DIY - Solar Phone Charging Unit

This article explains about how to make your own solar based mobile phone charging unit. The design is very simple and completing this should not take you more than 2 hours.

List of components required:

      1.       Solar panel : 3W,6V panel

      2.       Sealed Maintenance free lead acid battery: 6V,4.5AH

      3.       Diode: IN4001

      4.       DC -DC Step Down Buck Converter KIS3R33S Module 7V- 24V to 5V /3A

      5.       USB based mobile charging cable( Normal data cables will not work)

      6.       Connecting wires

      7.       Soldering kit

Circuit connections diagram:

Working principle:

Mobile phones have inbuilt batteries and they need to be charged every few days or every day depending on how often the mobile is used. Batteries can be charged only with Direct current whereas the electricity we get in our normal household sockets is Alternating current. A mobile phone charger does the job of converting AC to DC and keeping the output voltage and current levels suitable for mobile charging. Chargers typically have efficiencies ranging from 60-90% depending on the quality (This is why some of the chargers get heated up quickly)

On the other hand solar panels convert solar energy to DC electricity. With suitable circuitry we can store this DC electricity in an external battery and charge the mobile phone when ever required.

The selection of solar panel and battery depends on various parameters like number of mobiles to be charged and the voltage levels of the battery etc. We have used a 6V, 4.5AH battery which can charge a typical smart phone once every day.  A 3W 6V solar panel is chosen since that is enough to charge the external battery in 7-8 hrs. The solar panel is directly connected to the battery with a diode in between to avoid reverse flow of current from the battery to the solar panel when there isn’t enough sunshine and during night time.

A DC-DC converter module is used to convert 6V battery voltage to 5V output since mobile batteries are very sensitive to charging voltage and current( a normal car battery regulator can be used but the efficiency is very low)

Construction:

·      

            As shown in the circuit diagram, connect the positive end of the solar panel to the positive end of the diode (silver ring on the diode represents negative) and the negative end of the diode to the positive of the battery. The negative end of the solar panel can be directly connected to the negative terminal of the battery.

·         Solder the terminals and use insulation tape to make sure shorting of terminals doesn’t happen.

·         Identify the input side of the DC-DC converter and connect positive and negative of the battery to the positive and negative of the DC-DC converter input respectively.

·         The output of the DC-DC converter is a USB port where the charging cable is inserted. (Note: Normal data cables do not work so a simple charging only cable should be used)

·         If the connections are proper, you should be able to see a red light glow on the DC-DC board and your mobile phone should display charging.

·         We had used a voltage and current measuring device called a charger doctor at the output to verify if the voltage and current levels are in the suitable range. This unit is not required.

Try this fun project and let us know your experience or queries in the comments section below.

Where to buy?

1.       Solar panel : http://www.amazon.in/Sparkel-Solar-Panel-meter connection/dp/B01EB0C06Q?tag=googinhydr18418-21

2.       6V battery : http://www.amazon.in/6v-4-5Ah-SMF-VRLA-Battery/dp/B00MPJ66UM/ref=sr_1_1?ie=UTF8&qid=1474624382&sr=8-1&keywords=6+v+battery

3.       DC-DC converter : http://www.amazon.in/Converter-KIS3R33S-Module-Replace-KG106/dp/B00YURPEL4?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

4.       Diode IN4001,connecting wires, soldering kit and charging cable : Any regular electronics store

DIY - Solar Car

Yes! You read that right. We are going to build a car which runs only on solar energy! Well, a solar toy car to be exact.  If you are interested in playing around with solar panels, motors, wheels etc. then this article is for you. What better way to spend your leisure time building a solar toy car and flaunt your engineering skills with your friends and family, right?

This is a very simple yet exciting project for any class 8 and above student. With all the right components in place, it should take you anywhere between 1-2 hours to finish this. An instruction video is attached in the end and in case you get stuck somewhere, feel free to drop your queries in the comment section.

Let’s get started

You will need the following components. We bought our components from various places in Delhi NCR, like Chandni chowk , Sadar bazaar etc. you can order the components online and the link for each component is attached in the end.

	Component	Quantity
1	60 RPM DC motor	2
2	Dummy for the wheels	2
3	Wheels	4
4	3W solar panel	1
5	Soldering Iron	1
6	Wire stripper	1
7	Insulation tape	1
8	Soldering wire	1
9	Shoe box	1
10	Ruler	1
11	Connecting wire	1m
12	Tester or screw driver	1

This is how most of the components look like.

Once you have bought all the components and identified each of them, it should be fairly simple to finish the project.

Construction principle

This will be a four wheeled toy car. These wheels should be attached to the sides of a shoe box in the way shown in the picture below.  Make sure that the wheels are aligned i.e. the line joining the centre of the two wheels should be parallel to the side of the box (red line is parallel to the side of the box). Height of the wheel from the box edge is chosen in such a way that the cardboard doesn’t touch the ground when the car is resting on the wheels.

We need motors to run these wheels. A motor each is attached to both the back wheels. The other two wheels in the front are fixed with a dummy. These motors run on DC electricity and this will be provided by the 3W solar panel.

The job of the solar panel is to convert solar energy (sunlight) to electricity. Every solar panel has a junction box behind it. When you open the junction box, you will find two terminals namely a “positive +” and a “negative -“.

Connect wires to these terminals. The convention is to use a red wire for the positive and a black wire for the negative. This makes it easy to identify, helps avoid shorting and makes the connections easier. The other end of wires are connected to the motors as shown below. Use soldering iron to solder the wire on to the motors. A hump in the circuit diagram signifies there is no connection at that point. In this case, there is no connection between the black wire and the red wire.

To test if you have soldered properly, place the panel in direct sun light and see if both the motors rotate. Use trial and error to figure out the correct connection to the motors so that the car moves forward. Once you have figured the right combination, solder the joints and use insulation tape to cover the open ends.

The final product should look something like this.

or may be like this

Where to buy the components?

60 RPM geared DC motor

Motor Dummy

3W Solar Panel

Wheels

Wires

Soldering station

Check out the video

And here is a video of a solar toy car race that we conducted for school children: Solar Toy Car Race

Enjoy and let us know your experience with this