Introduction: Portable Solar-Powered USB Charger/Cigar Box


For Father's Day last year I wanted to make my Dad a cool, yet simple USB solar-powered charger that was also a cigar box so he could enjoy a nice stogie while relaxing and doing leisurely activities. Who doesn't like cigars on vacation AND having a charged phone?? Nobody, exactly.

Here are the detailed step-by-step instructions you can use to create your very own cost-efficient, portable, solar-powered USB charger. Cigars not necessary... Enjoy!

Step 1: What You Will Need (Hardware)

To create this project, you will need the following:

  • Housing, or box to hold your other components as well as anything else you may want. I personally got mine from for the handmade/quality aspect (has been taken down since my build) but a quick google search for wooden box can take care of all your needs One more thing to keep in mind with the box is to make sure that the solar cell's length and width is NOT larger than the box you are mounting it on.

  • Electrical tape for closing off the data wires from the Female USB Plug w/ cable

  • Female USB Plug with cable so you can insert your Male USB plug into the Female charger port

  • DC to DC Voltage Step-down Module to drop the transformed energy from the Sun (8-10V DC) to proper operating output power (in this case we are dealing with 5-5.2V DC, 2 amps max)

  • Solar Cell to harness the sun's energy, and through a Photovoltaic (PV) reaction, turn that energy into usable electricity... cool! Simply put: Solar panels work by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity between two semi-conducting materials, usually silicon. Metal conductive plates on the sides of the cell collect the electrons and transfer them to wires. At that point, the electrons can flow like any other source of electricity. Unfortunately the solar cell that I used for this project also got pulled, but from the first URL, one can use to this see the data specs, the second is a valid link to purchase your own similar solar cell.

  • #22 Gauge Wire This is necessary if you do not have a quality DC Power Supply (explained next step), and is not necessary, but essential if you accidentally trim the cable wires too short from the solar cell or Female USB Plug

  • Mounting Pegs are also unnecessary, but are nice to have if you want to elevate your Voltage step-down module from the base of your box/housing (any plastic pegs can also do the trick). I got mine from my school's lab, but the link provided may be helpful

    Next, let's move onto the tools and instruments you will need -->

Step 2: What You Will Need (Tools/Instruments)

As far as tools go, you will need the following:

Step 3: Setting Up the Voltage Step-down Module

This is a two-part step


  • While keeping the DC Power Supply OFF, connect the positive lead (V+) of the Power Supply to IN+ of the module

  • Next, connect the negative lead (V-) of the Power Supply to IN- of the module (see pictures above)


  • Connect the Voltmeter's lead from 'V, ohm, mA' (usually designated red) to OUT+ of the module

  • Next, connect the common/ground lead (black) of the Voltmeter to the OUT- lead of the module.

NOTE: Make sure Power Supply and Voltmeter are OFF during this process

Step 4: Regulating the Voltage Step-down Module

  • Once the module is properly secured, turn on your DC Power supply.

  • If you have a knob voltage adjuster, turn the knob so the output voltage reads 9V (remember the Sun can provide anywhere between 8 and 10V DC). If you purchased the Power Supply I provided the link for in Step 2, set the Voltage to 12V.

  • Turn on your multimeter/voltmeter and set the dial to 20V DC so you can get a proper reading. If you have a digital multimeter, press the V DC button as seen in the picture above

  • Once both of the instruments are turned on, you will need to adjust the potentiometer located on the Voltage Step-down module. (See close-up of module). A potentiometer is essentially a variable resistor, being adjustable through the flat-head screw looking object on the pot (little blue box).

  • When turning the adjuster on the potentiometer, (this is where the adjuster tool saves a lot of time) you will have to turn the dial at least 10 times in full rotation before the output will change. Once you notice the change in Voltage, continue turning it until your multimeter reads 5V. Turning the adjuster in one direction will either increase or decrease resistance resulting in a changed output Voltage. If you accidentally raise your voltage higher than 5V, rotate the adjuster in the opposite direction. This will increase the resistance resulting in a lower voltage.

NOTE: The reason why 5V is the magic number to adjust to is because this is the operating voltage in which cell phones use to charge. Setting a higher voltage does not mean that your phone will charge faster, your phone's hardware can only take so much voltage and current going through its system at once. This could result in PERMANENT damage to your phone, if not destroying it. Setting a voltage lower than 5V will not only NOT charge your phone, but will also drain it rather than fill it.

Step 5: Mounting the Solar Cell

  • For this step use your tape measure to center the solar panel on the top of the box.

  • After centering the cell, locate the spot on your box where you will make the hole for the solar cell's cable to go through to the interior of the box

  • For the solar cell mentioned in step one, I suggest cutting the button plug off before making the hole so your hole is only large enough for the cable to fit through rather than the plug which you will be getting rid of anyways. This will ensure a cleaner and better looking finish from the inside of the box.

  • To make the hole for the cell's cable on the top of the box, I simply used my soldering iron to burn through the wood and make the hole that way. This step will be much easier for the new solar cell design due to only a cable protruding from the bottom rather than the clunky black box pictured above.

  • Once the hole is established and the cable is fed through to the inside of the box, mount the solar cell to the top of the box where you measured it out, using the pegs provided or using Gorilla Glue.

  • After the initial hole created with the soldering iron, you can use sandpaper to get the hole just right (unnecessary), and use electrical tape to seal off any extra space of the hole between the cable and the interior of the box

Step 6: Putting It All Together

This is a multi-part step:

  • Part 1: Making the opening in the wall of the box for the Female USB plug

    • Line up the Female USB plug along the inside wall of the box before you go at it again with your soldering iron/wood burner.

    • Once it is lined up against the wall, use the soldering iron to create a hole large enough for your charger to fit through it and connect to the female plug.

    • After the hole is created, use your wire strippers to expose the copper wires for the red and black cables of the Fem USB plug. NOTE: USB cables have four wires, Red, White, Green, Black. We are only concerned with the red and black cables (V+, V- respectively) because the white and green wires are used for carrying data.

    • Snip the green and white cables and wrap the ends with electrical tape as shown in the pictures above.
  • Part 2: Soldering the Components together

    • Next, lay-out, but not secure where your module will go inside the box

    • Trim your solar cell's cable to a proper length, allowing your box to be fully open while still being able to reach the leads of the module which you have laid out. (See pictures 2 and 3 above).

    • After both sets of cables are at a proper length, solder the cables to their corresponding leads. If you have never soldered before, do not worry, here is a great YouTube tutorial for through hole soldering techniques:
    • From the solar cell, solder your red (live) cable to the IN+ lead of the module (see picture 1 above)

    • Solder the black (ground) wire from the solar cell to the IN- lead

    • Next, solder the + wire of the plug to the OUT+ of the module.

    • Lastly, solder the - wire to the OUT- lead of the module.

NOTE: It will be exponentially easier to do your soldering BEFORE you mount the components inside the box (as you can see from my burn marks on the inside of the sidewall)

  • Part 3: Secure all components to the box

    • Optionally mount the standing pegs to the module to raise it off of the surface of the box

    • Glue the female plug in its correct orientation and placement in the box with the plug opening facing the hole

    • Glue the module in place

    • Make sure the cable from the solar cell does not get in the way of the lid of the box when it opens/closes

Step 7: Finishing Touches

  • For all the glamour, I used(wasted) a breadboard to act as a wall/barrier between the electrical components and the rest of the housing to incorporate a tech feel within the box. The breadboard fit perfectly so I lucked out in this case. You do not need a barrier, but if you want one, you can use just about anything you get your hands on.

  • Since this is a cigar box and it was a gift, I also loaded it up with cigars, a cutter, and a Hula girl bottle opener, the perfect travelling Dad box.

  • My last and final test was the field test -->

Step 8: Field Test

  • For my field test, I brought the box, fully assembled, outside on a sunny day.

  • Luckily my brother's phone was low on battery and I had his phone and charger in hand

  • As you can see from the pictures, not only does the box look great, but it also works. (Notice the lightning bolt designated for charging on the phone)

  • I was very happy with this build and I hope that you can use this guide to create your own work of tech and art. If you have any questions, please feel free to comment and I will get back to you at my earliest availability. Thank you and enjoy!!!