Welcome page

Links to columns

Information on advanced driving

Welcome page

Links to columns

Information on advanced driving

Welcome page

Links to columns

Information on advanced driving

car                                                         previous / next column

A PHYSICIST WRITES . . .

(April 2011)

Another issue of Advanced Driving magazine: another article on electric cars! The last two pieces didnít tell us much of electrical and other scientific interest but instead, as I said in my January column, focused on how such vehicles drive and how they might look in the future (these things matter, of course, but not greatly to me). The heading to this latest article is more promising: THE BIG SWITCH ... ending our addiction to oil ... could a network of battery exchange stations and charging points be the answer? Well, I would say itís got to be, because thereís no prospect soon of increasing the range of an electric car (or rather, its fully charged battery) much beyond 100 miles. But letís read on.

The article describes an international project to develop firstly a system of charging points in every possible location ó providing a minute of driving, it says, per minute of charging ó and secondly (for longer journeys) a network of battery-swap stations, which will send you on your way as quickly as when filling up now. Close liaison with manufacturers will be essential, clearly, though so far only Renault has risen to the bait by making its new Fluence car (and batteries) suit the design of the robot loading mechanism in the exchange depots. If the project succeeds and the cars sell, however, other makers too will certainly want to match the design.

And where is this happening? The first roll-out of the depots and of the Fluence is in Israel, where thereís strong government support ó not to mention strong sunlight for the solar power-generation plants that are appearing there. Next will come Denmark, with its surplus of wind electricity. Australia is watching with interest. Then if the US can be tempted away from its oil-based transport system too...

Iím now scanning the article for a mention of this country. Ah, here we are: ďThe UK so far does not figure in the plan. Perhaps our peculiar general cynicism, our planning processes and the ancient chaos of our road system are just too intractable to contemplate.Ē I would class this as a self-fulfilling prophecy. We can only hope that it isnít read by anyone charged (sorry!) with deciding how to save us from the oil famine that will inevitably come one day.

But surely some workable national system will emerge here for rapid charging and easy battery exchange (together with more non-polluting generation of electricity ó it would be absurd just to transfer the toxic output from exhaust pipe to power-station chimney). Without such a system, the attraction of a cost per mile of only two or three pence will be lost on potential owners of an electric car, as they worry about whether it will get them there and back (even if the journeys they have in mind represent a shorter distance than the nominal range of the car). And hereís another slightly worrying aspect thatís news to me: when the present-day lithium-ion batteries are repeatedly given either rapid or full charges (or both), their working life shortens...

So thereís much development work still to be done! And not only in the critical area of powering electric cars, but also on the secondary problem of enabling pedestrians to hear them coming. Itís ironic that motor manufacturers have mostly tried to silence the internal-combustion engine (without success) and now, suddenly, we have electric vehicles that are too quiet for safety.

The indications from research, as I mentioned in January, are that the hazard is greatest when they are travelling at low speeds and producing no tyre or wind-flow noise. Me, I canít offer an opinion on this, because so far Iíve never encountered an electric car in motion. Or if I have, then I just didnít notice it.

Anyway, what is being doing to overcome the problem? All sorts of sounds can be generated artificially, of course, and different ones are being assessed both by the vehicle manufacturers and by companies who specialize in such systems. Is the ideal noise a simulated engine rumble (or purr, depending on the level of prestige you might hope to convey)? If so, then it will need to be reproduced with high fidelity: nothing could be more embarrassing than an expensive new car that seems to have a tinny clockwork motor under the bonnet.

Or should the warning sound like a warning? This opens up the field alarmingly (sorry again). There are many Ďacceptedí warning tones, from simple beeps to strident klaxons, and they all annoy me to varying degrees ó which is mostly a good thing, I suppose, otherwise I would be ignoring them. But imagine a future traffic flow of electric cars, all emitting either the same irritating noise or different ones: this would simply be pollution from the front of the car, replacing what we have now from the rear.

At least there seems to be general agreement in the industry firstly that the warning sound should not resemble an ordinary car horn, secondly that it should be inaudible to the driver, and thirdly that it can and should cease automatically when the vehicle reaches about 20 mph. But already thereís argument over whether a switch should be provided for disabling the sound system altogether: safety organizations say that it needs to remain active, but the UK regulation that bans the use of your horn late at night in built-up areas seems also to forbid automatic warning noises. If this difficulty isnít sorted out soon, someone is going to say: bring back the red flag!

Peter Soul

previous / next column

self
car
car