How to Use 20A digital PWM solar Controller with LCD and uSB output Port: Examples, Pinouts, and Specs

The BT61C by Blackt Electrotech is a 20A digital Pulse Width Modulation (PWM) solar charge controller designed to regulate the charging of batteries from solar panels. It ensures efficient energy transfer while protecting the battery from overcharging, over-discharging, and short circuits. The integrated LCD display provides real-time system status, including battery voltage, charging current, and load status. Additionally, the USB output port allows for powering or charging small devices directly from the controller.

• Off-grid solar power systems for homes, cabins, or RVs
• Solar-powered lighting systems
• Battery charging and maintenance for 12V or 24V systems
• Portable solar setups for camping or outdoor activities
• USB device charging directly from solar power

The BT61C features screw terminals for connecting solar panels, batteries, and loads. Below is the pin configuration:

1. Connect the Battery First:

   • Attach the battery's positive (+) and negative (-) terminals to the corresponding BATTERY terminals on the controller.
   • Ensure the battery voltage matches the system voltage (12V or 24V).

2. Connect the Solar Panel:

   • Connect the solar panel's positive (+) and negative (-) terminals to the SOLAR terminals on the controller.
   • Ensure the solar panel's voltage does not exceed 50V.

3. Connect the Load (Optional):

   • Attach the load's positive (+) and negative (-) terminals to the LOAD terminals on the controller.
   • Ensure the load current does not exceed 20A.

4. Monitor the System:

   • Use the LCD display to check the battery voltage, charging current, and load status.
   • The controller will automatically detect the system voltage (12V or 24V).

5. Use the USB Port:

   • Plug in USB devices (e.g., phones, power banks) to the USB output port for charging.

• Always connect the battery before connecting the solar panel or load to avoid damage to the controller.
• Ensure all connections are secure and free of corrosion.
• Use appropriately sized wires to handle the current (e.g., 12 AWG for 20A).
• Place the controller in a well-ventilated area to prevent overheating.
• Avoid exposing the controller to water or extreme humidity.

The BT61C can be used with an Arduino UNO to monitor battery voltage or solar panel performance. Below is an example code to read the battery voltage using an analog input pin:

// Arduino code to monitor battery voltage using BT61C
const int batteryPin = A0;  // Analog pin connected to battery voltage output
const float voltageDividerRatio = 5.0; // Adjust based on resistor divider used
float batteryVoltage;

void setup() {
  Serial.begin(9600); // Initialize serial communication
  pinMode(batteryPin, INPUT); // Set the battery pin as input
}

void loop() {
  int analogValue = analogRead(batteryPin); // Read analog value from battery pin
  batteryVoltage = (analogValue * 5.0 / 1023.0) * 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 (0-5V) for the Arduino analog input.

1. Can I use the BT61C with lithium-ion batteries?

   • No, the BT61C is designed for lead-acid, gel, and AGM batteries only.

2. What happens if I reverse the polarity of the connections?

   • The controller has reverse polarity protection, but it is recommended to double-check connections to avoid potential damage.

3. Can I connect multiple solar panels to the BT61C?

   • Yes, you can connect multiple panels in series or parallel, provided the total voltage does not exceed 50V and the current does not exceed 20A.

4. Does the controller support MPPT (Maximum Power Point Tracking)?

   • No, the BT61C uses PWM (Pulse Width Modulation) for charging.

5. Can I use the USB port while charging the battery?

   • Yes, the USB port can be used simultaneously with battery charging.

This concludes the documentation for the BT61C 20A Digital PWM Solar Controller by Blackt Electrotech. For further assistance, refer to the product manual or contact the manufacturer.