Introduction

In recent years, there has been a major advance in the area of embedded systems through the use of portable devices applied in various areas of monitoring with IoT (Internet of Things). These devices play a fundamental role in our lives, offering real-time monitoring of machine conditions, weather conditions, road monitoring and many other functionalities.

However, the growth in the use of these devices has also brought to light a significant challenge: energy consumption. As the application of these devices increases, so does the demand for solutions that extend battery life and reduce the need for frequent battery changes or recharges. In this context, developing low-power portable devices powered by batteries has become a priority for manufacturers and developers.

This article aims to present some fundamental circuits and techniques for the efficient development of portable devices with batteries that operate with low energy consumption. Throughout the next sections, we will discuss the importance of intelligent energy management and battery efficiency, some electronic circuits for use with batteries, as well as strategies for monitoring battery energy consumption in real time.

By understanding and implementing these strategies, developers can not only create more sustainable and cost-effective devices, but also deliver an improved and more reliable user experience.

This article will be divided into 3 topics:

• The main batteries used in IoT;
• DC-DC voltage converter circuits to operate with batteries;
• Battery charge monitoring circuits for real-time monitoring of consumption.

Devices for the Internet of Things powered by batteries

Battery-powered Internet of Things (IoT) devices with a focus on low energy consumption are essential to ensuring the efficiency and longevity of operations. These devices are designed to maximize battery life, enabling continuous, reliable operation over long periods.

The key to the success of these devices lies in the combination of hardware and software components optimized for minimal power consumption. This includes the careful choice of low-power sensors, efficient processors, intelligent power management strategies and advanced programming techniques for controlling the CHIP's peripheral circuits.

These devices find application in a variety of scenarios, from monitoring environmental conditions to asset tracking and connected health. By offering an energy-efficient solution, they not only reduce operational costs but also contribute to environmental sustainability, enabling broader and more effective adoption of IoT across diverse industries.

To carry out the electrical supply process, there are different types of batteries that are used. Below, we will highlight the most used types on the market.

Types of Batteries for IoT Applications

The types of batteries most commonly used in IoT devices are those that strike a balance between energy density, size, weight, and longevity. Below we have some types of batteries commonly used in the applications:

Lithium polymer (Li-Po) batteries

Li-Po batteries are a variation of Li-ion batteries, known for their flexibility and thin profile. They are often used in IoT devices with unique form factors or space constraints, such as wearable gadgets and small-scale sensors.

Lithium-ion (Li-ion) batteries

These batteries offer high energy density and a long lifespan, making them ideal for small IoT devices that require reliable power over an extended period. They are commonly found in wearable technology, smart home devices, and remote sensors.

Coin cell batteries

Coin cell batteries, such as those using lithium chemistry (e.g., CR2032), are commonly used in small, low-power IoT devices like temperature sensors, key finders, and small trackers. While they have limited capacity, they are compact and cost-effective for applications that don't require frequent battery replacement.

Alkaline Batteries

These are the most popular batteries that we have been seeing for a long time. It is used in low duty cycle applications mostly. The nominal voltage that a cell possesses is 1.5V and drops up to 0.9V.

They are common in low-power IoT devices, such as temperature sensors, key locators, and other small devices. With an affordable cost and adequate capacity, it offers a reliable source of energy for residential and commercial applications, being easily replaced when necessary.

After all, which battery to choose for the electronic project?

Overall, battery choice depends on factors such as power requirements, device size, and intended use. For IoT devices, where energy efficiency is key, lithium-based batteries continue to be the preferred choice due to their high energy density and long service life.

See the example of this electronic board. It was developed for the purpose of testing and validating internet of things applications with the ESP8266. As you can see, it is powered by a Li-Ion 18650 battery.

From a Li-Ion 18650 battery, we power the circuit of an electronic board with the ESP32. However, you need to be very careful, as this CHIP operates at 3.3V and the battery can supply a maximum voltage of 4.2V when fully charged. After all, how to provide a safe voltage to power the devices through the aforementioned batteries.

DC-DC voltage converter circuits to operate with batteries

Microcontroller devices on the market basically operate with two voltage values: 3.3V and 5V. However, battery voltages are not capable of providing adequate voltage to energize the CHIPs.

Li-Ion batteries, which are widely used, provide a voltage that varies between 3V and 4.2V. Alkaline batteries, for example, when operating with 2 units in series, provide 3V of voltage. These are 2 common cases that occur when working with battery power. However, we have the following problem: What should I do to ensure a safe 3.3V or 5V power supply for a project's microcontroller devices?

This is when the need to use DC-DC converters arises.

What are DC-DC converter circuits?

DC-DC converters are electronic devices that convert a direct current (DC) source from one voltage to another. They play a vital role in electronic circuits with microcontrollers, allowing you to adjust the voltage according to the specific needs of the system.

In microcontroller applications, DC-DC converters are often used to provide stable and suitable voltages to power circuit components, such as sensors, actuators and peripherals. They can raise battery voltage to levels required by devices or, conversely, lower it to meet component operating specifications.

This flexibility makes DC-DC converters indispensable in a wide range of applications, including portable devices, embedded systems and home automation, ensuring efficient and reliable operation of electronic circuits with microcontrollers.

Based on these principles, we have two case studies of using battery-powered DC-DC converters. See the first project below.

DC-DC Step-Up Converter for powering with Alkaline Batteries

The following electronic board project was developed to monitor air quality conditions in an indoor environment, as well as temperature, pressure and altitude through the BME680 sensor.

If you want to have access to the circuit, understand and download the files, click on this link and download right now.

This project uses an ESP32 and to power it it was necessary to use 2 alkaline batteries. The sum of the voltages of these 2 batteries is 3V, however it is not possible to use them to power the entire 3.3V circuit. To do this, it is necessary to use a DC voltage boost circuit.

Therefore, we use the TLV61046A CHIP. All calculations for each electronic component were obtained from the device datasheet. It is a great IC for raising voltages to a value of up to 28V. Check the datasheet and analyze all the information to adapt it to your electronic project.

Next, we have the second case study for Li-Ion batteries.

DC-DC Step-up Converter Circuit for Li-Ion Batteries

The electronic board below was developed to facilitate the creation of Internet of Things projects using the ESP32. It has numerous features and output voltages to facilitate powering sensors with 3.3V and 5V.

If you want to have access to the circuit, understand and download the files, click on this link and download right now.

The electronic board is powered by a Li-Ion battery. Battery voltage can vary between 2.7V and 4.3V. How to use this voltage to power the circuit?

In this project we use the TPS61023 CHIP. It was used with step-up configuration to raise the voltage to 5V. In this way, the voltage will be used to power the sensors and we will also use it to power the ESP32 from a 3.3V AMS1117-3.3 voltage regulator.

We want to highlight that, if you don't want to raise the voltage to 5V, you can configure it to supply a voltage of 3.3V. All of this can be done using the equations provided in the component datasheet.

The two cases above demonstrate the importance of using DC-DC converters to raise or lower the voltage level of batteries to power electronic projects. And another very important point in battery projects is monitoring battery consumption over time. To this end, there are circuits that can help monitor the current and voltage consumption of the circuit's battery.

Battery charge monitoring circuits for real-time monitoring of consumption

Most electronic devices that run on batteries operate with low energy consumption. Managing energy is of great interest to ensure that batteries operate for a long period of time.

Knowing this need, some calculations can be carried out to determine energy consumption and estimate the battery life time to power the project. Furthermore, there are some electronic circuits that are capable of monitoring energy consumption in real time.

What can be done with these electronic circuits?

A great strategy adopted is to use them to monitor the battery voltage, current and power consumed by the circuit. With these parameters in hand, it is possible to generate alerts when the battery is close to being changed or optimize the internal circuits to reduce energy consumption.

The INA219 sensor is the ideal solution for this type of application. This sensor allows you to read an input voltage of 0V to 26V and an input current of up to 3.2V. This sensor communicates via I2C and, in real time, you are able to monitor your battery and determine all desired parameters. Below we have the circuit provided by the manufacturer.

This circuit was developed and used on the development board below.

This electronic board was developed to allow the development of any prototype with the Internet of Things that require power from a Li-Ion 18650 battery and that operate with low energy consumption.

If you want to have access to the circuit, understand and download the files, click on this link and download right now.

On an electronic board like this, the developer can run the application, study energy consumption and adjust peripherals to minimize consumption and maximize battery power. Optimization is a very important point in circuits that operate at low power consumption.

Final Thoughts and Practical applications

All of the strategies presented above are very useful for developing devices that require battery power and that operate with low energy consumption. This makes it possible to develop more efficient devices and guarantee greater longevity for batteries.

Below we provide 2 electronic projects. In each one we explain all the fundamentals necessary for you to develop applications that can use 1.5V alkaline batteries and Li-Ion batteries.

Access every electronic project now and start developing battery-powered projects today.

ESP32 IoT Development Board

IoT Indoor Monitor System

Acknowledgments

We would like to thank PCBWAY for supportting the creation of this project and made some units available for you to earn for free and receive 5 units at your home. To receive them, access this link, create an account on the website and receive coupons for you to win right now.