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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."
Grandparent comment: You can't (simply) transform DC voltage to a different voltage.
Parent comment: Actually transforming DC is way cheaper and more efficient than transforming AC...
You can simply transform AC voltage using the simple and low-tech electronic device called a transformer. Just a bounce of wire wound a metal core.
I assume you are referring to solid state DC-DC converters which can be (far) more efficient (less waste, less heat) than a linear power convert, but they are not simplier.
Distribution to businesses and houses will remain AC because AC is easier to distribute over long distance. High power (wattage) is easier (more efficient) to distribute (power transmission) with a high AC voltage than high voltage DC. This goes back to the famouse Edision vs. Telsa fight over DC / AC power distribution near the previous turn of the century.
It is possible to distribute low voltage AC (say 12 VAC) within a house for electronic usage. Using high efficiency power supplies (i.e.: don't waste a lot of engery producing wasted heat as a by-product of the conversion process) such as found in newer laptop power supplies would be another positive step. Otherwise I don't know if we'll see the elimimation of inefficient wall-warts.
To the submitter: Don't forget about electric applicants that are high power (e.g. 1000W or higher), in my case that includes: electric force air heating, electric stove (aka range/oven) for cooking, air conditioning, refridgerator, microwave, toaster, hair dryer, and coffee maker. These devices would not work (easily) at a lower voltage without a large increase of current. Remember or learn Ohm's Law: Power (Watts) = Voltage (Volts) times Current (Amperes).
Plus, 120V AC current, if you get shocked, hurts like a B#TCH, but just leaves your ego bruised. 120V DC current will instantly cause your heart to stop
actually that is not entirely correct. 10ma of current across your heart period will cause serious issues be it DC or AC. In fact, DC is actually safer then AC when it comes to turning yourself into a light bulb. When the power grid was first being created, DC proponents used to fry small animals to prove that AC was unsafe while DC would do no damage. Granted, a DC power grid would need a power generation station almost every 3 blocks.
As a side, don't be fooled, 110v AC can kill you dead just like 400v AC can. It's all about your bodies internal resistance mostly due to moisture and the path the power takes.
www.linux-skunkworks.com
I wired it all up and: 16 watts again.
It was exactly the same between using all the individual supplies and using the centralized PC supply. Admittedly, 16 watts isn't exactly ideal for a 90-watt supply (hmm ... maybe I'll try a smaller source supply ...) but at least I get a nice solid 5 volts going to the USB hubs.
If you get one of those Kill-A-Watt (or equivalent) meters, it's a great help in figuring out what you might want to put on a power strip and switch off manually. My stereo components when off drew a total of about 50 watts so I started switching them all off. The battery chargers in the basement used about 10 watts total, but since I was only using them to keep batteries topped-off, I could reduce it by putting them on a timer and running them an hour a day instead.
In essence, do your experiments and figure out how much you'll really save.
--- Jason Olshefsky
Karma: Poser (mostly affected by adding this line long after everyone else did)
Recently, I did my own experiments on low voltage power distribution, mainly because I plan to install a large scale solar power charger with a lot of Pb accumulators. The best result is: 24V/35kHz AC home backbone, with a lot of switching voltage changers on rooms, those provide multiplicity of output voltage of 5V, 6V, 9V, 12V DC as well as 230V/50Hz for UPSes and consumer grade devices. LED lights are quite fine with low voltage already. It will take some 6-9 years to return the costs, but only because I design and build the circuitry myself.
Unlike DC or 50/60Hz AC, 35kHz (or even more) AC requires a lot cheaper wiring, very small transformers and have very little losses.
There you are, staring at me again.