Universal power to the people

COMPUTER EVOLUTION has taken some odd turns over the past three decades, like the fact that notebooks were for years sold with infra-red ports with nothing to talk to because few desktop PCs were IR-enabled. Perhaps the oddest of all is the fact that so little attention has been paid to power supplies for portable devices that we still have to carry round a ridiculous array of adapters.

We take Plug and Play for granted with any other peripheral. Plug a printer or scanner into a PC and the devices will exchange configuration details and (usually) set themselves up to work together. There is no technical reason why power supplies should not work the same way, simply delivering the voltage and current a device asks for.

It could have been done back in 1995, when Microsoft brought Plug and Play to PCs with Windows 95. If the industry had got its act together then, we could now have smart power supplies in hotel rooms, Internet cafes, trains, aeroplanes and homes. Goodbye power adapter.

As it happened the industry could not even agree on something so basic as what power connector to use.

Two standard DC power supplies have since emerged almost as afterthoughts, piggy-backing on data links. Power-over-Ethernet (PoE), as defined by the 2003 IEEE 802.3af standard, delivers up to 15.4 Watts at about 48V over the same cable that carries network data traffic. This is too little for all but the most frugal of notebooks. The latest PoE standard, 802.3at, boosts the supply to a maximum 25.5 Watts, though the power actually delivered is generally below that because of line losses.

PoE can be retrofitted to existing networks without recabling but this is not always straightforward because of thermal problems. So it seems unlikely to become common enough to be taken for granted as a universal DC supply.

More familiar is the humble USB port, which can deliver power as well as data. USB 2.0 can provide a maximum 500 milliamps per port at 5V, which is fine for a lot of small devices. Some draw more by using two ports. Emerging USB 3.0 can deliver up to 900ma.

USB power is enough to charge a phone but is not available to all mobile users. However USB connectors are used in a standard adapter shown above, called the Universal Charging Solution (UCS), adopted by a consortium of major mobile-phone companies in 2009 when the industry finally got around to addressing the issue. The energy-efficient design, scheduled to be used on most mobile phones by 2012, can deliver up to 1.5 Amps at 5V.

This still means mobile workers are likely to carry around at least two power adapters, one for a phone and one for a notebook.

There have been various attempts to provide a supply suitable to power any device from a mobile phone to a heavy-duty notebook. One of the most ingenious was a smart surface developed at Cambridge University that consisted of a matrix of contacts. You put a compliant device down on it in any horizontal orientation and it would sense where contact was made and configure itself for both power and data connections.

In 2004 a company called Mobilewise demonstrated a similar system powering two devices at two different voltages. Its website is no longer active.

More recently there has been a movement towards wireless power, delivered by electromagnetic induction, though as we reported recently it has been the subject of some industry infighting. A group called the Wireless Power Consortium has proposed a standard called Qi, based on technology already used in a number of products. It is used in the lurid wireless power adapter sleeves for the Iphone, pictured at left, sold in the UK by Case-Mate.

Wireless-power market-leader Powermat, which has so far refused to join the consortium, has demonstrated products powerful enough to drive a food mixer.

Wireless power does at least do away with the problem of what connector to use, but it seems a complication too far for a task that can be done by a simple plug. It is surprisingly efficient, but even if it was only marginally less so than a direct connection the global power wastage would be enormous.

The Powermat system does amount to a smart supply, in that it interrogates a device about its power requirement and then delivers it.

So does a promising design for a universal supply from a company called Greenplug, founded by Frank Paniagua, who also co-founded the Video Electronics Standards Association (VESA). It envisages a hub capable of driving a number of devices with different needs, using a USB connector modified for higher power. As its name suggests, the system also aims to be as efficient as possible.

None of these smart-power initiatives shows any signs as yet of gaining anything like the momentum needed to see it implemented routinely in new devices.

That would require backing from industry giants, who seem uninterested in the problem, which is curious when you consider how much money and effort goes into reducing battery drain on mobile devices. Battery life would be far less of an issue if smart power supplies were ubiquitous and you could top up more or less anywhere.

That is not going to happen soon. But if we can't have smart power, can we at least have manufacturers smart enough to follow the mobile industry's lead and agree on a standard adapter for notebooks? µ