) same 16 V wall wart, with the same male jack, but without a
ferrit stub). The only place I've seen that has a dc grid, is a 300 MW steam
power station, fossil fired with brown coal, but I have forgotten the
details, since it's been 15 years or so. It's in Kozani, west macedonia (not
the country, province of Greece). They needed it for the excitation circuits
of the main alternators. While large AC trasformers have a very high
efficiency (99% at full load) wall warts have a much lower, 50% IIRC. And if
they're DC/DC it needs more advanced technology. Not mentioning needing
probably #4 wires for the DC grid of a residence....
major in electrical engineering
When I was thinking about this, I was going to put a bank of inexpensive
(relatively) car/truck batteries in a dedicated vented area out behind my
workshop and potentially move to 24VDC rather than 12 due to the losses
involved in low-voltage DC appls over any kind of distance (initially
testing just for the workshop, and if successful wiring the house, too).
Charging / supplemental power could be via all sorts of means, of course.
The problem is that you'll either have the inefficiency of running DC-DC
convertors all over the place, or in hacking your devices to better match
them to the available power (lots of stuff does the regulation on-board
rather than in the wall-wart).
Personally I was thinking along the lines of doing it to power some of
the lighting and things like my laptop which can be easily adapted, but
it wouldn't be possible to completely switch off the AC supply at present
- but maybe one day there'll be a standard for low-voltage DC outlets and
devices will be available that'll just use them.
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