AAA research released a new study about the effect of temperature on electric vehicle range and they claim that the average electric car range drops “41 percent at 20°F and when the HVAC system is used to heat the inside of the vehicle.”
Tesla disputes the claims saying that data from their own fleet of vehicles show that the decrease is not “anywhere near” what AAA is reporting.
Here are the key findings from the study:
1. In isolation, hot and cold ambient temperatures resulted in modest reductions of driving range and equivalent fuel economy. Driving range and equivalent fuel economy reductions slightly differ due to the temperature dependency of both the recharge allocation factor (RAF) and battery discharge capacity.
- a. On average, an ambient temperature of 20°F resulted in a 12 percent decrease of combined driving range and a 9 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
- b. On average, an ambient temperature of 95°F resulted in a 4 percent decrease of combined driving range and a 5 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
2. HVAC use results in significant reductions of driving range and equivalent fuel economy.
- a. On average, HVAC use at 20°F resulted in a 41 percent decrease of combined driving range and a 39 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
- b. On average, an ambient temperature of 95°F resulted in a 17 percent decrease of combined driving range and an 18 percent decrease of combined equivalent fuel economy (when compared to testing conducted at 75°F).
3. Depending on ambient temperature, HVAC use results in a significant monetary cost increase.
The Tesla Model S was amongst one of five electric vehicles tested as part of this study.
Here are some of the results:
It performed relatively well compared to the some of the other electric vehicles tested.
The Nissan Leaf and the VW e-Golf lost a little less range in the cold than the Model S, but the BMW i3 and the Chevy Bolt EV lost a lot more, based on AAA’s tests:
Tesla disputes the results saying that its own data shows that it is not as bad as what AAA is claiming.
A Tesla spokesperson sent us the following statement:
“Based on real-world data from our fleet, which includes millions of long trips taken by real Model S customers, we know with certainty that, even when using heating and air conditioning, the average Model S customer doesn’t experience anywhere near that decrease in range at 20 degrees Fahrenheit, and the decrease in range at 95 degrees Fahrenheit is roughly 1%.”
While the company shared an actual number for the 95 degrees Fahrenheit scenario, it didn’t for the 20 degrees Fahrenheit scenario other than saying that AAA’s number is inaccurate.
Here’s the full study:
[scribd id=399096994 key=key-SkidwJvuIgpKzZ7wqn9j mode=scroll]
I don’t know about a 40% drop in range a 20 degrees Fahrenheit. I don’t remember experiencing that in any of my Tesla vehicles.
That said, I’ve certainly experienced a ~40% drop at -20 Celsius (-4 Fahrenheit).
Either way, there’s no doubt that any EV is going to experience a significant drop in range in cold weather, but it’s important to keep in mind that the fact that it is noticeable is because they are so much more efficient than gas-powered vehicles in the first place.
ICE cars are also subject to higher energy usage in cold climate, but the impact of higher energy usage is going to be more significant in an EV than in a vehicle already losing 75% of its energy capacity in normal operation.
But it is important to be aware of it and plan accordingly.
The good thing is that an electric car is actually going to start in cold weather – it’s not always the case for gas-powered cars.
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