European EV Vacationers Should Slow Down A Bit

European EV Vacationers Should Slow Down A Bit.

“The data shows even modest speed increases lead to steep range losses“

As Europeans prepare for the big return from hot southern summer beach vacations at the end of August, electric vehicle owners may be worrying about the negative impact the unprecedentedly hot weather might have on the range of their batteries.

According to Geotab Inc, a telematics company headquartered in Ontario, Canada, EV drivers have much more to worry about from speed on a long-range trip than the heat.

Geotab, which describes itself as a global leader in connected vehicle solutions, said in a report “Summer heat vs speed: what really impacts EV range?” that hot weather does have an effect, but driving speed can be the single biggest factor in range loss.

Europe has an extensive autoroute system allowing cruising speeds of around 80 mph or more for hours on end.  Germany’s autoroutes have sections without speed limits, although most powerful sports cars won’t allow speeds of over 150 mph. The trouble with EVs is that although they can match or exceed internal combustion engines over a range of tasks when speeds reach 60 mph their performance is seriously diminished. Range disappears at an alarming rate. Up to 50% of range can be wiped away at these higher speeds, according to WintonsWorld.com data.

“At higher speeds of between 50 and 80 mph in hot temperatures (30C to 86F), driving speed can be the single biggest factor in range loss,” the report said

Modest increases in speed lead to steep range losses
“The data shows that even modest increases in speed lead to steep range losses. For example, a 65-kWh electric van cruising at 50 mph in 86 °F Returning European Vacationers In Theirs EVs Should Slow Down heat with the air conditioning on has a typical range of around 143 miles. Increase that speed to 60 mph, and range drops to 121 miles. At 70 mph it falls further to 103 miles, and by 80 mph, you’re down to just 88 miles. That’s a 39% drop in range between 50 and 80 mph,” according to the report.

“The pattern is similar for electric sedans, though they’re slightly more aerodynamic. At 50 mph at 86°F, you can expect 277 miles. At 60 mph: 251 miles. At 70 mph: 226 miles. And at 80 mph: 200 miles – a 28% drop from the most efficient cruising speed.

The report said this sharp decline comes down to physics. The faster the speed the more the car has to fight air resistance. Aerodynamic drag increases with the square of the speed, so doubling speed requires four times the energy just to overcome wind resistance. That’s far more than the air conditioning system will ever use.

“Drivers tend to worry about using the aircon in hot weather, but our data shows that your right foot can make the biggest difference, particularly at high speeds,” said Charlotte Argue, Senior Manager, Sustainability, at Geotab. 

“Just slowing down by 10 or 15 mph can extend your range by 20–30%, depending on the vehicle, depending on the vehicle,” she said.

Peter Wells, Professor of Business Sustainability at Cardiff Business School has summed up the problem like this.

Range falls off a cliff
“Range falls off a cliff at high speed. For an electric car, the extra energy required getting from 60 mph to 75 mph is astonishing and virtually doubles energy consumption to move all that air out of the way,” according to Wells.

Emissions Analytics CEO Nick Molden has explained the problem this way.

“Air resistance (drag force) is proportional to the square of the speed. Drag will correlate (negatively) with range. So range will decline more than proportionately as speed increases. Vehicle design can change other factors, such as the coefficient of drag (Cd), which is why Tesla has focused so much on aerodynamics,” Molden said.

“All other things being equal, the drag force will be 164% higher at 130 km/h than at 80 km/h (50 mph) which is a speed increase of 63%,” Molden said.

As Europeans and their families return home at the end of August, there are often gigantic traffic jams stretching for miles. Perhaps the frustration this time will be mitigated slightly as EV owners can feel a bit smug about eliminating range anxiety.