How Electric Cars Work: The Basics
Electric cars share virtually no drivetrain components with traditional automobiles, which is noteworthy as car design hasn't really changed in the last 100 years.
Gone are the days of differentials, gear oil, driveshafts, oil pans, and fuel tanks. All of these components are nowhere to be found on electric cars, including those produced by Tesla.
So, how does an electric car work? The basic design principles are simple. Electric cars contain batteries, a control system, and electric motors. The batteries are charged from the wall or a charging station, and they store energy. When you press down on the accelerator pedal, energy is released from the batteries into the controller.
The controller regulates how much energy the electric motors get. The electric motors are connected to the wheels, so when they receive power from the batteries and the controller, the car moves. This drives the car forward and backward without the use of a transmission, transfer case, differential, or gears. That means no shifting and no fluid changes.
Electrical power is also furnished to heating and cooling systems, along with lights, speakers, infotainment systems, locks, and windows. The downside of battery storage is that it can't be instantly refilled with energy when they're discharged.
Electric cars store all of the energy they use to power onboard systems. Additionally, they can regenerate some energy when coasting downhill by allowing the electric motors to act as generators.
Basics of Tesla Design
In its simplest form, a Tesla is a battery pack connected to a computer and electric motors. The car is 100% electric, and it uses no liquid or solid fuel. Electric drive means no combustion, and that means no pollution—at least from the car itself.
The fundamental parts of a Tesla are the same as any other car on the outside. They have standard wheels, normal production tires, and other common automotive parts. However, under the hood is a different story, as there's nothing under the hood but storage space.
Let's use an all-wheel-drive model as an example. This particular Tesla vehicle has four large electric motors, with one connected to each wheel. These drive motors operate together or independently, depending on road conditions and driver input.
The motors are attached to the chassis of the car, which is of the unibody design. That means that the Tesla doesn't have a frame that separately supports the driveline—like most modern sedans (and some SUVs), the frame of the car is the car itself.
Between the motors are the batteries, which store the power necessary to drive the car along. These batteries are out of sight and only require occasional replacement. The batteries also power the complex computers, which control everything from steering to climate.
Tesla cars don't have a single large battery. Instead, the electrical power comes from hundreds of smaller batteries linked together. These are lithium batteries, as this type of battery can store a large amount of energy and charge quickly.
So, what kind of little batteries make up the big Tesla batteries? If you have any experience with electronics, you may recognize them. The batteries used by Tesla are 18650 lithium-ion cells, which are commonly used individually in everything from remote-controlled airplanes to mobile charging packs.
The 18650 batteries used by Tesla are manufactured by Panasonic, and they cost more to produce and obtain than off-brand batteries. The reason Tesla chose high-quality Panasonic batteries is because of the dangers involved with Li-Ion cells, which can melt or explode if punctured or improperly manufactured.
Tesla Battery Packs
The most popular Tesla battery packs contain a whipping 7,104 lithium-ion 18650 batteries. When disassembled, you can see carefully organized rows comprised of hundreds of identical silver Li-Ion cells. These battery packs store 85kWh of energy, which is enough to power the entire vehicle and all of its systems for a respectable distance.
The latest Tesla battery packs feature new 2170 battery cells, which are similar in function to 18650 batteries. Each battery pack contains modules of 516 lithium-ion 2170 cells, and the pack has a total of 8,256 individual 2170 cells. The new battery packs, which feature 2170 cells that are manufactured in-house at the Gigafactory, are rated at about 100mWh.
Battery Pack Cooling
A notable problem Tesla engineers had to contend with was heat. Powerful batteries, especially lithium-ion cells, discharge heat energy when being charged and depleted. Battery packs, especially filled with thousands of volatile cells so close together, can get extraordinarily hot.
So how do you keep a battery pack cool enough to be used in a car, especially in hot climates? Tesla designed an advanced cooling system to regulate the temperature of the battery packs. The cooling system dramatically reduces the risk of fire and explosion due to excess heat buildup.
How Tesla Steering Works
Traditionally, power steering relies on mechanical and hydraulic power generated by a pump on the motor. In a gasoline-powered car, a belt running from an engine pulley drives a pump that forces fluid into the steering box. This makes it easier to steer, as much of the energy required to turn the wheels is provided by the engine.
A Tesla has no engine and instead uses efficient electric power steering, which is more reliable and smooth than older hydraulic systems. It also allows for dynamic steering, which adapts to speed, road conditions, and driver preferences.
How Tesla Brakes Work
Brakes are similar to steering in the sense that power braking systems traditionally rely on some sort of mechanical assistance from a running engine. In traditional systems, a brake booster uses vacuum pressure from a gasoline engine to reduce the force required to push down the brakes.
Tesla uses a computerized electronic braking system, which doesn't require engine vacuum. Tesla vehicles still incorporate hydraulic brake calipers and lines in addition to electronic systems, as the hydraulic brakes will continue to work if the car loses power.
Are Tesla Cars Different than Other Electric Cars?
Tesla automobiles aren't typical electric cars. The computerized mechanical and information systems that Tesla integrates into its cars are far more advanced than the average plug-in car, which puts them into an entirely different class.
Why are Teslas So Fast?
Tesla cars have gained a reputation for being extremely fast, especially from a dead stop. So, how are Tesla vehicles so much faster than other electric cars and even performance gas cars? The answer lies in the difference between electric power and internal combustion engines.
The reason why Tesla cars beat virtually all gas-powered vehicles off the line is because electric motors get 100% other torque from a dead stop. Combustion engines, on the other hand, only reach peak power at specific RPMs, and it's usually different for horsepower and torque.
For example, let's say that a V8 engine has 600 foot-pounds of torque at 3700 RPM, but its idle speed is 550 RPM. That means it has to wind up to 3700 RPM to reach its maximum torque, and it also has to shift gears to continue accelerating. That means that, through every gear, the gasoline engine has to accelerate again and won't hit its max power immediately.
On the other hand, electric cars receive their entire torque peak as soon as power is applied to the motors. That's why Tesla vehicles pin you back in the seat when you floor it from a dead stop. And since they don't have to shift, you can ride the top of its power band all the way to the maximum speed.
But why are Tesla vehicles so much faster than other electric cars? The answer is less complex and has to do with the way Tesla designs and builds its cars. Tesla's design strategy takes cost into account, but unlike other automakers, Tesla relies on cutting-edge engineering instead of cheap and available parts to stay within budget.
Tesla simply uses better motors, more powerful and efficient battery packs, and more speed-friendly software systems. It's a premium car, and the extra speed gained by higher quality parts is the benefit of purchasing a premium car.
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding