BATTERIES AND POWER


Charging and keeping charged the batteries that keep today’s portable electronic devices alive has become a very popular topic, and CompTIA will no doubt target this topic on the A+ Core exam. There are several types of rechargeable chemical batteries available today, and each has its own characteristics. You do not have to focus on the detailed science of batteries. However, you do need to be able to identify the following battery types that CompTIA has included in their 2003 Core objectives:

NiCad (Nickel-Cadmium)

NiCad batteries are rechargeable batteries that lose their strength after only a few hours of use. Earlier NiCad batteries suffered from a phenomenon known as memory effect. If these battery types were recharged before most of their power was used up, they would lose their ability to become fully charged.

NiMH (Nickel Metal Hydride)

A NiMH battery is a rechargeable battery that was designed to provide long-lasting power and overall battery savings for such devices as energy-hungry PDAs and digital cameras. NiMH batteries are considered inexpensive at around $2.50 a battery. NiMH batteries do not suffer from the phenomenon of memory effect, as did early NiCad batteries, and they can store up to 50% more power. The average AAA NiMH battery has a standard rating of 1.2V. Traditional alkaline batteries carry a rating of 1.5V.

Lithium Ion

A lithium ion battery contains lithium derived from chemicals. Lithium is the lightest metal available. It is ideal for electrochemical potential. Lithium rechargeable batteries offer twice the power life of NiCad.

Lithium batteries are the most commonly used battery types for mobile systems. They are lightweight, safe, efficient, and do not suffer from memory effect. They are, of course, more expensive than the previously mentioned battery types.

Fuel Cell

The fuel cell is the latest and greatest power invention introduced in the struggle to efficiently deliver more power to laptops and mobile systems. A fuel cell produces hydrogen that is converted from methanol or alcohol. It is proposed that fuel cell technology will replace the popular lithium ion batteries that are used in most laptops today. Fuel cells can last up to 10 hours and may eliminate the need for rechargeable batteries.




The A+ Certification & PC Repair Handbook
The A+ Certification & PC Repair Handbook (Charles River Media Networking/Security)
ISBN: 1584503726
EAN: 2147483647
Year: 2003
Pages: 390

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net