In a 10-second pass, battery drain on teh
Bad Amplitude electric dragster is approximately 17.5%. Recharging the
lead-acid batteries takes about 15 minutes after a quarter-mile race.
Sydney, OH—Dennis Bieschke is one fast engineer. He's on a team at the engineering consulting firm Net Gain Technologies that designs, builds, and races electric vehicles. They set a new speed record and won the Outstanding Engineered Vehicle award in the dragster category at this year's World of Wheels competition in Chicago that is produced by International Show Car Association and features more than 500 vehicles.
"Our dragster, Bad Amplitude, reached a speed of 127 mph at the quarter mile with a 3.5g force at the start," notes Bieschke, the company's director of business development. The Net Gain team competes against electric and gas-powered vehicles that are sponsored by Pepsi, Lucas Oil, Winston, and other private companies. Teams lead by Jim Ludiker, Dennis Berube, and Bob Boyd made the other electric dragsters.
Making Bad Amplitude fast and safe required help from its numerous sponsors. Warfield Electric Co. (Frankfort, IL) produces dc motors, including many rebuilt and customized motors used by Bad Amplitude. "Since they already knew what the failure points were from their experience repairing motors, it was a simple matter for them to help us design motors that were intended for the unusual stresses encountered in electric dragsters," says Bieschke.
The dragster currently uses a modular dc motor that can be easily modified. For example, the team had previously used an 11-inch diameter motor with interpols. Now they use a 13-inch diameter case without interpols. "If we want to make a longer motor, we add another iron section to the case," explains Bieschke. The motor armature drive end uses a press-on integral keyway system that allows swapping of the drive shaft as needed.
LittelFuse (Des Plaines, IL) developed a unique line of fuses–EV49 Series–for use in Bad Amplitude's high-power electric system and other electric vehicles. A different line of fuses from Littelfuse protects the separate 12V system that provides power to critical gages and instruments. "Our safety system operates on 12V contactors, so the low-voltage fuses are as critical as the high-power fuses!" says Bieschke.
Bad Amplitude uses Panduit (Tinley Park, IL) wire ties throughout the vehicle. "When dealing with voltages that could prove fatal, it is necessary to use wire ties that we can trust," says Bieschke.
The dragster uses a 1,400A 336V Godzilla controller made by Electric Vehicle Components, Ltd. (Palo Alto, CA). The team also tested the vehicle with dual 1,000A controllers made by DC Power Systems (Bellingham, WA).
An accelerator pedal connected to a 12V power source controls power to the motor. The 12V power system closes the safety contactors and allows a 5 k-ohm potentiometer connected to the accelerator pedal to send signals to the Godzilla controller. The controller interprets the signal, draws power from the batteries, and delivers power to the dc motor.
Below half-throttle, the controller sends a pulsed dc signal. Beyond half-throttle, the motor receives full dc power.
Bad Amplitude's batteries are a spiral-wound, lead-acid devices from Optima Batteries (Aurora, CO). "Our power drain is so severe that we have exploded numerous batteries on discharge," says Bieschke.
Battery power is the single largest limiting factor in performance to date. So Net Gain Technologies is working with NASA Glen Research Center (Cleveland, OH) developing new batteries. They hope to demonstrate the new battery later this season.
"Our goal is to have fun and we are meeting that goal," quips Bieschke. "At the same time, we are showing the public that electric cars don't have to be slow, ugly, egg-shaped vehicles."