Projects Directory
This directory houses the many projects I have done over the years. Stay tuned as there are always new projects in the pipeline.
Solar Car Battery Monitor
I am one of the senior members of the Iowa State Solar Car Team, PRISUM. Every solar car contains a battery pack to store energy for later use, such as when the clouds come out or going up a steep hill. One of the biggest concerns with the battery packs in use is safety. The most common battery chemistry used for these batteries is Lithium-Ion (li-ion). While these batteries are very energy dense and lightweight, they are also volatile, and when damaged release their stored energy in a violent burst. The purpose of this project was to design and build the voltage and temperature monitoring portion of the battery protection system for the new battery pack.
For this project I was the lead designer and manager. The first stage of this project was the general concept and system design. The battery pack is physically organized as five rows of seven modules, each module consisting of one cell in series and 40 in parallel. The basic solution I devised was a circuit board for each row of modules that monitored the voltages and temperatures of the cells in that row. Those boards were connected together through a ribbon cable carrying power and communications between each board and the rest of the vehicle.
The next step was designing the schematic for the device, as seen below. I had to do many hours of research and planning to create the finalized solution, learning a lot about how battery management systems are designed and built. Many mistakes and misteps were made along the way but the final product is shown below. All seven cells are connected to a battery voltage monitor specifically designed for this task. This monitor also performs the task of controlling passive balancing, where energy from a single cell may be discharged to keep all cells together despite real-world irregularities. Temperatures are measured through a seperate interface connected to the bottom of the board for each module.
The next step in design a circuit board is laying out and tracing the physical board. While this is something I had done before, I had never done anything at this scale. In the process of making the final design many revisions were made and revised to make the components fit better and eliminating as many chances for inerference as possible. I'm quite happy with the final result even though there's much that I would change with what I've learned since doing this project.