Portable Devices: Batteries

Portable devices powered by batteries have experienced a dramatic growth in the last several years. In particular, devices such as cellular phones, portable computers, cameras, camcorders, and cordless tools have given a remarkable impulse to the market. The advancements in the field of transistors and other electronic components have been impressive and have played a very important role in this development. The so-called Moore’s law states, in its widely accepted form, that ‘the number of transistors in integrated circuits doubles every 18 months’. . | Portable Devices Batteries G Pistoia Via Giorgio Scalia Rome Italy 2009 Elsevier . All rights reserved. Electric and Electronic Devices Portable devices powered by batteries have experienced a dramatic growth in the last several years. In particular devices such as cellular phones portable computers cameras camcorders and cordless tools have given a remarkable impulse to the market. The advancements in the field of transistors and other electronic components have been impressive and have played a very important role in this development. The so-called Moore s law states in its widely accepted form that the number of transistors in integrated circuits doubles every 18 months . Certainly the improvements in power sources have not kept pace with this growth rate for instance lithium-ion batteries have only doubled their capacity in the last 10 years. Nonetheless the large proliferation of portable battery-powered items would have been impossible without the introduction of new batteries with better energy and power characteristics. Let us go for a while back to the 1940s-1950s. At that time portable applications were limited to torches a few toys and radios. Before the transistor era portable radios used thermo-ionic valves that needed two types of batteries a 2 V lead-acid battery to supply current to the valve filament and a high-voltage battery consisting of up to 120 dry cells in series to provide the voltage needed to accelerate electrons between the valve cathode and anode. This radio weighed several kilograms and had to be maintained in an upright position to avoid acid spillage. Obviously it was mainly used in military and industrial applications. This may sound rather funny to people now accustomed to tiny devices powered by cells of small dimensions. It has been estimated that today s family uses 30-60 batteries in various portable appliances. If this number seems too high just think about watches cameras camcorders calculators personal digital assistants

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