# DIY AUTOMATIC SOLAR CHARGE CONTROLLER

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## Introduction: DIY AUTOMATIC SOLAR CHARGE CONTROLLER

Hello friends

Today I am back with another project called DIY AUTOMATIC SOLAR CHARGE CONTROLLER.

It’s an automatic switching circuit that used to control the charging of a battery from solar panels or any other source. It’s a 555 based simple circuits the charge the battery when the battery charge goes below the lower limits, and stop charging when the battery reaches it's upper limit voltage

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## Step 1: My Goal

“To make a cheap and efficient solar charge controller”

## Step 2: Circuit

This is the driving circuit of the DIY AUTOMATIC SOLAR CHARGE CONTROLLER.

To make this circuit you need

1. NE555 IC with IC holder

2. One 2N2222 or PN222a Transistor

3. Three 1K Ohm resistors

4. One 330 Ohm & 100 Ohm resistors

5. Two 330 Ohm 1/5 w resistors(optional)

6. Two 10K variable resistor

7. Two LEDs (green & red)

8. 1N4007 Diode

9. 5V SPDT relay

10. two, 3-Pin PCB connector

11. Wires

12. PCB

13. LM7805 (TO-220 type)

14. Two capacitors(i am using .1uF,you can use any)

15.IRF 540 MOSFET

This is the finished circuit (Fig)

The 5v relay is the main component of this circuit; it’s an SPDT (Single Pole Double Throw) relay. It have one common (pole) terminal and 2 contacts in 2 different configurations. One is N.O (Normally Open) and other one is N.C (Normally closed)

In our case we connect the +ve of the solar panel to the pole of the relay and +ve of the battery to N.O when the battery is connected to the SCC (solar charge controller) the circuit check the battery voltage the voltage is less than or equal to lower limit the current is flows to the battery and battery start charging. When the battery voltage reaches the upper limit, the rely is activated and the current is redirect to N.C for dumping

## Step 3: Calibration

After finishing the circuit you need to set the upper and lower limits. Batter calibration is required to avoid the overcharging and over discharging of the battery. I am using 12v as lower lower limit and 14.9v as upper limits. that means when the battery charge reaches the 12v battery start charging.wen the battery voltage reaches the upper limit or 14.9 volt .the relay is activated and circuit start dumping

To set the limits you will need a multimeter and a variable power supply or two power supplies. one with 12v and other one with 15v.first you will need to set the lower limit. for that set the voltage to 12v and connect it to the circuit. connect the ground weir to the conmen of the multimeter and touch the testing probe to the pin 2 of the 555 IC. Adjust the voltage by adjusting the VR to get 1.66 volte. Then set the voltage to 14.9v and touch the probe to the pin 6 of the 555 IC. adjust the voltage to 3.33v.check once aging .now over SCC is ready for use

## Step 4: Wiring

The Fig show the wiring diagram of the SSC

First connect the +ve from the solar panel to the centre pole of the relay then connect a red wire from battery to N.O of the relay. connect the –ve wire from the solar panel to the -ve of the circuit then connect the battery’s–ve to the circuit.

## Step 5: Working

when the battery voltage is less than 14.9 v the it start charging by passing current through N.O of the relay. when the batteries voltage reached 14 volt its automatically switch the relay to N.C.if you are using solar panel you don't need an dummy load to dump the excess power. you can add an extra battery to the N.C to harvest the excess power

## Step 6: Moment of Truth

this is a quick video of the DIY AUTOMATIC SOLAR CHARGE CONTROLLER

## Step 7: Thank You

I will give thanks to you Mr. Mike Davis. this DIY AUTOMATIC SOLAR CHARGE CONTROLLER is based on the his design. I just modified it a bit to make it more compact. I will give all credit to Mr. Mike Davis

A New Solar / Wind Charge Controller Based on the 555 Chip

Third Prize in the
Solar Contest 2016

Participated in the
Circuits Contest 2016

Participated in the
LED Contest

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Large Motors Class

14,306 Enrolled

## 141 Discussions

I would love tho see the calculations so that I can modify this to my own needs

I would love to see the calculations that you used to design the circuit.

Hello sir. Do you have the schematic diaagram of the circuit in .sch for eagle?

Looking for clear schematic...nothing visivle in dis schematic..

What components do i need to change if 24V system and can i used it in High current. Thank for your circuit idea.

Hi there, it's a neat little project, has been keeping me busy for a bit now. I have one question about the output circuitry for the 555: what was the purpose of using an npn transistor and the mosfet? Would it not have been simpler to use only the mosfet, or is there something that I am missing?

Hi Sir, can I know how you conduct the calibration and to adjust the upper and lower of battery voltage?

what is the use of P.B in the circuit
What type of P.B must be used

What is the output current and voltage values of this charge controller and which type it belongs to? whether mppt,pwm....?

I tride this circuit but it is not working, Please share complete details..

Why didn't you tell us up front that this is a Premium instructable? :(

I started gathering the components, tried to understand the schematic and saw that not everything was mapped on there... and then I saw other people struggling with this instructable, because to see all information you have to have a Premium account.

what is the use of push buttons

How it will maintain the constant voltage?

The output of your 7805 is shorted to ground and the negative side of your 330r connected to batt+ in this schematic this is obviously a mistake, right?

Hi guys i have made this circuit twice and it works well as mentioned, but i have a question, i have 1kw 18v solar panels and requires a controller that can handle about 70amps so i used 2x 40amp relays connected in parallel to the circuit, this works but the controller fails after a few days showing that it cant handle such amperage. What should i change or add to the circuit so that it can handle 70amps?

Can i know how u got 1.66 volts for pin 2 and 3.33 volts for pin 6.

Just multi meter the pins on the 555 chip :)