In “Why you might want a heat pump in your electric car,” WaPo climate zeitgeist reporter (!) Shannon Osaka tries way too hard to defend EVs from the simple fact that they’re currently not great in cold weather:
Lithium-ion batteries perform more sluggishly in cold temperatures, cutting into an electric car’s range when temperatures drop close to freezing. (For what it’s worth, gas-powered cars also don’t perform perfectly in the cold.)
But that’s really beside the point, no?
Two factors account for why electric vehicles have a slightly harder time in cold weather than gas-powered cars. One stems from the simple reality that the massive lithium-ion batteries in electric cars perform best around 70 degrees Fahrenheit. “Cars are like humans,” said Anna Stefanopoulou, a professor of mechanical engineering at the University of Michigan. “They like room temperature.”
At cold temperatures, lithium ions — which flow from the anode of the battery to the cathode of the battery to create an electrical current — move more slowly through the battery and face greaterresistance. That causes the battery to function less efficiently.
But the second reason has to do with the human sitting inside. No one wants to sit in a frigid car during the winter. When it’s cold, gas-powered cars can redirect waste heat from the engine into the cabin to warm the driver and passengers. (Gas-powered cars aren’t particularly efficient — when the engine is on, only about 20 percent of the energy produced is actually going to turn the wheels.)
Gas vehicles “produce so much wasted heat,” said Scott Case, the CEO of Recurrent, a data science company that focuses on electric vehicles. “It’s a smart idea from an engineering perspective to make lemonade out of lemons.”
Again, while it’s true as a matter of physics that gasoline-powered vehicles waste a lot of energy and that the heat they produce is a byproduct of said waste, that really doesn’t matter if one’s concern is the vehicle conking out and leaving the driver stranded and freezing to death.
Electric cars, however, are super efficient. According to the Department of Energy, EVs use over 75 percent of their energy to propel the car. That means that there isn’t much waste heat available. Instead, many EVs warm their passengers through electric resistance heating (essentially heating a wire and blowing air over it).
Cabin heating accounts for the lion’s share of what drains the EV battery in cold temperatures. According to a 2019 study from AAA that tested five different EVs in 20-degree-Fahrenheit temperatures, on average the cars lost about 41 percent of their range with the cabin heater on. With the cabin heater off, however, they lost only about 12 percent of their range.
But here’s the thing: when it’s 20 degrees out, people are going to turn the damn heat on to avoid losing appendages. It really doesn’t matter how energy efficient the vehicle is without the heater on.
After so many paragraphs of weird defensiveness, though, we get to the important part:
But not all EVs are created equal. According to a study from Recurrent that looked at real-world data from thousands of electric vehicles, EVs can lose anywhere from only 3 percent (the Jaguar I-PACE) to 32 percent (the Chevy Bolt) of their range in subzero temperatures, depending on how the car manages cold weather.
Part of that, according to Case, is whether the car uses inefficient electric resistance heating or a much more efficient electric heat pump. Heat pumps work like air conditioners, moving heat instead of creating it — so they can be three to four times more efficient than other forms of heating.
Recurrent’s data compares cars like the Tesla Model Y — which comes standard with a heat pump — to cars like the Ford Mustang Mach-E, where no models offer a heat pump. According to the study, the Mustang loses almost 30 percent of its range at 20 to 30 degrees Fahrenheit, while the Model Y loses only about 15 percent.
“A car with a heat pump does much better when it drops down to freezing than one without,” Case said.
There are other means to minimize range loss when it’s cold. Many EVs come with seat heaters or even heated steering wheels, which can warm passengers without heating the cars entire interior. Some cars use the minimal waste heat from the engine to warm the battery and make the charge last longer. EV drivers can also direct their cars to warm up the battery while the car is still plugged in, again extending the range of the vehicle while driving.
That an easy, already-available, technological fix for the problem exists is the story, right? Ford and Chevy are doing it wrong and need to switch over to better technology.
(But even this section is weird. Seat heaters are nice but they don’t eliminate the need for cabin heat. My Mazda SUV has seat heaters and I enjoy them when it’s cold out, especially when I get into a cold vehicle, but I’ll turn them off at some point on a longer drive and still have the cabin heat on.)
This is also a small comfort, I guess:
One thing is certain, however — a stopped EV can keep its occupants warm for long periods of time in a snowstorm pileup. After the Virginia highway debacle, many EV owners, YouTubers and journalists tested their electric cars in freezing temperatures to see what would happen. One journalist for Car and Driver found that, at subfreezing temperatures, his Tesla Model 3 with a resistance heater could keep the cabin warmed to 65 degrees Fahrenheit for a maximum of 45 hours. That number could rise to 50 or 60 hours with a heat pump.
“You don’t have to worry about being stuck in long winter traffic jams,” Case said.
My sister-in-law recently got a Model 3 and, sure enough, she’s had significant range issues in the cold weather. Partly, that’s a function of her not having a charging station at home and living in a relatively remote exurb of Annapolis, making planning charging more difficult than it would here in Northern Virginia. Conversely, a work colleague who bought the same model, partly inspired by having inherited a Tesla charging station in the garage of his home, has had no real issues.
