Empowering the IoT: Strategies for Maximizing Battery Performance and Reliability
IoT (Internet-of-Things) has become the norm in various industries, including transportation, healthcare, smart homes, agriculture, wearables, and more, thanks to technological advancements and the miniaturization of PCBs (Printed Circuit Board). It seamlessly integrates into our daily lives. Some IoT devices, like wearables and sensors, are battery-powered. This feature ensures their portability without the need for direct power sources. However, it also limits their operational lifespan. Consequently, engineers must prioritize comprehensive monitoring of the device’s battery in their testing procedures. Optimizing the battery life is crucial to enhancing both reliability and lifespan.
This article discusses the significance of IoT device battery testing and how battery emulation and profiling software plays a crucial role in this case.
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 characterized 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. 0.5C rate discharge curve of Li-ion battery at different temperatures (Wang, 2017)
Wang, K. (2017). "Study on Low Temperature Performance of Li-Ion Battery" [Research paper]. Retrieved May 30, 2023, from HTML Scientific Research Publishing: https://www.scirp.org/journal/paperinformation.aspx?paperid=80512
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 characterizing the battery's performance under various conditions. Characterizing 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 specialized 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 valuable tool that can aid engineers in this process.
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 optimizing power management strategies and developing efficient algorithms to maximize battery life.
Figure 2. Battery profile created with Keysight BV9210B/11B PathWave BenchVue Advanced Battery Test and Emulation software.
Testing and Evaluation through Battery Emulation
Testing or simulating the device’s performance using a physical battery can be time-consuming and unsafe. One of the engineer’s tasks is to emulate the battery at various states to test it against the device’s design, software, and firmware. This test covers various test scenarios with a combination of hardware and software designs without waiting for an actual battery to go through charge and discharge. The emulator enables the engineers to mimic battery operation according to the selected profile and allows them to run battery tests at a specific SoC, hence reducing test time, improving safety, and increasing test repeatability. Emulating the physical battery behavior helps engineers assess the performance of their devices under different conditions.
Figure 3. Battery emulation using BV9210B/11B PathWave BenchVue advanced battery test and emulation software.
Evaluating Battery’s Long-Term Behavior 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 utilizing 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.
Conclusion
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 optimized 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.