The Rechargeable battery industry is growing very rapidly. Rechargeable batteries, are used in everything From Phones, Laptops, Toys, to Cordless Tools, and everything in between. Many aren't aware of the difference between the different types of rechargeable battery chemistries. The rest of the page will explain the advantages and disadvantages of the different types of rechargeable batteries. Note this page doesn't cover all the different types of rechargeable batteries just the most common used in consumer products.NI-CD
NI-Cd, NI-CAD, NICAD are all reference to a Nickel Cadium Batteries. Ni-CD's are the most common and have been used in consumer products the longest. Ni-CD's are starting to be replaced by the newer Ni-MH, and LI-ION, as new products replace the old. The Main advantage NI-CD batteries is that they are cheap, currently compared to the other battery types. However, as more and NI-MH and Li-Ion batteries spread into traditional areas that Ni-Cd once dominated the the prices should come nearer together in the long run.
Ni-CD hold less power per weight compared to NI-MH or Li-Ion batteries. So, if you have a cordless drill using a Ni-Cad battery pack it will weigh significantly more than a Li-Ion all things being equal(Voltage, and Amp Hours). Ni-CD are also bad for the environment and must be disposed of properly. This is also driving the conversion from Ni-CD, as this probelm isn't present in Ni-MH, and Li-ION batteries.
Ni-Cads also suffer from a Memory effect, which means that charging the battery in an unoptimized manner will degrade the performance of the battery. Ni-Cad's require for best performance, fully discharging the battery before charging again. For some applications this isn't practical.
Ni-CD are good in applications where weight isn't a concern, and recharging can be controlled in order to facilitate long battery life. Ni-CD should be avoided in instances, where weight is a concern, and optimal charging patterns more than likely would be applied. Ni-CD's are also good in applications that are sensitive to battery costs.Ni-MH
Ni-MH batteries, are becoming more popular at the expense of Ni-CD batteries, as they display several advantages over Ni-Cd batteries. Ni-MH hold more power for the same weight. Also Ni-MH batteries are more environmentally friendly than Ni-CDs. Ni-MH also don't suffer from the Memory Effect to as great a degree as Ni-CD, so can be charged in a less restrictive manner without suffering significant negative effects on Power holding capacity. However, Ni-MH batteries are currently more expensive than Ni-CD batteries.Li-ION
Li-ION are the higher end battery in the rechargeable market. They display the best qualities for the vast majority of todays rechargeable battery market. Lithium-ION are relatively environmentally friendly, They display no memory effect, so you can charge your battery in manner or charge state without ill effect. They also are the lowest weight battery, all things being equal. This is why they are used in higher end electronics like laptops that are sensitive to weight, and sporadic random charging patterns. However, Li-ION at present are by far the most expensive consumer rechargeable battery type.Overview
With rechargeable batteries like most things in life, you get what you pay for.
Ni-Cads come cheap but require following a charging procedure, and added weight. If that isn't a problem in your case, then Ni-CD batteries would be great
Ni-MH hold more power than Ni-CD's weigh less, and aren't as sensitive to charging patterns, though they cost more than Ni-CD's. You gain some convenience for a little higher cost.
Li-Ion are the most convenient and highest capacity by weight and care free rechargeable you can get at present in the consumer market. However, they cost significantly more.