With more IoT devices coming to market, battery duration is essential for product quality and customer satisfaction. More crucially, the safety of many applications and devices ultimately depends on battery performance. When this fails to meet real-world requirements, devices can become a serious threat. As an example, think about IoT devices used in medicine or public safety.
Therefore, the ability to maintain a long-lasting battery and understanding its lifespan is essential for many of today’s IoT innovations. Testing and predicting battery life is more important than ever. With battery emulation and profiling software, device designers can estimate battery life precisely. Moreover, emulation software can evaluate current drain to modify device designs that can extend battery duration.
Battery profiling and characterisation
Batteries are nonideal energy sources because they interact with devices, affecting current drain. Precise current consumption results are crucial for maximising battery life. When using a DC source to power a device, consider the battery’s features to ensure accurate results. Battery profiling and characterisation are essential to understand how much energy a battery can hold and deliver over time. As the battery drains, its open circuit voltage (VOC) and internal resistance (IR) change and these need to be plotted to reflect actual performance in the real world. Figure 1 shows a typical plot example of a battery profile.
Figure 1: A battery profile using a battery test and emulation software.
Factors such as temperature, load current profiles (constant/dynamic), and different operating modes also influence battery behaviour. Battery life depends on these parameters, so making different battery profiles that suit specific discharge situations is essential.
A general-purpose DC source aims to be a perfect voltage source with no output impedance by using remote sensing feedback to maintain its output voltage constant. Unlike a battery, its voltage does not decrease with load current. Moreover, feedback regulation is not instantaneous, which causes voltage drop and overshoot when loading and unloading changes. A significant transient voltage drop can activate a device’s low-battery-voltage shutdown.
When powering a device with a DC source, emulate the battery’s characteristics for current drain results comparable to those of a battery. A regular DC source differs from a battery, but a DC source that can imitate a battery helps users get more reliable results.
Extending battery life
Using a battery emulator instead of a battery has several advantages for device testing. Firstly, it creates a safer test environment as designers do not have to physically charge and discharge batteries, which can become dangerous with repeated cycles. In addition, an emulator achieves repeatable results because the characteristics of an emulated battery remain consistent. An emulator also reduces test setup times by allowing designers to instantly simulate any state of charge (SoC) versus manually draining a battery to the desired level.
A battery emulator operates through several steps. The initial step is to load a battery profile. This profile is the data from a graph of the battery voltage and internal resistance against the SoC. Designers can generate a battery profile using battery modelling software or obtaining a profile from a battery provider.
Creating a profile with modelling software will make the profile match the current consumption for a particular device, which is more precise than a generic profile from a battery supplier. Figure 2 shows a battery profiler with a current consumption profile from a device loaded into it. The software repeats the waveform until the battery runs out of power.
Figure 2: Example of a device’s current consumption waveform loaded into an advanced battery test and emulation software.
The next step is to choose the initial SoC and the termination voltage. Designers will link the device to the emulator and begin the battery emulation with software. Battery emulators constantly monitor the current, whether charging or discharging, to dynamically compute the emulated SoC. The emulator continually adjusts its output (voltage and resistance) according to the SoC to match the loaded battery profile. The test finishes when the emulator reaches the termination voltage if the emulator discharges.
Figure 3: Example of a device’s battery emulation using advanced battery test and emulation software.
Designers can learn more about a device’s behaviour by quickly emulating a battery at various SoCs. Figure 4 shows the information engineers can obtain from a device’s current drain. Engineers can use the data from this analysis to modify the design of the IoT device to improve battery performance.
Figure 4: Current drain analysis of a pulse oximeter medical IoT device using advanced battery test and emulation software.
Cycling battery charge
Engineers need to know the energy a battery can store and deliver to IoT devices. Battery test and emulation software helps monitor battery charging and discharging to measure capacity and support constant current (CC) and voltage (CV) modes. When the battery is nearly full, the software must switch from CC mode to a mix of CC and CV as batteries cannot charge at the same rate at maximum capacity.
The software should also support constant current, constant resistance, and continuous power modes when discharging a battery. Engineers can test and emulate current consumption profiles directly from a device, quickly discharging the battery with usage-matching profiles. Since battery performance deteriorates over time, simulating battery cycling is crucial. The software must also support data logging and various charging and discharging profiles to simulate complex cycles, measuring performance decline over time. Emulation software solutions are ideal for this as they can enable up to one thousand cycle operations to assess aging and reliability under sequence test conditions.
Summary
Battery profiling and emulation software are essential for IoT device power analysis. They help improve battery life, mimic any charge and battery profile state, create more reliable and consistent test environments, and measure capacity loss and aging effects. This is important for product quality, customer satisfaction, and safety in various consumer, medical, and industrial applications.
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