How to Use Adafruit MicroLipo Charger v2: Examples, Pinouts, and Specs

The Adafruit MicroLipo Charger v2 (Manufacturer Part ID: 1304) is a compact and efficient lithium polymer (LiPo) battery charger designed for charging small LiPo batteries via a USB connection. It features a built-in battery management system, ensuring safe and reliable charging. The charger is equipped with a status indicator LED to provide real-time feedback on the charging process. Its small form factor makes it ideal for portable and space-constrained projects.

• Charging single-cell LiPo batteries for portable electronics
• Powering wearable devices and IoT projects
• Prototyping with rechargeable battery-powered systems
• Educational and hobbyist electronics projects

The following table outlines the key technical details of the Adafruit MicroLipo Charger v2:

The Adafruit MicroLipo Charger v2 has the following key connections:

1. Connect the Battery: Attach the LiPo battery to the BAT+ and GND terminals. Ensure correct polarity to avoid damage.
2. Power the Charger: Plug the MicroLipo Charger into a USB power source using a Micro-B USB cable.
3. Monitor Charging Status:
   • The red LED (CHG) will light up while the battery is charging.
   • The green LED (DONE) will light up when the battery is fully charged.
4. Adjust Charging Current (Optional):
   • By default, the charger is set to 100mA charging current.
   • To increase the charging current to 500mA, solder the jumper on the back of the board labeled "500mA."

• Battery Compatibility: Only use single-cell LiPo batteries with a nominal voltage of 3.7V and a full charge voltage of 4.2V.
• Charging Current: Ensure the selected charging current (100mA or 500mA) is appropriate for your battery's capacity. A general rule of thumb is to set the charging current to 0.5C (half the battery's capacity in mAh).
• Ventilation: Avoid using the charger in enclosed spaces without proper ventilation, as it may generate heat during operation.
• USB Power Source: Use a reliable USB power source capable of supplying at least 500mA for optimal performance.

The Adafruit MicroLipo Charger v2 can be used to charge a LiPo battery that powers an Arduino UNO. Below is an example of how to monitor the battery voltage using the Arduino's analog input:

// Example code to monitor LiPo battery voltage using Arduino UNO
const int batteryPin = A0; // Analog pin connected to the battery's positive terminal
const float voltageDividerRatio = 2.0; // Adjust based on your resistor divider setup
const float referenceVoltage = 5.0; // Arduino UNO's reference voltage (5V)

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 / 1023.0) * referenceVoltage * 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 for the Arduino's analog input (0-5V). For example, use two resistors in series with a ratio of 2:1.

1. Red LED Does Not Light Up:

   • Cause: No power supply or improper connection.
   • Solution: Ensure the USB cable is properly connected to a power source and the charger.

2. Green LED Does Not Light Up After Long Charging Time:

   • Cause: Battery may be damaged or has a very high capacity.
   • Solution: Verify the battery's condition and ensure the charging current is appropriate for the battery's capacity.

3. Charger Gets Hot During Operation:

   • Cause: High charging current or poor ventilation.
   • Solution: Reduce the charging current to 100mA and ensure proper ventilation.

4. Battery Does Not Charge:

   • Cause: Incorrect battery connection or incompatible battery.
   • Solution: Double-check the battery's polarity and ensure it is a single-cell LiPo battery.

Q1: Can I use the charger with a power bank instead of a USB port?
A1: Yes, the charger can be powered by any USB source, including power banks, as long as it provides a stable 5V output.

Q2: Is it safe to leave the battery connected to the charger indefinitely?
A2: Yes, the charger includes overcharge protection, so it is safe to leave the battery connected. However, it is recommended to disconnect the battery once fully charged to prolong its lifespan.

Q3: Can I charge multiple batteries simultaneously?
A3: No, the charger is designed for single-cell LiPo batteries only. Charging multiple batteries in parallel is not recommended.

Q4: What happens if I connect the battery with reversed polarity?
A4: The charger includes reverse polarity protection, but it is always best to double-check connections to avoid potential damage.