CABLED trial shows EVs satisfy requirements of urban drivers

Data from the CABLED electric vehicle (EV) trial in the West Midlands indicates that EVs are capable of satisfying transportation requirements of urban drivers.

CABLED (Coventry and Birmingham Low Emission Demonstrators) is the largest of eight public trials taking part in the Technology Strategy Board’s £25m Ultra Low Carbon Vehicle Demonstrator programme.

The data, taken from 25 Mitsubishi i-MiEVs and 20 smart fortwo electric drives during the course of the trial, shows that in spite of initial scepticism surrounding the capability of EVs and concerns over range anxiety, they are able to meet the needs of motorists that require efficient urban transportation.

According to CABLED, this is reflected by the finding that 77 per cent of journeys undertaken lasted less than 20 minutes and only two per cent used more than 50 per cent of the battery, enabling a return journey to be made without the need for recharging in many cases.

The data also showed a trend towards drivers travelling longer journeys over time, indicating increased confidence and reduced range anxiety.

In relation to charging behaviour, the CABLED data is said to show that EV users are not motivated to replenish their vehicle’s battery by reaching a particular point of depletion.

CABLED said that the most popular point at which people commenced charging was when the battery had 81–87 per cent of its charge remaining. With the majority of journeys using less than 2kWh of power (around 12 per cent of charge) this behaviour indicates that charging habitually takes place when reaching a destination.

The average charge time was between two to three hours (typically equivalent to half of a full charge) with an energy transfer of 6kWh costing around £0.60–£0.80, depending upon tariff. Peak times for charging were observed from 0700–900 and from 1800–1900, which CABLED said can be most likely attributed to charging on arrival at work in the morning or home in the evening. Another peak was seen after 2300 when CABLED participants used timers to take advantage of off-peak energy tariffs.

Charles Bradshaw-Smith, head of e-mobility R&D at E.ON, said: ‘Meters installed at each user’s home are giving us invaluable information on charging behaviour. The most popular time to charge a vehicle is rightly overnight. But as most journeys are relatively short [with five average journeys per charge] this allows scope for exactly when the car is charged each night to minimise cost and maximise carbon savings.’

CABLED is one of several government measures designed to increase the number of low-carbon vehicles on Britain’s roads. Data collected over 12 months can now be used to support future decisions relating to transport and infrastructure planning.