Electric cars are becoming more popular with consumers, but until the infrastructure to keep them charged expands, there is the potential for very long waits to top up batteries. A computer model can help. By taking information about the electric car journeys on any given day it can slash waiting times by 97 per cent.
Sven Schönberg at Paderborn University and Falko Dressler at the Berlin Institute of Technology, both in Germany, simulated 5000 electric vehicles undertaking trips of 500 kilometres in a single day on Germany’s roads. They found that the average wait to charge was over 6 hours.
The researchers wondered whether they could reduce the wait by developing an algorithm to plan journeys more efficiently.
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Calculating the shortest path from point A to point B via charging stations is enormously computationally intensive, so the researchers pre-calculated the most efficient routes between nearby charging stations available on the German road network. On-board computers in cars can then customise an optimal route by creating a string of these connections.
The researchers also propose a central database to which drivers upload their planned routes and charging stops – like pilots filing a flight plan to an aviation administration. An algorithm can then process the information from all drivers to maximise the efficiency of the journeys.
For instance, using information from the algorithm, a car’s navigation system might suggest that a vehicle goes at a slower and more efficient speed if it knows there will be a wait at a charging station anyway. Doing so can actually reduce total journey time: travelling at a slower speed is more energy efficient and so when the car does arrive at the charging stop the driver won’t have to lose as much time fully charging the battery again.
“It is easy to find the fastest route or the most energy efficient route,” says Schönberg. “But sometimes the optimal solution is somewhere in between. We want to minimise travel time, so the fastest route seems to be the logical choice, but if that means another charge stop, it will probably increase the travel time overall.”
When the team reran the same simulation of 5000 electric vehicles using the central database and algorithm, it found the average waiting time to charge fell to 11 minutes.
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