The **EPRC05-R2M** is a high-performance, intelligent solar charge controller designed primarily for small-scale solar power systems, such as solar street lights or home lighting kits. It utilizes Pulse Width Modulation (PWM) technology to manage the charging of batteries and protect them from overcharging or deep discharging. ### Key Electronic Specifications | Feature | Specification | | :--- | :--- | | **Model** | EPRC05-R2M | | **Rated Charge Current** | 5A | | **Rated Load Current** | 5A | | **System Voltage** | 12V DC | | **No-load Current** | $\le$ 6mA | | **Charging Mode** | PWM (Pulse Width Modulation) | | **Operating Temperature** | -35°C to +55°C | --- ### Core Electronic Components & Functions #### 1. Microcontroller Unit (MCU) The "brain" of the device. It monitors the voltage of the solar panel and the battery in real-time. It uses digital logic to decide when to initiate charging and when to disconnect the load to prevent battery damage. #### 2. PWM Charging Circuit Instead of a simple "on/off" switch, the EPRC05-R2M uses **Pulse Width Modulation**. * **Bulk Stage:** Constant current sent to the battery. * **PWM Stage:** As the battery reaches its voltage limit, the MCU reduces the pulse width to maintain a constant voltage, ensuring a full charge without gassing or overheating the battery. #### 3. MOSFET Switches The unit utilizes high-efficiency Power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) as switches. These components handle the actual flow of current from the PV panel to the battery and from the battery to the DC load. They are chosen for low internal resistance to minimize heat dissipation. #### 4. Protection Circuitry The electronic design includes several safety layers: * **Over-discharge Protection:** Disconnects the load when battery voltage drops too low. * **Over-charge Protection:** Limits voltage when the battery is full. * **Reverse Polarity Protection:** Prevents damage if the plus/minus wires are swapped. * **Short Circuit Protection:** Protects the internal traces from melting during a fault. --- ### Visual Indicators (LEDs) The board features integrated LEDs to communicate the system status to the user: | LED Color | Status | Meaning | | :--- | :--- | :--- | | **Green** | On/Flashing | Battery is charging / Battery is full | | **Red** | On | Load is active (powering your device) | | **Red** | Flashing | Low battery warning or error |