I have garnered this information because I have found very little on how car owners who rely on street parking are expected to recharge an electric car.  If you live in a terrace house a parking space outside your home cannot be guaranteed and you will not be able to fit an external wall mounted charger.  In theory it is possible to live without local charging points but the cost per kilowatt hour will be higher than having you own charging point.  The result is unintended discrimination based on house ownership and annual salaries.

A good idea!  What are the advantages of electric cars over petrol- and diesel-powered cars?

It is stated that electric vehicles cause no pollution.  When in use petrol/diesel engines cause pollution but the electric car, when being charged, also produces pollution as gas and oil may be used to generate electricity.

Pollution is, or has been, produced during the manufacture/construction of the various types of power stations.  Pollution is produced during the manufacture of batteries for cars.  Both electric and petrol/diesel cars produce pollution during their manufacture.

Electric cars are not pollution free.

Why do people buy electric cars?  Are they value for money?  A petrol/diesel engine will last for 150,000 to 200,000 miles but do need maintaining which costs money.  Will traction batteries last for the same mileage?  One electric car manufacturer gives a 100,000-mile guarantee with its cars and I assume this includes the battery; what are the cost of replacement batteries?

Some people buy electric vehicles because they believe that electric vehicles produce no emissions.  Electricity transmitted by the National Grid is provided by a mixture of sources.

At the moment no road tax is paid for electric vehicles, that is a loss of income to the Treasury of say £200 per car.  As more electric vehicles are purchased, replacing petrol/diesel vehicles, the Treasury may introduce a road tax on electric vehicles, may introduce road use pricing (toll roads) else personal income tax, VAT and business taxes will be increased.  Petrol and diesel fuel taxes carry a high percentage of taxes compared with the taxes on electricity, business paying a higher tax (20% VAT) than domestic users.  Once again, the Treasury will have to raise money to cover the loss of Excise Duty.  Will the electricity used for electric vehicles eventually carry a “vehicle use” tax?  This will require separate meters for non-vehicle use and vehicle use.  The electric vehicle discount will probably be phased out.

Cars are purchased to give the purchaser freedom from bus, tram and train transport.  The range of the vehicle until now was rarely mentioned.  Does it matter that the petrol/diesel car has a range of 200 miles?  No!  What is the inconvenience of refuelling if it is a matter of say 10 or 15 minutes after a 4-hour drive?

The range of an electric car depends upon the battery size, the battery size tends to be proportional to the size of the car, smaller cars have smaller batteries.  Small capacity batteries give less range than higher capacity batteries.  The question then becomes what range do I need and how long will it take to recharge a battery.

For me to visit a hospital might require a round trip of approximately 66 miles.  On this trip I also need to allow for a diversion of 8 miles each way giving a total 82 miles.  The journey takes about 50 minutes therefore I need a heating allowance of, say, 2 hours, one hour each way.  I may need 2 kilowatts of heating per hour, a total of 4 kWh, for demisting and lights.  A 30kwh battery should give a 100-mile range but one car manufacture states that the range is reduced by 25% in temperatures of 0 degrees centigrade.  So, I will need a bigger battery than the manufacturer provides.

The travelling time, from my home to a hospital, by public transport (train, bus, and walking) could be at least 2½ hours each way compared with one hour each way by car.  Just think, a minimum of five hours travelling for a hospital appointment using public transport.   Another hospital, slightly closer, requires 2 hours travelling each way.  Miss a bus, that runs every hour, and there could be another hour on the time.

Is an electric car with a 100-mile range, in cold weather, of any use unless it used locally, i.e. up to 40 miles away?  A fast battery charge will only give an 80% charge with up to one hour charging time.  So, the return range with a 100-mile battery is now 80 miles not 100 miles and the cold weather range even less.

Consider a car with a 50kwh battery and a 250-mile range.  Summer range with a continual 80% charge is 200 miles not 250 miles.  The winter range could now be 150 miles not the quoted 250 miles.  My figures are approximations.

Refuelling on long distance journey may add 1 hour per charge.  Time can be saved by increasing battery capacity and thus range.  Just imagine wanting to recharge your electric car if there are four cars in front of you, each car will take one hour to recharge,

A 30-kWh battery if charged at 3kw will take 10 hours; 3kw being the rating of a 13-ampere plug.  A 50-kWh battery will take roughly 17 hours.  To charge a 30-kWh battery in 1 hour will need roughly 130 amperes at 240 volts or around 110 amperes for an 80% charge.  A 50-kWh battery will need around 180 amperes for an 80% charge.  What loads can the low voltage electricity supply withstand without causing voltage problems to other electricity users?

Regarding the car the size of the charging leads will depend upon the charging currents. What length of charging cable will be required as it might not be practical to have a charging point at the rear of the car?  Standardisation of electricity plugs on these leads will be required.  Standardisation of charger output voltage and maximum charging currents will also be needed.

A domestic electricity supply has a 20-kW capacity and the average demand per household is around 2kw for a 24-hour period.  This equates to charging a 20kwh battery for a 1 hour or charging a 40-kWh battery for 2 hours.  It would be more practical to charge the batteries at around 12½ kW giving charging times of say 1½ hours or 5¼ hours respectively. What needs to be stated is the optimum charging rate to achieve a 95% battery charge as well as the ‘trickle charge’ rate.

Please note that assumptions have been made about battery capacity, battery discharge (range).  These assumptions are based on sales information from electric car providers.

(To be continued with Part 2 tomorrow)




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