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How to Use FC-75 Li-Ion Battery Charging module: Examples, Pinouts, and Specs

Image of FC-75 Li-Ion Battery Charging moduleDesign with FC-75 Li-Ion Battery Charging module in Cirkit Designer

Introduction

The FC-75 Li-Ion Battery Charging Module is a compact and efficient solution for charging lithium-ion batteries. It is designed to provide safe and reliable charging with features such as overcharge protection, adjustable output voltage, and high charging efficiency. This module is ideal for applications requiring rechargeable power sources, such as portable electronics, IoT devices, and DIY projects.

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Image of Battery-Powered 18650 Li-ion Charger with USB Output and Adjustable Voltage Regulator: A project utilizing FC-75 Li-Ion Battery Charging module in a practical application
Battery-Powered 18650 Li-ion Charger with USB Output and Adjustable Voltage Regulator

This circuit is a battery management and power supply system that uses three 3.7V batteries connected to a 3S 10A Li-ion 18650 Charger Protection Board Module for balanced charging and protection. The system includes a TP4056 Battery Charging Protection Module for additional charging safety, a Step Up Boost Power Converter to regulate and boost the voltage, and a USB regulator to provide a stable 5V output, controlled by a push switch.

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Common Applications

Technical Specifications

Below are the key technical details of the FC-75 module:

Parameter Value
Input Voltage Range 4.5V to 6V
Output Voltage Range Adjustable (default: 4.2V)
Maximum Charging Current 1A
Battery Type Supported Single-cell Li-Ion/Li-Po (3.7V)
Protection Features Overcharge, overcurrent, short-circuit
Efficiency Up to 92%
Dimensions 25mm x 19mm x 5mm

Pin Configuration and Descriptions

The FC-75 module has a simple pinout for easy integration into circuits:

Pin Name Description
IN+ Positive input voltage terminal (connect to power source, e.g., USB or adapter)
IN- Negative input voltage terminal (connect to ground of power source)
BAT+ Positive terminal for the lithium-ion battery
BAT- Negative terminal for the lithium-ion battery
OUT+ Positive output terminal (for powering external circuits, optional)
OUT- Negative output terminal (for powering external circuits, optional)

Usage Instructions

How to Use the FC-75 Module in a Circuit

  1. Connect the Power Source:

    • Attach the positive terminal of your power source (e.g., USB 5V or DC adapter) to the IN+ pin.
    • Connect the ground of the power source to the IN- pin.
  2. Connect the Battery:

    • Connect the positive terminal of the lithium-ion battery to the BAT+ pin.
    • Connect the negative terminal of the battery to the BAT- pin.
  3. Optional Output Connection:

    • If you want to power an external circuit while charging the battery, connect the load to the OUT+ and OUT- pins.
  4. Adjust the Output Voltage (if needed):

    • Use the onboard potentiometer to adjust the output voltage. The default is set to 4.2V, which is suitable for most single-cell lithium-ion batteries.
  5. Monitor Charging Status:

    • The module typically includes an LED indicator to show the charging status:
      • Red LED: Charging in progress
      • Green LED: Charging complete

Important Considerations and Best Practices

Example: Using the FC-75 with an Arduino UNO

The FC-75 module can be used to power an Arduino UNO via its OUT+ and OUT- pins. Below is an example of how to monitor the battery voltage using the Arduino's analog input:

// Define the analog pin connected to the battery output
const int batteryPin = A0; 

void setup() {
  Serial.begin(9600); // Initialize serial communication
}

void loop() {
  int sensorValue = analogRead(batteryPin); // Read the analog voltage
  float batteryVoltage = sensorValue * (5.0 / 1023.0) * 2; 
  // Convert the analog reading to voltage. Multiply by 2 if using a voltage divider.

  Serial.print("Battery Voltage: ");
  Serial.print(batteryVoltage);
  Serial.println(" V");

  delay(1000); // Wait for 1 second before the next reading
}

Note: If the battery voltage exceeds 5V, use a voltage divider to scale it down before connecting to the Arduino's analog pin.

Troubleshooting and FAQs

Common Issues and Solutions

  1. Module Overheating:

    • Cause: Charging at maximum current (1A) for extended periods without proper ventilation.
    • Solution: Use a heat sink or ensure adequate airflow around the module.
  2. Battery Not Charging:

    • Cause: Incorrect wiring or insufficient input voltage.
    • Solution: Double-check the connections and ensure the input voltage is within the 4.5V to 6V range.
  3. Output Voltage Not Adjustable:

    • Cause: Faulty potentiometer or incorrect adjustment.
    • Solution: Gently turn the potentiometer with a small screwdriver and verify the output voltage with a multimeter.
  4. LED Indicators Not Working:

    • Cause: Damaged LEDs or incorrect input voltage.
    • Solution: Verify the input voltage and check the module for physical damage.

FAQs

Q1: Can I use the FC-75 module to charge multiple batteries in series?
A1: No, the FC-75 is designed for single-cell lithium-ion or lithium-polymer batteries only. Charging multiple batteries in series requires a specialized balancing charger.

Q2: What happens if I connect a battery with a different nominal voltage?
A2: Using a battery with a nominal voltage other than 3.7V may result in improper charging or damage to the battery. Always ensure compatibility with the module's default output voltage (4.2V).

Q3: Can I use the module without a battery connected?
A3: Yes, the module can function as a voltage regulator to power external circuits, but it is primarily designed for charging batteries.

Q4: Is the module protected against reverse polarity?
A4: No, the FC-75 does not include reverse polarity protection. Ensure correct wiring to avoid damage.