To begin with, this article show how to make charger which uses sunlight to charge 12V battery like car or some toy.
Normally, charger need electricity, but here it uses solar panel, so it is good for place where no power is there.
We call this circuit Simple Solar Battery Charger Circuit with IC LM317 which takes sun energy and charge battery, so we can use it for phone, laptop, car battery, lamp, fan and more.
However, this charger do not connect direct to device, but instead, it has one battery inside, so this battery store solar power like small juice box.
Later, we use this stored power to charge our devices and capacitors also help in this process.
Now, if anyone want to know how it work and how to make it, then go and read more in this article.
What is a Solar Battery Charger Circuit:
A simple solar battery charger is a small device that charges a battery using sunlight and this easy design uses a solar panel to take in sunlight, convert it to electric power, and then charge the battery
Solar Battery Charger Circuit Diagram:

Parts List:
| Components | Quantity |
|---|---|
| Resistors | |
| 220Ω 1/4 watt | 1 |
| 680Ω 1/4 watt | 1 |
| Potentiometer 2k | 1 |
| Capacitors | |
| Ceramic 0.1µF | 1 |
| Semiconductors | |
| Diode 1N5402 | 1 |
| Schottky Diode 50V 3A | 1 |
| IC LM317 | 1 |
| Solar Panel 18V 1A | 1 |
Circuit Working with Formulas:
Solar panel have one special part called photovoltaic cell, it changes sunlight into electric power when sun hit it.
So, we have used one IC chip called LM317 and one knob resistor potentiometer to control voltage.
We get output voltage using this formula:
Vout = 1.25V × (1 + (R2 / R1))
where:
- Vout is the voltage we want.
- R1 connect to adjust pin on LM317.
- R2 connect between output and adjust pin.
Reverse Supply Protection:
Here, we used one diode Schottky, 3A 50V to stop reverse power going back and diode work like this formula below:
I = Is [V / (enV/n.Vt – 1)]
where:
- I is current through diode.
- Is is small reverse current.
- V is voltage across diode.
- n is around 1 for Schottky diode.
- Vt is small voltage which is about 0.026V at room temp.
Also, this help understand how voltage and current move in the circuit and these formulas help to check if circuit is working good.
Furthermore, using 12V power we can charge many electronics device and many devices work fine with this kind of voltage.
How to Build:
To build a Simple Solar Battery Charger Circuit with IC LM317 follow the below mentioned steps:
- First, take solar panel wire positive (+) and negative (–) and connect them to input pin of LM317 chip.
- Also, be sure solar panel gives more voltage than what battery need.
- Now, connect LM317 output pin to positive side of capacitor.
- Then, connect capacitor negative side to batteries negative (–) side.
- After that, take one side of potentiometer and connect to adjust pin on LM317.
- And other side of potentiometer connects to capacitors negative (–) side.
- Also, middle pin of potentiometer is for setting exact voltage we want.
- Now take Schottky diode and connect anodes flat side to batteries positive (+).
- Then connect cathodes side with line to LM317 output pin.
- If we want to show charging then add one LED with resistor and put it across output side in parallel.
- Fix all parts nicely on breadboard or PCB and check all wire and solder properly so there is no short circuit happen.
- After finishing everything, connect it to the solar panel and place the panel under strong sunlight.
- Finally, how fast or well battery charges depends on LM317 setting and solar panel power.
Application and Uses:
Solar battery charger have many uses like:
Firstly, it is very easy to use, just connect USB and charging start, it charges things like laptop, mobile phone and other small electronic stuff.
Furthermore, it help people charge devices easily even when no power plug is there and is good for travelling, camping or going to remote place.
Moreover, circuit is small and portable, as it use low power and is good for small devices like mobile, gadgets.
Conclusion:
This Simple Solar Battery Charger Circuit with IC LM317 is an easy way to take sun power and make it charge our daily devices is using small solar battery charger.
Overall, if we follow all steps and learn how it work, then we can make our own good charger for phone and other things.
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