“A Review Of Power Sources For Mobile Applications ” Presented by

1. “A Review Of Power Sources For Mobile Applications” Presented by Dantam Suresh Roll# EE200117128 At NIST,Berhampur Under the guidance of Mr.Bhawani Shankar Pattnaik

2. Need for Mobile Power Sources • Development of Mobile devices is fuelled by change in mobile communication services and technologies • Current & next generation mobile devices are pushing existing battery technology to its limits • Incremental improvements in battery performance will not keep pace with tomorrow’s power hungry mobile devices • Thus alternatives to battery are emerging to fulfill 21st century electronics demands

3. Market Growth in Portable Electronics • The market for portable power sources is driven by consumer demand for portable electronic devices • Portable devices are increasing finding resonance with a wider range of consumers as the functionality of such devices increases and prices fall • Because of inconvenience of rechargeable batteries, manufacturer are seeking to adopt miniaturization of circuitry that consumes less power • One major growth area in portable electronics sector is the PDA which is very much seen as the convergence of mobile phone and computing technologies.

4. Battery Technology • Battery is effectively an electric cell that produces electricity from a chemical reaction • The cell when connected to the external load, the negative electrode supplies a current of electrons that flows through load and collected by the positive electrode • Non-rechargeable batteries are primary batteries as they can convert its chemical into electricity only once • Rechargeable or secondary batteries are those, whose electrodes can be reconstituted by passing electricity back through it

5. Smart Batteries • By using bits of intelligence or software, new battery technologies can communicate with their devices and power down when certain functions are not being used • This technology not only conserves power but also works to prevent battery overheating • Market research by Darnell.com Inc. showed a growth rate of 22% for Smart Batteries • Nokia phones uses robust power management software to communicate with battery and charger to know if it should be powering full speed or slow down to a trickle

6. Performance comparison of rechargeable Battery • chemistries • Nickel Cadmium • Long life, high dischargeable rate, cheap but contain toxic metals,used in two way radios, biomedical equipment etc. • Over 50% of all rechargeable batteries for portable • equipment are NiCd • Nickel-Metal Hydride • High energy density than NiCd but reduced cycle life,Use of environmental friendly metals • Used in mobile phones and laptop computers • Lead Acid • First rechargeable battery for commercial use,economical for larger power applications • There are two variants: sealed lead acid & valve-regulated lead acid • Used in hospital equipments, emergency lighting and UPS systems

7. Lithium Ion • Light weight, so suitable for notebook computers and cell phones, relatively high price • The energy density is twice that of the NiCd, and the life expectancy is high when cobalt is used instead of manganese • Lithium Ion Polymer • Lower cost version of Li-ion and appropriate for mobile phones • Li-polymer battery consists of a gelled electrolyte that allows the battery to be formed into convenient shapes and provides enhanced ion conductivity • Reusable Alkaline • Have limited life cycle but used in portable electronic devices and torches, they are designed for repeated recharge • Inexpensive but the cost per cycle is high compared to Ni based rechargeable batteries

8. Fuel Cells • A fuel cell is a electrochemical energy-conversion device that can be recharged. • A basic fuel cell used hydrogen and oxygen. Similar operation as battery but with a performance potential for energy storage and power delivery far exceeding the Li-polymer batteries • Lack of abundance of hydrogen lead to alternate fuels like natural gas, propane etc. and some metal fuels such as zinc and aluminum • The cells themselves are classed by the type of electrolyte they use, they include phosphoric acid, proton-exchange membrane, molten carbonate,direct methanol fuel cells and regenerative fuel cells • One major area of the fuel cell development is the automotive sector for next generation hybrid petrol-electric and fully electric vehicle

9. Micro Fuel Cells • Fuel cell, which separate the energy storage and power conversion functions, is an attractive solution for the power portable applications • Fuel cells are expected to make mobile equipment much easier to use because of their long life and help facilitate development devices consuming large amount of power • There are three technical hurdles in realizing micro fuel cells for miniature electronic devices, namely cell power management, miniaturization and safety • Fuel cells may be able to provide 10 times the peak power of conventional batteries and they may allow 5 times the standby time provided by batteries

10. Power Storage Components • The development of ultracapacitors, sometimes termed ‘supercapacitors’, was a direct outgrowth of diverse applications in the area of material and electric science\ • ultracapacitors are a combination of electrochemical charge-discharge capability and capacitor technology • The capacitor accomplishes this energy storage task by moving positive charges in one direction, negative charges in the other, hence the double layer • In a sense they resemble batteries because the charge is stored by ions as in a battery, but as no chemical reaction need take place, so an ultracapacitor also resembles a traditional capacitor

11. Power Storage Components (contd…) • ultracapacitors differ from batteries in that their voltage increases linearly with the state of charge and the problems of electrochemical irreversibility, so common with batteries, have been minimized or eliminated • The ultracapacitors are connected in parallel with the existing power supply, the ultracapacitors discharge to regulate power whenever the status of the main supply change and the electric load is perceived by the capacitor • Commercial ultracapacitors provide extra power for portable computers on initial power-up and during the operation of hard-drives • They are an ideal companion technology for automotive fuel cells and hybrid-electric vehicles, delivering additional power where required and recovering energy from activities such as braking

12. Mechanical Power Sources • characterized by simple hand-cranked winding mechanisms converting mechanical power into stored energy, the energy within the spring being capable of release upon demand • Broadening term ‘manual charging or personal power’, Freeplay have introduced a manual mobile phone charger that enables users to make calls when the phone’s internal battery has run flat • The charger consists a crank, turning the crank generates mechanical energy, which is converted to electrical energy within the charger and then stored within a small internal battery • North Yorkshire, have developed prototype wind-up units designed to power laptops and so. The systems use a hand-cranked generator, instead of a rechargeable battery they have a supercapacitor as the energy storage device

13. Mechanical Power Sources (contd…) • Supercapacitors can absorb large amounts of charge in seconds, supercapacitors can also be charged and discharged many more times than a rechargeable battery, high efficiency than NiMH battery • Trevor Baylis, is seeking to develop shoes that channel sufficient energy from the action of walking to power a mobile phone • Other sources of human activity or human biology may also be used to power a new generation of body worn electronics • mechanically powered devices offer the potential for a significant reduction in the number of batteries and chemicals cells used to power mobile devices • It also alleviates the problems attendant on the recycling of these products

14. Conclusion • With the proliferation of an increasing array of mobile devices has come the challenge of developing suitable mobile power sources • innovation and new developments are bound for supplementing or replacing battery technology • One such technology is fuel cells, which hold out the possibility of greater power density • The concept of personal power, typified by the wind-up radio, is also an appealing one