After a lot of hard work, the Hybrid Electric Vehicle Team of Virginia Tech (HEVT) finally commissioned its A123 battery near the end of Year Two. The number of steps it took to get to that point kept the electrical subteam busy all year.
“Commissioning the battery pack essentially means that our pack has been deemed safe by A123,” said electrical subteam leader Brian Kelly. “We are now able to distribute power to the rest of the vehicle.”
The team’s first step in the process was to become familiar with its batteries. “We needed to know how they work and how they communicate with each other,” Brian said. The electrical subteam completed a checklist where the batteries were placed on a work bench so that the team could safely work with high and low voltage systems. The low voltage harness was connected to the high voltage batteries in a series and the team performed various tests to ensure the connection was working properly.
The next step was to complete the internals checklist as the team built its Energy Storage System (ESS), the actual structure that holds the batteries. “We first built the ESS with wood so we could see what parts of the ESS we could build outside the car and the parts that we had to weld while in the car,” said electrical subteam member Tyler Erickson.
The ESS was built out of 20 gauge steel along with ⅛ inch tube steel, painted in maroon and orange, and then covered in Kapton tape. The Kapton tape isolates the steel from high voltage so the batteries are completely separated from any passenger in or out of the vehicle.
After building the ESS, it was time to install the batteries! “That was my favorite part,” said electrical subteam member Justin Hylton. “It was a lot of work, but when it was all done it was so rewarding.” The time lapse video below captures 30 hours of the team’s work in under two minutes.
After everything was installed in the vehicle, it was time to submit the internals checklist to A123. “We talked with A123 over the phone and they had us fix any issues that they saw,” Brian said. “After we fixed everything, A123 gave us the okay to power the vehicle with our battery pack.”
With the completion of the ESS and support from all three subteams, the rear traction motor and inverter were connected to the batteries and the car was ready to run in electric vehicle mode in time for Year Two Competition!