Automobile electronics, Electronics, Electronics components, Energy comsumption, Motors

Advantages and disadvantages of electric vehicle

In this post, is made a comparison of electric car with the vehicle moved by internal combustion. Reporting the strong and weak points of electric vehicle.

To see the posts about electric car, click in the buttons below.

Electric car (Parte 1)Click here

Electric car (Parte 2)Click here

Engine and motor

The motors of electric vehicles are much more efficient. The best internal combustion engines have an efficiency between 30 and 40%, while the electric motors have between 80 and 95% efficiency.

The combustion engine is heavier than electric motor, because the engine needs to convert the linear motion of pistons in circular using the crankshaft. It needs counterweights to keep the balance, the engine also needs a flywheel to create a smooth rotation and transfer power to the transmission. A DC motor is used to start.

Another important component to combustion engine is the alternator.

It is linked to engine’s axis by a belt, generates alternate current, the later is converted to continuous, and provides energy to recharge the battery.

While the induction motor is electronically controlled by the inverter, many parts in combustion engine are dispensed. It contributes to electric car be quieter.

In this point, the electric vehicle is better.

Resupply

The combustion vehicles are resupplied in few minutes, while the electrics can take more than 1 hour.

Considering the current technology, the combustion vehicle is better in this point.

Energy density

The energy density of Li-ion batteries is much lower than in combustion fuels. These graphics compare the energy densities of many types of batteries and fuels. Li-ion battery with cobalt as cathode have the biggest energy density between the batteries.

The electric vehicle’s battery pack occupies much more area in comparison to fuel tank in combustion automobile. In the figures below, can observe battery pack size in electric car in yellow and gas fuel in purple. The ethanol car has the same gas tank size of gasoline.

This is another advantage of combustion vehicle.

Environmental impact

The electric vehicle does not produce emissions, which improves the air quality in urban centers. However, if electric car resupply’s source is originated from a fossil fuel thermoelectric, it becomes as polluter as the gasoline car. The electric car needs lithium to batteries, this element can be extracted from mines or brines in desert. The extraction by brines causes a lower environmental impact and it is from where comes most production of this metal.

The batteries of electric vehicle needs cobalt, nickel, manganese and phosphate. Internal combustion engine needs aluminum, copper and steel, which is produced from iron. The catalyzers for combustion automobiles need platinum, rhodium and palladium to filter toxic gases. All these elements are extracted from mines and causes the environmental impact of mining.

A bigger number of electric vehicles will require more recharge stations and higher demand of electric energy. Therefore, it is imperative that the advance of electric cars walks together with the advance of clean and renewable energy sources.

If the energy source is clean, then electric vehicle will be clean tech.

Range

The range varies with model, however internal combustion vehicles still have a bigger range than the electrics. The main factor is battery’s limitation and energy’s density. This graphic is from 2016, but it is useful to make a comparison.

These are the 6 electric cars with greatest range. To convert miles in km, access this link.

Although range of electrics tends to increase, the average of combustion vehicles is still higher.

Cost

Electric cars still are more expensive than the moved by combustion, big part of cost come from batteries. However, the electric vehicle maintenance cost is smaller, because has less parts and don’t need to exchange motor’s oil. The cost per kilometer is also cheaper due to regenerative braking and electric energy’s price in comparison with fuels (this depends on the place).

Transmission

Transmission of electric vehicle is simpler. Graphic below shows that the optimum band, where power and torque are high, of a typical combustion engine is very narrow. The combustion engine needs a DC motor to start, because the torque is too low in lower speed. This type of engine needs a gear box to keep to engine in operation power.

The electric motor can keep constant torque in a great range of speed. So don’t need a transmission box and has better traction control.

The electric vehicle has a clear advantage in this point.

 

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About Pedro Ney Stroski

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