A Solar LED Lantern Circuit is a circuit that uses solar energy to power LEDs in a lantern or light fixture.
It typically consists of a solar panel a rechargeable battery, LEDs and various electronic components such as diodes, resistors and transistors.
Circuit Working:
Parts List:
| Type | Value | Quantity | Note |
|---|---|---|---|
| Resistors | 15Ω | 1 | 1/2W |
| 1.5Ω | 1 | 1/2W | |
| 1k | 2 | 1/4W | |
| Semiconductors | Transistor BC547 | 1 | |
| Transistor 2N2222 | 1 | ||
| Diode 1N4007 | 1 | ||
| LEDs | white straw hat 5mm | 20 | |
| Others | Battery 3.7V | 1 | 800mAh |
| ON/OFF Switch | 1 | ||
| Solar panel 6V | 1 | 5W |
The LED solar lantern circuit described here utilizes a 6V 1W solar panel and a 4V 800mAh lead acid Battery.
It employs common 5mm white straw Hat LEDs as the light source.
The solar panels 6V DC output charges the battery through diode D1 1N4007 and resistor R1 15R.
Diode D1 prevents reverse current and R1 limits the charging current to a safe level.
Transistor T1 BC547 acts as an automatic switch, controlling the LED driver transistor T2 2N2222.
When the solar panel provides sufficient power T1 disables T2.
Switch S1 serves as an ON/OFF switch.
Resistor R4 sets the operating current for the LED assembly.
The solar panels no load voltage is approximately 7.2V delivering around 170mA at 6V DC output in moderate sunlight.
The fully charged battery has a no-load voltage of about 4.6V.
The 5mm white straw hat LED has a forward voltage of 3 to 3.2V and a maximum continuous current of about 20mA with a peak current of 30mA, as per the datasheet.
Formulas:
Formula for Li-ion Battery Backup Time is mentioned below:
Backup time (hours) = (Battery capacity (Ah) * Battery voltage (V) * Battery efficiency) / Load current (A)
here,
- The batteries capacity, expressed in amp hours, indicates how much charge it can hold.
- Battery voltage V is the batteries nominal voltage.
- Battery losses during charging and discharging are taken into account by battery efficiency,usually it falls between 90% and 95%.
- The current that the battery connected gadget draws is known as the load current A.
Crucial Points to Remember:
An estimate is given theoretically by this formula.
Factors like as battery age, load profile, and temperature might affect the actual backup time.
See the batteries discharge curve, which illustrates how voltage varies with capacity for more precise computations.
The battery manufacturers datasheet should always be consulted for precise specifications and performance features.
Extra Information
The total voltage of battery packs with several cells connected in series is the total of the voltages of each individual cell.
The overall capacity of battery packs with many cells connected in parallel is the total of the capacities of each individual cell.
You may determine the backup duration for your Li-ion battery application by comprehending these elements and correctly using the algorithm.
How to build:
To build a Simple Solar LED Lantern Circuit follow the below mentioned assembling steps:
Connect the Solar Panel:
- Connect the positive terminal of the solar panel to the anode of diode D1 1N4007 and the negative terminal to the negative terminal of the battery.
Connect the Battery:
- Connect the cathode of diode D1 to one terminal of resistor R1 15 ohms, and connect the other terminal of R1 to the positive terminal of the battery.
- Connect the negative terminal of the battery to the negative terminal of the solar panel.
Connect the Transistors:
- Wire transistor T1 BC547 as an automatic switch.
- Connect its collector to the positive terminal of the battery, its emitter to the collector of transistor T2 2N2222, and its base to a suitable point in the circuit where it can sense the solar panels output voltage.
Connect the LEDs:
- Connect the anode of each LED to the collector of transistor T2 and connect all the cathodes together.
- Use a resistor R4 in series with the LEDs to limit the current flowing through them.
Connect the Switch:
- Connect the switch S1 in series with the positive terminal of the battery to control the circuits ON/OFF function.
Finalize Connections:
- Ensure all components are securely connected and insulated to prevent short circuits.
Test the Circuit:
- Place the solar panel in moderate sunlight and verify that the LEDs illuminate.
- Adjust resistor values if necessary to achieve desired brightness and current levels.
Note:
- Please note that working with electricity can be dangerous.
- If you are not familiar with electronics consider seeking assistance from someone with experience or consulting a professional.
Conclusion:
A Solar LED Lantern Circuit is a cost effective and eco friendly lighting solution that utilizes solar energy to power LEDs.
It consists of a solar panel, rechargeable battery, LEDs and electronic components to control the flow of energy.
This circuit provides illumination in areas without access to electricity making it a practical and sustainable lighting option.