How to Use 4S 2A 18650 Lithium Battery Charger Board USB C: Examples, Pinouts, and Specs

The 4S 2A 18650 Lithium Battery Charger Board USB C (Manufacturer: Arduino, Part ID: 4S 2A C-Type) is a compact and efficient charging module designed for charging four 18650 lithium-ion batteries connected in series. It supports a maximum charging current of 2A and features a USB-C input for modern and convenient power delivery. This board is ideal for applications requiring a reliable and safe charging solution for high-capacity battery packs.

• Power banks and portable energy storage systems
• DIY electronics projects requiring a 4S lithium battery pack
• Robotics and remote-controlled devices
• Solar energy storage systems
• Backup power supplies for embedded systems

Below are the key technical details of the 4S 2A 18650 Lithium Battery Charger Board USB C:

The charger board has the following key connections:

1. Connect the Batteries:

   • Ensure the 18650 batteries are connected in a 4S configuration (four cells in series).
   • Connect the battery terminals to the corresponding pins on the charger board:
     • B+ to the positive terminal of the first cell.
     • B- to the negative terminal of the last cell.
     • B1, B2, and B3 to the intermediate points between the cells.

2. Power the Charger:

   • Use a USB-C cable to connect the charger board to a 5V power source, such as a USB wall adapter or power bank.

3. Monitor Charging:

   • The onboard LEDs indicate the charging status:
     • Red LED: Charging in progress.
     • Green LED: Charging complete.

4. Connect the Load:

   • Use the P+ and P- terminals to connect the load (e.g., a motor, microcontroller, or other devices).

• Battery Safety: Use only high-quality, protected 18650 cells to ensure safety and performance.
• Heat Management: Ensure adequate ventilation around the charger board to prevent overheating.
• Input Voltage: Do not exceed the 5V input voltage limit to avoid damaging the board.
• Polarity: Double-check all connections to ensure correct polarity before powering the board.
• Balancing: The board includes cell balancing functionality to maintain equal charge levels across all cells.

The charger board can be used to power an Arduino UNO via its P+ and P- terminals. Below is an example code to monitor the battery voltage using the Arduino UNO:

// Example code to monitor battery voltage using Arduino UNO
// Connect the P+ terminal to A0 and P- terminal to GND on the Arduino UNO

const int batteryPin = A0; // Analog pin connected to the battery's positive terminal
float voltageDividerRatio = 5.7; // Adjust based on your resistor divider values

void setup() {
  Serial.begin(9600); // Initialize serial communication
  pinMode(batteryPin, INPUT); // Set the battery pin as input
}

void loop() {
  int rawValue = analogRead(batteryPin); // Read the analog value
  float batteryVoltage = (rawValue * 5.0 / 1023.0) * voltageDividerRatio;
  
  // Print the battery voltage to the Serial Monitor
  Serial.print("Battery Voltage: ");
  Serial.print(batteryVoltage);
  Serial.println(" V");
  
  delay(1000); // Wait for 1 second before the next reading
}

Note: Use a voltage divider circuit to step down the battery voltage to a safe range (0-5V) for the Arduino UNO's analog input pins.

1. The board does not charge the batteries:

   • Ensure the USB-C cable and power source are functioning correctly.
   • Verify that the batteries are connected in the correct 4S configuration.
   • Check for loose or incorrect connections on the B+, B-, B1, B2, and B3 terminals.

2. The board overheats during operation:

   • Ensure the board is not placed in an enclosed space without ventilation.
   • Verify that the input current does not exceed 2A.

3. The load does not power on:

   • Check the P+ and P- connections to the load.
   • Ensure the batteries are fully charged and properly connected.

4. LED indicators are not working:

   • Verify the input power supply and USB-C connection.
   • Inspect the board for any visible damage or loose components.

Q1: Can I use this board to charge fewer than four 18650 cells?
A1: No, this board is specifically designed for a 4S configuration. Using fewer cells may result in improper operation or damage.

Q2: Can I use a power source other than USB-C?
A2: The board is optimized for USB-C input. Using other power sources is not recommended and may void the warranty.

Q3: Does the board support fast charging?
A3: The board supports a maximum charging current of 2A, which is sufficient for most applications but not classified as "fast charging."

Q4: Is the board compatible with other lithium battery types?
A4: The board is designed for 18650 lithium-ion cells. Using other battery types may result in improper charging or damage.