A somewhat outlandish idea a few years ago, the eight-hour notebook is moving closer to reality as promising trends in battery materials and power consumption converge. If all goes well, within three to four years, portable PCs could see battery life double from today's four-hour stretch.
Chip manufacturer Intel, in fact, is so bullish on the matter that it recently moved up a deadline for notebook makers by two years. It's now asking them to produce thin and light notebooks by 2008 that can run for eight hours without the use of additional external batteries, said Mooly Eden, vice president of the company's mobility group.
Notebooks are an area of keen interest for Intel and other processor companies. Chips for those systems generally sell at higher prices than their desktop counterparts, and are more profitable to boot. The notebook segment of the PC market is growing fast, and currently accounts for about 30 percent of PC processors sold.
Computer makers, meanwhile, are working on making notebooks lighter to help get the most life out of whatever type of battery they use.
Four hours is the current standard for thin notebooks, although that allotment remains elusive in real life.
"The spec says this, but it depends to some degree on usage," said Roger Kay, an analyst at IDC. "Batteries also don't have that life for long. They might have four hours at the beginning of the year, but if you start doing more multimedia, it might go down to 2.5 hours by the end of the year."
The biggest gains in battery life are likely to come from the guts of the batteries themselves.
For instance, start-up Zinc Matrix Power has devised a way to produce batteries out of zinc alkaline that can provide more energy than conventional lithium ion batteries but don't take up any more space inside a laptop, according to Mike Trainor, chief mobile technology evangelist at Intel.
Competitor Pionics has designed a lithium ion battery that could offer similar performance. Others are working on variations such as lithium polymer.
Can you say 'supercharged'?
"By changing the metals in the cathode you can change the capacity curve of the battery," Trainor said. "The next question is whether you can take a cathode with that mix of metals into mass production."
The equation for studying battery performance, Trainor said, is relatively straightforward: divide the amount of energy stored in batteries -- measured in watt hours -- by the average power consumption of a notebook.
Today, a high-performance thin and light notebook might come with batteries that can provide 58 watt hours of energy. The average power consumption of those notebooks, however, comes to 12 watts or more. Hence, battery life totals about four hours, at best.
The goal now is to boost capacity to 72 watt hours and reduce average power consumption to 9 watts.
"Internally, we call it 1-2-6: one watt for the processor, two for the chipset and six for the rest of the system. If you want to get to eight hours, we recommend integrated graphics in chipsets," Trainor said. "We can demonstrate lab-built batteries that can do 72 watt hours and we believe one or more companies will be in production in reasonable volumes (toward 2008)."
Easy on the accelerator
Other elements of a notebook also make a difference. For the last several years, component makers steadily increased energy efficiency in many parts. LCD manufacturers, for instance, started to sell panels that consumed only 3 watts of power on average, a substantial improvement. LCD panels typically account for about 30 percent of overall notebook power consumption.
Another recent improvement for screens comes in the form of Intel's Display Power Saving Technology. With it, the pixels in a digital picture or graphic image are wider than normal, which lets more light out. In ordinary circumstances, the added light would wash out the picture, but the chipset also turns down the light source inside the panel. In the end, the image looks the same, but overall power consumption eases back from 4.8 watts to 3.2 watts. (The technology in part derives from Taiwan's Toppoly, in which Intel Capital has made an investment.)
On the other hand, screens that use OLED, or organic light-emitting diode, technology may take a while to reach notebooks. Mobile phone manufacturers already use them. However, mobile phone screens are mostly dark -- only the numbers light up -- while notebook screens are generally fully lit. OLEDs, therefore, may not provide power consumption advantages, Trainor theorised.
The hard drive, which on average consumes about 8 percent of a notebook's overall power, will also see improvements. At Microsoft's WinHEC gathering earlier this spring, Samsung showed off a hard drive in which most data gets stored to flash memory first. With the addition of flash, the hard drive can hibernate most of the time, and thereby extend battery life of a notebook by a half hour or more, according to Samsung.
Intel's upcoming Yonah notebook chip, due in the first quarter of 2006, will also consume less power than current Pentium M processors, Eden said. In addition, chipsets will begin to include more energy efficiency technology. Chipsets typically cost far less than processors and the same degree of energy conservation has not been applied to them.
Competitor Via Technologies also recently came out with a power-efficient notebook chip, the C7.
Despite the changes, consumers aren't likely to see radical shifts in notebook design. Enthusiasm for fuel cells, for instance, appears to be waning.
Fuel cells are bulky, Trainor said, and more time and money will be required to shrink them. Energy efficiency will also have to be improved. In addition, fuel cell refills cost money, in contrast with the seemingly no-cost charging of a lithium ion battery via a wall socket.
"It may be the next decade," Trainor said," before we see fuel cells inside the battery cavity."