General Motors has shed some light on the lighter, sprightlier and more efficient plug-in hybrid drivetrain that will underpin its second-generation 2015 Chevrolet Volt.
As we know, the new and improved Volt will make its world premiere at the North American International Motor Show in Detroit this coming January before hitting US roads by the second half of 2015.
Far from just fettling the current setup, General Motors claims to have enacted much more substantial changes, based partially on data collected from current Volt drivers.
The new Voltec extended range electric vehicle propulsion system (that’s GM phrasing), encompassing the drive unit, range-extending engine and power electronics, will be smaller in size but more efficient. Expect a more practical car with a greater travel range therefore.
Revised cell chemistry, developed with South Korean company LG Chem, increases storage capacity by 20 per cent on a volume basis when compared to the original cell, while the number of cells decreases from 288 to 192.
The cells are positioned lower in the pack for a lower centre of gravity and the overall mass of the pack has decreased by almost 13kg.
GM will carry over the batteries’ active thermal control system that maintains electric range over the Volt’s life. About 20 million battery cells have been produced for the more than 69,000 Volts sold with fewer than two problems per million cells produced reported.
The next-generation Volt’s drive unit was reengineered for better efficiency and performance, improved packaging and reduced noise and vibration characteristics. The two-motor drive unit operates between 5 to 12 per cent more efficiently and weighs 45kg less.
The Traction Power Inverter Module, which manages power flow between the battery and the electric drive motors, has been directly built into the drive unit to reduce mass, size and build complexity.
The boost in performance comes from both motors operating together in more driving scenarios, in both EV and extended-range operation, according to GM. The ability to use both motors helps deliver more than 20 percent improvement in electric acceleration.
GM engineers designed the Voltec electric motors to use significantly fewer rare earth materials. One motor uses no rare earth-type magnets at all.
Energy for the extended-range operation comes from a new direct-injected 1.5L four-cylinder engine in place of the current 1.4. This engine is familiar from the new-generation Cruze. The engine features a high-compression ratio of 12.5:1, cooled exhaust gas recirculation and a variable displacement oil pump.
The drive unit will be made in Michigan, while the engine will be made for the first year in Mexico before also shifting to Michigan, at GM’s Flint plant. This is good PR, with the company pumping funds into one of the US’ most cash-strapped places.
The gist of all this is that GM promises the Volt will travel further on electric power and take off faster. That said, the EV range estimates will not be revealed until NAIAS in January. The current car manages, at best, 87km on electric power (claimed), and can travel more than 600km with a full tank of petrol.
As we have gleaned from spy images, the largely Cruze-based Volt is poised to retain its signature aerodynamically-friendly wedged body. Given the increased global scale of battery production, you’d expect some savings too.
The current Volt sells in Australia as a Holden for $59,990 and has been on sales since September 2012. A little under 250 units have been sold in that time. With its lack of incentivisation, Australia is regarded by car-makers as a niche market at best for EVs and plug-ins of this ilk.
We've contacted Holden for confirmation of if/when the new Volt will come here.