In this project, I will be showing you how to create your own home-made Lithium
Solar USB Charger.

Before you decide to do this project, it is important for you to know the basics of soldering. I would suggest you to go and watch some soldering tutorials on websites before you start this project. (Only if you haven’t done soldering before)

This Lithium Solar USB Charger has 2 USB outputs, 2 rocker switches (One for each output), and finally two 3.7V 3000mAh Lithium Ion Batteries which should be able to charge around three iPhone 5’s up to 100% if the battery was fully charged at the start.

Step 1: Parts

Parts:

2 x 5V DC-DC USB Charging Circuit

1 x 3.7V Lithium Battery Charge Controller

2 x 3.7V Lithium Battery 3000mAh

1 x 6V 5W Solar Panel

2 x Toggle Switch

2 x JST Female Connector + JST Male Connector

1 x Stranded Wire

1 x Heat Shrink Tube

1 x Circuit Diagram of Project

Tools:

1 x Soldering Iron (40W works well)

1 x Soldering Iron Stand + Sponge

1 x Helping Hand

1 x Digital Multimeter (optional)

1 x Wire Stripper

1 x Scissor

1 x Solder Pump

1 x Lighter

1 x Tweezers (optional)

Materials:

1 x Solder (0.8mm)

1 x Soldering Flux Paste

1 x Double Sided Foam Tape

1 x Super Glue (Depending on what material you choose to use for the enclosure)

Enclosure:

1 x Laser Cut Box

Step 2: Enclosure

Please go to the following link to download the Enclosure File.

http://www.thingiverse.com/thing:1262191

Step 3: Solar Panel Preparation

1. Take out the 6V 5W Solar Panel and slide off the small back cover

2. Take out the JST Male Connector (the smaller one) and arrange the wires as shown (negative wire to left hole, positive wire to the right hole). If you are still unsure which one is positive or negative, you could use a multimeter to test it out by placing it in the sun and putting the probes in each hole.

3. Solder both wires onto the 6V 5W Solar Panel

4. Preparation for the Solar Panel is now complete. You may direct the wires through the small hole and slide the cover back on.

Step 4: Assembling Circuit (Charge Controller)

1. Take out the JST Female Connector

2. Put it through the small hole as shown in the enclosure

3. Attach the 3.7V Lithium Battery Charge Controller to your helping hand

4. Stick the positive wire into the Solar + hole and stick the negative wire into the Solar - hole

5. Solder both wires onto the Charge
Controller

6. Cut out two 8cm wires (one negative and one positive) and strip off one end off of each wire

7, Twist the wires as shown, then put the positive wire into the +Batt hole, and the negative wire into the -Batt hole

8. Solder both wires onto the Charge Controller. Preparation for the Charge Controller is now complete.

Step 5: Battery

1. Put some Double Sided Foam Tape onto

one of the 3.7V 3000mAh Lithium Batteries and stick the two batteries together

2. Strip off the ends of the wires

3. Twist the negative wires together and the positive wires together as shown. Preparation for the Lithium Battery is now complete.

Step 6: Rocker Switches and Charging Circuits

1. Cut out 6cm and 7cm positive wires,

then strip off both ends of the 5cm wire + one end of the 7cm wire. Twist all of the ends that you’ve stripped off.

3. Use your helping hand to secure a rocker switch, then guide the twisted wires in the previous step through hole on the side (not the middle)

2. Twist one end of the 5cm wire together with the 7cm positive wire

4. Solder the twisted wire onto the rocker switch

5. Fit the rocker switch that has wires on it in the middle of the enclosure and the other rocker switch on the side as shown above.

6. Solder the other end of the 6cm wire to the hole on the side of the other rocker switch (not the middle).

7. Cut out two 5cm positive wires, one 5cm negative wire and one 7cm negative wire. Then strip off both ends of every wire except the 7cm negative wire where you strip off only one end and finally twist all of the ends that you’ve stripped off.

8. Take out the 5V DC-DC USB Charging Circuits

9. Put one end of one of the 5cm positive wires into the + hole of the Charging Circuit (square)

10. Solder the wire onto the Charging Circuit

11. Twist one end of the 5cm negative wire you cut out together with the 7cm negative wire

12. Put the twisted end of the two negative wires wires through the hole that has the letters “JA” next to it (circle)

13. Solder the two negative wires in the previous step onto the Charging Circuit

14. Put one end of the second 5cm positive wire into the + hole of the Charging Circuit (square)

15. Solder the wire onto the Charging Circuit

16. Use your helping hand to secure both Charging Circuits (keep them close)

17. Put the other end of the 5cm negative wire from the first Charging Circuit you worked on through the hole on the other Charging Circuit that has the letters JA next to it (circle).

19. Stick some Double Sided Foam Tape onto the bases of both Charging Circuits

18. Solder the other end of the 5cm negative wire onto the second Charging Circuit you’ve worked on

20. Place the Charging Circuit with 2 negative wires and 1 positive wire under the Rocker Switch that has 2 positive wires attached to it as shown in the above picture. Then place the leftover Charging Circuit under the other Rocker Switch.

21. Put the positive 5cm wire of the first Charging Circuit you worked on through the middle hole of the toggle switch that is directly above it. Repeat this step for the other Charging Circuit.

22. Solder the two positive 5cm wires onto the middle holes of the Rocker Switches as shown above.

23. You should now have every wire connected to a component except two 7cm negative wires (one from the Charge Controller and the other from the Charging Circuit) and two 7cm positive wires (one from the Charge Controller and the other from the Charging Circuit).

24. Strip off the ends of all 4 wires and twist them each individually.

Step 7: Connecting Everything

25. Twist the two positive wires together and the

two negative wires together

26. You’re almost there!

Twist the two positive wires from the Charge Controller and the Charging Circuit together with the two positive wires from the two Batteries.

Twist the two negative wires from the Charge Controller and the Charging Circuit together with the two negative wires from the two Batteries.

Place the Battery on the right side as shown in picture #3 (You could put some Double Sided Foam Tape on the base of the two batteries to secure it)

You may tape the Charge Controller as well so that it stays in place.

27. With or without Flux Paste, solder the wires together. If you choose to use Flux, simply apply a small amount onto the connection between the wires. Then melt some solder onto your soldering iron tip and let it touch the connected area where you’ve you’ve applied Flux paste on.

28. Take out the 2mm/3mm Heat Shrink Tube and cut it into two bits. The length and size will depend on how well you’ve soldered the wires together. For example, the soldering I’ve done for for one of the wire connections clearly seems larger than the other one in step 25. Therefore, I’ve used both 3mm and 2mm Heat Shrink Tubes.

29. Slide the Heat Shrink Tubing onto the wire connection.

30. Use a lighter to shrink the tubing

Step 8: Finished Product / How to Use It

To charge up the two 3.7V 3000mAh batteries, simply plug the JST Male Connector from the Solar Panel into the JST Female Connector from the Charge Controller

Once plugged in, the light on the right side should light up and the light on the left side should go off if the sunlight is strong enough

You do not need to worry about the left light as it is used for other purposes unrelated towards this project. You should simply ignore the left light.

The right light will turn off if: the Battery is fully charged or no charge is occurring.

The right light will turn on if: the Battery is being charged through the Solar Panel

It usually takes a full day of very strong sunshine in order to fully charge up both of the batteries.