Brought to you by Keysight Technologies
By Shawn Lee, Keysight Technologies
The Internet of Things (IoT) has become the norm in various industries, including transportation, healthcare, smart homes, agriculture, wearables, and more, thanks to technological advancements and the miniaturisation of printed circuit boards (PCBs). It seamlessly integrates into our daily lives.
Some IoT devices, like wearables and sensors, are battery-powered and low-powered. This feature ensures their portability without the need for direct power sources. However, it also limits their operational lifespan.
Consequently, engineers must prioritise comprehensive monitoring of the device’s battery in their testing procedures. Optimising the battery life is crucial to enhancing both reliability and lifespan.
Navigating the complexities of IoT battery testing
The intricate nature of testing IoT device batteries arises from multiple factors. A key consideration involves the influence of environmental conditions on battery longevity.
Given the deployment of these devices in environments characterised by fluctuating temperatures, IoT devices must adapt to diverse surroundings, including extreme cold or heat. Such environmental extremes have the potential to significantly impair the battery life of your IoT devices.
Charging or discharging a battery at a high temperature can accelerate the chemical reactions within the battery, reduce its internal resistance, and increase its performance and storage capacity, and prolonged exposure to high temperatures causes accelerated aging and reduces the battery’s lifespan.
It is the same when the IoT device operates in an extremely cold environment; the battery temperature drop increases internal resistance. This is because the movement of ions, their transfer rate, and the overall chemical reactions between the electrodes and electrolytes within the battery are reduced at cold temperatures.
This translates to higher internal resistance, making charging and discharging difficult. This, in turn, reduces the amount of energy that the battery can produce or store. Hence, it is vital to thoroughly test or simulate batteries under different operating conditions to ensure their dependability.
Figure 1 shows how temperature can affect the capacity curves of a battery.
Testing products in real-world environments is of paramount importance, including the simulation of a device grappling with subpar network coverage. This scenario necessitates the data’s recurrent retransmission to achieve successful data transfer.
The frequency of retransmissions directly correlates with heightened power consumption and accelerated battery depletion. As a result, most IoT devices employ diverse modes, such as sleep, active, and idle modes, to conserve battery life.
Each mode exhibits a distinct power consumption profile, necessitating comprehensive simulation of the device’s battery life across various power states to ascertain the overall battery performance precisely.
Another challenge in testing IoT device batteries is their small size. Manufacturers often use small batteries with limited capacity to keep IoT devices lightweight and compact. This makes it challenging to test battery life accurately.
Unleashing battery potential: Profiling, emulation, and long-term evaluation for extended battery performance
Besides selecting the appropriate battery chemistry and device design, an essential factor in achieving extended battery life is accurately characterising the battery’s performance under various conditions.
Characterising or profiling the battery early in the product design phase is crucial as it can help prevent unnecessary costs resulting from poor designs.
Testing the battery life presents unique challenges that require specialised equipment and software for accurate evaluation. This includes using battery profilers and emulators, data loggers, and other necessary software capable of emulating and profiling batteries in various operating modes and conditions to ensure device reliability.
These instruments measure essential parameters like battery capacity, cycle life, impedance, and optimal operating temperature. There are various all-in-one battery emulators and profiler solutions available in the market that can perform various tests on batteries.
Among these are the Keysight E36731A Battery Emulator and Profiler and the Keysight BV9210B PathWave BenchVue Advanced Battery Emulation software.
Let’s look at how the battery emulator and profiler can be a valuable tools that can aid engineers in this process in the following sections
Understanding battery performance through profiling
Battery profiling provides a deep understanding of the battery’s energy storage and discharge characteristics over time. By accurately mapping the battery’s OCV (open circuit voltage) and IR (internal resistance) during discharge, profiling enables a realistic assessment of its capacity and performance in real-world scenarios.
Parameters such as temperatures, load current profiles (constant/dynamic), and different operating modes, including constant current, power, and internal resistance, can affect battery life, so it is important to create different battery profiles to match specific discharge conditions.
This information is invaluable for optimising power management strategies and developing efficient algorithms to maximise battery life.
Evaluating battery’s long-term behaviour through charge/discharge cycling
Over time, the chemical composition of batteries deteriorates naturally. Engineers need to understand how batteries perform as they age.
Here, the cycler function of battery emulators becomes valuable. Engineers can simulate the battery operating for extended periods, spanning years, using the emulator and utilising the cycler to repeat charging and discharging cycles to assess battery aging.
These insights are invaluable in designing batteries for IoT devices. With the battery cycler feature, an engineer can easily monitor the performance and capacity degradation over time.
Designing a good battery for IoT devices requires a thorough understanding of battery technology, device requirements, and environmental considerations.
By taking an integrated approach to battery design and incorporating the latest industry standards and testing equipment, manufacturers can create batteries that are safe, reliable, and optimised for the needs of their devices.
Selecting the right tool is key to designing a good battery, resulting in improved device performance, longer battery life, and better user experiences.
About the author
Prior to joining Keysight Technologies, Shawn Lee worked as an instructional designer at Dell and Motorola Solutions. He holds a degree in Computer Science from the University of Bolton in the UK. His current area of specialisation is board test technology