Yahoo Autos Does Your EV Suffer from the Heat? And What Can You Do about It?
The past few decades have seen much U.S. migration from colder northern climates to warmer southern ones, with states such as Arizona, Florida, and Nevada gaining millions of residents. Some of those states get really hot—and the problem is worsening from the effects of climate change.
So it's reasonable to ask if electric cars can hold up to temperatures that may surpass three digits in Fahrenheit—which can even be at night.
Just like questions about EVs and cold weather, the answer is yes. All cars, EVs included, are designed to function in temperature extremes far above and below what most drivers ever see.
EV Range May Fall a Bit in High Temperatures
The hottest temperatures may cause EVs to use more energy to keep their batteries cool, which can reduce range. (You'll be just fine inside in the air conditioning.) Data from Recurrent, which analyzes electric-car battery health, shows EVs retain 95 percent of their range in temperatures of 90 degrees Fahrenheit or below. Above that temperature, range loss may be more noticeable.
That's because like humans, electric-car batteries are happiest around 70 degrees F. When temperatures soar, the battery devotes some of its energy to keeping itself as cool as possible—along with a bit more for climate control. Note: It still takes less energy to cool the cabin to 70° F from, say, 100° F than it does to warm it up in winter from 20° F to the same 70° F.
If it has one, your EV's Eco mode may increase range; the tradeoff is somewhat slower acceleration, and often less aggressive cabin cooling.
Be Sure to Precondition
Just as in cold climates, an EV that is plugged in to recharge overnight will conserve more range if the owner "preconditions" it before leaving. Drivers use their phone app to specify a desired cabin temperature and a departure time; the car then starts to change interior temperature while it's still plugged in. That means it's using grid power to cool the cabin, and perhaps to ensure the battery is at its desired operating temperature. While it doesn't reduce energy use overall, it retains energy in the battery for maximum driving range.
Ventilated Seats Help Too
While most EVs now have heated seats available, ventilated seats remain a higher-end feature more often found on premium makes and models. Still, if your backside is pleasantly cool, you may be able to keep the air conditioning at a higher setting and remain comfortable. Here, extremely efficient EVs subtly teach owners about their energy use—versus gasoline cars that waste three-quarters of their energy in heat and noise, so the effect of turning the climate control on is less apparent.
Keep the Car in the Shade
This is hardly EV-specific advice; anyone who lives in a place like Phoenix knows their car stays cooler if it's under cover. Office-park or mall parking lots may not offer shade for parked cars, but a few now do. Some sites may even put solar panels on the roof to capture energy from the blazing sun. But whether it's a carport or an actual garage, keeping the EV shaded in hot climates will cut the amount of energy required to cool both battery and humans.
Charging in High Heat May Be Slower
All gas stations now have canopies over the pumps. It's not to make customers happy; they hide the fire-suppression gear needed while pumping a highly flammable liquid. But they shelter drivers from rain, snow, and extreme sun nonetheless. EV charging sites today usually forgo this nicety; they sit right out there in the direct sun (though the Ionna network plans to change that).
If a charging station has been sitting in blazing sun for hours, its metal components may have heated up. That can sometimes lead to slower charging rates, as the station and car work to limit power so as not to exceed safe temperatures at high rates of electricity transfer. It's not all that common, but if you see slower than usual charging on very hot days, it's a possible explanation.
High Heat Can Degrade Batteries
Operating in continuously higher temperatures—well above that 70-degree-F level—can lead to more battery degradation than in more temperate or colder climates. It's important to note here that all makers warrant their batteries against failure and a specified amount of capacity degradation for either eight years and 100,000 miles or 10 years/150,000 miles. And, of course, only a minuscule number of EV batteries ever fail.
Owners can take a few steps to prolong battery life during extreme heat. As noted above, keep the car in the shade. If you can charge during cooler parts of the day, do that. And if it fits your schedule, don't recharge all the way to 100 percent— on days where you know you're not driving hundreds of miles, limit your maximum charge to 50 to 80 percent. Batteries heat up more when charging close to their full energy capacity.
A Note on Nissan Leafs
Before Tesla released the Model S in mid-2012, the 2011 Nissan Leaf hit the market as the world's first mass-market EV built in volume. Leafs soon got a bad rap in hot climates like Arizona and Nevada, where surface temperatures in parking lots potentially reach 140° F or more.
That's because unlike virtually every EV today, the Leaf used "passive" thermal control for its battery. That meant that rather than pumping liquid through the under-floor battery pack to absorb heat, then passing it through a radiator, a Leaf could only radiate the heat from the pack directly. A handful of Leaf batteries failed prematurely in those hottest climates, leading to bad publicity for the maker. Disputes over the conditions under which Nissan would replace batteries that swiftly lost capacity didn’t help.
Today, passive battery cooling is a relic of the past. Every high-volume EV uses active thermal management—that liquid-and-radiator setup—and battery temperatures are much more regulated, even in the hottest climates.
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