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Allied to the question: How does cold weather affect electric vehicles?

How does hot weather affect electric vehicles, particularly when the atmospheric temperature is above 30 C and closer to 40 C, as can be experienced in tropical or desert climates during summer?

Within the category of performance I'm also interested the performance and efficiency of critical components such as the battery/batteries.

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  • Not much if there is no air conditioner. Dec 5, 2019 at 15:45
  • It's all good news if there is no air conditioner. I love a hot Wyoming night; I get a very notable MPG boost in my gas car cruising at posted limits. Dec 16, 2019 at 2:08

4 Answers 4

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The performance of lithium ion batteries (LiB), which currently power electric vehicles begins to deteriorate above temperatures of 26 °C.

LiBs deployed in hot regions need to use some of their stored energy to maintain lower temperatures, since battery performance begins to deteriorate above temperatures of 26 degrees Celsius, however the introduction of Na-ion and lithium-iron-phosphate (LFP) chemistries overcomes some of these safety concerns, but still does not meet the LDES holy grail.

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One issue that has not been mentioned, and which particularly affects older electric vehicles, is battery temperature. This can be exacerbated by using fast (50kW+) chargers which also increase the temperature of the battery.

I have personally struggled to complete a long journey in temperatures of around 30C using an old Nissan Leaf - the journey was long enough to require a couple of stops to fast charge. Each charge raised the battery temperature considerably, and the combination of high ambient temperatures and high power requirements for motorway driving meant that the battery just couldn't cool down - for pretty much the whole journey the battery temperature gauge was right on the verge of going into the red, which made for a pretty nerve-wracking drive...

It should be noted that the Leaf only uses basic air-cooling for its battery, most modern EVs will use much more sophisticated liquid cooling.

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It takes less energy to cool a passenger compartment from 90 degrees F to 70 degrees F than it does to heat a passenger compartment from 25 degrees F to 70 degrees F:

https://www.greencarreports.com/news/1102028_electric-car-battery-energy-why-waste-it-on-cabin-heating-video

And hydrogen-fuel-cell buses are claiming the biggest advantage over battery-powered buses in cold weather:

https://blog.ballard.com/battery-electric-bus

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  • And it gets better still if the heating is resistive, because air conditioning is always heat-pump based. Also, air conditioning is not necessary. I haven't had an A/C car since 1998. Dec 16, 2019 at 1:58
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Hotter air is less dense. If you turn off the AC, you should be getting increased range.

However, most people value comfort over range, and thus, the increased range won't materialize but rather the range decreases due to more AC need.

Also, if you don't do anything to the tires, hotter air increases tire pressures, reducing rolling resistance.

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  • The air density has a negligible effect, the difference between a car full of warm air and a car full of cold air is about 1 lb. Dec 6, 2019 at 11:33
  • @ChristopherGilmour Disagreed. It affects air resistance by 25%, see my comment to sustainability.stackexchange.com/a/9729/6393
    – juhist
    Dec 6, 2019 at 11:46
  • Do you have any references that back-up your claim about 25% more air resistance?
    – THelper
    Dec 6, 2019 at 16:54
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    @ChristopherGilmour you're wrong. Google "hot-and-high" which is an aviation term, and understand why it has such a profound effect on aviation. What makes it hard for airplanes to fly gives my gas car better MPG. It's not the air in your car. It's the air you're pushing out of your way. Thelper look at aviation performance charts. Dec 16, 2019 at 2:03

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