Popular Mechanics gets behind the wheel of the pre-production Chevy Volt and first experiences the car in pure-electric and sustained-charge modes.
LOS ANGELES—We’ve been following the Chevy Volt as it has progressed through many milestones before it became a development mule based on the 2011 Chevy Cruze last May. That test drive was completed entirely in electric-only mode. Today, we had a chance to slide behind the wheel of a Volt that looks and feels much closer to production. We experienced the car in both pure-electric and sustained-charge modes, when the conventional gas engine powers an on-board alternator to supply the needs of the electric motor when the batteries reach an elected state of discharge.
The Volt is still about a year away from production, with an intended launch date of November 2010. But for chief engineer Andrew Farah, the process has been remarkably condensed.
The prototype Volt we drove in the parking lot of the Dodgers Stadium in downtown Los Angeles is what Farah calls a 65-percent write-off vehicle, meaning it’s about 65-percent of the way to full production standards. As such, it had a few technical bugs already identified and rectified for future cars. Still, this prototype is a fully representative vehicle in terms of structure and drivetrain.
Electric propulsion systems are well known for their smooth and quiet operation. So the unobtrusive cycling of a gasoline engine is considered a crucial aspect of this kind of hybrid system. Consumers simply won’t tolerate a system that doesn’t operate seamlessly. Here is how the Volt performed.
The Volt uses a three-phase AC induction motor rated at 120 kilowatts, or 160-horsepower, powered by a six-foot long, 375-pound array of lithium-ion cells mounted low along the Volt’s floorpan. Though Farah wouldn’t say precisely how much the Volt weighs at this point (we suspect it will tip the scales at around 3500 pounds), he did mention that much work has been done to keep the center-of-gravity as low as possible, to help diminish a driver’s perception of mass. Of course weight mounted higher in the chassis would result in more noticeable roll.
The engine is a normally aspirated 1.4-liter inline four-cylinder unit from GM’s global Family Zero range, manufactured in Flint, Michigan, and it is hooked to a 53-kilowatt alternator to provide current for the Volt’s electric motor once the battery pack has discharged about half way. To prolong battery life the cells are never allowed to recharge higher than about 80-percent of maximum, and they are never permitted to discharge more than about 50-percent unless an emergency occurs, and “limp home mode” is triggered.
Careful cell management is key to efficient utilization, not to mention the safe operation of lithium-ion cells, some of which have been known to fail in spectacular pyrotechnic fashion unless stringent temperature controls are in place. The Volt has dedicated cooling and heating systems in place for the battery pack, along with elaborate cell-condition monitoring mechanisms for optimal efficiency.
The chassis is based on GM’s Delta architecture, similar to that underpinning the new Cruze model, which promises contemporary ride and handling performance.
Continue reading about the Volt drive, sport mode and recharging at Popular Mechanics…