Yes, EV's have reduced performance and range in cold weather. But, is the reduce range mainly from heating the battery and car? Can you keep the range reduction to a minimum by not heating the interior? The battery should still have the energy in it, even if cold. Yes, some energy won't be available if the battery is cold, but If the battery heats up, you should recover the energy? And what percentage of the battery energy isn't available if the battery is at 0F (-18C)?
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Is reduced range in cold just from heating the car?
- Thread starter cstork
- Start date
2012MS85
Member
Cold air outside is also more dense, causing more drag. So more energy is required to drive the same distance, even before you hit the bacon for your seat or cabin heat/defrost. Even when you use zero cabin heat in the winter, your Tesla will get less range because the battery is cold and less efficient as it tries to keep itself warm, just like the driver w/o heat 
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You’ll get reduced range in cold temperatures regardless of whether you’re heating the cabin or not. You won’t see as big of a range hit if you turn the heat down in the cabin. If you are on a long drive the battery will eventually heat up and you’ll see better efficiency. In the winter my average consumption is about 280Wh/mi. During the spring and summer it’s closer to 230Wh/mi. So in the mid-Atlantic region during the winter you would probably see at least a 22% decrease in range. Obviously if you’re in a colder climate than that you’ll see an even greater range hit during the winter months.
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There are bunch of things at play.
There is battery heating itself, and I'm not entirely clear on when this system activates. I do know it does activate before reaching a supercharger when the car says "preconditioning battery for supercharging".
Here is some info on the unique way the Model 3 does battery heating.
Tesla Model 3: Exclusive first look at Tesla's new battery pack architecture - Electrek
There is cabin heating which the OP mentioned.
There is the dense air that's been mentioned by someone else. But, lots of range estimator websites say it's not really that much and to generally not worry about it.
Then there is the less regen when you initially start out when its cold. This one in particular really destroys my daily efficiency when the weather is under 50F. The reason is my commute is only 9 miles so it never heats up enough. I also don't leave it plugged in the night before.
I also believe the efficiency of the entire energy transfer is lower when the battery is cold. But, I don't know how by how much.
There is battery heating itself, and I'm not entirely clear on when this system activates. I do know it does activate before reaching a supercharger when the car says "preconditioning battery for supercharging".
Here is some info on the unique way the Model 3 does battery heating.
Tesla Model 3: Exclusive first look at Tesla's new battery pack architecture - Electrek
There is cabin heating which the OP mentioned.
There is the dense air that's been mentioned by someone else. But, lots of range estimator websites say it's not really that much and to generally not worry about it.
Then there is the less regen when you initially start out when its cold. This one in particular really destroys my daily efficiency when the weather is under 50F. The reason is my commute is only 9 miles so it never heats up enough. I also don't leave it plugged in the night before.
I also believe the efficiency of the entire energy transfer is lower when the battery is cold. But, I don't know how by how much.
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Heat seating and hand gloves do wonders.
The trickier part is keeping the windows defogged, but you probably start with an advantage in Colorado. I pre-heat and implore my wife to not bring hot beverages into the car.
It’s quite a few factors at play. Cold air is more dense, so your car needs to push more air out of the way. This is more significant at higher speeds, and barely matters at low speeds. Cold also tends to mean lower battery temperatures, which increases internal resistance and the intrinsic losses from pulling energy out of the battery. The lower temperatures also reduce regen power as well as reduce the energy the battery captures due to the higher losses. This is minimized by limiting acceleration and regen as much as possible. Even things like the wheel bearings are less efficient in the cold, this is measurable but not that significant. The tires are a fair bit less efficient at low temperatures as well. And of course, in addition to this the driving style often changes with temperature. Tack on the heating, seat heaters, defrosters, possibly battery warming energy, and often times longer drives at slightly slower speeds.
If you turn the HVAC off entirely, you get a fair bit of the range back, but certainty not all of it. The aero and rolling resistance factors are moderately significant in very cold weather. Traveling very slow helps offset this, but it also means the tires stay quite cold and inefficient. So comparatively it’s always going to be a bit worse in cold weather. Most of these factors also impact ICE vehicles, they just happen to make heat as an abundant waste product so there’s some savings there. And if you’re driving through snow, the rolling resistance can shoot way up and devastate range. Even rain has some moderate impact.
If you turn the HVAC off entirely, you get a fair bit of the range back, but certainty not all of it. The aero and rolling resistance factors are moderately significant in very cold weather. Traveling very slow helps offset this, but it also means the tires stay quite cold and inefficient. So comparatively it’s always going to be a bit worse in cold weather. Most of these factors also impact ICE vehicles, they just happen to make heat as an abundant waste product so there’s some savings there. And if you’re driving through snow, the rolling resistance can shoot way up and devastate range. Even rain has some moderate impact.
In addition to all of the great replies above, you don't get as much regeneration when the battery is cold, which also decreases your total range unless you're exclusively driving on a highway, not going downhill and not hitting any traffic to cause you to slow down.
When the battery is cold, it's hard on it to accept a charge, so until the battery is warmed, your efficiency will go down. This is why Tesla has recently added the option to do scheduled departures so that the battery is conditioned (warmed in this case) at the start of your trip and you receive maximum regeneration when slowing down.
Additionally, when it is cold your tire pressure goes down, which increases rolling resistance. Make sure your tires are properly inflated.
I can get near 100% efficiency on a below-freezing day when I keep my HVAC off and my seat warmer on, even if the battery is somewhat cold (some dotted section, but not all).
When the battery is cold, it's hard on it to accept a charge, so until the battery is warmed, your efficiency will go down. This is why Tesla has recently added the option to do scheduled departures so that the battery is conditioned (warmed in this case) at the start of your trip and you receive maximum regeneration when slowing down.
Additionally, when it is cold your tire pressure goes down, which increases rolling resistance. Make sure your tires are properly inflated.
I can get near 100% efficiency on a below-freezing day when I keep my HVAC off and my seat warmer on, even if the battery is somewhat cold (some dotted section, but not all).
Thanks much for the comments.
One thing I want to point out is that air is 30% less dense at 10,000 ft altitude (15% at 5000ft). A reduction of 20C (36F) increases air density by 7%, which is not that much. I drive between 5000-10,000 ft a lot, and don't really notice the improved range.
(I do notice that I have a lot of power at 10,000 ft while my ICE car has 30% less power!)
One thing I want to point out is that air is 30% less dense at 10,000 ft altitude (15% at 5000ft). A reduction of 20C (36F) increases air density by 7%, which is not that much. I drive between 5000-10,000 ft a lot, and don't really notice the improved range.
(I do notice that I have a lot of power at 10,000 ft while my ICE car has 30% less power!)
FWIW - I took a trip last weekend in northern MN. -21 degrees and 210 miles between the supercharger and destination. Very shortly after leaving the supercharger with 100% battery, I was told to keep it under 75. Then 65, then 55... then "charge before destination" in red.
I ended up crawling to my destination at 50mph with the heater set to low, fan speed 2 (to keep the windows from fogging) and seat heater on the lowest setting.
I was getting 'rated' range according to the energy graph at those conditions but did end up getting the snowflake symbol by the time I reached my destination with 2% battery to spare.
So, I'm thinking the primary killer for winter driving is the cabin heater, next speed, next battery heat (which won't keep up in -20f)
I ended up crawling to my destination at 50mph with the heater set to low, fan speed 2 (to keep the windows from fogging) and seat heater on the lowest setting.
I was getting 'rated' range according to the energy graph at those conditions but did end up getting the snowflake symbol by the time I reached my destination with 2% battery to spare.
So, I'm thinking the primary killer for winter driving is the cabin heater, next speed, next battery heat (which won't keep up in -20f)
Yup, less dense air will definitely help cut the losses by the denser colder air. But also, higher elevations tend to be colder in general... That being said, if you're driving around on mountains a lot, the constant uphill/downhill will kill efficiency too. Although regen recovers some of the power lost climbing a hill, it's not 100% efficient. So, that may be playing a factor as well.
Ha, we refer to the seat heaters as "butt bacon". Has a nice alliteration to it.
640k
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my SR+ would not make it that far. i just took a trip between Cincinnati and Detroit and I was seeing 300-320wh/mi at 75 MPH. each time i stopped at a supercharger, my efficiency got worse. I was hitting over 340wh/mi for the first 40% of my battery to when it eventually started to "even" out. by the time I was under 40%, my battery efficiency dropped (increased?) to 280wh/mi. i made ZERO adjustments to my driving or the cabin. cabin was set at 67 and seat heater at 2 strips of bacon. maintained 75mph the entire trip.
around town i love my SR+ but damn if it doesn't give me range anxiety on trips. 160 miles MAX with temps hovering around 40°. makes me wish i sprung for the bigger battery every damn day.
I always got great MPG on my old CR-V (like 30 MPG when it was rated at 24 MPG) for 20 years. I always attributed it to living in Colorado and the elevation and lots of highway miles. Whenever I would spend time in Kansas, Nebraska, etc., the mileage would drop by 20% or more. I tracked every tank for 20 years and also always noticed a 20% to 25% decrease in the winter vs. my summer MPG. It was still always better in Colorado vs. when I was out of state.
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Heating the cabin, no doubt, is the majority of range loss in winter. Without running HVAC, assuming a warmed battery, my observations tell me the cold has very minimal effect on range, at least above 20F.
I routinely get under 200wh/mi when it is colder than 30F.
Even if the battery is cold soaked and needs to be warmed as you drive, I'd say this results in a 10% hit to range TOPS.
It's all about the HVAC.
I routinely get under 200wh/mi when it is colder than 30F.
Even if the battery is cold soaked and needs to be warmed as you drive, I'd say this results in a 10% hit to range TOPS.
It's all about the HVAC.
640k
Member
i don't understand how this is possible. are you using seat heaters? are you driving 50 MPH? i can't even get 200wh/mi during the summer when temperature isn't a factor.
I've seen even lower numbers (150 Wh/mile on my 17 mile commute) in my S100D...but it was when I was stuck in 15 MPH traffic on the highway.
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