GM has released some details of the second-generation Voltec electric-drive system that will power the 2016 Volt. According to Volt Lead Engineer Andrew Farah, the primary goals for the new powertrain were to improve performance, raise overall efficiency, and cut engine noise.
The new Volt has a pair of electric motors, either or both of which can power the car and/or act as generators to maximize efficiency. The two motors use the same stator, but different rotors. The two-motor drive unit is 5-12 percent more efficient, and 100 pounds lighter, than the existing system.
The 2016 Volt has five modes of operation – one more than the current model – including an all-electric mode and four different combinations of gas engine and electric motors/generators. The ability to use both motors helps deliver a 20-percent improvement in electric acceleration.
The range-extending engine is a 1.5-liter four-cylinder version of GM’s new Ecotec series, which has an aluminum block (instead of cast iron), and three features that are unique to the Volt: a 12.5-to-1 compression ratio for more efficient combustion; cooled exhaust-gas recirculation, which allows the use of regular unleaded gasoline while keeping nitrous oxide emissions low; and wide-authority cam phasers, which allow a broader spread of valve timing, boosting efficiency significantly.
In the new powertrain, the inverter and other power electronics are built directly into the transmission, achieving a weight reduction of 130 pounds.
Reducing the noise and vibration of the engine was a primary goal – GM workers who’ve tested the new powertrain said it was almost impossible to tell when the engine switched on.
LG Chem will continue to supply lithium-ion battery cells for the new Volt, but the new cells have 20 percent more volumetric energy density than the old, allowing the number of cells in the pack to be cut from 288 to 192, while producing the same total voltage. The pack is slightly smaller, and 30 pounds lighter.
GM didn’t specify the pack’s total energy capacity, but Larry Nitz, Executive Director of GM Powertrain’s electrification engineering team, said that it had higher energy capacity and used more of it, so presumably we’ll see at least a slight increase in the Volt’s electric range of 38 miles.
“The current generation Volt’s battery has proven to provide our owners exceptional performance when it comes to quality and reliability,” said Nitz. “It would have been simple for us to tweak our existing battery to provide nominally increased range, but that’s not what our customers want. So our team created a new battery system that will exceed the performance expectations of most of our owners.”
Meanwhile, GM CEO Mary Barra has confirmed that most of the Volt’s components will be built in Michigan: the drive unit at GM’s Powertrain plant in Warren, and the battery pack at its battery assembly plant in Brownstown. “We must provide the breakthrough technology that our customers want,” said Barra. “Our investments in the Chevy Volt and Michigan signify our commitment to lead the industry in technology and innovation.”
More details, including range estimates, will be revealed when the new Volt makes its debut at January’s Detroit Auto Show. The 2016 Chevrolet Volt will go on sale during the second half of 2015.