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Low Voltage Power Distribution?
thesp asks: "As I look around my apartment, I am continually struck by the plethora of high-voltage AC to low-voltage DC power adapters I use to power my various devices. At a recent estimate, around 30% of the power consumed in my house is via these adapters. From my laptop to my digital music player, and from my mobile telephone to my PDA, each device is down-converting its own power through its own adapter. Double this number to include my partner's devices. Many of these run hot, and are inconvenient to remove/replug to conserve power and outlets. Does Slashdot know of any moves to standardize power delivery to such devices, or of hobby/home-brew projects to distribute low-voltage power from a central power converter? Alternatively, are there reasons as to why this would not be a simple and effective solution to the proliferation of wall-warts."
"On closer examination, these adapters seem to fall into four major categories, 7V, 5V and 3V, with the most common being 5V. Despite this, each device uses a different DC plug configuration, which makes efficient use of adapters difficult. It seems to me that, just as AC power is standardised, portable electronics power requirements should be also be standardised, with a standard wall outlet and car outlet at, say, 5V, and a standard device cable and interface. Electronics manufacturers would save money on power adapters, and the consumer would have the cost of the converter written in to home construction or automobile construction costs. No longer would we have to lug 4 separate power adapters with us on an overnight business stay to power our various equipment."
Depends on your current draw. Check out this table. Remember that by time you wire your entire house, there will be several hundred feet of wire.
There's a reason we feed houses with AC.
If you don't want crime to pay, let the government run it.
On Topic:
Just about every device needs power in the 5 to 20 volt DC range to operate. No matter if it is 25 days old, or 25 years old.
In the old days there was a transformer and an AC/DC rig to achieve this. And a big fat Power switch, to connect the transformer to the high voltage AC supply.
This used to be all built into the device - think: big old fat radio, stereo, or TV. Because it was easy and convenient, because it was a big fat apparatus anyway.
And ON really meant ON, and OFF meant OFF.
Then came Stand-by mode. OFF suddenly meant: a little bit ON.
Goodbye to the big fat Power switch. Enter the apparatus that consumes power all day long.
Then, everything started shrinking, to become portable, "personal", etc.
So now we have the i-Pod, mobile phone, MP3 player, laptop computer, Discman, PDA, GPS. "We" want to take them wherever we go, so they have to be light, Battery powered, nobody wants a big heavy transformer inside of course. Enter thousands of battery chargers. And because we are lazy, we keep the chargers plugged in, all year long.
It's a trend. Not one that I necessarily like.
Why are there no chargers that we can keep plugged in, with true mechanical ON/OFF switches?
I liked my next sig a lot better
The problem is that wires have resistance, which wastes power turning it into heat. The amount of power wasted follows this equation
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% Power loss = Power * Resistance / Voltage Squared
So, with a length of wire that has a resistance of 10 Ohm, with 120V at 1 amp (120W), you lose
%P = 120W * 10 Ohm / 120V^2
or 8.3% of the total power, about 10W.
If you were to run the same amount of power over a 5V line (120W, or 24A), you would lose
%P = 120W * 10 Ohm / 5V^2
or a whopping 48% of your power, about 58 Watts. So you see, having all those transformers is actually more efficient. This is the reason why we have high voltage lines. The power that comes into your house is 120V, but if it were to be 120V all the way from the power plant 20 miles away, most of the power would be lost. So, power is sent on high tension wire at about 200,000V, then steped down to several thousand volts on main streets, then to less than 1,000V for your side street, then finally transformed down to 120V (or 240V if you live in some countries) right before it goes to your house. This minimizes loss.
On the other hand, if you have lots of devices that all use the same voltages right next to eachother, it can be efficient to get a single transformer. Musicians (like me), who have dozens of effects pedals that run on 9V, can buy special power bricks that power up to 6 devices. You can buy these from musician's supply stores (like musiciansfriend.com). You can even make one from parts at radioshack. You have to make sure you have a beefy transformer, then wire on several plugs in parallel.
If you want more info about power line waste, there is good info at:
http://www.bsharp.org/physics/stuff/xmission