Reliable, light, long-lasting: how Li-SOCI2 batteries have powered the wireless revolution
In the West, it’s easy to take our water supply for granted. We turn the faucet and water flows out. However, much is wasted on its way to us, predominantly because of aging infrastructure. A 2009 European Environment Agency report into leaky pipes found that up to 50 percent of the supply was lost to leaks in Bulgaria, 30 percent in France and around 20 percent in the UK. Only Germany, with negligible losses, was below 10 percent.
Not only does this increase prices, but also it wastes an increasingly precious resource. UN-Water warns that, by 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity.
One way that Western water companies are combatting losses is by installing smart meters across the network. These detect leaks quickly, enabling the supply to be cut off. A smart meter in your home might alert the water company to a leak if it shows you continue to use water right through the night, for example. Others can be installed on the pipes themselves, allowing the company to spot leaks between the treatment plant and the premises.
But water companies aren’t the only ones making increased use of smart meters. Energy companies have taken to them to give a more accurate measure of gas and electricity use. They can also nudge householders and businesses into more environmentally friendly habits by showing them just how much energy every appliance is using. These meters are often designed for more than 20-years of uninterrupted use in harsh, outdoor environments, so the batteries must be designed to last just as long. The technology the metering companies rely on is the primary lithium thionyl chloride (Li-SOCl2) from Saft and its subsidiary company Tadiran. These batteries have enabled a new generation of meters that can save energy and save money.
It used to be the case that meters were mechanical and had to be read manually, once a month or once a quarter. After battery powered electronics were added meters could be read over short distances, so that the meter reader would be able to save a little time at each stop by not having to get out of their car. The present generation of remote, smart meters don’t need to be read by a person at all; they can transmit all the relevant information back to base automatically. Batteries are used instead of line power for safety reasons, to keep costs down and to ensure that the customer cannot cut the power to the meter.
The batteries making this possible were developed in the 1970s from electrochemistry invented by Saft in 1969. The concept of Li-SOCl2 was developed by Jean-Paul Gabano, an outstanding engineer and researcher who spent 27 years at Saft. It still forms the basis of most of Saft’s primary lithium batteries today.
At the time, Saft and Tadiran, which was acquired by Saft in 2001, were leaders in the technology. The batteries were developed for computer motherboards, providing the power to keep the system clock running when the machine was powered off. This was a booming market in the 1970s, but as computers began to shrink so the batteries were replaced by coin-sized cells.
They soon found a new use, however, in the home-security market, powering intruder alarms. The low power needs of such devices meant that batteries were a good alternative to wired power.
Another use emerged at around the same time; the E-ZPass system employed to collect tolls on roads, bridges and tunnels. With the arrival of long-range transponders, it was possible to replace manned toll booths with dashboard devices that charged a fee without the vehicle needing to stop. Saft/Tadiran has more than 100 million batteries in these gadgets – able to withstand the temperatures of 85°C (185°F) sometimes reached by the inside of a car.
One crucial benchmark for these tasks is long life. Having pioneered batteries that can last for 20 years, Saft is now deploying batteries with a lifetime of 25 years. This is valuable for meter manufacturers because the battery can last as long as the meter. Saft’s batteries are already achieving 40-year battery life.
New uses for lightweight and reliable Li-SOCl2 batteries are still appearing; wireless tracking used to require a lot of power because the tracking devices had to communicate with satellites. However modern units transmit over a shorter range to cellphone towers, which then relay the signal to where it needs to go.
This means less power is required and so Li-SOCl2 primary cells can be used for tasks such as asset tracking, tracking endangered animals or monitoring soil conditions for farmers. The cells are ideal for situations where the battery can’t be changed very often, perhaps because the sensor is in a remote location or even strapped to an elephant.
In smart cities, the battery can be used to power tools such as parking sensors that will share information with the local network, allowing cars to be directed to the nearest available space.
Forty years on from its beginnings as a solution for the nascent personal-computer industry, the Li-SOCl2 primary cell is a technology that still has its best days ahead of it.
These batteries have enabled a new generation of meters that can save energy and save money.
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