Although it has yet to be given approval by the French company's board of management, the concept is a likely contender for production in 2001 - and with an operating limit of 160 miles, the novel workhorse could well replace the Electrique, which stores sufficient power for just 50 miles before needing to be recharged. Despite having only 23 nickel-cadmium batteries compared with the bank of 28 in the Electrique, Dynavolt is able to go further because it uses a compact four-stroke engine as an auxiliary generator. It is sized at a mere 500cc, but the twin-cylinder unit can provide sufficient charge to keep the van mobile if the main battery pack runs flat.
'We think this is a viable answer to the problem of extending the range of electrically-driven vehicles while maintaining low pollution levels. It's perfect for use in cities and urban areas,' said research and development chief Thierry Malingre. 'The decision about making Dynavolt a commercial proposition will be taken by the end of September, and we're confident it will get the green light,' added Malingre as Fleet NewsNet put a Multispace version of the van through its paces in a Paris suburb.
Total sales of the Electrique have reached only 1,600 in France and Britain, even though Government subsidies effectively match its price with that of the diesel-powered Berlingo. 'Everybody accepts that the electric vehicle is in the front line as far as safeguarding the environment is concerned, but many potential users have a real fear of being unable to complete their journeys and of being left stranded with flat batteries,' said Malingre. 'We understand this concern and have spent the last two years working on overcoming it. We're proud that our vehicle can provide zero emission transport in towns and still be viable over longer distances - I think it should be ideal for operators running delivery fleets.'
Now being put through extensive trials, the high-capacity van is the second phase of Citroen's efforts to prove the innovative Dynavolt concept. Smart computer technology lies at the heart of the Dynavolt system of intelligent energy management. Based on the distance the vehicle is required to cover and the driving conditions, it balances the electric motor's supply of power between the batteries and the LPG-driven auxiliary generator.
'All the driver needs to do is enter the distance figure and the computer does the rest. Depending on the battery charge and the power which is required, the power management system will decide when the generator will be started. Another significant feature of the system is that the computer always aims to use up all the battery charge in one day's travel. This enables a full recharge to take place overnight to gain most benefit from low operating costs and to maximise battery life,' said Malingre.
The Dynavolt principle was first shown in the Saxo at the Paris Motor Show in September 1998 and was subsequently further developed to become the Berlingo Dynavolt which debuted at the Geneva Motor Show in March. It is that prototype which is now being driven and, according to Citroen insiders, is closer to the 'real thing'. 'The van could be the next zero-emissions vehicle we produce, but these are essentially short-term solutions to alternative power. In the longer term, we think the answer lies with the fuel cell, and we are busy carrying out research into that area,' added Malingre.
Dynavolt Berlingo weighs 375lb more than its diesel-powered stablemate - but that doesn't prevent the noiseless van from being a sprightly performer in city streets. And even when loaded with five people plus luggage, the concept vehicle has the acceleration to match most conventionally-powered vehicles in the traffic-light grand prix.
The van proved to be a surprising performer over a test route near Versailles which took in a variety of traffic conditions - but its DC motor didn't have quite enough muscle for an overtaking manoeuvre which was attempted at about 45mph. 'While we claim the Dynavolt is viable over much longer distances than you'd contemplate for a normal battery-driven vehicle, it is not intended as open-road transport or for use on motorways,' explained Malingre.
Like the Berlingo Electrique, Dynavolt has a lively demeanour and is capable of nudging 60mph all-out. Apart from the fact that it operates in total silence and makes only a slight whirring sound when the Italian-built Lombardi generator unit springs into action, it behaves much like a fossil-fuel vehicle. On the concept, a radio-sized aperture on the dashboard is used to operate the computer which controls the power system. In Citylogic mode, Dynavolt is a purely electrically-powered vehicle which has a range of 50 miles. At speeds above 44mph, the auxiliary generator cuts in and effectively extends the range to about 90 miles.
Switched to Autologic mode, the point at which the generator operates can be as low as 25mph to give a maximum range of 150 miles. Two other modes are available to the driver, however. If the vehicle needs to be operating at zero emissions level in order to gain access to areas which could be subject to future restrictive legislation, a button can be pressed to revert the van to zero vehicle emissions running.
And should the main batteries become completely discharged, the auxiliary generator is able to take over the power supply to the electric motor - an emergency measure which limits maximum speed to 37mph.