Mini Solar Powered Capacitor Vehicle

Hi Everyone!

I’ve created this instructable to show you how to build your own Mini Solar Powered Capacitor Vehicle. 

Solar cars have mainly been built for racing but are getting faster and more efficient each year. They are powered by electricity through the use of solar energy and have solar panels typically attached to the top surface of the vehicle. These solar panels have photovoltaic cells which convert the sun's energy directly into electrical energy. In this project, this electrical energy is stored in a capacitor which is then released to power different parts of the vehicle. 

However, the main focus of this project is to learn more about how capacitors and electronic systems manage power. I have used a capacitor here instead of a battery as even though a capacitor can't store as much energy as a battery it can charge and release its energy much faster. This is typically very useful and more efficient when paired with a solar panel. 

We may never drive cars covered in solar panels, but building a miniature solar car is a fun way to see how solar energy, capacitors and electronic systems can be used together.

The following equipment, components, cables and materials are needed for this project. Most supplies are required, however some alternatives are mentioned throughout this instructable.

Equipment

• Laser Cutter
• 3D Printer

Components

• Solar panel
• Hobby Motor
• Solar Power Manager
• Micro:bit Driver Expansion Board
• 5V Capacitor
• Micro:bit
• Micro servo
• Breadboard
• Resistors (43 Ohms x2, 330 Ohms x1)
• Axle rod (10 to 15cm in length)
• Pre-built plastic wheels x2 (approx 5cm in diameter)

Cables

• Alligator clip/dupont pin (male) cables
• Double-ended Alligator Clip cables
• Only if required: Male/female dupont cables

Materials

• Recycled mdf/mat board
• Plastic cardboard
• Cable/zip ties
• Glue, tape, screws or other adhesives

First up, you will need to use the attached stl files to 3d print the following parts:

• Back wheel x2 (Ensure you print this twice)
• Motor case/holder x1
• Servo mount x1

If you prefer to make adjustments and modify the design, you can use this OnShape document. 

Alternatively, if you don’t have access to a 3D printer you can purchase a similar ready-made version of these parts OR try to use adhesives or cable/zip ties to secure the components together (this should work, however may damage the component for further use after this project).

Optional: After printing the two back wheels, for further grip, you can add strips of rubber (from a tire) or rubber bands to the outside of the wheels.

Next, you will need to use the attached SVG, stl or illustrator files (whichever one works best for your laser cutter) to laser cut the chassis (body) of the vehicle.

For this, I used recycled mdf/mat board in 3mm thickness. However, you could also use cardboard, acrylic or any other sturdy material with similar thickness. 

If you don’t have access to a laser cutter, you can visit the attached OnShape document to view dimensions and accordingly cut out the design using woodworking equipment or a knife (X-acto knife).

To create the front steering system, you will need to start with cutting a strip of plastic cardboard that will be wide and long enough to fit your axle rod (10 to 15cm). 

Slide the axle rod through the plastic cardboard strip and attach one pre-built plastic wheel to each side. Secure with glue or another adhesive if necessary.

If you do not have any pre-built plastic wheels, you can 3D print another set (x2) of the back wheels mentioned above.

After this, you will need to slide the micro servo into its mount/case (3D printed in step 1) and then attach its hardware blade (plastic attachment in + shape that is provided with your purchase). 

Next, use double sided tape and cable/zip ties to secure the servo component to the plastic cardboard component. This is now your front steering system. 

Then, attach this newly made system to the front tip of the chassis (cut in step 2) using screws in the servo mount or other adhesives. See image for reference.

For this step, you will need to slide the hobby motor into the motor case/holder and secure it with cable/zip ties. 

Next, slide the 2 back wheels (3D printed in step 1) onto the axles on the sides of the motor. Secure the wheels into the axles using screws or glue. 

Then, using cable/zip ties, attach this motor/wheel system to the underneath of the chassis (same side as you attached the micro servo), and at the opposite end to the steering system. It should be secured to the middle strip of the back 2 cut-outs and have the motor facing forward (wheels close to the back of the vehicle).

Now, download the required Micro:bit code from the attached hex file (or this link) and upload it to your Micro:bit (do this by attaching the Micro:bit to your computer and drag the code file onto the Micro:bit file, then eject the Micro:bit and detach from your computer). 

Once you have done this, place the Micro:bit into the allocated slot on the Micro:bit Driver Expansion Board, ensuring the front of the Micro:bit (the side with the buttons and LEDs) is facing outwards/towards the edge of the board.

For a deeper understanding of the purpose of this code and what exactly it does, view the images above.

Next up, you will need to connect and attach all wires, alligator clips, pins and other included components, according to the diagram above (ensure everything is connected exactly as the diagram shows). If needed, the diagram is also attached as a file below.

Now, secure the circuit you have created with all the components, wires and cables attached, to the top of the chassis (opposite face from the wheels/motor and steering system). For now, secure everything but the solar panel. 

In order to safely attach these, you will need to use adhesives such as blu-tac, double sided sticky tape or other glues. Ensure the components are correctly placed, so that no cables have disconnected, are pulling, are being damaged, or are in the way of wheels and other systems. Also, to neaten everything up, you can use cable/zip ties to group together cables. 

Lastly, place and secure (using cable/zip ties or an adhesive) the solar panel to the chassis, on top of all the other components. You may secure it at an angle (as seen in attached images) or lying flat on top of the other components, supporting it with standing pieces of acrylic, mdf/mat board or other sturdy materials. It should look like a slanted or flat “roof”.

You have now finished creating your very own Mini Solar Powered Capacitor Vehicle, make another, race them with friends, and enjoy!!