For portable equipment

In addition to these smaller applications, fuel cells can be used in portable generators, such as those used to provide electricity for portable equipment. Thousands of portable fuel cell systems have been developed and operated worldwide, ranging from 1 watt to 1.5 kilowatts in power. The two primary technologies for portable applications are polymer electrolyte membrane (PEM) and direct methanol fuel cell (DMFC) designs. 

Batteries for portable equipment 2 Wh-100 Wh Flashlights, toys, power tools, portable radio and television, mobile phones, camcorders, lap-top computers... 

Ene way to meet the energy needs of the future is to find effective ways of generating electricity from chemical reactions. Small but efficient sources of electricity are needed for portable equipment, from artificial hearts and pocket computers to electric automobiles and space habitats. We shall see in this chapter how chemical reactions—particularly redox reactions—can provide this energy. 

The technical specifications of these monitors are impressive they luminesce in the entire visible spectrum, they are bright and efficient. They are thinner and lighter than LCD monitors (liquid crystal displays) and are therefore especially suited for portable equipment. They are intrinsically emissive, and thus require no background illumination, and they have a display angle of nearly 180°. Furthermore, they are fast and thus suitable for rapid video sequences. The image points (pixels) can be switched to a completely dark state, so that higher contrast can be obtained. 

Even when taking into account the lower number of electrons, the specific energy content of borohydride remains rather high. Under the assumption of six electrons, it is close to 7kWh/kg. This substance, therefore, is rather promising for the development of small-size fuel cells as power supply for portable equipment. 

Commercial Lithium-Ion Battery Packs for Portable Equipment.388... 

This Chapter discusses the nature of commercial lithium-ion battery packs used for portable equipment in Section 2, limitations of commercial lithium-ion cells in Section 3, quality control of commercial lithium-ion cells in Section 4 and the commercial li-ion cells and battery pack safety certification process in Section 5. 

The principle is that the live conductors are covered by two discrete layers of insulation. Each layer would provide adequate insulation in itself but together they ensure little likelihood of danger arising from insulation failure. This arrangement avoids the need for an earth wire. Double insulation is particularly suitable for portable equipment such as drills. However, safety depends on the insulation remaining in sound condition and the equipment must be properly constructed, used and maintained. 

Before the development of batteries for electric vehicles considerably changed the situation, the available lithium-ion batteries tended to have a small capacity around 1 Ah to a few tens of Ah depending on the manufacturers. Therefore, it was necessary to connect the elements in series and in parallel to increase the voltage and capacity. These assemblies were made by intermediary companies, re-selling battery packs for portable equipment or for small autonomous systems. Today, manufacturers and companies specializing in connectics are working to develop methods of assembly and connection which offer the best performances of the pack. The assembly is of crucial importance to ensure the perennity of the performances over time (choice of connectors, management methods) and to make the battery safe (inclusion of fiises", etc ). 

With some exceptions, higher-temperature systems (MCFC, SOFC, PAFC) tend to be best suited for larger applications, while low-temperature systems (DMFC, PEMFC, AFC) can, in addition to units up to some hundred of kilowatts, be configured to provide as little as a few watts of power or less and hence be applied for portable equipment etc. (Fig. 20.7). 

The most important performance indicators for power supplies designed for portable equipment are the specific energy per unit mass (weight), Ym (in J/kg) and/or per unit volume, Yi> (in J/L). Often, miniplants with fuel cells are used in portable equipment as a replacement for lithium-ion batteries, which have specific performance indicators of 150 Wh/kg and 350 Wh/L. 

Today, almost half of all efforts worldwide to develop fuel cells for portable equipment come from North America, which has to do with the relatively large resources made available by the U.S. military (see Crawley s review, 2006). Japan carries a share of about 20%, the support coming from the many large companies making portables Sony, Casio, Fujitsu, Hitachi, NEC, Toshiba, and others. Considerable contributions come from other countries, such as South Korea (Samsung), France, Italy, Germany, and some others. In almost 90% of all such developments, the fuel cells involved are those of the PEMFC and DMFC type (at approximately equal shares). Mini-fuel cells based on SOFC constitute a minor part they are of interest primarily for military purposes. 

In the Crawley review of 2007 mentioned earlier, data are given from which one can see the distribution of military support for the development, improvement, and production of fuel cells for various military uses 45% for portable equipment, 22% for all kinds of ships, 11% for land vehicles, 10% for flying vehicles (unmanned aerial vehicles), traffic controllers, etc.), 6% for various weapons, and about 5% for stationary installations. 

Similar tables indicating the decision tree and test requirements for portable equipment and fixed equipment have been developed by Underwriters Laboratories. In each case, the procedure for determining the suitability of a plastic material used in electrical equipment is basically the same. If the plastic parts used in this application are required to go through a special process such as plating,... 

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