Better Laptop Battery Gauge
Traditionally, the reading on your laptop battery's power levels can be off by as much as 50%, but that's about to change. This winter, Texas Instruments plans to introduce an inexpensive "gas gauge" chip that not only takes into account a battery?s original capacity but also measures its impedance -- the resistance to electrical current caused by age, frequent use, and other factors.
Better Battery Gauge (MIT's Emerging Technologies Newsletter, November 12, 2004)