A Universal Power Bus?

mjpalm21 asks: "A friend of mine recently sent me this story on a new universal power technology that charges devices through your desk. This is a cool idea, but it seems complex. I have long wondered why there isn't a universal power bus (UPB) along the lines of universal serial bus (USB). UPB would work like this: You would buy a n port UPB hub for your desk, and then all of your electronic devices (cell phone, PDA, computer speakers, modem, phone, hubs etc.) would plug into the hub via a standard UPB cable. I would think that the device manufacturers would be all over this as it would reduce their product cost (no need to bundle a power brick), reduce their packaging cost (smaller box), increase customer satisfaction (I know I would be happier), and give them another device to sell (the UPB hub and all those cables)! Why hasn't this happened yet and what would prevent it from happening?"

Comments

Already invented

[nocent]

They have already invented such a device. Take a look here

You can connect your devices using these universal cables.

Voltage

[vincent99]

Different devices require different voltages.. if the device is going to have a power brick built-in to it to convert from "UPB" voltage to what they need, then your UPB is what's known as a "power strip".

It'll not happen soon

[rtaylor]

Remember back to the 80s and how clunky things seemed to be? Most of that was due to the battery. Everyone used the same batteries to help bring down costs, but then the final design was around the battery.

Since formed batteries have dropped in price significantly, they can make nice sleek designs and work the battery in rather than the other way around.

Whats this have to do with your question? If everyone could use the same power source, it would mean all devices would be required to support N Volts at N Amps (or set internal resistance accordingly). This means the addition of a step up or down DC-DC transformer to all devices, and taking a step backwards on battery design as you must accommodate the lowest common demoninator again.

However, not all is lost. There is a slim possibility you could add a layer of communications with the block and request a specific voltage from it, thus placing the logistics into the power block.

Figure out how to do that in a small package, and it may simply become the AC outlet. Quite clunky to accomodate at the moment, so specific individual bricks rather than an über brick is far cheaper, smaller, and much less prone to failure.

For now, just be glad the brick isn't an integrated part of the device.

Reasons NOT to do it

[ka9dgx]

For discussion, lets just assume that everyone agreed that 5 Volts, +/- 10% was good enough, and made it a standard, in the same manor as 110-125 VAC/60 Hz, and 220-240 VAC/50 Hz is for most of the world. It would then be feasable, with low cost, to do this.

However, things still get murky, even in a 5V standard world. You run into issues

• Over current protection of the source
• Transient protection both ways
• Accidental polarity inversion
• Ground loops
• Noise
• Devices supplying power inapropriately

The easy (cheap) way around this is to specify a standard charger that is specifically NOT interconnectable to anything else, thus resulting in the plethora of incompatible devices that frustrate you.

My choices for a standard

• 5 Volts, TTL standard power with a new connector
• 13.8 Volt lighter plug, perhaps a mini version
• Standard plug/polarity/voltage sizes for barrel connectors.
• A new 5 volt, 3 phase 10Khz standard power connector

3 Phase power is cool, too bad it doesn't make it into more homes.

--Mike--

Replying to all the sarcasm about power strips:

[uradu]

What he's asking for is a very sensible idea. Airlines have already picked up on the notion that providing a low voltage power source for laptops would be quite handy by removing the need for the power brick, and have helpfully come up with multiple standards . If you think that the idea of a standard low-voltage power source in the modern household--and especially around the computer--is so wayward, just look at the growing number of USB peripherals that are learning to make do with 500mA at 5V in order to live entirely off the USB bus.

In fact I think USB will turn out to be the motivator of a revolution in standardized low power busses, because manufacturers will get used very quickly to the ubiquitous availability of a power source for their TLL logic and stepper motors without having to worry about power supplies. This has never really been the case in the past, serial and parallel devices (almost) always requiring separate power sources.

The standard could be a lot simpler than what some are suggesting. A system could consist of an under-the-table brick that plugs into a wall outlet and contains a switching power supply, with a low-voltage power strip going up to the desktop. The connectors could be simple USB-plug-like affairs with pins for ground plus 12V and 5V, satisfying the vast majority of consumer electronics devices. The standard would specify what the maximum current draw could be at each voltage level, and device manufacturers would simply design their devices towards this standard. Almost everything around your computer except for the CRT and laser printer can run off 12V and a few amps.

Face it, the 110V power system was designed for exactly the same reasons, to provide convenient and standardized power to the devices in your household. Except that that was at a time when your average consumer electronics used tubes, ran its signals at dangerously high voltages, and also doubled as space heaters. In this growingly low-power world, 110V AC just isn't all that convenient anymore. So don't be surprised if the homes of the future will indeed sprout new wall sockets.

Here is why you haven't seen this.

[crapulent]

First of all, the manufacturer would not save any money in this scenario. People have come to expect to be able to purchase a device, and for the most part, receive everything they need for it to function. A manufacturer that left out the traditional "power brick" would be asking for customer dissatisfaction when people realize that they also need an additional accessory to power it. It's not worth it to exclude the cheap wall-wart, which probably adds $5 or less to the bottom line. This also means that the people who are interested in this idea get to pay twice: once for the built in conventional design and again for the sophisticated (and hardly inexpensive) power hub.

"Well, that may be, but wait until it's ubiquitous, then they can stop including the conventional power supply."

This is true to some degree, but there are plenty of situations where it would be inconvenient to require a power hub. Sometimes you only have one DC-powered device in an outlet or a given area. In fact, I would say the majoriry of the time this is the case. Certainly, most people could think of a situation where they have more than two wall-warts, but outside of the computer room these cases become more rare. And your whole argument is based on ubiquity, that everything would use this universal standard. I don't think that's necessarily practical. You may be tempted to imagine a range of power hubs, so that you can choose a "lite" version for just these situations. I submit that the wall-wart is exactly this, and that trying to sell as a seperate device that which has always been included (at a higher price, no doubt) is just asking for customer dissatisfaction.

"But surely, as the ueber-nerd that I am, it would eliminate a big mess?"

It would help, no doubt. But really, does it buy you that much? Every device still has a power cord. Yes, you would not have to deal with a number of smaller "power bricks", but you still have to deal with one rather large power brick. Don't expect this device to be small and slim like your network hubs. Instead envision something along the lines of a computer power supply. So you save some weight, and some volume, but in the end all that you're really getting is not worrying about how to make all those wall-warts fit onto power strips. And again, the people to whom this will be most useful (those with a number of devices) will likely already have a large number of power strips, since they're power users anyway. For the more modest installation of one or two devices it's nearly as bulky and doesn't gain you much.

There's also the issue of whether such a device is even practical to build. It would obviously have to support a number of output voltages, which complicates things a great deal. On top of that, since this is a general device, you cannot make assumptions about the relative output strengths required. On a computer power supply, you optimize the design for the 3.3V and 5V outputs since those provide a great deal more current than -12V and -5V supplies, which are mere trickles in comparison. For your "power hub" you can really make no such assumption -- remember that the point is to be able to run anything and everything from this device. And that's the real kicker, it will have to be rather beefy, since it runs everything. Things like modems may not draw much, but things like speakers certainly can. Yes, you could make these things in a range of varying output levels. But again, if you're going to have a "lightweight" version for only a couple of devices, you're better off from a marketing and price standpoint to just continue using wall-warts. So much for ubiquity...

Let's not even get started on the issues of who makes the standards, since after all, every consumer electronics manufacturer has to agree on a standard (and then follow through on it) to make this useful.

So, to summarize:

Nontrivial engineering to provide arbitrary outputs

Only really benefits a minority of "power users" (ugh! bad pun) yet requires universal acceptance

Implies industry-wide cooperation and adherance to a standard (yeah right)

Does not lower product cost (in fact it increases total cost significantly for those who adopt it)

In the best case, reduces clutter marginally

I'm sorry, it's a nice idea but I don't think it's realistic.

They make too much from the cables...

[Wee]

When I was at Qualcomm, I did some work for the guys writing the PC-to-phone connectivity software. A lot of effort went into the software. They bundled it with a data cable (or a data/power combo cable) and sold it for like 60 bucks (or something outrageous). They also let people download the software for free. See, they made a killing selling the cable. That's where the money was.

They change the connectors/pinouts on every rev of a phone for a reason, BTW. There's no way they would have gone in for a plan to adopt a standard connector. They may have done something like make a cable that has the UPB end and the proprietary phone end, however. But I doubt it.

-B