Cost Comparison Electric Car vs Petrol Car
Electric cars and petrol cars are two vastly different technologies that have different strengths and weaknesses. In this article, we will examine both technologies to better understand their differences, advantages, and disadvantages.
A Brief History of Electric and Petrol Cars
Electric cars were the preferred mode of transportation in the early 1900s, but their popularity waned due to the rise of petrol cars, which had better battery technology and greater fuel efficiency. However, electric cars have made a comeback in recent years due to improvements in battery technology and power electronics.
The Power Source and Prime Mover
Petrol cars use an internal combustion engine (IC engine) as their prime mover, while electric cars use a battery pack as their power source. In a petrol car, the fuel supplied to the engine produces combustion and enough pressure and temperature energy to move the pistons. The linear motion of the piston is transferred to rotary motion using a slider crank mechanism. On the other hand, in an electric car, an inverter converts the DC battery power into three-phase AC, which can turn an induction motor that will, in turn, turn the drive wheel.
Uniformity of Power and Speed Production
The force and power production in an IC engine is never uniform due to mechanical balancing issues caused by reciprocating components. The engine is also not self-started and requires many accessories to sort out these issues, making it quite heavy. These issues are not present in an electric motor. Induction motors work with the help of a rotating magnetic field generated by the stator. Motor speed can be easily controlled by adjusting the frequency of the AC power input. They produce uniform power and speed output and are self-started. For these reasons, an induction motor is much lighter than an IC engine and produces much greater power and torque output.
Heat Generation and Cooling
Both petrol and electric cars require cooling to keep their prime movers from overheating. However, the waste heat generated by an induction motor is much lower than that of an IC engine. Therefore, cooling is not as critical in electric cars as it is in petrol cars.
One major advantage of petrol cars over electric cars is the ease with which they can be refueled. A petrol car can be refueled in 5 minutes or less. However, recharging electric cars can take at least an hour at present.
The energy density of current lithium-ion batteries used in electric cars is nowhere near that of gasoline used in petrol cars. The poor energy density of the battery produces a huge weight penalty for the electric car. The large battery pack’s weight reduces the coefficient of friction between the tire and the road, making cornering difficult.
Advantages of Battery Packs in Electric Cars
The battery pack in electric cars has several advantages as well. The heavy battery pack is sitting very low to the ground, lowering the center of gravity and increasing car stability, thus increasing overall safety. The large battery pack is also spread across the floor, offering structural rigidity against side collisions.
Power Dynamics and Regenerative Braking
Electric cars are the clear winner when it comes to power dynamics. Induction motors can work efficiently in a wide speed range, and their speed is accurately controlled by the inverter. An IC engine cannot be operated beyond a certain speed range, necessitating the use of a complex and costly transmission mechanism for speed control. Moreover, electric cars have inherent advantages when it comes to regenerative braking, which is more complex and expensive to implement in petrol cars.
Electric cars are generally more expensive than petrol cars. However, to get the full picture, the cost required to travel a mile must also be compared. The calculation is based on current US gasoline and electricity.
Battery Cooling vs No Cooling
One major difference between electric cars and petrol cars is their energy storage systems. Electric cars use lithium-ion cells that require continuous liquid cooling to maintain normal battery temperatures. On the other hand, petrol cars do not require any cooling mechanism for their energy storage. The heat generated from the battery in electric cars is rejected to the atmosphere via a radiator.
Lower Center of Gravity and Structural Rigidity
The heavy battery pack in electric cars is located very low to the ground, which results in a lower center of gravity, increasing car stability and overall safety. Additionally, the battery pack is spread across the floor, offering structural rigidity against side collisions. In contrast, an IC engine car requires a complex exhaust gas treatment to keep pollutants and noise at statutory levels.
Power Dynamics: Electric Cars Win
Electric cars have a clear advantage over petrol cars when it comes to power dynamics. IC engines cannot be operated beyond a certain speed range, which necessitates the use of a complex and costly transmission mechanism for speed control. In contrast, the motor in electric cars can work efficiently in a wide speed range, making it possible to control speed directly from the motor without a varying transmission. The induction motor speed is accurately controlled by the inverter, simply by adjusting the output power frequency.
Superior Traction Control and Regenerative Braking
Electric cars have superior traction controls compared to petrol cars because they can produce great torque even at the start, whereas IC engine cars struggle at low RPM. A DC motor is needed to take the engine to the optimum RPM range at the start. Additionally, the torque and power of an electric motor can be controlled instantaneously while IC engines have a low response. Moreover, electric cars have inherent advantages when it comes to regenerative braking, which is not the case in petrol cars.
Economical and Low Maintenance
Despite the high initial cost of electric cars compared to petrol cars, the cost required to travel a mile is much cheaper for electric cars. Based on current US gasoline and electricity prices, electric cars are at least one-third cheaper than petrol cars. Moreover, the maintenance cost of electric cars is also low when compared to IC engine cars.