Notebook Battery and Extend Its Life
Laptops of old featured Nickel-Cadmium (Ni-Cad) batteries, which were not environmentally friendly?especially when improperly disposed. They had very little up time compared to today's notebook battery, and had debilitating issues with battery memory.
Source: http://www.articlesbase.com/laptops-articles/notebook-battery-and-extend-its-life-4268995.html