11 A Brief History

1.1.1 Early days

The first electric vehicles of the 1830s used non-rechargeable batteries. Half a century was to elapse before batteries had developed sufficiently to be used in commercial electric vehicles. By the end of the 19th century, with mass production of rechargeable batteries, electric vehicles became fairly widely used. Private cars, though rare, were quite likely to be electric, as were other vehicles such as taxis. An electric New York taxi from about 1901 is shown, with Lily Langtree alongside, in Figure 1.1. Indeed if performance was required, the electric cars were preferred to their internal combustion or steam powered rivals. Figure 1.2 shows the first car to exceed the 'mile a minute' speed (60mph) when the Belgium racing diver Camille Jenatzy, driving the electric vehicle known as 'La Jamais Contente',1 set a new land speed record of 106kph (65.7mph). This also made it the first car to exceed 100 kph.

At the start of the 20th century electric vehicles must have looked a strong contender for future road transport. The electric vehicle was relatively reliable and started instantly,

1 'Ever striving' would be a better translation of this name, rather than the literal 'never happy'.

Electric Vehicle Technology Explained James Larminie and John Lowry © 2003 John Wiley & Sons, Ltd ISBN: 0-470-85163-5

Figure 1.1 New York Taxi Cab in about 1901, a battery electric vehicle (The lady in the picture is Lillie Langtry, actress and mistress of King Edward VII.) (Photograph reproduced by permission of National Motor Museum Beaulieu.)
Figure 1.2 Camille Jenatzy's 'La Jamais Contente'. This electric car held the world land speed record in 1899, and was the first vehicle to exceed both 60mph and 100 kph

whereas internal combustion engine vehicles were at the time unreliable, smelly and needed to be manually cranked to start. The other main contender, the steam engine vehicle, needed lighting and the thermal efficiency of the engines was relatively low.

By the 1920s several hundred thousand electric vehicles had been produced for use as cars, vans, taxis, delivery vehicles and buses. However, despite the promise of the early electric vehicles, once cheap oil was widely available and the self starter for the internal combustion engine (invented in 1911) had arrived, the IC engine proved a more attractive option for powering vehicles. Ironically, the main market for rechargeable batteries has since been for starting IC engines.

1.1.2 The relative decline of electric vehicles after 1910

The reasons for the greater success to date of IC engine vehicles are easily understood when one compares the specific energy of petroleum fuel to that of batteries. The specific energy2 of fuels for IC engines varies, but is around 9000 Whkg-1, whereas the specific energy of a lead acid battery is around 30 Whkg-1. Once the efficiency of the IC engine, gearbox and transmission (typically around 20%) for a petrol engine is accounted for, this means that 1800 Whkg-1 of useful energy (at the gearbox shaft) can be obtained from petrol. With an electric motor efficiency of 90% only 27 Whkg-1 of useful energy (at the motor shaft) can be obtained from a lead acid battery. To illustrate the point further, 4.5 litres (1 gallon3) of petrol with a mass of around 4 kg will give a typical motor car a range of 50 km. To store the same amount of useful electric energy requires a lead acid battery with a mass of about 270 kg. To double the energy storage and hence the range of the petrol engine vehicle requires storage for a further 4.5 litres of fuel with a mass of around 4 kg only, whereas to do the same with a lead acid battery vehicle requires an additional battery mass of about 270 kg.

This is illustrated in Figure 1.3. In practice this will not double the electric vehicle range, as a considerable amount of the extra energy is needed to accelerate and decelerate the 270 kg of battery and to carry it up hills. Some of this energy may be regained through regenerative breaking, a system where the motor acts as a generator, braking the vehicle and converting the kinetic energy of the vehicle to electrical energy, which is returned to battery storage, from where it can be reused. In practice, when the efficiency of generation, control, battery storage and passing the electricity back through the motor and controller is accounted for, less than a third of the energy is likely to be recovered. As a result regenerative breaking tends to be used as much as a convenient way of braking heavy vehicles, which electric cars normally are, as for energy efficiency. For lead acid batteries to have the effective energy capacity of 45 litres (10 gallons) of petrol, a staggering 2.7 tonnes of batteries would be needed!

Another major problem that arises with batteries is the time it takes to recharge them. Even when adequate electrical power is available there is a minimum time, normally several hours, required to re-charge a lead acid battery, whereas 45 litres of petrol can be put into a vehicle in approximately one minute. The recharge time of some of the new batteries has been reduced to one hour, but this is still considerably longer than it takes to fill a tank of petrol.

Yet another limiting parameter with electric vehicles is that batteries are expensive, so that any battery electric vehicle is likely not only to have a limited range but to be more expensive than an internal combustion engine vehicle of similar size and build quality.

2 'Specific energy' means the energy stored per kilogram. The normal SI unit is Joule per kilogram (Jkg-1). However, this unit is too small in this context, and so the Watthour per kilogram (Whkg-1) is used instead. 1 Wh = 3600 J.

3 British gallon. In the USA a gallon is 3.8 litres.

Vehicle with a range of about 50 km

Vehicle with a range of about 50 km

Engine and gearbox with an efficiency of 20%

Shaft energy obtained is 7200 Wh

Tank containing 4 kg (4.5 litres) of fuel with a calorific value of 36 000 Wh

Tank containing 4 kg (4.5 litres) of fuel with a calorific value of 36 000 Wh

Engine and gearbox with an efficiency of 20%

Shaft energy obtained is 7200 Wh

Lead acid battery with a mass of 270 kg, volume 135 litres, and energy 8100 Wh

Electric motor and drive system with overall efficiency of 90%

Shaft energy obtained is 7200 Wh

Vehicle with a range of about 500 km

Vehicle with a range of about 500 km

Tank containing 40 kg (45 litres) of fuel with a calorific value of 360 000 Wh

Tank containing 40 kg (45 litres) of fuel with a calorific value of 360 000 Wh

Lead acid battery with a mass of 2700 kg, volume 1350 litres, and energy 81 000 Wh

Shaft energy obtained is 72 000 Wh

Figure 1.3 Comparison of energy from petrol and lead acid battery

Engine and gearbox with an efficiency of 20%

Shaft energy obtained is 72 000 Wh

Electric motor and drive system with overall efficiency of 90% ' /

Shaft energy obtained is 72 000 Wh

Figure 1.3 Comparison of energy from petrol and lead acid battery

For example, the 2.7 tonnes of lead acid batteries which give the same effective energy storage as 45 litres (10 UK gallons) of petrol would cost around £8000 at today's prices. The batteries also have a limited life, typically 5 years, which means that a further large investment is needed periodically to renew the batteries

When one takes these factors into consideration the reasons for the predominance of IC engine vehicles for most of the 20th Century become clear.

Since the 19th century ways of overcoming the limited energy storage of batteries have been used. The first is supplying the electrical energy via supply rails, the best example being the trolley bus. This has been widely used during the 20th century and allows quiet non-polluting buses to be used in towns and cities. When away from the electrical supply lines the buses can run from their own batteries. The downside is, of course, the expensive rather ugly supply lines which are needed and most trams and trolley bus systems have been removed from service. Modern inductive power transfer systems may overcome this problem.

Early on in the development of electric vehicles the concept was developed of the hybrid vehicle, in which an internal combustion engine driving a generator is used in conjunction with one or more electric motors. These were tried in the early 20th century, but recently have very much come back to the fore. The hybrid car is one of the most promising ideas which could revolutionise the impact of electric vehicles. The Toyota Prius (as in Figure 1.11) is a modern electric hybrid that, it is said, has more than doubled the number of electric cars on the roads. There is considerable potential for the development of electric hybrids and the idea of a hybrid shows considerable promise for future development. These are further considered in Section 1.3.2 below.

1.1.3 Uses for which battery electric vehicles have remained popular

Despite the above problems there have always been uses for electric vehicles since the early part of the 20th century. They have certain advantages over combustion engines, mainly that they produce no exhaust emissions in their immediate environment, and secondly that they are inherently quiet. This makes the electric vehicle ideal for environments such as warehouses, inside buildings and on golf courses, where pollution and noise will not be tolerated.

One popular application of battery/electric drives is for mobility devices for the elderly and physically handicapped. Indeed, in Europe and the United States the type of vehicle shown in Figure 1.4 is one of the most common. It can be driven on pavements, into shops, and in many buildings. Normally a range of 4 miles is quite sufficient but longer ranges allow disabled people to drive along country lanes. Another vehicle of this class is shown in Figure 11.2 of the final chapter.

They also retain their efficiencies in start-stop driving, when an internal combustion engine becomes very inefficient and polluting. This makes electric vehicles attractive for use as delivery vehicles such as the famous British milk float. In some countries this has been helped by the fact that leaving an unattended vehicle with the engine running, for example when taking something to the door of a house, is illegal.

Hybrid Cars The Whole Truth Revealed

Hybrid Cars The Whole Truth Revealed

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