Introduction: Clean Energy Phone Charger
In this project, you will be building a very simple solar power bank that can charge your phone. A lot of people are unaware of how cheap and it is easy to build a DIY power bank. All that is really required a couple of electronic boards, a USB cable, a rechargeable battery, and sufficient soldering skills.
Essentially what happens is that a battery is charged up using a 18650 battery charging circuit. The input power for charging the battery can either come from a USB or the solar panel. Afterward, a 5V USB booster is used so that you can connect a USB from your phone to the battery.
The circuit can also take in AC power sources such as a cycle dynamo or a portable turbine. You would do this by converting the AC source into DC current using a bridge rectifier.
1) 1 x DB107 Bridge rectifier link
2) 1 x TP4056 board with protection link
3) 5cm x 5cm Perf board link
4) 1 x 5V USB booster link
5) Jumper wires or normal wires link
6) 1 x 18650 rechargable battery link
7) 1 x 18650 battery holder link
8) 1 x 6VSolar panel link
9) 1 x 1000uF electrolytic capacitor link
10) 2 x IN4007 diodes link
Step 1: Understanding the Circuit
There are actually three parts to the circuit
The first part processes the DC voltage from your solar panel. The second part processes the AC voltage. The third part takes the energy and stores it in the battery, allowing you whenever you wish to plug in a USB cable.
I'll start with part 3
For this part of the circuit, the battery, the TP4056, the 7805 voltage regulator, and the 5V booster is used. The power coming from your Voltage regulator is sent to the TP4056 board. The board then changes the current and voltage to optimize charging up the battery. There is also a protection feature in the TP4056 board that prevents the rechargeable battery's voltage from becoming too high or too low. Here is a good video explanation: link
The TP4056 will charge the battery when a voltage between 4.5V-6.0V is supplied. Anything above and the board will fry. This is why we use a 7805 voltage regulator. The Voltage regulator steps down the voltage from whatever value to 5V and thus ensures that the TP4056 board does not spoil.
The board is also connected to a 5V step-up booster which takes the voltage in the 18650 battery and converts it into the form that is usable for your phone or other USB powered devices. You can now just plug your phone into the USB port and it should start charging.
This is the part that processes that voltage coming from your solar panel DC power source. There is a diode used to prevent current from the AC power source from flowing into the solar panel as both of them are connected to the 7805 in parallel.
This part of the circuit processes the current coming from the AC power source. Here is a good video to explain what AC current is: link. The AC current is turned into DC using a full-wave bridge rectifier. The bridge rectifier has 4 pins. Two for the input, and two for the output. The two output pins now carrying DC voltage are connected to a 1000uF capacitor in parallel to help smoothen the DC voltage. Finally through a diode, for the same reason as before, the positive lead is connected to the 7805 voltage regulator and you enter part 3 of the circuit.
Step 2: Putting Together Part 1 of the Circuit
DC solar panel is connected to 7805 through an IN4007 diode.
Solder the joints for permanent connections
Step 3: Putting Together Part 2 of the Circuit
The AC power source is connected to the AC inputs of the bridge rectifier.
The bridge rectifier then converts the AC input into DC output with a positive and negative terminal.
A 1000uF capacitor is attached in parallel to the two terminals coming out of the DB107 bridge rectifier.
The positive wire from the bridge rectifier is connected to a diode and the diode is then connected to Pin 1 of the 7805. The negative wire is connected to pin 2.
Step 4: Making DB107 Bridge Rectifier With Diodes (optional)
If you can't buy a DB107 bridge rectifier easily, then you can make one using diodes.
Just follow the diode configuration and match it to the original schematic.
In the image, the two horizontal terminals are the AC input pin while the two vertical pins are the DC output terminals.
Solder the joint for a secure connection.
Step 5: Putting Together Part 3 of the Circuit
This part is very simple if you follow the schematic.
Pin 3 of the 7805 is connected to the positive input of the TP4056.
Pin 2 of the 7805 is connected to the negative input of the TP4056.
Make sure to wrap up any open connections with insulation tape as it may cause the Lithium-ion battery to short circuit and blow up.
Step 6: PCB Design Option
I have designed a PCB for this project. If you wish to skip the rough work you can order the finished PCB from SEEED and it should arrive in around a week. The final circuit will look a lot more polished.
Here is a link to the Gerber file: https://drive.google.com/open?id=1iUivo-afLw3i5XBT...
In the PCB, A stands for the AC source, D+ and D- stand for the positive and negative DC source respectively. And O+ and O- stand for the positive and negative output to the TP4056 respectively.
To order a PCB go to this website: https://www.seeedstudio.com/fusion_pcb.html
Attach the Gerber file that is there in the google drive folder. Change the dimensions to 39.5mm and 21.4mm. Leave all the other settings as it is. And then order it.
Step 7: Housing
There are a couple of different options that you have for the product's housing. But before that, there are actually two ways to house the circuit. First is just a simple box with no additional features. However, if you do want to take on a challenge and add more functionality to your circuit then I have also designed a version of the housing which has bars on the side and a curved base. This allows you to tie the product around your arm or bottle using a belt or just even plain cloth. The challenge is that you would have to 3D print the design to get this additional functionality.
1) Leaving it without a casing. Not ideal but the easiest
2) Laser cutting a simple box that can then be put together using super glue. You can find the .dxf for the laser cutter in this google drive folder: https://drive.google.com/open?id=1iUivo-afLw3i5XBT... All you need to do, if you don't have a laser cutter, is to find a local laser cutting service and give them this file on a USB drive.
3) 3D printing the housing with an additional securing feature. You will be able to find a .STEP or .STL file in this google drive folder: https://drive.google.com/open?id=1iUivo-afLw3i5XBT... You will need a CAD software like Fusion360, Onshape, Tinkercad, etc, to 3D print the housing.
4) Here is a link to the online fusion design: https://a360.co/2QguUVI
You can secure the components and board in the box using hot glue or super glue. Do not try and use nuts and bolts.
Participated in the
PCB Design Challenge