Volvo ReCharge Concept:
Ground-breaking plug-in hybrid with a range of 100 km on battery power and with a combustion engine for back-up power
The Volvo ReCharge Concept is a plug-in hybrid with an electric motor at each wheel and batteries that are recharged every day via a household electric power socket. This gives the driver about 100 kilometres on electric power alone. When necessary, the car's four-cylinder combustion engine is activated to recharge the batteries on the move.
"A certain proportion of electric cars will be an integrated part of our future product portfolio. Since the Volvo ReCharge Concept has an excellent operating range on battery power alone while at the same time integrating its own combustion engine for back-up power on the move, this is a highly interesting concept for the future," says Magnus Jonsson, Senior Vice President Research and Development at Volvo Cars.
The concept car was developed at the Volvo Concept and Monitoring Center (VMCC) in Camarillo, California.
"This is a ground-breaking invention. Anyone driving less than 100 km a day will seldom or never need to visit a filling station. In the USA, that applies to about 80 percent of all motorists," explains Magnus Jonsson.
The excellent battery range means that the Volvo ReCharge Concept is exceptionally kind to the car owner's wallet.
When driving on electricity alone, running costs will be about 80 percent lower than for a petrol-powered car of the same size. For distances longer than the range of the batteries and with the combustion engine operating, fuel consumption will vary from 0 till 5.5 l/100 km depending on the fuel and on how much the combustion engine is run.
"Used in the most efficient way, the plug-in hybrid should give about 66 percent lower emissions of carbon dioxide compared with the hybrid cars available on the market today. And if the electricity comes from CO2-favourable sources such as biogas, hydropower and nuclear power, the figure improves still further," comments Magnus Jonsson.
An electric motor at each wheel
There is no mechanical power transmission from the combustion engine to the wheels. The Volvo ReCharge Concept is what is known as a series hybrid featuring a number of interacting technologies:
- The battery pack installed under the luggage compartment's floor consists of lithium-ion-polymer batteries. They are designed for a lifetime longer than that of the car itself.
- Four electric motors, one at each wheel, provide individual four-wheel drive.
- A four-cylinder combustion engine drives the advanced generator that provides power for the wheel motors when the battery requires a recharge. Possible engine alternatives are for instance a four-cylinder 1.6-litre diesel or a four-cylinder Flexifuel engine.
Electric car with a combustion engine for backup power
In principle one might say the Volvo ReCharge Concept is a battery-powered electric car with an efficient generator or Auxiliary Power Unit (APU) which steps in when battery power gets low.
The generator has been designed to distribute electric power to the electric motors at each wheel. Since the combustion engine only drives the generator, its combustion process can be fully optimised as regards both fuel consumption and CO2 emissions.
The APU is sufficiently powerful to be able to supply an entire villa with current. With a minor modification it would be able to serve the car owner as an electric generator in the event of a mains power failure.
The driver can choose the power source
The combustion engine is automatically started when 70 percent of battery power is consumed. However, the driver can also manually activate the engine via a button on the instrument panel.
"There is a significant difference between our plug-in hybrid and today's hybrids, which only use the electric motor to support the combustion engine for short periods. Our solution instead makes it possible for most car owners to drive one hundred percent on electric power, with the extra security of knowing there is an on-board combustion engine for backup," explains Ichiro Sugioka, project manager for the Volvo ReCharge Concept. He adds:
"What is more, our C30 with plug-in hybrid technology retains its alert and sporty characteristics. Acceleration from 0-100 km/h takes 9 seconds and top speed is almost 160 km/h."
Specially developed electric motors
The central electric components in the Volvo ReCharge Concept - the generator for the APU and the four wheel motors - have been developed in close cooperation with British specialists PML Flightlink.
With one electric motor per wheel, both weight distribution and power transmission are optimal, without geartrain losses. The car has no traditional gearbox so there is no gear lever either.
In order to further optimise its environmental benefits, the Volvo ReCharge Concept runs on high-efficiency tyres from Michelin. The tyres have been specially developed to afford space for the wheel motors.
The car is four-wheel drive in the true sense of the term. Drive to each wheel can be adjusted individually.
The energy that is generated during braking is diverted back to the battery pack. When the system has been fully developed, Volvo hopes to be able to replace the conventional brakes with electric brakes that cut energy losses caused by friction.
An electronic control system with quadruple redundancy contributes to the driveline's and braking system's operating reliability.
Green solution for commuters
The Volvo ReCharge Concept is best suited for car drivers who cover short distances every day. For example, a car owner with less than 100 km to drive between home and work can cover the entire distance on electric power alone.
Even someone who covers longer distances than the range afforded by the batteries can count on significant environmental benefits. A trip of 150 kilometres that starts with a fully charged battery will use less than 2.8 litres of fuel, which corresponds to fuel consumption of 1.9 l/100 km.
"The only requirement is that the car owner should have access to a regular household power socket within a convenient distance, at home or at work. A full charge takes 3 hours. However, even a one-hour quick charge will provide a range of about 50 kilometres," says Magnus Jonsson.