h a l f b a k e r y
This is what happens when one confuses "random" with "profound."

meta:

account: browse anonymously, or get an account and write.

 user: pass:
register,

# External Power Supply Standard

Free the Juice!
 (+2, -1) [vote for, against]

Consider the process of supplying power to the average computer. Mains voltage goes into a UPS where it is converted to 12V, then converted back to mains voltage before being converted to 12V, 5V, and 3.3V. Doesn't that seem like a total waste of at least one step? (Granted, that's a bit of a simplification of how most UPSes work, but it's close enough for most purposes.)

There's really no good reason for power supplies to be inside the computer case anymore. The UPS already converts mains voltage to 12V, so at the very least that output should simply be fed into the computer case, where it is converted to whatever voltages are necessary. The problem is quite simple technically, but the trouble is getting everyone to agree on a standard. So I'm proposing one.

Both computers and (external) power supplies would have a "power class" rating from 1 to 3:

Class 1 computers would accept mains voltage, and class 1 power supplies would basically be, well, an outlet. A standard UPS that supplies mains voltage would also be a class 1 power supply (but with battery backup). Class 1 is pretty much the way things are now.

Class 2 computers would accept 12V, and convert it internally to any other required voltages. Class 2 power supplies would supply 12V. Optionally, class 2 connectors can support (but are not required to have) a data connection such as USB, for communicating information such as battery status, power draw, temperature, and so forth. Class 2 would really be a transitional class, so that existing UPS and computer designs could be tweaked to simply eliminate a single step on each side. The key thing is that to meet the class 2 standard, any given device would have to use a standardized connector.

Class 3 computers would accept a connector that carries 12V, 5V, and 3.3V, along with a mandatory data connection. Class 3 power supplies would similarly provide these voltages plus the data line. The data connection would be required to be able to talk to multiple systems at once, as under the standard one power supply could be used to power multiple computers. Additionally, class 3 computers could be able to (but are not required to) accept multiple power supplies, for redundancy or load distribution purposes. Again, to meet the standard a standardized connector would have to be used on all equipment.

The various power classes would not be compatible with each other in any way, but any device could be certified for multiple power classes. For example, a UPS that provided both mains voltage and 12V with a data connection would be certified as power class 1/2. As long as the power supply and computer have at least one matching power class, you can be certain that they will work with each other.

 — ytk, Feb 14 2011

DC PC PSUs http://www.powerstream.com/DC-PC-48V.htm
[Wrongfellow, Feb 14 2011]

What counts as a ‘computer’? A desktop terminal? A slimline laptop? A solid state tablet? A smartphone? The embedded chip in your washing machine?
 — pocmloc, Feb 14 2011

I'm really using "computer" here to refer to the power supply found inside the computer case. I'm using that convention to avoid confusion between the external power supply or UPS and the internal power supply similar to what is almost universally found on desktop computers. So to answer your question, anything that has a power supply COULD technically be classified under this system, but it's not really useful for power systems that wouldn't normally make use of an external UPS, such as laptops, phones, or anything else with an internal battery. It would probably only be used for desktop computers, servers, and so on.
 — ytk, Feb 14 2011

You can get PC power supplies that run off various DC inputs, including 12V (link).
 — Wrongfellow, Feb 14 2011

 The point isn't simply to get a power supply that can take DC voltages, but rather to eliminate the redundant conversion of AC to DC to AC to DC as is normally the case with most computers with a UPS attached. Since the UPS is already converting mains voltage to 12V anyway, why not let it power the computer directly? Power supplies could be made significantly cheaper due to fewer parts, and peak power ratings could be increased for the same equipment because the battery would be available as a fallback in case the power supply output rating is temporarily exceeded.

[bigsleep], I'm not sure what you mean. It states in the description that in order to meet the standard, all equipment would need to use a standardized connector for a given power class.
 — ytk, Feb 14 2011

 I haven't changed the description since I wrote it. I hardly blame you for not noticing it though—it's my own fault for making the description so verbose. Truth be told, my eyes always glaze over a bit when I read some of the lengthier descriptions on here.

The answer is I probably should quit Halfbaking at 3AM, but when inspiration strikes...
 — ytk, Feb 14 2011

 //The point isn't simply to get a power supply that can take DC voltages, but rather to eliminate the redundant conversion of AC to DC to AC to DC//

 Well, that's exactly why people make power supplies that can take DC.

 The power circuitry for a phone exchange goes roughly

mains in ----> BIG HONKING SCARY BATTERY ----> PCs and stuff
 — Wrongfellow, Feb 15 2011

 So where exactly is the standard for "BIG HONKING SCARY BATTERY" specified? I have no doubt that it can be (and is already) done. That's what I meant by //The problem is quite simple technically, but the trouble is getting everyone to agree on a standard. So I'm proposing one.//

There are tens—perhaps hundreds—of millions of desktop computers and servers out there attached to UPSes that are undergoing the wasteful and ridiculous process of converting AC to DC only to convert it back to AC then back to DC. What's needed to solve this problem is a /standard/, not a one off solution.
 — ytk, Feb 15 2011

So desktop PC's with built-in laptop-battery PSU's... as a bonus your laptop battery gets charged up.
 — FlyingToaster, Feb 15 2011

 [annotate]

back: main index