How Battery-Powered Wireless Sensors Help Preserve Water Resources

Wireless monitoring system

Wireless monitoring systems are becoming essential to numerous applications, including smart metering, leak detection solutions, pipeline and tank level monitoring and valve actuation.

By Sol Jacobs

Battery-powered remote wireless sensors are at the heart of modern water infrastructure. Within industrialized nations, wireless monitoring systems are essential to numerous applications, including smart AMR/AMI metering, leak detection solutions, pipeline and tank level monitoring and valve actuation, just to name a few. Advanced wireless technology is also being utilized in underdeveloped nations to help people in need, including the wireless monitoring of hand pumps that deliver fresh potable water to remote villages.

Common to all of these applications is the need for battery-powered devices that are designed to deliver long-life reliability.

Lithium Thionyl Chloride Batteries Support All Types of Water Infrastructure

Bobbin-type LiSOCl2 batteries are preferred for long-term deployment in low-power applications that draw current measurable in micro-amps. This battery chemistry delivers unique performance benefits, including higher capacity and energy density along with the widest possible temperature range (-80°C to 125°C). Most importantly, bobbin-type LiSOCl2 cells feature very low annual self-discharge.

While all batteries experience some level of annual self-discharge, even when disconnected from an external load, Bobbin-type LiSOCl2 cells deliver the lowest self-discharge of any commercially available technology. This is due to their unique ability to harness the passivation effect.

Passivation occurs when a thin film of lithium chloride (LiCl) forms on the surface of the lithium anode, thus impeding the chemical reactions that cause battery self-discharge. Whenever a load is placed on the cell, this passivation layer causes high initial resistance along with a temporary drop in voltage, which quickly recedes: a process that repeats each time the load is removed.

Cell passivation is also affected by other factors, including; cell capacity; length of storage; storage temperature; and cell discharge temperature. Partially discharging a cell then removing the load increases the passivation effect relative to a new battery. While high levels of passivation can be beneficial, too much of it can be problematic if it blocks energy flow.

Battery self-discharge is additionally influenced by the purity of raw materials and the method by which the cell is manufactured. The highest quality bobbin-type LiSOCl2 cells lose just 0.7 percent of their total capacity each year due to self-discharge, enabling up to 40-year battery life. By contrast, an inferior quality bobbin-type LiSOCl2 cell can lose up to 3 percent of its nominal capacity each year due to self-discharge, exhausting 30 percent of its capacity every 10 years, which limits its operating life to as little as 15 years.

The reality of 40-year battery life was validated by Aclara. When replacing older MTUs with upgraded technology, Aclara tested random samples of the older batteries and found that they had retained a significant amount of unused capacity even after 28-plus years in the field.

Related — The Power of Metering: How Long-life Batteries Affect AMI Profitability

AMR/AMI Metering Devices

AMR/AMI metering systems are proliferating, with extended battery life deemed as essential. Ultra-long-life batteries can be critical to the deployment of ultrasonic meter transmitter units (MTUs) that contain no moving parts, thus able to last indefinitely, limited only by the life of the battery.

A study by Dr. Hans Allender entitled “Determining the economical optimum life of residential water meters” analyzed non-commercial water usage in Arundel County, MD. This study indicated that mechanical water meters operate reliably for years but become increasingly inaccurate over time, reaching a point where the accrued savings do not match the growing water losses. This data identified a point of optimization where mechanical meters should be replaced after 16 years. As electronic meters cost twice as much, they and their batteries should ideally work for 30 years before they are replaced. Ultrasonic meters can last even longer as they have no mechanical parts that wear out.

To extend the operating life of an MTU, leading AMR/AMI meter manufacturers rely upon bobbin-type lithium thionyl chloride (LiSOCl2) cells. How important is extended battery life to a successful AMR/AMI deployment? Very important, according to a survey conducted by the California Energy Commission (CEC-2010-08). This survey found that 62 percent of respondents from the Association of California Water Agencies (AWCA) indicated ‘meter battery life’ as a major concern, ranking even higher than cost (60 percent).

Powering an ultrasonic MTU that features practically unlimited operating life with a short-lived battery is hard to justify since it can result in unnecessary battery change-outs, delayed and inaccurate billing, reduced customer service, and loss of vital data. The potential fallout from a premature large-scale, system-wide battery failure is so problematic that municipalities have been forced to preemptively replace thousands of batteries each year just to avoid potential chaos.

Two-Way Wireless Communications Demand High Pulse Energy

Standard bobbin-type LiSOCl2 batteries are designed to deliver low-rate power, but not to generate the periodic high pulses required to power two-way wireless communications. This challenge can be easily overcome with the use of a patented hybrid layer capacitor (HLC). The standard bobbin-type LiSOCl2 cell delivers low daily background current, while the HLC delivers periodic high pulses to power wireless communications. As an added bonus, the HLC also features an end-of-life voltage plateau that can be interpreted to deliver ‘low battery’ status alerts, providing utilities with ample time to schedule battery replacements.

Battery-Powered Sensors Bring Fresh Water to Remote Villages

Remote wireless technology isn’t just essential to the industrialized world. It also works in underdeveloped nations to ensure continuous access to clean potable water.

The installation of remote wireless monitoring devices is being funded by Charity Water, a not-for-profit that supports the construction and maintenance of hand-pumped water wells in remote villages and hamlets. To date, Charity Water has financed the construction of more than 50,000 wells, positively affecting 785 million lives or roughly one tenth of the world’s population.

bringing water to remote villages

Charity Water and Twisthink partnered on a portfolio of IIoT-based solutions that leverage the capabilities of remote wireless sensors, two-way communications and AI to ensure proactive pump repair and maintenance in underdeveloped nations.

Lack of access to clean drinking water is responsible for nearly half of all diseases found in underdeveloped nations. Unfortunately, a heavily used hand-pump typically needs repair after just 11 months. Yet, on average, it takes four years to repair a broken hand-pump, leaving 30 percent of water wells inoperable at any given time.

To rectify this problem, Charity Water engaged Twisthink, a leading engineering and industrial design firm, to develop a portfolio of IIoT-based scalable solutions that leverage the combined capabilities of remote wireless sensors, two-way communications, and artificial intelligence (AI) to ensure more proactive pump repair and maintenance. The latest sensors measure not only water delivered but also the vertical travel of the rod during pumping. This metric is a predictor of pump health.

“The goal was to see if we could take a water pump in the middle of Ethiopia, connect it to the cloud, see how much clean water was flowing remotely, and know the community would continue to be served over time,” says Scott Harrison, CEO of Charity Water.

Lack of access to clean drinking water is responsible for nearly half of all diseases found in underdeveloped nations. Unfortunately, a heavily used hand-pump typically needs repair after just 11 months. Yet, on average, it takes four years to repair a broken hand-pump, leaving 30 percent of water wells inoperable at any given time.

The battery-powered sensors are integrated or affixed to the pump housing to create a weather- and tamper-proof solution. To extend battery life, these devices operate mainly in a low-power ‘stand-by’ mode, transmitting data via 2G and 3G cellular radio or satellite twice a day or whenever hand-pumping activity is detected.

Use of a bobbin-type LiSOCl2 cell ensures reliable performance for up to 10 years, resulting in a cost-effective solution that is compact and lightweight for ease-of-transport.

Twisthink specified Tadiran TLP-913111 bobbin-type LiSOCl2 batteries in combination with an integrated Hybrid Layer Capacitor (HLC) that delivers the periodic high pulses required to power advanced two-way wireless communications. TPL-9311 batteries were preferred for their extended operating life, high capacity, high energy density and the ability to withstand extreme temperatures. Having attained major international safety certifications, these batteries provide Twisthink with greater confidence knowing that consistent product quality can be maintained over multiple production runs.

To date, Charity Water has installed nearly 7,300 of these wireless sensors, keeping fresh water flowing to approximately 100 million people in need. From wealthy industrialized nations to poor underdeveloped nations, scalable IIoT-enabled battery-powered wireless devices are increasingly essential to providing worldwide access to safe drinking water.

Sol Jacobs is the vice president and general manager of Tadiran Batteries. Jacobs has more than 30 years of experience in developing battery-powered solutions for remote wireless devices. His educational background includes a BS in Engineering and an MBA.

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