Portable Energy Sources

A complete ES power supply package reported by Jordan and Spyker [8] incorporated a DC converter circuitry on a 50 F, 2.5 V ELNA Dynacap. By 

55 F 85 mfi dual-ceU ES delivers 5 W power bursts to drive peak power functions such as audio and LED flash. A battery covers a phone s average audio power needs of 0.5 to 1 W, recharging the ES between bursts. 

Compared to conversional capacitors for portable devices, ESs can overcome the power delivery constraints of batteries and the energy delivery limitations of conventional capacitors. They handle peak power events for wireless transmission, GPS, audio, LED flash, video, and battery hot swaps, and then are recharged from a battery at an average power rate. 

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The difference in the reactivity between the two metals used in the cell creates a particular voltage reading on the voltmeter shown in Figure 6.23b. The more the two metals differ in reactivity, the larger is the voltage shown and delivered by the cell. This method can be used to confirm the order of reactivity of the metals (Chapter 10, p. 150). Other types of chemical cell in common use are dry cells used in radios, torches, and so on, and lead-acid accumulators used in motor vehicles. These are convenient and portable energy sources. 

From thermodynamic considerations the maximum energy that can be derived from a specified mass of reactants can be calculated. This calculation is of particular interest in the design of portable energy sources. The theoretical specific energy is the ratio of Gibbs free energy of the reaction to the mass of the reactants ... 

ES application areas include power electronics, memory protection, battery enhancement, portable energy sources, power quality improvement, adjustable speed drives (ASDs), high power actuators, hybrid electric vehicles, renewable and off-peak energy storage, and military and aerospace applications. All these application areas will be discussed in this chapter. 

Voltaic cells are used commercially as portable energy sources (batteries). In addition, the basic principle of the... 

The DMFC is the most attractive type of fuel cell as a powerplant for electric vehicles and as a portable power source, because methanol is a liquid fuel with values for the specific energy and energy density being about equal to half those for liquid hydrocarbon fuels (gasoline and diesel fuel). 

Therefore, methanol is the top candidate because of its low price, less toxicity, high energy density and easy handling. Although direct methanol fuel cells may need an auxiliary system to treat unoxidized or partially oxidized fuel in the exhaust gas, direct methanol fuel cells are still a very attractive system as a portable power source. 

Fuel cells are electrochemical devices that convert the chemical energy of the fuels directly into electrical energy, and are considered to be the key technology for power generation in stationary, automotive, portable and even microscale systems. Among all kinds of fuel cells, direct methanol fuel cells have really exhibited the potential to replace current portable power sources and micropower sources in the market (Yao et al., 2006). 

Portable systems must operate on a portable power source. Often this simply means batteries. When heating becomes a part of the operating sequence, batteries can be consumed quickly. A well-defined energy budget is necessary early in the design process. 

It appears as if one of the level K electrons of the atom disappears into the nucleus. The void created induces X-ray fluorescence from the nucleus Y. There are several known radionucleides of this type, which have sufficiently long periods that they can be used as different energy sources (see Table I3.l). These are typically used in portable instruments. The activity of these isotopic sources is generally in the order of a few mCi and they can yield a flux of 106 to 108 photons/s/steradian. Because these sources require a permit for use as well as permanent protection because they emit continuously, their use is rapidly diminishing. 

Many types of rechargeable batteries have been developed as portable power sources for small electronic devices, such as watch, calculator, video camera, computer and so on. Lead-acid battery, Ni-Cd battery, Ni-Metal hydride battery, and lithium battery are well known and used in some portable electronic devices. Lithium batteries are the most attractive with regard to energy density or power density. Recently, a new rechargeable lithium battery, that is a so-called Lithium Ion Battery , was proposed by Sony Company [5]. In this battery, carbon materials... 

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