ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Tuesday, March 26, 1996 TAG: 9603260025
SECTION: EXTRA PAGE: 3 EDITION: METRO
COLUMN: AT HOME WITH TECHNOLOGY
SOURCE: DAVID BUTLER
Q: I own two cordless phones, a cellular phone and a camcorder. After my less-than-positive experience with rechargeable batteries, I've been hesitant to buy a portable computer. Now it seems that I have several new battery technologies from which to choose. Which is best?
A: Since rechargeable ("secondary") batteries debuted in the mid-60s, advances in battery technology have played a key role in each new generation of portable electronics. In recent years, new battery chemistries have yielded impressive gains in energy storage capacity. Here's a quick overview, including the old and the new:
Lead-acid, an old workhorse of a battery, is characterized by its high energy capacity. The trade-off is weight and size. Typical applications for sealed lead-acid batteries include heavy duty lanterns, camcorders and "bag" phones. Fully discharging a lead-acid battery will shorten its life.
Nickel Cadmium (NiCd or "NiCad") batteries have been around for several decades. Until recently, virtually all cordless and cellular telephones and portable computers used NiCad batteries. They remain by far the best value in terms of price per unit of energy capacity. This makes them well suited for portable power tools, where the battery represents about half the total cost!
Unlike other rechargeable batteries, NiCads are available in common single-cell sizes (AA, C & D). If you own a portable product that eats batteries for breakfast, you'll save many times the price of a charging station by switching to NiCads. Be sure to check the product specs to see if NiCads are acceptable - NiCad cells produce 1.25 volts (versus 1.50 volts for alkaline).
Nickel-Metal Hydride (NiMH) batteries, introduced in the early '90s, are rapidly replacing NiCads in portable computers and cellular phones. NiMH cells store up to 30 percent more energy than NiCad (per unit-volume). This means longer run-times between charges. However, better performance comes at a premium: NiMH batteries cost at least 50 percent more than NiCads.
Lithium Ion (Li Ion) is the new kid on the block - the first US plants will open later this year. Per unit-weight, a Li Ion cell stores 70 to 80 percent more energy than NiCad! Again, the major trade-off is price: Li Ion batteries cost about three times more than NiCads. They also take longer to charge.
So far, Li Ion batteries have only shown up in a few high-end cell phones and camcorders. Not so with portable computers where the battery represents less than 5 percent of the overall cost. To avid users of notebook computers, Li Ion means being able to get through a morning without a recharge. Notebook manufacturers are gobbling up lithium ion batteries as fast as they're produced.
Zinc-Air has by far the highest energy density per unit-weight. It achieves this by relying on air rather than heavy metal for oxidization. AER Energy Resources, the sole producer of zinc-air batteries, claims its add-on power unit can keep a notebook computer running for 12 hours or more! The unusual 12 x 9 x 1.3-inch case fits beneath the computer and weighs 3.7 pounds.
What's next? Lithium Polymer, developed at Bellcore (formerly part of Bell Labs), marks a radical departure from conventional battery technology. The electrolyte itself is made of plastic! Imagine a battery that can be molded into almost any shape - even part of the product case! All major battery manufacturers have lithium polymer research and development programs. Expect to see products in two years.
With an ever increasing array of portable electronics, secondary battery producers and their OEM customers need desperately to move toward standard-size battery packs. Duracell has taken the lead with its "DR" series of standard sizes for cell phones, camcorders and computers.
However, size standards do nothing to address differences in chemistry. In an effort to ensure true interchangeability, Duracell has partnered with Intel, while Energizer is working with National Semiconductor to develop "smart" battery technology. But that's another story!
To receive a list of rechargeable battery manufacturers, please send $1.50 and a self-addressed envelope to David Butler F-605, Department TWN, 14713 Pleasant Hill Road, Charlotte, N.C. 28278-7927. The list also includes suppliers of after-market replacement batteries for portable phones, cellular phones, camcorders and notebook computers.
LENGTH: Medium: 80 lines ILLUSTRATION: GRAPHIC: Except for powering portable computers, nickel-cadmiumby CNBbatteries still domintae the rechargeable-battery market.