You can build a simple solar charger with a IC 555, this little circuit watches the voltage going to your battery from the solar panel.
When the battery gets full, the circuit acts like a switch and cuts off the power from the panel.
This helps prevent the battery from getting overloaded and potentially damaged.
Circuit Working:
Parts List:
| Category | Description | Quantity | Wattage/Specifications |
|---|---|---|---|
| Resistors | R1 330Ω set to 14.9V | 1 | 1/4 watt |
| R2 330Ω set to 11.9V | 1 | 1/4 watt | |
| 470Ω | 2 | 1/4 watt | |
| Potentiometer | 10k | 2 | |
| Semiconductors | IC1 555 | 1 | |
| IC2 7805 | 1 | ||
| Transistor BD139 | 1 | ||
| LEDs | Red 5mm 20mA (charging indicator) | 1 | |
| White 5mm 20mA (general indicator) | 1 | ||
| Green 5mm 20mA (dumping indicator) | 1 | ||
| Switches | Push button (for dumping) | 1 | |
| Push button (for charging) | 1 | ||
| Diode | 1N4004 | 1 | |
| Relay | 12V relay (40 amp) | 1 | |
| Power Source | Solar panel (16V 60W) | 1 | |
| Battery | 12V battery | 1 |
In this circuit if your solar panel can fully charge the battery in less than 10 hours, then that is the only circumstance in which you need to dump extra current.
The solar panels energy is released into a load when the battery is fully charge, a high power resistor or a 12V 100W globe can be used as this load.
If the battery needs to be charged for at least 14 hours in the sun that is equivalent to two days of light.
The battery can handle this slow rate of charging so you might not even need this circuit.
To charge a battery without using this circuit, just connect a high wattage resistor and diode in series with the batteries and the solar panels positive lines.
After then the battery will only be gradually charged by the solar panel over a few days.
Switch to a flexible power source.
The high wattage resistor, battery, solar panel and relay are not necessary.
Link the variable power supply with the 11.9V setting.
Turn on the charging LED by adjusting the top 10k pot.
To turn on the dumping LED, raise the voltage to 14.9V and adjust the bottom 10k pot.
Before installing the project connect all the parts as indicated in the circuit and double check the voltage levels.
Since the IC1 555 does not like a voltage as low as 5V, the white LED jacks up the IC2 7805 to generate an output of 8.5V
Simply push either button fast to manually charge or dump energy.
The IC1 555 will toggle to the necessary state and carry out the charging or discharging process.
Here is what to do if your power source is not variable:
Fit a little 12V battery into the circuit.
It will charge rapidly, and throughout that time, you will be able to continuously monitor the voltage across the battery.
Observe how closely the high and low voltages also known as set points are adjusted and then observe as the circuit cycles up and down.
You may adjust the precise voltages each time it appears to cycle until it shifts between 11.9V and 14.9V.
In fact, this test is as simple as reading a high and low voltage and waiting for the battery to attain these values over a brief period of time thus you may use any old junk rechargeable batteries.
How To Build:
To build a IC 555 Solar Charger Controller Circuit follow the below mentioned steps for connections:
- Assemble all the components as shown in diagram.
- Connect pin 1 of IC 555 to ground.
- Connect pin 2 of IC 555 to push button 1 to ground, and connect R1 resistor through pin 2 of IC 555 to center leg of P1 pot.
- Connect pin 3 of IC 555 to positive supply of 12V battery through charging LED red and resistor R3, and connect from pin 3 of IC 555 a resistor R4 to base of transistor T1.
- Connect pin 4 of IC 555 to positive supply of 12V battery.
- Connect pin 6 of IC 555 to center leg of pot P2 through resistor R2.
- Connect pin 8 of IC 555 to positive supply of 12V battery.
- Connect input pin of IC2 7805 to positive supply of 12V battery.
- Connect ground pin of IC2 7805 to negative supply.
- Connect output pin of IC2 7805 tp pin 4 and pin 8 of IC 555 and to the rest of IC 555 circuit
- Connect transistor T1 emitter to ground, collector to one terminal of the relay coil and the other terminal of relay coil is connected to the positive supply, connect base of transistor T1 through dumping LED green , and resistor R4 to pin 3 of IC 555.
- Connect 16V solar panel positive terminal to the common terminal of the relay and negative terminal of solar panel to ground.
- Connect dumping push button1 from pin 2 of IC 555 to ground, and connect charge push button2 from pin 6 of IC 555 to output in of IC2 7805.
Safety Measures:
- Consider utilizing a pre built solar charge controller with integrated safety measures for dependable and safe functioning particularly when working with priceless batteries and solar panels.
Conclusion:
To conclude, In order to ensure effective charging and avoid overcharging, the solar charge controller circuit restricts the pace at which electricity from a photovoltaic PV cell is supplied into a battery.