Powerful Change Part 1: Batteries and Possible Alternatives for the Mobile Market

obile phone companies sell more batteries than phones to consumers. The devices users buy generally include rechargeable batteries so that they are immediately useful. On average, however, the consumer must own more than one battery during the phone's life. The same is probably true for laptops and camcorders. Companies try to protect their batteries with various design and utility patents to keep third-party vendors from competing too heavily with their after-market sales. This protection is necessary because battery technology changes slowly—consumers receive little incentive to upgrade their batteries unless they fail or the consumer desires a larger one. Additionally, battery cost is tied to raw material costs, more than silicon chip or software costs, making batteries more similar to traditional trade goods than to the high-profit centers with which high-tech companies are familiar. Power is a difficult issue and is often overlooked in mobile computers. However , innovative opportunities abound for exploring this problem. In this installment, we introduce the issue and propose some alternatives to batteries. In subsequent issues we'll address methods of being more power efficient by using resources both on the body and in the environment. Battery energy is one of the most lag-gard trends in mobile computing. 1 Figure 1 shows the progression of technology in the last decade for laptop computers, which are now mostly mature. Generally, the laptop technology that the graph represents could be used—if repackaged in a body-worn device—while standing on a street corner in a major US city. The graph depicts increases in performance as multiples of the state of the technology from 1990. Owing to the improvements' exponential nature, the y-axis is on a logarithmic scale. A high-end machine from 1990 (the base value of 1 in the graph) would be a 16-MHz 80386 with 8 Mbytes of RAM and 40 Mbytes of hard-drive space. The figure compares processor performance in terms of Intel's iCOMP index (www. cpuscorecard.com), RAM and disk storage on the basis of size, and wireless networks on the basis of maximum bits per second of data transfer. I determined the battery energy density on the basis of the technology type (nickel cad-mium, nickel metal hydride, or lithium ion) and the progression these technologies made in increasing the joules stored per kilogram. I determined the graph's statistics by examining the typical specifications of the highest-end laptop advertisements in the December issues of Byte and PC Computing magazines …