LCD-LED DisplayLights and Display Board CircuitsSolar Charger


20 Amp Solar Charge Controller Circuit: The Equalize key rapidly charges the battery when activated. If the battery overheats, the charging process is automatically cut off. The controller maintains a constant low current charge to prolong the battery life, similar to how a car charger functions.

Circuit Diagram:

The circuit diagram for a typical 20-amp solar charge controller includes the following components:

  1. Solar Panels: These are the sources of solar energy.
  2. Diode: Prevents reverse current flow from batteries to solar panels during low or no light conditions.
  3. 20-Amp Charge Controller: Contains the control circuitry and MOSFETs to regulate the charging process.
  4. Battery Bank: Stores the energy generated by the solar panels.
  5. Load: The electrical appliances or devices powered by the battery bank.
  6. Indicator LEDs: To display charging status, battery level, and system faults.
  7. Voltage Regulator: Maintains a stable voltage output to the load.
  8. Current Sensor: Measures the current flowing from the solar panels and to the battery bank.
  9. Temperature Sensor: Monitors the temperature of the batteries to adjust the charging voltage accordingly.


  1. Overcharge Protection: Prevents batteries from getting overcharged, ensuring their longevity.
  2. Deep Discharge Protection: Prevents deep discharge of batteries, extending their lifespan.
  3. Short Circuit Protection: Safeguards the system from short circuits in the wiring or load.
  4. Temperature Compensation: Adjusts charging voltage based on the battery temperature to optimize charging.
  5. LED Indicators: Provides information about charging status, battery level, and system faults.
  6. Load Output Control: Can automatically disconnect the load during low battery voltage conditions to prevent complete discharge.
  7. Efficiency Optimization: Utilizes Maximum Power Point Tracking (MPPT) technology for efficient energy harvesting from solar panels.
  8. Low Voltage Disconnect (LVD): Prevents excessive discharge of the batteries by disconnecting the load when the battery voltage is low.
  9. Manual Control: Some controllers come with manual control options to override automatic functions if needed.
  10. LCD Display (Optional): Displays detailed information about solar panel output, battery voltage, and current.


  1. Solar Panel Input: The solar panels generate DC electricity, which is fed into the charge controller.
  2. MPPT (Maximum Power Point Tracking): MPPT technology optimizes the power output from solar panels by adjusting the operating point for maximum power transfer.
  3. Battery Charging: The charge controller regulates the current and voltage supplied to the batteries, ensuring they are charged efficiently without overcharging.
  4. Load Management: The controller supplies power to the connected load, monitoring the battery voltage. If the voltage drops to a specified level (LVD), the load is disconnected to prevent deep discharge.
  5. LED Indicators: The LEDs indicate various system statuses such as charging, battery level, and faults, providing valuable information to the user.
  6. Temperature Compensation: The temperature sensor monitors the battery temperature and adjusts the charging voltage to compensate for temperature variations, ensuring optimal charging under different conditions.
  7. Protection Mechanisms: The charge controller continuously monitors the system for overcharge, deep discharge, short circuits, and other faults. If any issue is detected, the controller takes appropriate actions to protect the components.

Please note that this circuit does not support charging at a rate of 10 amps. To set up the system, I connected the battery output to the battery terminals using an 18V power supply designed for a 12-volt battery. The red LED stays lit continuously and turns off when the power is cut or when the solar panel is disconnected.

To adjust the charging voltage, turn the knob clockwise or counterclockwise until it reaches the desired voltage, such as 14.4 volts (adjustable based on the battery manufacturer’s specifications, for instance, it might be set to 13.8 volts). It’s crucial to connect the outputs to the battery terminals before taking any measurements. When the battery reaches 14.4 volts, the value blinks rapidly, indicating that the battery is charging. The green LED also blinks rapidly, signifying the healthy operation of the system.

I tested the charge circuit with 20 amperes on the breadboard and there is no PCB drawing.



An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second.
One ampere of current represents one coulomb of electrical charge, i.e. 6.24×1018 charge carriers, moving in one second. In other words, “an ampere is the amount of current produced by the force of one volt acting through a resistance of one ohm”.
An ampere is a unit used to measure electric current. Current is a count of the number of electrons flowing through a circuit. One amp is the amount of current produced by a force of one volt acting through the resistance of one ohm. (An ohm is a way of measuring resistance.

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