Batteries in a Portable World: A Handbook on Rechargeable Batteries for Non-Engineers

Simpo PDF Merge and Split Unregistered Version - http://www. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Part One Battery Basics Everyone Should Know Author`s Note Battery user groups have asked me to write an edited version of Batteries in a Portable World. The first edition was published in 1997. Much has changed since then. My very first publication in book form was entitled Strengthening the Weakest Link. It was, in part, a collection of battery articles which I had written. These articles had been published in various trade magazines and gained the interest of many readers. This goes back to the late 1980s and the material covered topics such as the memory effect of NiCd batteries and how to restore them. In the early 1990s, attention moved to the nickel-metal hydride (NiMH) and the articles compared the classic nickel cadmium (NiCd) with the NiMH, the new kid on the block. In terms of longevity and ruggedness, the NiMH did not perform so well when placed against the NiCd and I was rather blunt about it. Over the years, however, the NiMH improved and today this chemistry performs well for mobile phones and other applications. Then came the lithium-ion (Li-ion), followed by the lithium-ion polymer (Li-ion polymer). Each of these new systems, as introduced, claimed better performance, freedom from the memory effect and longer runtimes than the dated NiCd. In many cases, the statements made by the manufacturers about improvements were true, but not all users were convinced. The second edition of Batteries in a Portable World has grown to more than three times the size of the previous version. It describes the battery in a broader scope and includes the latest technologies, such as battery quick test. Some new articles have also been woven in and some redundancies cannot be fully avoided. Much of this fresh material has been published in trade magazines, both in North America and abroad. In the battery field, there is no black and white, but many shades of gray. In fact, the battery behaves much like a human being. It is mystical, unexplainable and can never be fully understood. For some users, the battery causes no problems at all, for others it is nothing but a problem. Perhaps a comparison can be made with the aspirin. For some, it works to remedy a headache, for others the headache gets worse. And no one knows exactly why. Batteries in a Portable World is written for the non-engineer. It addresses the use of the battery in the hands of the general public, far removed from the protected test lab environment of the manufacturer. Some information contained in this book was obtained through tests performed in Cadex laboratories; other knowledge was gathered by simply talking to diverse groups of battery users. Not all views and opinions expressed in the book are based on scientific facts. Rather, they follow opinions of the general public, who use batteries. Some difference of opinion with the reader cannot be avoided. I will accept the blame for any discrepancies, if justified. Readers of the previous edition have commented that I favor the NiCd over the NiMH. Perhaps this observation is valid and I have taken note. Having been active in the mobile radio industry for many years, much emphasis was placed on the longevity of a battery, a quality that is true of the NiCd. Today’s battery has almost become a disposable item. This is Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com especially true in the vast mobile phone market where small size and high energy density take precedence over longevity. Manufacturers are very much in tune with customers’ demands and deliver on maximum runtime and small size. These attributes are truly visible at the sales counter and catch the eye of the vigilant buyer. What is less evident is the shorter service life. However, with rapidly changing technology, portable equipment is often obsolete by the time the battery is worn out. No longer do we need to pamper a battery like a Stradivarius violin that is being handed down from generation to generation. With mobile phones, for example, upgrading to a new handset may be cheaper than purchasing a replacement battery. Small size and reasonable runtime are key issues that drive the consumer market today. Longevity often comes second or third. In the industrial market such as public safety, biomedical, aviation and defense, requirements are different. Longevity is given preference over small size. To suit particular applications, battery manufacturers are able to adjust the amount of chemicals and active materials that go into a cell. This fine-tuning is done on nickel-based as well as lead and lithium-based batteries. In a nutshell, the user is given the choice of long runtime, small size or high cycle count. No one single battery can possess all these attributes. Battery technology is truly a compromise. Introduction During the last few decades, rechargeable batteries have made only moderate improvements in terms of higher capacity and smaller size. Compared with the vast advancements in areas such as microelectronics, the lack of progress in battery technology is apparent. Consider a computer memory core of the sixties and compare it with a modern microchip of the same byte count. What once measured a cubic foot now sits in a tiny chip. A comparable size reduction would literally shrink a heavy-duty car battery to the size of a coin. Since batteries are still based on an electrochemical process, a car battery the size of a coin may not be possible using our current techniques. Research has brought about a variety of battery chemistries, each offering distinct advantages but none providing a fully satisfactory solution. With today’s increased selection, however, better choices can be applied to suit a specific user application. The consumer market, for example, demands high energy densities and small sizes. This is done to maintain adequate runtime on portable devices that are becoming increasingly more powerful and power hungry. Relentless downsizing of portable equipment has pressured manufacturers to invent smaller batteries. This, however, must be done without sacrificing runtimes. By packing more energy into a pack, other qualities are often compromised. One of these is longevity. Long service life and predictable low internal resistance are found in the NiCd family. However, this chemistry is being replaced, where applicable, with systems that provide longer runtimes. In addition, negative publicity about the memory phenomenon and concerns of toxicity in disposal are causing equipment manufacturers to seek alternatives. Once hailed as a superior battery system, the NiMH has also failed to provide the universal battery solution for the twenty-first century. Shorter than expected service life remains a major complaint. The lithium-based battery may be the best choice, especially for the fast-moving commercial market. Maintenance-free and dependable, Li-ion is the preferred choice for many because it offers small size and long runtime. But this battery system is not without problems. A relatively rapid aging process, even if the battery is not in use, limits the life to between two and three Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com years. In addition, a current-limiting safety circuit limits the discharge current, rendering the Li-ion unsuitable for applications requiring a heavy load. The Li-ion polymer exhibits similar characteristics to the Li-ion. No major breakthrough has been achieved with this system. It does offer a very slim form factor but this quality is attained in exchange for slightly less energy density. With rapid developments in technology occurring today, battery systems that use neither nickel, lead nor lithium may soon become viable. Fuel cells, which enable uninterrupted operation by drawing on a continuous supply of fuel, may solve the portable energy needs in the future. Instead of a charger, the user carries a bottle of liquid energy. Such a battery would truly change the way we live and work. This book addresses the most commonly used consumer and industrial batteries, which are NiCd, NiMH, Lead Acid, and Li-ion/polymer. It also includes the reusable alkaline for comparison. The absence of other rechargeable battery systems is done for reasons of clarity. Some weird and wonderful new battery inventions may only live in experimental labs. Others may be used for specialty applications, such as military and aerospace. Since this book addresses the non-engineer, it is the author’s wish to keep the matter as simple as possible. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Chapter 1: When was the battery invented? One of the most remarkable and novel discoveries in the last 400 years has been electricity. One may ask, “Has electricity been around that long?” The answer is yes, and perhaps much longer. But the practical use of electricity has only been at our disposal since the mid-to late 1800s, and in a limited way at first. At the world exposition in Paris in 1900, for example, one of the main attractions was an electrically lit bridge over the river Seine. The earliest method of generating electricity occurred by creating a static charge. In 1660, Otto von Guericke constructed the first electrical machine that consisted of a large sulphur globe which, when rubbed and turned, attracted feathers and small pieces of paper. Guericke was able to prove that the sparks generated were truly electrical. The first suggested use of static electricity was the so-called “electric pistol”. Invented by Alessandro Volta (1745-1827), an electrical wire was placed in a jar filled with methane gas. By sending an electrical spark through the wire, the jar would explode. Volta then thought of using this invention to provide long distance communications, albeit only addressing one Boolean bit. An iron wire supported by wooden poles was to be strung from Como to Milan, Italy. At the receiving end, the wire would terminate in a jar filled with methane gas. On command, an electrical spark is sent by wire that would detonate the electric pistol to signal a coded event. This communications link was never built. Figure 1-1: Alessandro Volta, inventor of the electric battery. Volta’s discovery of the decomposition of water by an electrical current laid the foundation of electrochemistry. ©Cadex Electronics Inc. ... - tailieumienphi.vn