From the Linux Mobile Guide - Installing, Maintaining and Tuning of Linux on Mobile Computers: The available battery types are Lithium Ion (LiIon), Nickel Metal Hydrid ( NiMH) and Nickel Cadmium (NiCd). LiIon batteries are the most expensive ones, but a lot lighter than NiCd for the same energy content, and have minimal - but present - memory effects. NiMH is better than NiCd, but still rather heavy and does suffer some (although less than NiCd) memory effects.
Unfortunately most laptops come with a proprietary battery size. So they are not interchangeable between different models. Often it is difficult and expensive to get a replacement battery.
"The Battery Council International (BCI)(http://www.batterycouncil.org) is a not-for-profit organization with the mission of promoting the interests of the international lead-acid battery industry. With more than 175 members worldwide, the Battery Council International (BCI) brings together lead-acid battery manufacturers and recyclers, marketers and retailers, suppliers of raw materials and equipment, and industry consultants.
BCI is the authoritative source of battery-related information in many areas. Through its committees and research arms, it researches, develops and publishes technical data, engineering standards, marketing practices, trade issues and governmental and legislative initiatives."
The BCI offers some interesting battery manuals.
The European Portable Battery Association (EPBA)(http://www.epba-europe.org) is the European organisation of companies manufacturing, selling or distributing portable batteries. The mission of the EPBA is to ensure that the ideal conditions are created for responsible development of the portable battery industry in Europe. Acting in the common interests of all of its members, the EPBA aims to sustain a competitive industry in an increasingly complex commercial climate.
Hardware and Linux software to recalibrate and refurbish notebook batteries(http://sweb.cz/Frantisek.Rysanek/battery.html) controlled by the BQ2092 and BQ2040 chip (and maybe others). You may download it here.
Batteries in a Portable World fills a definite need for
practical information about rechargeable batteries. Quite often, performance
specifications for batteries and chargers are based on ideal conditions.
Manufacturers carry out battery tests on brand new equipment and in a
protected environment, removed from the stress of daily use. In Batteries in a
Portable World, Mr. Buchmann observes the battery in everyday life in the
hands of the common user. By reading Batteries in a Portable World, you will
acquire a better understanding of the strengths and limitations of the
battery. You will learn how to prolong battery life; become familiar with
recommended maintenance methods and discover ways to restore a weak battery,
if such a method is available for that battery type. Knowing how to take care
of your batteries prolongs service life, improves reliability of
portable equipment and saves money. Best of all, well-performing
batteries need replacement less often, reducing the environmental
concern of battery disposal.