Is Battery Power the Coming Rage?

Power is very much on the minds of Automation World readers.

A few have expressed a desire for cheaper and greener electrical power. Readers such as Juan Ojeda, general manager at Control Ingenieria y Automatizacion, in Mexico, said that they would like to see innovations that would reduce the cost of solar and wind energy.

Other readers, however, are looking elsewhere for energy conservation. "Most factories need large amounts of power delivered in a reliable and stable manner," explained Bob Hamilton, systems engineer and consultant, Point Consultants. "Therefore, the answer for them is not solar cells or wind generators." He advocates instead better ways of massaging the power available now.

The lithium battery is one of these ways. In fact, Hamilton believes that the growing popularity of these batteries in computers and peripheral devices is but the beginning of a quiet energy revolution that is already underway. "The lithium battery has done more than anybody would have thought in the last year and a half—more than nickel-cadmium, lead-acid, or the old carbon-zinc have in the last 45 years," he said.

One reason is that lithium batteries are stable over long periods. Not only can a small one last seven to 10 years, but it also can deliver energy at a consistent voltage throughout most of that life. For this reason, most automation suppliers already use these batteries to power their memory devices.

Recharging efficiency is another reason for the revolution that Hamilton describes. "Batteries have always been seen as the most stable power system that we have, but they were always considered to be power hungry," he explained. "You can never get out of it what you put into it." He estimates the efficiency ratios for charging most conventional batteries at around 50 percent. The lithium batteries, however, are revolutionary in that their efficiency is in the 90s.

This efficiency not only reduces the amount of energy needed to recharge them but also makes it easy for production facilities to recharge them with recovered power that would otherwise go to waste. An example is the energy dissipated in motors through magnetic fields. "You could tune a device to pick up that 60 Hertz of magnetic energy," noted Hamilton. Rather than plugging cell phones and other communications devices into chargers plugged into electrical outlets, you could lay them close to an incandescent light or magnetic field. They would recharge themselves from what Hamilton calls "rescued" power.

This combined ability to recover wasted power and to make it available again in a highly stable form has important ramifications for automation. When used on wireless sensors, for example, a lithium battery can power both the collection and transmission of data on remote or moving devices.

Stability of the power also permits moving a growing number of sensitive, bench-type instrumentation into production environments. Such instrumentation has always required a large capital investment to massage and "clean" the incoming bulk power to be stable enough for these devices. Consequently, these instruments were usually confined to laboratories. As these devices continue to shrink, however, they can be fitted with lithium batteries, which can provide nanovolts of resolution and, therefore, remove the barrier barring these laboratory-grade devices from production facilities. Not only does the move enhance the level of control and monitoring, but it also consumes less power.

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