Electric charge

The Peugeot 106 Electric is being put through its paces in Coventry. And no one’s talking milk floats: the model boasts an electronic power management system and can go from 0-30mph in 8.3 seconds. David Fowler reports

A new type of vehicle is making its debut on the streets of Coventry. At first glance it looks remarkably like the Peugeot 106. But listen. It is strangely quiet. It emits no exhaust fumes. Inside, next to the speedometer is a big dial calibrated from 0-100% and marked `Energie’. The gear lever is unaccountably absent.

The car is the Peugeot 106 Electric – powered by an electric motor. Fourteen 106 cars and vans are being evaluated by Coventry City Council, East Midlands Electricity, PowerGen and the Royal Mail in a trial lasting a year, with an option to continue for a further 12 months. Funding from the Energy Saving Trust allows the users to lease the vehicle for the price of the 106 diesel.

Peugeot approached Coventry City Council because its UK operations are based there. A similar trial in La Rochelle, France, ended in 1995. As a result, Peugeot put the 106 Electric on sale. With subsidies from the French government and Electricite de France to bring the price down to the same level as a well equipped internal combustion 106, it sold 700 in its first year, mainly to fleet users.

The 106 Electric is the latest manifestation of an £80m research programme started by Peugeot’s parent company PSA in 1968.

Now, the 106 Electric, equipped with nickel-cadmium rather than lead-acid batteries and with sophisticated electronics to control power delivery, drives much like a normal car around town. It is no motorway cruiser, but it accelerates from 0-30mph in 8.3 seconds on the way to a top speed of 56mph.

There are some problems with electric cars, Graham Deeming, Peugeot’s UK project manager, explains: lack of range, lack of speed, perceived lack of refinement (mention electric vehicle and people think of milk floats) and high cost.

For fleet vehicles in an urban environment the first two are not so important. The 106 Electric can comfortably keep up with town traffic. As for range, 60 miles is achievable, and enough for fleet vehicles in the city. Royal Mail plans to use one on a 70-mile daily route in Coventry, with an interim recharge during the day.

As for refinement, part of the point of the Coventry trial is to expose how far electric car technology has moved.

Key to this is the car’s electronic power management system. This governs delivery of power to the motor under control of the accelerator and brake, through thyristor `choppers’; recovery of energy during braking; and management of battery recharging. When the driver’s foot is lifted from the accelerator, the motor becomes a generator and recharges the batteries.

The electronics were developed initially by Peugeot’s engineers, bringing in the French electronics firm Sagem, at the point where the technology needed industrialising.

Peugeot also did the initial development of the DC electric motor, a 20kW unit supplied by Leroy Somer and delivering 127Nm torque from 0-1500rpm. It is mounted transversely at the front of the car, coaxially with the front driveshafts. Because an electric motor develops torque from zero revs and is stationary when the car is at rest, there is no clutch. It reaches 6500rpm via a 7.2:1 reduction gear, roughly equivalent to second gear, so there is no need for a gearbox. A dashboard switch selects forward or reverse.

Batteries, supplied by Saft, are wet nickel-cadmium. They weigh 30% less for the same power as lead-acid batteries and give satisfactory operation from -10-30iC. They also have a longer life expectancy than lead-acid – up to eight years, says Deeming. Batteries are recharged by an onboard charger connected to a 13A socket. A normal charge is four hours, though around once a week a longer equalisation charge is recommended to equalise the voltage from each cell.

Battery weight and size is still considerable, however. There are nine 6V units under the bonnet and another 11 in the boot, instead of the spare wheel. Because of the extra weight the car is designated a four-seater rather than, as in the case of the normal 106, a five-seater.

There is a conventional water cooling system and fan to cool the batteries and electronic controller, but this is mainly needed during charging. There is little waste heat, so a petrol combustion heater is provided for interior heating, with a 10 litre tank under the rear seat.

Many would argue that the environmental benefits of electric cars have been oversold, particularly given the Californian misnomer `zero emission vehicle’. Though electric cars produce no local emissions, the power station producing the electricity still produces carbon dioxide, sulphur dioxide or nuclear waste. However, there are obvious potential benefits for local air quality in congested city centres.

Internal combustion engines are least efficient in congested traffic. They burn fuel while stationary, whereas the electric vehicle uses energy only when moving. Figures verified by the Energy Saving Trust show that the energy consumption of an electric vehicle in town traffic can be as little as 30% of that of a petrol vehicle. Taking account of the energy consumption in the supply chain from extracting the fuel from the ground to using it in the vehicle itself, electricity saves 17% in total lifecycle energy consumption.

Fewer carbon dioxide and other greenhouse gases are produced by the power station than are emitted from an internal combustion engine vehicle. Emissions of sulphur dioxide would be greater, however, from coal power stations without flue gas desulphurisation.

Peugeot says the 106 Electric has generated enormous interest from local authorities. But cost remains the biggest obstacle. Most of the car is produced on the main 106 production line at the rate of 1,500 a day, then fitted with electric components at the rate of only 30 a day. And the cost of the batteries is unlikely to get much lower.

The question of whether a market for electric cars will develop without government subsidy remains open.