How to Use Adafruit 20mm Coin Cell Breakout Board : Examples, Pinouts, and Specs

The Adafruit 20mm Coin Cell Breakout Board is a small, convenient holder for 20mm coin cell batteries, such as the CR2032. It provides an easy way to incorporate a small power source into your electronics projects. This breakout board is particularly useful for low-power applications, wearable electronics, and small portable devices.

• Wearable electronics
• Small gadgets and toys
• Real-time clocks (RTCs)
• Backup power for memory chips
• Small microcontroller projects

• Battery Compatibility: 20mm coin cell batteries (e.g., CR2032)
• Operating Voltage: Typically 3V (depending on the battery used)
• Maximum Current: Dependent on the battery specifications
• Operating Temperature: -20°C to +85°C
• Dimensions: 23mm x 12mm x 2mm / 0.9" x 0.5" x 0.08"
• Weight: 1.4g

1. Inserting the Battery:

   • Open the battery holder by gently prying the clip.
   • Place the 20mm coin cell battery with the positive side facing up.
   • Close the clip to secure the battery in place.

2. Connecting to a Circuit:

   • Solder wires or connect alligator clips to the BAT+ and BAT- pins.
   • Connect the BAT+ to the VCC or power input of your circuit.
   • Connect the BAT- to the ground (GND) of your circuit.

• Ensure the battery is inserted correctly with the positive side facing up.
• Do not apply force when closing the battery holder clip to avoid damaging the board.
• Check the battery voltage and current capabilities to ensure they match your circuit requirements.
• Avoid short-circuiting the battery terminals as it may lead to battery damage or depletion.
• When soldering, be quick and precise to prevent heat damage to the board and battery.

• Battery not providing power: Ensure the battery is properly inserted and the holder clip is securely closed.
• Intermittent power: Check for loose connections or cold solder joints at the BAT+ and BAT- pins.
• Short battery life: Confirm that the battery is fresh and that there are no short circuits or excessive current draws in your circuit.

• Double-check the orientation of the battery.
• Inspect solder joints and re-solder if necessary.
• Measure the battery voltage with a multimeter to ensure it is within the expected range.
• If the battery drains quickly, review your circuit's power consumption and consider power-saving techniques.

Q: Can I recharge the coin cell battery using this breakout board? A: No, this breakout board does not support recharging. Use only non-rechargeable batteries.

Q: What is the maximum battery size that can fit in this holder? A: The holder is designed for 20mm diameter coin cell batteries, such as the CR2032.

Q: Is it possible to replace the battery while the circuit is powered? A: It is not recommended to replace the battery while the circuit is powered, as this may cause voltage fluctuations that could damage sensitive components.

// Example code to read the battery voltage using an Arduino UNO

const int batteryPin = A0; // Connect BAT+ to analog pin A0

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(batteryPin); // Read the battery voltage
  float voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage
  Serial.print("Battery Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");
  delay(1000); // Wait for a second before reading again
}

Remember to adjust the voltage conversion calculation if you are using a reference voltage other than 5V. The code above assumes that the Arduino's AREF is set to 5V and that the battery voltage does not exceed the AREF voltage.