Year Two Media:
About the Second Year:
A much more manageable-sized group of students were selected to participate in the second year of the Solar Car project. With the more focused goal of creating a larger, more durable, 2-passenger vehicle, a single team of about 20 students worked collaboratively to create one solar car. In the first semester, we focused again on learning, but put more emphasis on the basic process of engineering. There were a number of students who had not participated in the class last year, and so we began by reiterating some of the previous curriculum: basic electronics and mechanics, the science of photovoltaics, key chapters from "The End of Oil", and how to use the various shop machines at our disposal. A mentoring approach was taken, wherein the more experienced students helped the new ones learn these background skills and knowledge specific to our project. We completed several learning projects, including building solar-powered iPod chargers, and solar-powered radio-controlled cars.
In the final semester of the Solar Car project, a great group of students worked together to build our final solar car. Many of the students in this year's class had participated last year, and so brought with them the experiences and knowledge of what it took to design and build a successful vehicle. The ability to learn from their mistakes from year one was a major focus in the design of our final solar car. Although the students were very eager to get into hands-on building, they had learned that jumping into machining parts before making smart choices was actually more time consuming. Instead, we spent more time doing initial research and planning. The students researched the street-legal requirements for neighborhood electric vehicles, and applied their prior knowledge to set their own additional functional requirements. We made careful component selections. We chose a much more powerful motor with a built-in cooling fan, as last year's models used underpowered CIM motors that the students had been familiar with from their robotics team, and that had overheated during the race. We chose Nickel-metal hydride batteries over previously-used lead-acid batteries to save on weight. We chose to use a custom charge controller and a high-voltage speed controller, build in numerous electrical fail-safes, and use appropriately-thick wiring. Also, we followed the engineering principles that we had studied in the first semester, from functional requirements to design parameters and project schedules.
Finally, the result of our efforts was a durable, fully functional, renewable-energy commuter car, powered only by the sun. We had numerous challenges along the way, and we did not take the project quite as far as our initial hopes, but the students finally succeeded in creating a solar car of which they could be proud. The final solar car runs very well, successfully carries two passengers, and has never used any power source other than sunlight. It is equipped with a speedometer, tail lights, key switch, potentiometer accelerator, battery charge/voltage/current meter, and reverse switch. In our testing on short drives around the campus we achieved a speed of 35 mph, and our conservative estimate of the battery run time is around 1 hour. We did not finish testing the charge time, but a few hours in the sun was all it took to top off the batteries after our informal driving tests. We presented (and utilized) our solar car during HTHLA's 2008 graduation, and it was a big hit!
As a step towards our community awareness program, the students also made websites, videos, powerpoints, and posters. These supplementary products detail the specifications and inner workings of the vehicle, harnessing solar power, analyzing the energy crisis, and learning the skills that the students needed, and will be used in conjunction when we share the vehicle with others. The students, collaborating professors, mentors, and teachers involved in this project all did an outstanding job. We all learned a great deal, and we successfully finished the task that we had set out to accomplish two years ago: to create a cool renewable-energy neighborhood commuter vehicle, a solar car. Perhaps more importantly though, the project has fostered a great deal of interest in science and engineering amongst both the students involved and all those who have witnessed the building process and final vehicle.
For specific details about our final solar car, I recommend visiting Bell's Solar Car Two: Challenges Overcome website.
Second Year Main Projects:
- Project 1: Build solar iPod chargers
- Project 2: Build solar, radio-controlled cars
- Project 3: Build the final two-passenger solar car, the R.E.C.C.