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An electric motor uses electricity stored in batteries to power electromagnets which ultimately drive the vehicle axle.
An electric motor uses electricity stored in batteries to power electromagnets which ultimately drive the vehicle axle.
( Source: ©bong - stock.adobe.com)

BACK TO BASICS - DRIVES Combustion engine vs. electric engine: What’s the difference?

Author / Editor: Seth Lambert / Nicole Kareta

There are a number of important differences between a combustion engine and an electric engine that play a part in the appeal of both types of propulsion. This article explains how the drives differ from one another and how this affects suppliers.

Combustion Engine Definition

Since the earliest days of the automobile, most cars have run on gasoline that gets exploded in minute quantities within an enclosed space inside a car’s engine—a process we know as combustion. This combustion moves pistons, which—via connecting rods—rotate an engine crankshaft, which in turn drives the rotation of one of a vehicle’s axles (usually the rear axle). This type of engine is known as an internal combustion engine.

Electric Engine Definition

By contrast, an electric motor uses electricity stored in batteries to power electromagnets which ultimately drive the vehicle axle (or axles, in cases where there are multiple electric motors).

The difference between a combustion engine and an electric engine

Internal combustion engines can differ in a number of factors such as the type and number of parts, energy storage, refuelling and requirements for suppliers of electric motors.

How do the built-in components differ between a combustion engine and an electric engine?

Because generating motion via the process of combustion is more complex, a combustion engine necessarily has many more parts and takes up much more space than an electric engine. Electric engines on average may have something like 20 parts, whereas combustion engines may have more than 2,000. According to the electric motor definition above, there’s no waste material generated by driving because there’s no disposable “fuel.” In a combustion engine, the disposable fuel is gasoline, and it must be stored (carefully, as it can ignite), flowed in just the right amount to the engine, processed (combusted), and then its leftovers must be exhausted out of the motor and the vehicle after combustion takes place.

While an electric engine has no fuel, it does utilize batteries, and these batteries take up space and are heavy. Fortunately, however, the batteries can be spread out in a flat layer at the floor of a vehicle (most are configured this way), thus creating much more space in an electric vehicle (EV) than one with a combustion engine.

Energy storage - differences between tank and battery

Some people are under the impression that an electric motor requires more energy to operate than a combustion engine, but it takes the same amount of energy to make two identical vehicles drive at the same speed. The difference is that with an electric motor, very little energy is wasted, whereas combustion is by nature a highly inefficient process where much energy is lost along the way. Therefore, it’s the gas-powered vehicle that needs more energy.

Replenishing gas vs. electricity

There’s also the matter of replenishing the resources that are needed for both a combustion engine and electric engine. A car can only store so much gasoline; every so often, a driver must stop at a gas station and pay for gas, which is sold by the liter or gallon. Fortunately, this process only takes a few minutes. With electric motors, battery charging can take place wherever there’s a charging station. Unlike gas stations, EV charging stations vary for types of EVs. There are a finite number of charging stations in most countries around the world (some cities may not even have a single charger for the EV a person is driving!). Although many EV charging stations use “rapid” chargers, recharging at one of these usually still takes between 20 and 30 minutes (some companies are working on “ultra”-rapid chargers that will allow a charge to take place in around 5 minutes, but these likely will not appear on roadsides for several more years).

Demands on suppliers

Whereas combustion engines necessitate more maintenance, EVs by contrast contain far fewer parts, and they will generally undergo much less wear and tear than the components of combustion engines. In a combustion engine, more components mean more processes that can go wrong and more parts that can wear out or break down. With EVs, the parts that are most critical to daily operation are the batteries, and these may be able to be replaced at the end of their life if an owner so chooses (although this is not likely to be the case as batteries are expected to last 10 or more years on average).

Because of this, many part supplier companies will either need to consolidate or move into different sectors of the automotive business as electric motor maintenance for EVs will be less onerous and necessitate less aftermarket support than combustion engines in gas-powered vehicles.

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