(July 17, 2011) Volvo this past week announced the next step in the company's electrification strategy by producing three test cars with Range Extenders — electric cars that are fitted with a combustion engine to increase their effective range.

Range extenders add an internal combustion engine to a primary electric motor to generate electricity once the battery gets low, meaning owners can use them for long journeys without the need to stop the car and plug in for a recharge.

In some set-ups, the gas or diesel engine can also indirectly drive the wheels, supporting the electric motor.

The Chevrolet Volt is the first such mass produced version of this technology.

The projects, supported by the Swedish Energy Agency and the EU, encompass three potential technology combinations. Tests of the various concepts will get under way in the first quarter of 2012.

"This is an exciting expansion of our increasing focus on electrification. Battery cost and size mean that all-electric cars still have a relatively limited operating range. With the Range Extender, the electric car has its effective range increased by a thousand kilometers (620 miles) — yet with carbon dioxide emissions below or way below 50 g/km," says Derek Crabb, Vice President Powertrain Engineering at the Volvo Car Corporation.

The company's technological developments in this area currently encompass three different technology combinations, with three-cylinder gas engines being installed to complement electric drive to the front wheels. All the variants feature brake energy regeneration. The engines can run on both gas and ethanol (E85).

Two of the solutions are based on the Volvo C30 Electric. In both cases, the standard battery pack has been somewhat reduced in size to make room for the combustion engine and its fuel tank.

The range extended gives the Volvo the ability to travel more than 600 miles without stopping.



Technical concept I: Volvo C30 with series-connected Range Extender

This is based on a C30 Electric with a three-cylinder combustion engine producing 60 horsepower installed under the rear load compartment floor. The car also has a 10.5-gallon fuel tank.

The combustion engine is connected to a 40 kW generator. The power it generates is used primarily to drive the car's 111 horsepower electric motor, but the driver can also choose to let the generator charge the battery, thus increasing the car's operating range on electricity.

The Range Extender increases the electric car's range by up to 620 miles on top of the 68-mile range provided by the car's battery pack.

Technical concept II: Volvo C30 with parallel-connected Range Extender

Here the car gets a more powerful three-cylinder combustion engine at the rear and a 10.5-gallon fuel tank. The difference between this and the first solution is the parallel connection, whereby the turbocharged 190-horsepower engine primarily drives the rear wheels via a six-speed automatic transmission. This gives a better fuel efficiency rating when driving with the combustion engine cruising on the highway. Via a 40kW generator the battery can also be charged to give the car increased range on electricity alone.

Here too the electric motor is a 111-horsepower unit. The two power sources give the car more than 300 horsepower in total, and acceleration from 0-60 in less than six seconds.

The Range Extender increases the electric car's range by more than 620 miles — in addition to the range of up to 45 miles provided by the car's battery pack.

Technical concept III: Volvo V60 with parallel-connected Range Extender

This is a solution whereby the entire drive package is installed under the hood at the front. The 111-horsepower electric motor is supplemented with a three-cylinder gas turbo engine producing 190 horsepower, a two-stage automatic transmission and a 40 kW generator. Power from the combustion engine drives the front wheels via the gearbox and recharges the battery pack whenever needed.

For up to 31 miles, the car is always powered solely by electricity. The combustion engine is activated at higher speeds. What's, it charges the battery pack when its charge drops below a predetermined level.

The car also has a 12-gallon tank for gas or E85.

With this technology, the Range Extender increases the car's total range by more than 620 miles.