[ Short Guide on Laptop Batteries] Laptop batteries have evolved to meet up with the power demand and size requirements of mobile computing. There is a trend towards packing more energy-efficient cells into smaller packages while keeping down the total weight. The first laptop batteries are the Rechargeable Nickel Cadmium batteries. While batteries are no longer used, they once were the only kinds available. The disadvantages of Nickel Cadmium batteries include their weights, lower efficiencies and the “ memory effect ”. The memory effect is a common fault of Nickel-based batteries. Even with Nickel Metal Hydride batteries that replaced Nickel Cadmium ones in laptops, the memory effect can be noticed, even though it is less. The memory effect affects the efficiency of Nickel-based laptop batteries by keeping the characteristics of the last charging cycle. This means that if in the previous cycle the laptop battery is not fully charged, the battery will remember this and cut down on the energy output of the next cycle. However, for all the demerits of Nickel-based laptop batteries, they are cheap to produce and safe to make. Nickel Metal Hydride batteries are more reliable and provide better output than Nickel Cadmium ones. Lithium Ion cells are today’s laptop battery leader. While there are different types of this kind, they are all noted for their energy efficiencies, reduced weight, better output and ease of manufacturing different sizes and shapesof them. So what makes Lithium better for laptop batteries? First the basic chemistry: Lithium is the lightest metal, it has the largest electrochemical potential and it packs the biggest energy density for its weight. However, it is rather unstable as a metal especially during charging. The workaround is to use non-metallic Lithium sources which are much safer while sacrificing only a slight energy density. Therefore, today’s Lithium Ion laptop batteries use intercalated Lithium compounds for electrodes rather than Lithium metal. During discharge, Lithium ions carry current from the negative electrode to the positive one. The reverse occurs while charging the battery. Clear advantagesof Lithium Ion batteries include: •
higher energy densities (at least twice that of Nickel Cadmium), low self-discharge (half of the rate for Nickel-based batteries),
low maintenance and no memory effects.
They are also much lighter and can be made for specialty equipment with special power requirements. All of these make Lithium Ion cells ideal as laptop batteries.
However, Lithium Ion batteries are not without their demerits. They are more susceptible to aging, more sensitive to high temperatures and are more expensive. To even make them more costly, these batteries require special circuits to protect them from overheating and maintain output within safe limits. As laptop batteries, they also require onboard computers to manage them. Furthermore, since manufacturers are constantly developing better, slimmer and specialty Lithium Ion batteries, the metals and chemicals in these cells are always changing, making it difficult for economy of scale of materials and processesto reduce costs after a while. In spite of the high cost and few limitations, Lithium Ion batteries still represent the biggest proportion of laptop batteries. In fact, the most economical Lithium Ion battery is the kind produced for mobile computing needs especially for laptops. This type of Lithium Ion batteries is cylindrical with a dimension of 18 mm x 650 mm. In all, scalability and better efficiency are the main reasons why Lithium Ion batteries are the commonest and the most promising laptop batteries. These are the reasons why we use them too. They are light, energy-efficient, durable, simple and require low maintenance. When you weigh all the factors involved, you will see that Lithium Ion batteries represent the best choice both for users and manufacturers, if you need true mobility and reliable power. Source: Needbattery.com/laptop
Published on Dec 20, 2010
Laptop batteries have evolved to meet up with the power demand and size requirements of mobile computing. There is a trend towards packing m...