Highlights

This year I took on the role of Electrical Lead, with a focus on the battery system of our car. Because of it's importance to the powertrain and overall function of the car, I inderstood the importance of timely delivery and ensuring reliability. My team for this project grew to a trio, and we contributed countless hours on planning, research, testing, and integration.

Because it was our first year doing Battery Electric Prototype (the Shell name for our section), we had no prior experience to base our designs from. Forming separate teams for the BMS (battery voltage balancing system), motor controller, and PDU (power delivery unit), we split the work of creatig the power electronics into manageable pieces that made it a solveable challenge. Before the design and manufacture of our components, we set standards for power delivery and communication to follow the CAN (controller area network) specification over an RJ-45 connector.

Each low-voltage board on our car is CAN-compatible, and can be used for board control, configuration, data logging/telemetry, or debugging. Working closely with the BMS team, we built the balancing board and tested it on a mock battery to ensure functionality. Because we had standardized the pinouts, voltage levels, and communication protocol, the actual network layout and installation in the car was wonderfully effective. This year we accomplished full PnP (plug-and-play) functionality for our CAN bus, allowing us to test boards in various configurations outside of the car and in a safe environment.

Besides this year's huge success with the CAN networking and electrical intercommunication, the battery team did a great job with actually implementing and testing the battery packs and charging system. Building a battery sounds easy on its own, but the lack of infrastructure, experience and tools within our team specifically related to electric vehicle design meant that each component had to be designed to be as fault tolerant and reliable as possible. Within our team, this took the form of engineering the battery to absolutely never be the failure point of the car. Given the serious hazard posed by lithium-ion cells, we took an abundance of caution and made provisions for several worst-case scenarios.

Making the "unkillable battery" manifested in several collaborations, each strengthening our communication and planning skills. First, we collaborated with mechanical team on waterjetting sheet metal for the case, with me welding it to make a waterproof enclosure. Secondly, the whole-team discussion took place of integration and spatial planning. Since each board, mechanical assembly, and miscellaneous item occupies space, discussing to make sure everything was accessible in the field was a priority. Finally, and most importantly, we designed the battery to be maintainable in sections. Because our team lacked tried-and-tested tools for charging and balancing the 36-volt battery, we needed an alternate way to guarantee it's usability, should the BMS and charging boards encounter issues. 

Our efforts in collaboration and contingency paid off, with secure, watertight enclosure; separable charging ports; and solid attachment to the mechanical frame. Our battery ended up being more than enough volume-wise, which is exactly what it was intended to be.

Because of our constant effort, we entered Shell EcoMarathon with a car that passed technical inspection on the first try, suffered no major mechanical or electrical issues, and completed 6 separate timed runs on a single charge, achieving a best-run efficiency 27x that of a Tesla!

I'm incredibly happy with the process and result by which we built the team and the car this year. It was the best hands-on crash-course in project managment, communication, and planning I've ever had, and I can't wait to see what next season will bring.