The Capacitor Powered Car

The idea of our project was to build a small capacitor powered car that would be charged by solar panels and designed to go as far as possible on one charge.

The first thing we had to do was figure out the power of our motor we were given, which was a small erector set motor. We found the torque constant was 6.5 oz inches/amp, and the voltage constant was 1833 volts/rpm, and it had an operating voltage of 3-6 V. We also figured out the amount of power in our capacitor, which was a 5 V, 1 Farad capacitor. Link to the capacitor on Digikey HERE.

We then decided on an ideal gear ratio and wheel diameter, which was about 5:1 and about 1.5 inch diameter drive wheels, which was determined by using the Team Tentacle Torque Calculator. we used a 57-tooth gear and an 11-tooth gear, giving us a ratio of about 5.2:1.

After finding all the information needed on the car, we started building our chassis on solidworks.  At first, the car chassis was a basic rectangular shape. We changed it over time while making it stronger and lighter. Our final design ended up looking like a regular car chassis. Also we designed a section on the car that allows the motor to move to different positions to distribute the weight and this would allow us to adjust the motor to get the correct center to center distance between the gears. We made our chassis using a 3D printer, using about 1 cubic inch of material. If you download this chassis, make sure to adjust the axle holes to your specific axle size, and allow tolerances for your specific 3D printer.

We used axles that were 3.7 inches long, since the chassis is 3 inches wide, and 0.16 inches in diameter, because they were the axles that fit the gears we had.

We used a momentary on/off switch wired so that when the switch was not pressed, it would remain on, and it would be off when it was pressed. We would hold down the switch to charge the capacitor, which only took about 10 seconds, and release the switch when we were ready to let it go.

When we first tested it, it initially spun its wheels for a few seconds because the smooth plastic wheels did not have enough traction, so we put rubber bands on the drive wheels to increase traction. the next few tests went very well, at first going about 80 feet, on the second try it went 92 feet, 9 inches. The farthest we got was about 107 feet 7 inches, which is shown in the video.