How to Use Lithium Ion Polymer Battery 3.7v 100mAh: Examples, Pinouts, and Specs

The Adafruit Lithium Ion Polymer Battery (Part ID: 1570) is a lightweight, compact, and rechargeable power source designed for portable electronic devices. With a nominal voltage of 3.7V and a capacity of 100mAh, this battery is ideal for low-power applications where size and weight are critical factors. Its robust design and reliable performance make it a popular choice for wearables, IoT devices, and small robotics.

• Wearable electronics (e.g., fitness trackers, smartwatches)
• Internet of Things (IoT) devices
• Small robotics and drones
• Portable sensors
• DIY electronics projects

The battery is equipped with a JST-PH 2-pin connector. Below is the pinout description:

1. Connecting the Battery:

   • Ensure the device or circuit is compatible with a 3.7V power source.
   • Connect the JST-PH 2-pin connector to the corresponding port on your device or battery management system (BMS).
   • Verify the polarity of the connection to avoid damage.

2. Charging the Battery:

   • Use a dedicated LiPo battery charger that supports 3.7V batteries and limits the charge voltage to 4.2V.
   • Connect the battery to the charger using the JST-PH connector.
   • Monitor the charging process to ensure safety and avoid overcharging.

3. Discharging the Battery:

   • Ensure the load does not exceed the maximum discharge current of 100mA.
   • Avoid discharging the battery below 3.0V, as this can damage the cell.

• Safety: Never puncture, short-circuit, or expose the battery to high temperatures.
• Storage: Store the battery in a cool, dry place at a charge level of approximately 50% for long-term storage.
• Battery Protection: Use a battery management system (BMS) to prevent overcharging, over-discharging, and short circuits.

To power an Arduino UNO with this battery, you will need a boost converter to step up the voltage from 3.7V to 5V. Below is an example of how to monitor the battery voltage using the Arduino's analog input:

// Example code to monitor battery voltage using Arduino UNO
const int batteryPin = A0; // Analog pin connected to battery voltage divider
const float voltageDividerRatio = 2.0; // Adjust based on your resistor values
const float referenceVoltage = 5.0; // Arduino UNO's reference voltage

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

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 scale down the battery voltage to a safe range for the Arduino's analog input (0-5V). Choose resistor values accordingly.

1. Battery Not Charging:

   • Cause: Faulty charger or incorrect connection.
   • Solution: Verify the charger is functioning and the JST-PH connector is securely attached.

2. Device Not Powering On:

   • Cause: Battery voltage too low or incorrect polarity.
   • Solution: Check the battery voltage with a multimeter and ensure proper connection.

3. Battery Overheating:

   • Cause: Overcharging or excessive discharge current.
   • Solution: Use a proper charger and ensure the load does not exceed the maximum discharge current.

4. Short Battery Life:

   • Cause: Frequent deep discharges or improper storage.
   • Solution: Avoid discharging below 3.0V and store the battery at ~50% charge.

Q1: Can I use this battery to power a 5V device directly?
A1: No, you will need a boost converter to step up the voltage from 3.7V to 5V.

Q2: How long will the battery last on a single charge?
A2: The runtime depends on the load current. For example, at a 10mA load, the battery can last approximately 10 hours (100mAh ÷ 10mA).

Q3: Is it safe to leave the battery connected to the charger?
A3: It is not recommended to leave the battery connected to the charger indefinitely. Use a charger with overcharge protection.

Q4: Can I use this battery in parallel with another LiPo battery?
A4: Yes, but ensure both batteries have the same voltage and capacity, and use a proper balancing circuit.

By following these guidelines, you can safely and effectively use the Adafruit Lithium Ion Polymer Battery (3.7V, 100mAh) in your projects.