Voltage measurement - Arduino

Continuing the overview of modules for the Arduino, we move from current measurement to voltage measurement. We will introduce several compatible sensors for Arduino, which have the option of 5V power supply with max. 5V output. All of the modules are designed in the manner of a voltage divider, while the maximum measurable voltage is at the level of 25 / 26V. They use a 5: 1 voltage divider.

Voltage sensor

Voltage sensor 0-25V is the most primitive sensor available for measuring voltage in DC circuits with a measurable range of 0-25V. As it does not contain any chip / circuit, no name, it is only referred to as a voltage sensor. The sensor includes a terminal block for parallel connection of the circuit on which we want to perform the measurement.

The sensor is equipped with a 5: 1 voltage divider using a 30kohm and 7.5kohm resistor. The power supply of the sensor is at 5V. The sensor also includes a mounting hole for attachment to an object / object. The cheapest available module with a price level of 0.28 €.

INA3221
We introduced the INA3221 sensor in more detail in the last article focused on current measurement. This sensor can measure voltage and current, even on up to three appliances at once. A power supply is also connected to the sensor. The range of measurable voltage is 0-26V.

The advantage is communication via the I2C bus, while it is possible to emulate up to 3 other sensors by soldering the surfaces A0 and A1. In total, it is possible to connect up to 4 INA3221 modules with voltage measurement for 4 separate circuits to the Arduino I2C bus. As the sensor consumes only 350µA, it is suitable for embeeded battery-operated applications. Power supply of the module is possible in the range

In addition to these modules, there are a number of modules for measuring voltage, either at the level of separate modules or extended by other chips that allow you to measure the flowing current. For example, the MAX471 is available, which exists in various versions on the modules offered.

It contains a voltage divider, MAX471 performs current measurement. Measurable voltage according to the seller in the range of 3-26V.

When measuring voltage, it is advisable to perform several measurements and averaging. It is recommended to perform at least 100 measurements before the average voltage value. The maximum measurable voltage range can be adjusted by changing a suitable voltage divider. However, the measurable voltage resolution decreases to a greater extent.

Overview of projects implemented by me: https://arduino.php5.sk

Examples of the use of voltage sensors:

• IoT low-power device with battery status control, which runs on the order of years
• Project using solar panel and Li-ion battery
• Addition of current measurement and calculation of power of peripherals, appliances

Example of practical use: