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Motorway charging points could unshackle electric cars

Tuesday 2nd October 2012

A network of rapid charging points for electric cars are to be installed in motorway service stations around the country (Telegraph).

The charging points – where an electric car can be recharged in 15 minutes – could be the catalyst for electric cars to break out of the cities and onto the open road, suggests the Telegraph.

Conventional charging points usually take several hours to provide enough power and with a range of around 100 miles electric cars are more commonly used for short journeys in towns and cities.

But manufacturers hope that a network of charging points in motorway service stations will allow owners to make longer journeys and help electric cars become more mainstream on Britain’s roads, says the Telegraph.

Dale Vince, founder of Ecotricity, the company installing the new charge points, said: “The super-chargers we are installing can recharge a car in the time it takes to have a cup of tea in a service station.”

They plan to install charging stations at every motorway service station in the country to allow electric car owners to ‘fill up’ their vehicles just as they would a petrol car.

However, a recent report by the Transport Committee warned that provision of charging points may not stimulate demand for plug in vehicles.

But Mr Vince said: “We don’t believe putting charging points in towns and cities is the right approach as that is not where people will need them as they are close to their homes.

“Most car journeys are not more than 20 miles, but putting charge points in motorway service stations means that people will be able to make longer journeys if they want to.”

Click here to read the full Telegraph report.

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15 minutes does sound optimistic. 30 minutes is the more commonly touted number. Electric cars can indeed use much higher voltages than 240, so the currents required are not so significant.

Also remember that not all cars are pure electric. My car has quite a short plug-in range, and does support fast charging, so I could make use of this to improve my fuel efficiency, but not power my whole journey.

Manufacturing electric cars is expensive (to the environment), but so is any other new car, and the general population continues to buy new cars.
Matt, Essex

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0

I can see all the electric cars waiting for transporters on the hard shoulder now! The whole life CO2 cost of these is massive compared to an efficient modern diesel. The power stations are not carbon neutral so the wisdom of electric cars for most people won't work at all. The mining of the materials, transportation and building them is about as clean as running a 1964 Morris Oxford on leaded fuel! Emperor's new clothes.
Olly, Lancs

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+1

Hi Gerry, I had not worked out the numbers but, now that I have, I agree with your calculations.

There is no way that an e-car can carry a 100KVA transformer or SMPSU on board (cost, weight, size) so the station would have to feed the batteries direct. If they are 12v, that's around 8,000A. If that is even possible, it's going to need a car specially adapted to accept such massive current flows.

Obviously, the idea of super-fast charging solves a specific problem of range for e-cars but it is very difficult to achieve in practice. I doubt the claim of a full charge in 15 minutes is true and there may be other issues over heat, battery life and who pays if damage caused, etc.
Dave Finney - Slough

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+2

As an electrical engineer for 52 years (and user of rechargeable batteries longer) I very much doubt that any otherwise suitable battery could accept such rapid charging without overheating and quite possibly exploding (as smaller fast charge ones often do in model aircraft).

The energy difference between what is put in and what the battery retains has to be dissipated as heat, the quicker the charge the faster it has to happen, in this example equating to 5 to 7 fan heaters inside the battery.

With car battery voltage lower than 240, current via the charging lead would be higher (120v needing 800 Amps, 60 volt 1,600 amp, the latter needing 125 times the conductor area (11 times the diameter) of a household 13 amp cable.

The electric car dream is dying on its feet - the "wisdom of crowds" applies, owners and drivers can do the arithmetic and are voting with their wallets.
Idris Francis Petersfield

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0

Some back of envelope calculations...

Assuming that a plug-in-to-a-13A-domestic-outlet e-car takes 8 hours to charge, then a 15-minute charge would draw a massive 416A at mains voltage (needing some seriously fat cables, plugs and sockets), or lower currents at higher voltages. Hmmmm...

Given the slower throughput compared to a petrol station, there would need to be many more e-pumps. 240V and 416A is nearly 100kW per e-car, so each charging station would presumably need to be underneath a pylon.

And if unexpectedly high numbers of e-cars turn up during the rush hour, well, that’s why there’s a handy Travelodge on site...
Gerry, London

Agree (6) | Disagree (0)
+6

To fully charge an electric car in 15 minutes would require a huge current flow. There are risks of fire and even explosion along with possible damage to battery life. The cars will have to be designed specifically to allow such a fast charge. Does anyone know the voltages and currents required?

Also, I did ask the presenter of a talk on electric cars “If a gallon of fuel is burnt at the power station to charge an electric car, how many miles would it be expected to travel on average?” Even though he had given detailed figures with split sources of power, he didn't actually know.

Does anyone know "what is the average mpg of an electric car?"
Dave Finney - Slough

Agree (7) | Disagree (1)
+6