|
Resources |
Students at Brigham Young University have had a good year when it comes to electric vehicles. Two of the engineering school’s class projects recently set speed records, one at the Bonneville Salt Flats, the other on a drag strip at the Mason Dixon Dragway in Hagerstown, Md.
Electric Blue
After seven years of design, development, and testing, BYU students saw their Electric Blue streamliner set a world’s land speed record for vehicles in the E-1 class, which covers electrically powered cars weighing less than 1,100 lb. Power comes from 88 stripped-down battery packs originally designed for DeWalt cordless drills. Each pack holds 10 lithium-ion batteries.
A long, slender, carbon-fiber body encloses all four wheels, making the car light and aerodynamic. The rear wheels are solid aluminum, which lets them handle the high torque and speed, as well as ground conditions on the Utah salt flats.
The car has a 600‑ft turning radius. (An average car’s is 35 ft.) But steering is not an issue when making speed runs at Bonneville.
The car averaged 155.8 mph over two runs conducted on two consecutive days, a requirement for setting a land-speed record, On one run, it clocked 175 mph. (In a shot at the record last year, the BYU car hit 180 mph on the second day, but then hit a rut and rolled before it could complete that second run.)
EV 1
A different team of BYU students converted a 1997 EV-1 donated by General Motors into a dragster powered by ultracapacitors. It set a new record for modified-production/Class A electric vehicles, which is for production cars running on more than 240 V. The BYU entry was the only one in its category, but the team challenged itself to best the record it set two years ago, which was 77 mph, or 15.9 sec in the quarter mile. The new record is 93 mph and 14.08 sec, which the team set on its third run. The team went for a fourth run, trying to top 100 mph and 13.5 sec, but a sheared drive sprocket ended that effort.
One of the changes the team made to the car since the last record-setting run was to switch from a transmission with only one gear to a chain-driven two-speed transmission. The transmission, by the way, is the only component on the car that makes an appreciable amount of noise.
The car runs on 260 ultracapacitors from Maxwell Technologies, San Diego, which initially presented problems. Students designed the car to run on 400 V, but by the end of quarter-mile run, the capacitors would be down to 275 V. The team solved that problem by doubling the number of capacitors. The bank of capacitors is recharged between runs from the team’s specially outfitted truck, a process that takes 15 to 20 min. Some of the benefits of using capacitors instead of batteries include their quick cycle times and longer life.