Better Batteries Are Key to Maintaining Portability in Laptops

TO paraphrase Reebok, the athletic-shoe company, computer-battery life is short. Too short. You know this because:

* Businesswomen crawl under assorted office furniture to plug in their laptop computers.

* Grown men fret that their portable wonders will run out of juice midway through their sales presentations.

* Your best travel tip is which airports have seats placed next to wall sockets.

Batteries, in other words, are crucial to portable computing. Their limits define how mobile we are. Their breakthroughs determine whether future gizmos will really be powerful and useful.

We're at the beginning of one of those battery breakthroughs. I got my first glimpse of this a few weeks ago when AST Research sent me a portable computer, the Ascentia 910N. It's powered by a new lithium-ion battery.

Batteries depend on chemicals to store and release energy. Portable computers started out on alkaline batteries. Then came nickel-cadmium. Then nickel metal-hydride or NiMH, today's standard. The move to lithium-ion chemistry is a big step. Sony, the leading maker of the new batteries, claims they are 30 percent lighter and deliver up to 30 percent more energy per cubic inch than NiMH. Proponents believe lithium-ion represents the next generation for portable computing.

After a month with AST's Ascentia, I'm a believer too. Instead of two hours with nickel-cadmium batteries on my old computer, I got six hours of constant use. On days when my computer needs were moderate, I could even skip a day before recharging. The clincher came one morning after I inadvertently left the machine on all night. To my delight, the Ascentia was still running.

Battery chemistry is only part of the story. To take advantage of the new power source, computer companies have to create power-management systems. I noticed, for example, that the Ascentia took its time to power up. That's because AST found it takes less energy when the machine turns on the display and the hard-drive sequentially rather than at the same time. Once I knew it was saving power, the slight delay didn't bother me.

Several companies are jumping aboard the lithium-ion bandwagon. Yet the battery supply is constrained. Only Sony is making the batteries in mass quantities.

Of course, as soon as the battery industry lurches forward with a new technology, computer companies sprint ahead again. This summer, computer companies are introducing new portable machines with top-of-the-line Pentium microprocessors. Apple Computer is expected to offer PowerBook portables later this year that use the industrial-strength PowerPC chip. This fall, look for some laptops with color screens that break the 11-inch barrier.

The result? Serious battery drain. AST's new Pentium-based portable gets only about half the computing time out of its lithium-ion that my slower AST machine did. Someday, though, we'll have both portability and power. Laboratories are already working on better batteries. One is the lithium-polymer battery, which is supposed to be half again as powerful per cubic inch as the lithium-ion battery. Zinc-air batteries also show great promise if engineers can find ways to ensure proper air flow.

I can't wait for that day in computer evolution when I can hold the equivalent of a Pentium computer in my hand. It will run a week off a single battery charge. That will be the day we finally get off our hands and knees hunting for wall sockets and stand tall as the mobile-computer users we're supposed to be.

* Until then, plug in and send me e-mail via Internet (laurentb@delphi.com) or CompuServe (70541,3654) or America Online (LBELSIE).