In focus: IoT and batteries in the extreme cold

IoT applications are often exposed to challenging environmental conditions.

When it comes to extreme cold – the devices and their components need to withstand sub-zero temperatures while maintaining reliable performance. That’s true of outdoor uses (no one wants to replace failed batteries in freezing temperatures) but also for indoor applications. Smart devices in buildings play a vital role for security, safety and day-to-day operations, and they need to function yearround, regardless of climate.

Batteries work best at moderate room temperatures. That’s because chemical reactions are affected by temperature and, since a battery relies on a chemical reaction to provide energy, even a small change in temperature can affect a battery’s capacity and service life.

At low temperature, the chemical reactions in the cell are less efficient and molecules slow down. As a result, internal resistance of the battery increases and it won’t be able to deliver the same level of power. It can deliver the current but at a lower voltage level, resulting in a lower efficiency of the electronics and therefore higher consumption.

So, anticipating and planning for cold temperature conditions is important before selecting the optimum battery solution for a device. In extreme settings ‘off the shelf’ is rarely the way to go, and innovative bespoke solutions are the best path towards efficient, reliable performance.

See our infographic. What you need to know about the impact of temperature on lithium batteries

Here we explore some of the ways in which IoT devices are being used in super-cold settings.

At the extremes

The most obvious cases might be found in remote communities or industrial installations in polar regions.

Here, the batteries powering ‘day to day’ IoT devices require an ability to perform despite freezing temperatures, but there are further requirements for more location-specific applications including cargo asset tracking, maritime Automatic Identification Systems (AIS) and environmental sensors (e.g., weather/ocean buoys).

One such location is Svalbard, a Norwegian archipelago in the Arctic Ocean covered with glaciers.

Here, Kongsberg Seatex AS uses Saft batteries to power their AIS base stations, providing a continuous overview of the identity, position, speed, and course of ships that can be transmitted for efficient vessel traffic management.

Each station is powered by 33 battery packs of rechargeable lithium-ion MP 176065 xtd cells, each containing 9 smaller battery packs, designed and assembled by Saft using a special insulating casing and drawing on an innovative charging solution using silicon coated wind turbines coupled to solar panels.

Once the station’s batteries are fully charged, excess energy created by the turbine is used to heat the base station cabinet that holds the batteries, thus preserving the batteries’ capacity – helping to provide up to 10 years lifetime in the field.

Operating beyond cold climates

Performance at cold temperatures is a concern beyond these remote locations.

Though rising global temperatures will intensify the incidence of extreme heat events, studies suggest that the risk of more severe cold events too, per the findings of a study published in the journal npj Climate and Atmospheric Science.

Aiguo Dai, Distinguished Professor in the University of Albany’s Department of Atmospheric and Environmental Sciences, explained “Studies have shown that while the overall global temperature is rising due to climate change, extreme cold events can still occur and may even become more frequent in certain regions due to the rapid warming of the Arctic.”

Perhaps there is no more striking example than the freezing temperatures seen in Texas during February 2021. This historical winter event set many records, including the longest freezing streak in the state’s recorded history, and caused state-wide blackouts, hundreds of fatalities, and serious environmental damage.

With that in mind, the likelihood is that other uses for IoT devices in cold temperatures will emerge as city planners, industry, utility providers the agriculture sector adapt to the possibility of extreme cold snaps.

There are also cases where batteries are deployed in devices specifically to keep things cold.

Refrigerated transport is essential for moving vital resources – not least food and medical shipments such as donor organs and vaccines. Failure to keep the cargo’s temperature within the required parameters is highly costly (not just in financial terms).

During the Covid-19 pandemic, Saft’s Tadiran batteries were used to ensure the cold chain of vaccines.

For Pfizer / BioNTech’s vaccines, round-the-clock monitoring was needed to ensure that they stayed between -80°C and -60°C to remain effective. Pfizer designed thermal shippers that use dry ice to maintain the doses in that temperature range, and each precious shipment was monitored by a GPS-enabled thermal sensor, which tracked its route and temperature from the factory floor until delivery.

More than two million lithium thionyl chloride (LiSOCl2 ) batteries were ordered by companies supplying temperature loggers to vaccine manufacturers. The battery works by using an electrolyte that is not water-based, and so does not freeze, providing a highly reliable battery with a long lifespan that can operate extremely cold conditions.

Planning for the effect of cold temperatures on a battery’s lifetime

Developers will often use computer modelling to assess how a battery, and other components, will respond when deployed in operating conditions.

Jean-François Savin, Application Engineer in the Connected Smart Energy (CSE) division, explains how Saft uses its own temperature models to see how batteries might adapt.

“We have a series of temperature profiles that allow us to gauge likely performance in multiple places across the globe. Sometimes a customer is developing a device specifically for use in Arctic conditions, but often they’re thinking about how more universal products might perform differently in different temperatures.”

“So, we can pick Moscow, Paris, and Dubai, for example, and show a customer how a battery will perform in those different locations when considering their application’s particular profile. These models are vital because temperature is rarely a linear consideration. You must account for seasonal variations and in a desert city, for example, the difference between day and night temperatures can be vast.”