The Main Ingredients Of An Electric Vehicle
What goes into making an EV
It’s no secret that Electric Vehicles (EVs) are the talk of the town. Among millennials anyway. But does anyone know how they actually work?
If you’re interested in getting your hands on an EV, it might be worth knowing. So here are some basics…
There are five primary aspects that differentiate EVs from petroleum-burning, combustible engines:
- The Charger
- The Battery
- PCU (Power Control Unit)
- The Motor
- The Gearing mechanism
Drive anywhere in the US using the Supercharger network, now in all 50 states pic.twitter.com/SptUN4ipRK
— Tesla (@Tesla) January 10, 2022
The Charger
Contrary to popular opinion, the device that is installed in an EV owner’s garage isn’t actually the charger. It is known as Electric Vehicle Service Equipment, and providers power to the actual charger inside the EV. The charger within the EV converts the incoming AC power into DC power, making it easier for the battery can store. That is usually done using a slow Level I charge where the car is connected to a 120-volt device, or a faster Level II charge when it’s drawing on 240 volts like those used in Europe or South Africa.
When using a fast charger however (like a Tesla Supercharger), a DC power connection is used. These are at far higher levels of current than the standard home can provide, so aren’t common domestically.
The Battery
The battery is the heart of an Electric Vehicle. It is the primary device that determines the car’s range (a big selling point for EV buyers), is usually one of the higher costing components, and adds significant weight to the car.
The battery is most commonly inserted as a large, flat panel on the underside of the car. Inside this panel are smaller modules containing smaller cells. Some EV makers forgo the undercarriage design and shape it more like a traditional piece of luggage tucked away in selected cavities of the car’s body.
Tesla Model 3 battery
There’s plenty of room under a Tesla Model 3 for a huge, flat battery pack. This “skateboard” layout is preferred across the auto industry but isn’t the only way to orient an EV battery.
Tesla
Batteries store DC power, whether they’re in a flashlight, phone or a car. That’s why the charger has to convert AC to DC to recharge the battery and that’s also one of the main jobs of the next component, though in reverse.
PCU (Power control unit)
The power control unit is an assembly that goes by various names and is not something carmakers typically advertise, but it’s important. Its most critical job is to convert the DC power stored in the battery back into AC that most EV motors use. This is done with a component called an inverter, a version of which you may already use to power your laptop or other house current device from the 12-volt port in your car’s dash.
What looks like a little four-cylinder engine under the hood is actually the power control module for the lithium ion battery pack and electric motor. Below it sits an 80-kilowatt motor that turns the front wheels.
Josh Miller/CNET
The power control unit also interfaces the drivetrain to the accelerator pedal, start button and drive mode controller. And, crucially, it oversees regeneration which is how an EV puts power back into its own battery when coasting or braking.
Much of Tesla’s success has been its ability to optimize the various power flows and conversions that take place in its EVs, testament to the importance of the least-touted component in an EV.
The Motor
Unlike with traditional combustion engines, electric vehicles can have more than one motor. More motors make an EV faster, provide it with advanced all-wheel drive, or… both. But under the hood you won’t see an impressive-looking motor as you might a conventional car. They’re actually pretty compact, and not much to look at, most times hidden out of sight.
Taking Tesla as an example, a Tesla electric motor produces 248 horsepower and can push the Roadster up to a governed 201 kmh, and make 97 kmh (60 mph) from a standing start in 3.9 seconds.
It’s valid to compare horsepower and torque between a combustion and electric cars. Electric cars can deliver most of their torque starting at low RPMs, while combustion-engine cars need to be revved up to provide max acceleration. Motors are quite simply different from engines, which is one of the most obvious things about driving an EV for the first time.
The Gearing Mechanism (Transmission)
Electric motors don’t actually need a transmission. The nature of their engineering makes them efficient and powerful across a much wider range of RPMs than combustion engines, so they don’t need six, seven or even 10 gears as crutches to help them accommodate different speeds or loads.
Having no typical transmission an EV has a drive mode selector instead of a PRNDL. Most government regulations require that cars comply with certain conventions including rules such as placing Park at the end of the drive controller’s travel and Reverse adjacent to that (a US law). But EV drive controllers often take some unconventional shapes and are often placed in an unfamiliar position that puts the car into a higher mode of the regeneration while driving, as described earlier.
As you can see by the above image, the shifter of a Toyota Prius is pretty different to your standard gear shifter most drivers are accustomed to – and highlights the difference in an EV “powertrain” compared to combustion-engine transmissions.
CONCLUSION
In summary, electric vehicles have simpler drivetrains that use between 75% and 90% fewer parts than a combustion-engined cars. That collection of less parts still costs considerably more than a petrol-powered car, but as scale drives down EV cost, their inherent simplicity could augment those savings even further.
