Electric Car Terminology Guide
One of the more confusing aspects of researching electric cars has to do with all the new terminology associated with electric motors and batteries. For over 100 years, we’ve been accustomed to words like horsepower, cylinders, and miles per gallon; with electric vehicles, there’s a whole new set of terms to learn.
Fortunately, once you’ve learned what each of the new terms means, it’s easy to relate them to their traditional equivalents and compare electric vehicle specs to figure out which one is best for you.
EV Battery Capacity
When comparing electric vehicles, one of the key points to consider is battery capacity. Think of this as the size of the gas tank on a gasoline-powered vehicle. The bigger the battery, the more energy you can have “on board” the vehicle, which should give you more range.
EV batteries are typically measured in kWh, or kilowatt-hours. A base Nissan Leaf, a commuter car, has a relatively small 40 kWh battery; while the Porsche Taycan, a high-performance luxury car, has a 93.4 kWh battery, more than double the size. But that doesn’t necessarily mean that the Taycan will deliver more than double the range.
That’s because a kilowatt (1,000 watts) is a unit that measures the expenditure of energy over time; equivalent to about 1.34 horsepower. The Nissan Leaf has a 140-horsepower electric motor while the Porsche is available with up to 750 horsepower, at which point it’s drinking electricity up to five times as quickly. This explains why a base Leaf has a 150-mile range and a Taycan only adds about 50 miles to that total, according to EPA estimates.
As with a gasoline car, the more power you use – basically, how aggressively you drive it – the greater the impact on range. Make use of all of the Taycan’s 750 horses and you’ll see its EPA-rated range reduced even further.
Electric Car Range and Efficiency
An electric car’s battery size, the power output of its motor(s), and other factors like its weight, size, and aerodynamic characteristics will affect its efficiency; which can be measured in several different ways. Using basic math lets you determine how far you can go on a charge.
One method of measuring distance over time is MPkWh, or miles per kilowatt-hour. The higher the MPkWh, the more efficient the vehicle. For instance, an EV with a 100-kWh battery rated at 2.5 MPkWh will deliver a range of about 400 miles.
You may also see ratings for kWh/100 miles. Divide the battery’s capacity by the kWh/100 miles rating then multiply by 100 to determine your range. An EV with a 75-kWh battery rated at 35 kWh/100 miles will go 214 miles on a full charge. (For those of you that think in metric, a similar measure is kWh/100 km.)
Some manufacturers and media outlets use an MPGe (or miles per gallon equivalent) rating; this gives you a sense of the overall efficiency of the vehicle you are considering. As an energy measure, MPGe doesn’t necessarily provide a good comparison of operating costs for EVs. Gasoline is gasoline (well, premium fuel is more expensive than regular fuel, but you get the idea…) while the price of electricity can vary widely.
Charging and Electricity
The other major consideration for most potential EV buyers is, “how long does it take to charge an electric car?”
Most charging will be done at home with a charger in your garage or driveway, at which point, charging speed isn’t really an issue; you’ll probably leave home with a full “tank” every morning.
When taking a longer trip, however, there can be significant differences in charging speed, based not only on your vehicle’s ability to charge, but also on the specs of the charger you’re hooking up to.
On the vehicle side of things, there are two major stats to look out for: the voltage rating of the car’s electrical system and its maximum kW rating.
Electric Car Voltage
Think of voltage as the electrical “pressure,” how fast electrons can flow through a pipe. The higher the voltage of your EV’s system, the faster electrons can be pushed into it. Most electric cars use 400- or 450-volt electrical systems. 800-volt systems, in cars like the Porsche Taycan, Hyundai Ioniq 5, Kia EV6, and others, can significantly improve charging time.
First introduced in racing series such as the Formula E global electric championship, an 800-volt system’s higher voltage and lower current means that the same amount of power can be moved using thinner wires. This reduces their weight and allows higher performance. A simplified analogy is a power drill: the higher the voltage, the more powerful it is – and the faster it charges.
For instance, the Porsche Taycan, one of the few vehicles currently available with 800-volt systems, can charge its battery from 5 to 80 percent in 22.5 minutes on a 270-kW 800-volt level 3 charger; while the same amount of charge on a 50-kW, 400-volt level 3 charger takes up to 90 minutes.
Electric Car Kilowatt Ratings
The kW rating is a measure of energy over time. Think of it as the size of the pipe delivering electrons from the charger to your car. How quickly your vehicle can ingest electrons may be limited by how quickly a charger can push them out.
When charging an EV, the bigger the kW rating, the bigger the pipe – and the faster your car charges. All things equal, a vehicle with a 200-kW rating can charge twice as fast as a vehicle with a 100-kW rating.
Different types of electric car chargers have different kilowatt ratings.
Level 1 chargers run on household 120-volt AC current and are the slowest, offering less than 5 kW – you’d need all day or more to fully charge up an empty electric car.
Level 2 chargers run on 240-volt AC current. They can charge an EV with 7 to over 20 kW capacity – meaning a full charge might take a few hours. They are perfect for home charging.
Level 3 chargers run on DC current. They are large, heavy, expensive, and found in public places. When you want and need a fast charge, they are perfect for use on a long trip. DC current means a direct pipe into your electric car’s battery. That pipe can be as “skinny” as 50 kW, or as wide as 350 kW.
The kW rating of the charger will give you a rough approximation of how quickly your vehicle’s battery can be charged. If your car has a 100-kWh battery and is on a 50-kW charger, it will take roughly two hours to fully charge; that same battery connected to a 100-kW charger would only require roughly one hour for the same result; on a 200-kW charger half an hour, and so on.
Why do we say “roughly?” Most Level 3 chargers will not deliver their full speed until they’ve been connected for a few minutes and other conditions may affect performance as well. Level 3 chargers will also slow down their charging once your battery reaches 80 percent or so to prevent over-charging.
Remember: just because a charger can push out electrons at a high rate may not mean your car can ingest them that fast. Ultimately, charging speed will be limited by your car’s kW rating. For instance, a Volkswagen ID.4, which can be charged at 125 kW, will max out at 125 kW, even if it’s connected to a 350-kW Electrify America charger. While a Hyundai Ioniq 5 can make use of the full 350 kW.
What's Next for the Future of Electric Cars?
If all of this sounds like a lot, it is – for a little while. The more you read about electric vehicles, the more familiar you’ll become with doing the basic math that lets you easily compare the vehicles you’re considering.
More importantly, the technology and charging infrastructure in the EV space is moving so quickly that you’ll need to do less math and less guessing over time. More and more, chargers are being opened every day. Meaning that, should you choose to go electric, your experience is sure to get better over time – no matter what vehicle you choose.