Ni-MH Batteries Promise More Power

Is Ni-Cd running out of gas?

High-resolution, backlit LCDs and power-hungry disk drives put power at a premium in portable pen-based computers. Consequently, the current crop of stylus systems are, for the most part, able to only operate from 3 to 5 hours between battery charges — clearly not enough to satisfy the demands of mobile users.

To this end, battery vendors are moving rapidly to provide nickel-metal hydride (Ni-MH) batteries for portable computers as an alternative to the now-familiar closed-lead acid and nickel-cadmium (Ni-Cd) batteries. In general, Ni-MH batteries have almost twice the capacity over their Ni-Cd counterparts, while providing up to 500 charge/discharge cycles.

Currently, Sanyo Electric in Japan is one of the few manufacturers of rechargeable Ni-MH batteries in the AA-size, 1.2 volt category. Although Sanyo began sampling these batteries in late 1990, mass production has just recently begun. The characteristics of one Sanyo Ni-HM model (the HR-AA) are: capacity, 1100mAh; voltage, 1.2V; standard charge current, 110mA; standard charge time, 14-16 hours; weight, 26 grams; and size, 14.2x50mm.

Currently, the Sanyo Ni-MH batteries are being used as power sources for portable computers and communications equipment in Japan. The company is also developing different sizes and capacities of the batteries for general consumer electronic applications.