Introduction: Solar Charged Thrust Cars

By TCPL
About: Tompkins County Public Library (Ithaca, New York), founded in 1864 by Ezra Cornell, serves the 104,926 residents of Tompkins County and is the Central Library for the Finger Lakes Library System, serving libra…
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Make fast and fun solar-charged cars! These working models are inspired by the Landspeed world record cars. TCPL offered this activity over the summer of 2022. Participants learned how to make two circuits: one to charge a supercapacitor and the other to power a small DC motor. In this Instructable you will be given instructions on how to prepare and assemble TCPL's 3D-printed car kit. This Instructable will also provide instructions on how to build these cars without 3D printing and laser cutting.

Safety Warning: These cars use fans to push them forward. Please keep hair and animals away from the cars when powered on. Do not overcharge or short supercapacitors or they will become very hot or pop. Do not use cars to chase animals or pets


Made and developed by Joah Tang, Teen Service Library Assistant at TCPL..

Supplies

Tools

  • Plastic Nippers
  • Pin Vise with a .8mm drill bit
  • 600 - 1200 grit sandpaper
  • *3D Printer
  • *Laser Cutter
  • Soldering Iron
  • Hot glue gun

Materials

*Required only with 3D-printed cars.

**Required only for non-3D printed cars

***Required for laser-cut charger see Step 4 for alternatives.

Step 1: Print

You can find instructions for the non-3D printed car on steps 3-5.

3D print one kit for each of your participants. Here are the settings I use on a Prusa Mini:

  • Print Settings .025 Draft
  • Filament Prusament PLA
  • Support on build plate only
  • Infill: 10%
  • Brim Yes

One kit takes about 1 hour and 18 minutes. If you have a large number of participants see the following links to bulk print four kits at a time.


Single Kit:



Bulk Files:









Step 2: Clean and Package Print

Using plastic nippers remove supports and brim. Use the 600 or 800-grit sandpaper to remove any burs or stray plastic. If you are printing these for an event I like to package the parts in leftover plastic bags. This program is a great way to recycle small packaging.

Step 3: Solder Electronics

Supercapacitor

Using the plastic nippers snip the positive tail of the supercapacitor to be even with the negative tail. Note: the supercapacitor will have a marking on one of its sides to signify ground. Cut a Micro JST 1.25mm female connector's wires to about the length of the supercapacitor's tails. Strip the end of each wire attached to the Micro JST. Make sure to cut the heat shrink tube to about the size of the female adapter for each wire. Slide the heat shrink tube over each wire. Next, solder the black wire to the negative tail as close as possible to the supercapacitor. Do the same for the red wire to attach it to the positive tail of the supercapacitor. Slide the heat shrink tube over the solder joints of each wire and shrink it to prevent the wires from coming loose. Bend each of the supercapacitors' tails up at a 90-degree angle to form the charger attachment. The supercapacitor is now ready!


Motor

If you are making a 3D-printed car take the 3D-printed motor mount and stretch it open with a pen. Slide the motor wire side first into the mount until about three-quarters of it have been pushed in. Make sure both wires are sticking out the back of the mount. Cut a Micro JST 1.25mm male connector's wires to about the length of the motor. Strip the end of each wire attached to the Micro JST. Make sure to cut the heat shrink tube for each wire and place one over each motor wire. Solder the connector to the motor and apply the heat shrink tube over the solder. Attach a prop and your motor is ready!


Solar Panels

When unpacking solar panels please keep the plastic film on until after soldering is complete to prevent scratching. Flip the solar panels over and align them next to each other so the plus and minus symbols are horizontal to each other. Take a red or orange breadboard wire and cut the pins off the end and strip both ends. Do this with a black or brown breadboard wire. Solder the red/orange wire to both outer positive terminals on the solar panel. Solder the black/brown wire to the outer negative terminals. Take a red/orange breadboard wire with two male connectors and cut this in half. Do this with a black/brown wire with two male connectors too. Strip the cut ends of one red/orange and black/brown wire. Solder the red/orange one to a center positive terminal and the black/brown one to a center negative terminal. Now your solar panels are ready to be attached to the box!

Step 4: Assemble Solar Charger

Laser-Cut Charger:

One cut produces 3 boxes. Snap the boxes together and run wood glue along the edges. Once dry hot glue the solar cells on top. Make sure to run the breadboard wires through the holes on each end of the box. Take a mini breadboard and adhere it to the closed side of the box.

You can find the circuit for full sun here:



You can find the circuit for overcast days here:



Note: When attaching the wires that will connect to the capacitor use breadboard wire with both a male and female connector. The female connector attaches to the supercapacitor for charging.

If you are using this project for an event I usually have the participants put the circuit together. Also, make sure to remove the film from the solar panels at this point.

Cardboard Charger:

Cut out the template. With a glue stick adhere the templates to cardboard and cut them out. Hot glue pieces together to form a box, see pics. Once dry hot glue solar cells to the box. Make sure the breadboard wires are placed through the square cutouts first. Take a mini breadboard and adhere it to the closed side of the box.

You can find the circuit for full sun here:


You can find the circuit for overcast days here:


Note: When attaching the wires that will connect to the capacitor use breadboard wire with both a male and female connector. The female connector attaches to the supercapacitor for charging.

If you are using this project for an event I usually have the participants put the circuit together. Also, make sure to remove the film from the solar panels at this point.

Attachments

Step 5: Assembling the Car

3D Printed Car:

Select the wheels you wish to be at the front of the car, see pics for orientation. Push the smaller axle into one of the selected wheels. Slide the axle and wheel through the front axle well. Push on the other wheel. Repeat this process with the larger axle for the rear wheels. Snap into place the two supercapacitor clips at the center of the car. Snap in the supercapacitor. Insert the motor and mount it in the rear with the prop behind the rear wheels. Your car is now ready to race!

Crafted Car:

Cut a piece of foamboard or cardboard to about 100mm long and 23mm wide. Remove wheels from a 1/64 diecast car. You can find a great tutorial here: https://mycustomhotwheels.com/how-to-take-apart-hot-wheels-metal-bases/

Tip: If you purchase unbranded diecast cars with plastic bottoms you can use nippers to cut the wheels and axles out. Instead of having to drill out Hotwheels/ Matchbox rivets.

Decide which end will be the front and back of the vehicle. Adjust the width of the board to fit the wheels. Then hot glue wheels to the appropriate ends of the board. Attach prop to DC motor. Measure and cut a fin from foamboard or cardboard to act as a motor mount. Make sure the prop does not touch the ground. Hot glue the motor to the top of the fin and then the fin to the rear of the car. Hot glue the supercapacitor to the vehicle and make sure the micro JST connector reach each other before gluing. Cut a small shape to act as a bumper for the front of the vehicle and attach it with hot glue. Your crafted car is ready to race!

Step 6: Charging the Car

On sunny summer days, the cars will charge within 10 minutes. You can achieve this on cloudy days with the overcast circuit too. If the weather takes a turn for the worse you can use a 2AA 3v battery case to charge the cars in 45 seconds.

Make sure the car's motor is not connected to the supercapacitor. Attach the negative wire from the charger to the negative tail of the supercapacitor. Take the positive wire from the charger and attach it to the positive tail of the supercapacitor. Set a timer and place the charger in the sun or switch on the battery case. Once the selected amount of time passes unhook the charger from the supercapacitor making sure to not touch the tails of the supercapacitor together. If you do this it will short the capacitor out and you will need to recharge it. When you are ready to launch the car plug the micro JST connectors together and the car will shoot forward.


Step 7: Going Faster

3D Printed Cars:

Using sandpaper smooth the center of the axles to reduce friction. Make sure to only sand the center of the axles or it may become too loose to attach wheels. Experiment with different-sized wheels. Does it move faster with small or large wheels up front? Adjust the placement for the supercapacitor.

Crafted Car:

Remove any unnecessary weight from the car. Bend one of the front wheels slightly up so only three wheels touch the ground. Sprinkle graphite powder in between the wheels and axles. Adjust the placement of the supercapacitor.

Step 8: Troubleshooting

Car Driving Backwards: Props come in two different orientations clockwise and counterclockwise. The direction of thrust depends on the prop orientation and the polarity of the motor. If the car is moving in the wrong direction swap the prop for a different orientation. If you don't have both types of props you can use a pen vise with a .8mm drill bit to drill a hole through the center of the prop. This will allow you to flip the prop around to change the direction of thrust.

Not Charging: Check to make sure the circuit is correct. If you are using batteries make sure they are fresh.

Car not moving: Make sure the axles and wheels rotate freely.

Motor making a loud noise: Debre is stuck in the prop, remove and clean.

The motor is not working: Make sure both wires are still attached. If one has been removed you will need to get a new motor.

Step 9: Tips for Running an Event

Here is the scaffolding we used to run a Solar Charged Thrust Car Event event:

TCPL’s Solar Charged Thrust Car Racing

Age Range: Tween and Teen

Participation levels: 30

Program season

  • Summer 2022

Description: Participants will have the opportunity to build a 1/64 scale electric thrust-driven vehicle and solar charger. Participants will also be able to keep the vehicles and chargers they make. The topics that will be covered include basic solar engine circuits, EV technology, and the World Landspeed record for EVs (at the time of writing this document the current record was broken by Team Vesco reaching a speed of 350mph).

Participant Goal:

  • Compete in a solar car race while learning about circuits and solar energy.

Participant Objectives:

  • Build one solar car with a working motor circuit.
  • Complete the appropriate circuit for the solar charger
  • Modify the car in some way after the first race.
  • Charge and race their car at least twice.

Program Goal:

  • Provide a free solar car event for the Fingerlake Library System's patrons and local youth.

Program Objectives:

  • Provide calendar events and registration to the communities.
  • Provide one kit containing a car and charger to each participant.
  • Provide step-by-step hands-on instructions through trained staff and volunteers
  • Provide track.
  • Provide a designated charging area.
  • Provide resources for participants to further explore electronics, EVs, Landspeed cars, and solar energy.

*Part List

  • 42x Super Capacitors – $12.00 per 6 pack.
  • 40x Solar Panels – $16.99 per 10 pack.
  • 35x mini breadboards – $6.98 per 7 pack.
  • 40x Resistor 100 ohm – $6.98 per 100 pack.
  • 40x Resistor 15 ohm – $5.99 per 100 pack.
  • 40x 615 DC Quadcopter motors – $8.49 per 4 pack.
  • 40x .8 Props – $7.99 per 12 pack.
  • 40x Micro JST adapters – $8.99 per 30 pack.
  • 2x 1/64 quarter-mile tracks – $22.99 per track kit.
  • 20ft of 1mm heat shrink tube – $6.38 per bundle.
  • 120x MF Red and Black Wires – $10.59 per 60pack.
  • 120x MM Red and Black Wires – $10.99 per 60pack.

Total Cost: $409.14

Tips:

  • Find volunteers.
  • Get the whole family involved.
  • Make sure to have water and first aid supplies readily available on hot days.
  • Have one leader to three through four participants.
  • Complete soldering while 3D printing kits.

*Prices of components on 3/9/22. Ordered 10 extra cars for replacement parts.

Step 10: Resources

Here are some helpful links I shared with the participants and their families: