Study Shows Summer Heat Is Not The Biggest Drain On An EV's Battery Range

Forbes

08-07-2025

Baby it's hot outside, but a new study shows that heat is not the biggest drain on an EV's state of ... More charge.
Those who intend on taking a road trip this summer in a full-electric vehicle should take note: While it's been widely circulated that driving in extreme temperatures – including the sweltering summer heat much of the nation is suffering – can take a heavy toll on an electric vehicle's range on a charge, it's not the worst kilowatt killer in this regard.
A recent study conducted by the automotive analytics company Geolab found that while running an EV's air conditioning on a hot day can accelerate its energy consumption, driving at higher speeds can actually prove to be a more significant detrimental effect on its operating range.
Geolab's experts mined telematics data from 350,000 trips in 500 battery-powered sedans, totaling over 180,000 hours of driving. It shows that even modest increases in an EV's speed can result in a pronounced loss of battery capacity.
When last we checked, testing conducted by the Society of Automotive Engineers (SAE), determined that an EV can be expected to lose an average 17% of its effective range when the temperature reaches 95 degrees. Like an internal combustion vehicle, it takes additional energy to operate a car on a hot day with the air conditioning running, though the penalty tends to be more pronounced with an EV.
However, Geolab's findings take a different tack by comparing vehicle speeds at higher temperatures. The researchers found that a full-electric sedan can expect a 28% drop in operating range at 86 °F when cruising at 80 mph versus 50 mph. At 50 mph an EV that has 277 miles of driving range, will drop to an average 251 miles at 60 mph, 226 miles at 70 mph and just 200 miles at 80 mph.
It may take an EV owner a bit longer to get to a far-flung destination driving at a slower speed, but doing so can ensure he or she will have that extra 77 miles of battery power to get there and perhaps avoid having to frantically find a working public charging station along the way when the state of charge runs low.
The laws of physics are working overtime here, with an EV's aerodynamics largely coming into play. Just as it is in a conventionally powered ride, the faster a vehicle travels, the harder it has to work to combat an increasing amount of wind resistance.
Sleeker is better in this regard, with the Lucid Air EV's svelte silhouette at around a 0.21 coefficient of drag, which makes it one of the slipperiest cars on the planet. Combined with an active rear spoiler that engages at higher speeds and other advanced technology. It's EPA-rated as high as the electric equivalent of 142 mpg in highway driving.
According to Geolab's analysis, doubling an EV's speed requires four times the energy just to overcome the added wind resistance, which is more than its cabin air conditioning system will ever use.
Of course, vehicle speed is not the only factor in play at robbing an EV of range in hot weather. At lower speeds – especially in stop-and-go city traffic – where wind resistance is negligible, running the air conditioning becomes a more prevalent penalty. Ambient temperatures become an even more significant factor in winter, where tests have shown that EVs can lose as much as around 41% of their battery capacity at 20 degrees Fahrenheit and an even greater percentage at chillier ambient temperatures while running the cabin heater.
As with most of us, EVs prefer more temperate conditions, with the SAE's data showing a zero loss of range while driving at 75 degrees.
"Modern EVs have increasingly large batteries, and many can comfortably handle most daily driving - including fleet routes - on a single charge," explains Charlotte Argue, Geotab's Senior Manager for Sustainability. "But range, on EVs or internal combustion vehicles, will always vary with real-world conditions: temperature, topography, traffic, and yes, speed."
Whether taking an extended highway road trip or running errands around town, there are a number of ways prudent EV owners can help maximize their vehicles' range on a charge, no matter what the thermometer reads: