SIMULATION FOREGROUND READING
Back Bay Battery, Inc.
The battery industry is enormous, with worldwide revenues of approximately $45 billion. It is highly fragmented with at least 20 major manufacturers in each technology segment. Because of the wide range of applications of batteries, companies have tended to specialize in a particular technology or market application. Disposable batteries, such as the widely available carbon-zinc and alkaline cells, are available in standard sizes such as AA, C, and D, and they are a fast-moving consumer-good category with emphasis on manufacturing efficiency and scale, marketing and branding, and distribution efficiency.
One of the earliest forms of rechargeable battery was the wet lead-acid battery, the chemistry for which was invented in 1859. The application that drove this battery into prominence was to power a starter motor for vehicles, but today lead-acid batteries are commonly used for uninterruptible power supplies—in forklift trucks, golf carts, boats and submarines, and vehicles for indoor operation. They are inexpensive, albeit heavy. A variant on the lead-acid battery is the Gel Cell, which is a sealed lead-acid battery with a jellified electrolyte, allowing a higher degree of portability. Smaller rechargeable batteries began as size-compatible replacements for disposable batteries and used technologies such as nickel-cadmium (NiCd), nickel-iron (Ni-Fe), nickel metal hydride (NiMH), and lithium ion (Li-ion) and lithium polymer. As demands for portable electronic devices such as laptop computers, music players, and cellular telephone handsets rose, makers responded with new sizes and custom packaging to meet the unique needs of customers.
Battery Performance Criteria
Important battery performance criteria include:
Energy Density: The amount of charge stored within a battery. A battery with a higher energy density can store more charge, and thus can power a device for a longer time or deliver more power in the same time period. As laptop computers took on larger screen sizes and more powerful processors, the demand for higher energy density drove a switch from NiMH to Li-ion batteries.
________________________________________________________________________________________________________________ Professors Willy Shih and Clayton Christensen prepared this reading. Copyright © 2012 Harvard Business School Publishing. No part of this publication may be reproduced, stored in a retrieval system, used in a spreadsheet, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—without the permission of Harvard Business Publishing.
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Back Bay Battery, Inc.
Recharge Cycles: The number of times a battery can be recharged. Most batteries can go through only a limited number of deep discharge – recharge cycles. Many batteries can typically only stand around 500 cycles and then need to be replaced. This is a challenge for portable device designers; the first failure mode is often the battery’s inability to hold a charge.
Self-discharge to 50%: The time it takes for a battery to self-discharge. Most rechargeable batteries lose some amount of their charge just sitting on a shelf. This limits their application in devices such as safety equipment that might sit for unpredictable time periods between use.
Recharge Time: How quickly a battery will recharge. Fast recharge time is usually a consumer benefit, especially for things like mobile phones or music players. A typical NiMH battery can be recharged in two to four hours.
Price: The cost variance of different battery types. Since small rechargeable batteries tend to come in standard form factors and output voltages, they are a fungible commodity with almost no barriers to substitution. Different battery types might require different chargers, but in general the...
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