How to Use USB LiPoly Charger: Examples, Pinouts, and Specs

The USB LiPoly Charger (Manufacturer Part ID: PRT-10083) by SparkFun Electronics is a compact and efficient device designed to charge lithium polymer (LiPoly) batteries via a USB connection. It provides a safe and reliable charging solution with built-in protection features, such as overcharge prevention and short-circuit protection. This charger is ideal for powering portable electronics, wearables, and DIY projects that utilize LiPoly batteries.

• Charging lithium polymer batteries for portable devices
• Powering wearable electronics
• DIY electronics projects requiring rechargeable power sources
• Robotics and IoT devices

The USB LiPoly Charger is designed to work seamlessly with single-cell LiPoly batteries. Below are its key technical details:

The USB LiPoly Charger has the following pin layout:

1. Connect the Battery: Attach the positive terminal of the LiPoly battery to the BAT pin and the negative terminal to the GND pin.
2. Power the Charger: Plug the USB connector into a 5V USB power source (e.g., a computer or USB wall adapter).
3. Monitor Charging: Use the STAT pin to connect an LED for visual feedback. The LED will indicate the charging status:
   • ON: Charging in progress
   • OFF: Charging complete
4. Adjust Charging Current (Optional): To modify the default 500mA charging current, connect an external resistor to the PROG pin. Refer to the datasheet for resistor values corresponding to desired current levels.

• Battery Compatibility: Ensure the connected battery is a single-cell LiPoly battery with a nominal voltage of 3.7V.
• Heat Dissipation: The charger may heat up during operation. Ensure proper ventilation to avoid overheating.
• USB Power Source: Use a reliable 5V USB power source to prevent damage to the charger or battery.
• Polarity: Double-check the polarity of the battery connections to avoid short circuits or damage.

The USB LiPoly Charger can be used to power an Arduino UNO via a LiPoly battery. Below is an example of how to monitor the charging status using the Arduino:

// Example code to monitor USB LiPoly Charger status with Arduino UNO
const int statusPin = 2; // Connect STAT pin of the charger to Arduino pin 2
const int ledPin = 13;   // Built-in LED on Arduino for status indication

void setup() {
  pinMode(statusPin, INPUT); // Set STAT pin as input
  pinMode(ledPin, OUTPUT);   // Set LED pin as output
}

void loop() {
  int chargingStatus = digitalRead(statusPin); // Read the STAT pin
  if (chargingStatus == LOW) {
    // If STAT pin is LOW, charging is in progress
    digitalWrite(ledPin, HIGH); // Turn on the LED
  } else {
    // If STAT pin is HIGH, charging is complete
    digitalWrite(ledPin, LOW); // Turn off the LED
  }
}

1. Battery Not Charging

   • Cause: Incorrect battery connection or polarity.
   • Solution: Verify the battery is connected to the correct BAT and GND pins with proper polarity.

2. Charger Overheating

   • Cause: Insufficient ventilation or excessive charging current.
   • Solution: Ensure proper airflow around the charger and reduce the charging current by adjusting the resistor on the PROG pin.

3. LED Not Lighting Up

   • Cause: Faulty connection to the STAT pin or damaged LED.
   • Solution: Check the wiring and replace the LED if necessary.

4. No Output Voltage

   • Cause: USB power source not providing sufficient voltage.
   • Solution: Use a reliable 5V USB power source and verify the USB connection.

Q: Can I use this charger with a multi-cell LiPoly battery?
A: No, this charger is designed for single-cell LiPoly batteries only. Using it with multi-cell batteries may result in improper charging or damage.

Q: How do I adjust the charging current?
A: Connect an external resistor to the PROG pin. Refer to the datasheet for the resistor value corresponding to your desired current.

Q: Is it safe to leave the battery connected after charging is complete?
A: Yes, the charger includes overcharge protection, so it is safe to leave the battery connected.

Q: Can I use this charger with a power bank instead of a USB wall adapter?
A: Yes, as long as the power bank provides a stable 5V output, it can be used to power the charger.