Akku-Craft Arduino INA226 Hand Crank Generator

An Arduino-based measurement system for a hand generator (crank dynamo) with INA226 current sensor and OLED display.

Project Overview

This project measures and displays real-time parameters of a hand generator:

• Voltage (U) - in Volts
• Current (I) - in Amperes
• Power (P) - in Watts
• Energy (E) - in Watt-Hours (Wh)

The measured values are displayed simultaneously on a small OLED display and via serial console.

The Hand Crank Generator

Hardware

Components

• Arduino Uno R3
• INA226 Current Sensor
• SSD1306 128 x 64 OLED Display - Buy on Amazon
• Hand Crank Generator - Buy on AliExpress

Schematics

The schematics will be available soon.

Features

Measurements

• Real-time Values: Continuous capture of all parameters
• Energy Calculation: Cumulative storage of generated energy based on power and time
• Threshold Detection: Measurements start at voltages > 3.0 V

Display

• OLED Display: Compact display for portable use
• Serial Monitor (9600 Baud): Detailed data output for analysis and debugging

Software

Libraries Used

• GyverINA - INA226 sensor control
• U8g2lib - OLED display driver
• Wire - I2C communication

Installing Dependencies

# Via Arduino IDE or PlatformIO
# Search term: GyverINA
# Search term: U8g2

Configuration

Adjusting Shunt Resistance

The file src/main.cpp contains the shunt configuration (around line 18):

INA226 ina(0.002f, 5.0f);  // 2 mOhm shunt, max. 5 A

Calculation for other shunt values:

• Max. expected current: 5 A
• Max. voltage drop across shunt: 80 mV
• Shunt resistance = 0.08 V / 5 A = 0.016 Ω

I2C Addresses

• INA226 (default): 0x40
• OLED Display (default): 0x3C

Upload & Operation

Using Arduino IDE

1. Open Arduino IDE
2. File → Examples → GyverINA → ... load example
3. Install required libraries
4. Board: Arduino Uno
5. Select port
6. Upload

Using PlatformIO

pio run --target upload

Serial Monitor

• Baud rate: 9600
• Shows: Sensor status, calibration value, live measurement data

Measurement Results

The system displays the following information:

On OLED Display:

U: 12.5 V    I: 0.45 A
P:  5.6 W    E: 0.12 Wh

In Serial Monitor (example):

INA226...connected!
Calibration value: 20480
U: 12.5 V, I: 450 mA, P: 5.6 W, E: 0.12 Wh

Important Notes

⚠️ Warning! INA226 Shunt Voltage Measurement Range:

• Maximum shunt voltage: ±81.92 mV
• With 0.1 Ω shunt: max. ~820 mA measurable
• With 0.002 Ω shunt: max. ~5 A measurable
• Shunt voltage should not exceed 80 mV!

Troubleshooting

Problem	Solution
INA226 not found	Check I2C address, call Wire.begin()
Display stays black	Check OLED I2C address (default: 0x3C), verify connections
Measurement values inaccurate	Adjust calibration value, check shunt resistance
No data in Serial Monitor	Set baud rate to 9600, check USB cable

License

This project uses open-source libraries. See the documentation of the used libraries for details.