Photo credit: Harvard Club of New Jersey
Battery-Electric Vehicle (BEV): The formal name for what folks usually call an “EV” or electric vehicle, but with an electrical-storage battery being the sole source of energy for the powertrain. Why the distinction? Because a hybrid-electric vehicle (like a Prius) or a plug-in electric vehicle (like the Chevy Volt, see below) is also an EV, but still burns some gasoline.
Charge Rate: The speed at which a charging system stores or recharges the battery in an EV. It’s usually expressed in kilowatts (kW, see below) or sometimes in miles of range per hour. A higher number will charge your car faster, but charge rates always slow as the battery nears its maximum capacity. Read more about charging at home here or away from home here.
Kilowatt (kW): A measurement of energy that’s the most common way to talk about the electrical energy that turns the motors and does a hundred other things in an EV. But what is it? First, you should know about watts. Named after inventor James Watt, it represents the amount of physical force—work—needed to push against an opposing force of one newton. Physics professors we’re not, so we’re leaving out some nuance, but imagine pushing against a heavy door that’s swinging shut. That’s roughly a watt. Multiply that force by 1,000 and you have a kilowatt, commonly abbreviated as kW, shorthand for how much work a given amount of energy can do.
Kilowatt Hour (kWh): Exert a kilowatt for an hour (see definition for kilowatt) and now you have a kilowatt hour, usually abbreviated as kWh. This is how we measure the stored energy in an EV. To give you an idea of the energy involved, the US Department of Energy tells us the average person uses 909 kWh a month for residential use. A Chevrolet Bolt has a 65 kWh battery and can drive 259 miles on a charge, so it can go about four miles per kWh. Imagine pushing a 3500-pound car up a hill (compared to keeping it rolling on flat ground) and now you understand why your range decreases if you drive fast through the mountains.
J1772 Charging Adapter: The standard charger plug for what’s called level one or level two charging. Named after a Society of Automotive Engineers (SAE) standard, it’s the plug that is sold with an EV and it’ll work in most EVs built in the last couple of decades. One end is a big pistol-shaped handle that plugs into the car’s charge port, and the other end goes into some kind of unit that plugs into the electrical grid, whether it’s the wall outlet in your garage or a public charging station. Never plug one into an extension cord.
ChaDeMo: If you’re of a certain age you’ll remember the struggle between Betamax and VHS in the early days of VCRs. If you’re younger, it’s Snapchat versus TikTok. Well, the same thing is kind of going on with “Fast” or direct-current charging, the kind of charging you’d do on a road trip and you wanted to quickly add 100 or 200 miles of range. The word is kind of a contraction of a Japanese phrase that means you can charge the car in the time it takes to have a cup of tea (really!) and it was primarily adopted by Nissan in its Leaf models. It’s still widely supported by the large charger networks.
Lithium-Ion Battery (Li-ion): Most cars use a lithium-based battery (the ions are in lithium atoms), as do phones, toys, laptops, hearing aids…practically anything electronic. That’s because the lithium-ion design has an energy density—meaning how much energy can be stored per ounce of battery—that’s much greater than older designs that use lead or nickel. Lithium is number three on the periodic table of elements, which means it’s the most plentiful substance in the universe behind hydrogen and helium. That’s a good thing, because about 20 pounds of this non-toxic salt is in an average EV battery, according to Argonne National Laboratory. Concerns about shortages of lithium, which is plentiful in the universe but not as plentiful in a usable state here on Earth, are valid, but recycling and technological advances are likely to greatly reduce or eliminate the future demand for lithium as well as other metals found in Li-ion cells like cobalt and cadmium.
MPGe: The little “e” stands for “equivalent,” and it’s how the EPA compares EV efficiency to ICE vehicles. To calculate the number, the EPA uses an average price for electricity and uses it to calculate how far an EV can travel compared to a 27-mpg car (the US fleet average) burning $2.33 per gallon gas (in case you can find it). Most EVs get roughly 100 MPGe, with the most efficient returning 141. We don’t think that really illustrates how efficient EVs really can be, so we like to calculate the cost of fuel per mile. At today’s (December, 2021) national gasoline price average of $3.29 a gallon, a 27-mpg car will run you 12 cents per mile. One of Flux’s hyper-efficient Tesla Model 3s, using electricity priced at the national average of 14.1 cents per kWh, will only cost three and a half cents per mile, about a third what you’d spend on gas. The US Environmental Protection Agency (EPA) also gives “kWh per 100 miles” on its website and on new-car window stickers.
Plug-in Hybrid Electric Vehicle (PHEV): A hybrid electric vehicle (HEV) is your standard Prius kind of car, which uses an ICE engine that operates with an electric motor and battery. The electric motor boosts the car’s acceleration, allowing it to use less fuel, and the battery stores energy (see “regenerative braking,” below). A plug-in hybrid has an even bigger battery that allows the car to drive for a limited number of miles on electricity alone, usually with reduced acceleration and top speed, as the ICE is turned off in “EV mode.” You may think you can recharge that battery while running the ICE motor, but it (sadly) doesn’t work that way—PHEV owners plug their cars in at night or maybe at work or other public charge stations, and so use less fuel than HEV drivers. PHEV EV ranges can be as little as eight or 11 miles to 50 or more depending on model, but the fuel economy tends to run a few mpg less than a similar HEV because of the added weight of the bigger battery—these tend to be almost as expensive as a pure battery electric (BEV). A related vehicle is a “range-extended EV,” which is a BEV that has a small gasoline generator that can recharge the battery and extend the car’s electric range. The main difference is that the gasoline motor alone can’t propel the car.
Range: The number of miles a car can travel on its store of energy, be it electricity in a battery or gas in a fuel tank. This number isn’t as important to ICE drivers, as it’s easy and quick to stop at a gas station and add another few hundred miles of range in a few minutes. Since EVs take so much longer to “refuel,” fear of running out of range—range anxiety—is a concern for EV drivers. Having a good understanding of your car’s range is crucial for overcoming it. The EPA tests all car models to measure their efficiency, and predicts EV ranges with admirable accuracy. Still, these predictions are made with ideal conditions in mind, so if your car is rated by the EPA for 259 miles, speeding, hilly terrain, aggressive acceleration, using the heater and extreme hot or cold weather can reduce it, sometimes dramatically. Having friends with the same model of car—and it’s easy to meet them using social media—is a great way to predict your range in any condition and alleviate your range anxiety. Read more about range anxiety here!
Regenerative Braking: When you take your foot off the accelerator pedal (can’t call it the gas anymore!) or step on the brake while driving your EV, the electrical system changes the polarity of the motor so it becomes a generator (there’s a lot going on in there from an electrical-engineering perspective, but this is the Cliff-Notes version), recharging your battery. Instead of turning that energy into heat and brake dust as in an ICE car, much of it gets returned to the battery where it can be used later—pretty neat, eh? And not only do you extend your car’s efficiency (HEVs and PHEVs do this as well), it also dramatically reduces brake usage and wear, sometimes enough to make the brakes last the life of the car.
Torque: It’s a measurement of physical work an electric motor can do, expressed as “twisting” force. Imagine pushing a kid on a swing—that push you give her is torque, and it’s important to understanding what makes EVs so awesome to drive. Internal-combustion engines (ICE) usually get horsepower to describe their power output, but horsepower (hp) is actually a function of torque times how fast the engine is spinning in revolutions per minute (rpm). That’s because it takes a while for ICEs to reach their peak output—that delay is called a “power curve,” and different types of ICEs have different power characteristics. Not electric motors, though! They all produce their peak power starting from the second current is applied, so though you can calculate an hp equivalent, it’s really more useful to look at torque, which is usually pretty impressive! That’s why a car as unassuming as the Kia Niro EV makes as much torque as boy-racer favorites like the Volkswagen Golf R or Subaru WRX Sti and may be even more fun to drive, as that torque is served up as soon as the accelerator gets pressed, no waiting.