How Exactly Does Weather Impact Your Tesla Battery/Range – Video

Tesla

OCT 28 2017 BY STEVEN LOVEDAY 31

Ben Sullins of Teslanomics teamed up with TezLab to get a better handle on what impacts EV efficiency and how Tesla owners (or really any electric car owners) can improve range.

Electric vehicle efficiency is basically how many miles you get compared to what your “supposed” to get. So, if you should get 200 miles on a charge but you get 150, that’s 75 percent efficiency. If that same vehicle got 250 miles on a charge, then efficiency is up at 125 percent.

Tesla

Tesla Charging

Weather affects EV efficiency much like it affects ICE cars, but there are some marked differences. The folks over at TezLab in Brooklyn measure range using a somewhat complicated system, but since they do the hard work for you, there’s no need to get into the specific details.

Let’s take a quick look at what the team discovered:

  • Most everything the study found can be related back to temperature
  • it’s widely known that cars are less efficient when it’s cold, however, the study shows that temps over 80F also have a negative effect
  • Parking in a windy area can drain more range than you may think
  • Cold temps increase charging times

Sullins goes into a much greater level of detail regarding specifics in the video. Although many EV aficionados are well aware of this type of information, the general public isn’t necessarily apprised.

Video Description via Teslanomics by Ben Sullins on YouTube:

If you already own an EV, you know that your rated range, that is how far you can travel on a single charge, never is as advertised. 

Tesla

Tesla Charging

Today I have a special episode for you. I’m here in Brooklyn with the TezLab team, and we’ve been digging into what effects your battery range and what you can do to improve it.

Efficiency for a Tesla, or rather any car really, relates to the distance you expect to get from your fuel compared to what you get. So if your Tesla is telling you you’ll get 200mi on a charge and you only get 180 miles, that’s 90% efficiency.

Conversely, if you got 210 miles on a 200 mile rated charge, that would be 105% efficiency.

So in this way, your car can be wildly inefficient or quickly get over 100% depending on some key variables.

EVs and ICE cars are similarly affected by things like hills however that’s where the similarities end. Most EVs, like Tesla’s, have regenerative braking which slows the vehicle down and recharges the battery at the same time.

This is extremely helpful when you’re headed down mountains where your car can regenerate loads of power.

The way Tezlab measures this is by looking at the distance traveled by the range difference reported from the Tesla API. This can get a bit tricky, so I’ll spare you the details and suggest you check out the app where you can see the efficiency for every trip you take as well as other factors like Phantom Drain.

// When is efficiency the worst?

When looking at the data from all the cars in the fleet, it became immediately apparent that the correlation between temperature and efficiency was strong. This means that if you’re in a colder climate, you will likely get less range out of your car then in the warmer climates.

For those of you living in these areas already, this is a no-brainer. It wasn’t until this we analyzed this data however that we realized it also affects warmer climates.

In fact, over 80 degrees F seems to have a negative impact on the driving efficiency as well. Now, both of these may seem obvious that you’re using our heating and cooling, but there’s more going on than just the interior of the car that could be affecting your driving efficiency.

// Insight #1 – Avoid parking in a windy area

Wind seems to have an impact on the phantom drain as well. This is again due to temperature, but even over a short period, a cold, windy area can zap the energy from your Tesla.

// Insight #2 – Below 50 degrees efficiency falls off a cliff

Once the temp drops below 50 degrees, F is when you need to be conscious of your driving habits and charging. Data suggests that you’ll lose an additional between 10 and 20 percent with a median efficiency around 60% overall.

// Insight #3 – Expect Charging Delays

The last thing we’ve learned is about charging times. Again it has to do with temperature, and the data we have suggests that in colder temps you’re going to spend extra time charging.

If you’re using a level 3 charger like a Supercharger and are used to topping up in about 45 minutes, you may need more like an hour and a half. The data we have for this vary greatly, so it’s hard to say exactly what to expect, but the trend is clear, as the temp drops the charging times go up.

As time goes on, we’re going to continue to monitor this and develop more insights to help you get the most out of your Tesla. If you haven’t already get the TezLab app from the link in the description above and start monitoring your efficiency today.

Source: Teslanomics

Categories: Tesla, Videos

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31 Comments on "How Exactly Does Weather Impact Your Tesla Battery/Range – Video"

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This is one of the main reasons people living in colder climates need longer ranges in electrics. If I need to be able to go 150 miles on a charge, one would think I’d be good with something like the new Leaf since it has a 150-mile range. However, since I live where it gets cold in winter, I actually would need 250 or more miles of advertised range (like a long-range Model 3 or 100D Model S) to get that same 150 miles below zero degrees Farenheit.

This is one of the reasons why the Leaf is a big deal for an economy EV. Combine degradation with winter range loss and 75 mph driving, and the 22-30 kWh EVs became limited too often, especially for long commuters (for whom EVs make the most impact).

90 miles worst case range is so much more useful than 50 or 60.

I would commute 40 miles per day round trip in my 2012 Leaf. During the winter, I had to go to work with no heater freezing my arse off just in order to make it home. 40 miles is a pretty average commute.

So in the cold, do BEV’s actually use more electricity (other than for cabin heating), or is it just limiting how much of the batteries capacity is actually usable? Meaning, does the actual kwh/mile go up or do you just have access to fewer usable kwh?
I’m guessing that for the charging side, it’s not using twice the energy to charge if it takes twice as long, but rather the batteries can only absorb the charge at half the rate.

From how I understand it, significant temperature differences change the battery capacity itself. So it’s not that less of the capacity can be used; instead, the battery can hold less electricity than it would in optimal conditions, and it takes longer to charge since the temperature difference increases electrical resistance. So you’re correct on the charging side.

The electrons are in there you just can not get all of them back out. A battery is an electro chemical device and chemistry depends on temperature.

QED. Thermal battery management does not really help on this front, b/c the amount of energy spent to keep the battery warm is of the same magnitude as the direct loss in thermodynamic battery efficiency due to cold.
Simple thermodynamics.

That is not true.

“Simple Thermodynamics”.. I thought Pushi was the big thermo expert here. Anyways in English what are you talking about?

Do you mean that the ‘increased availability of a warm battery’ is compensated for by the resistance heater’s wasting of the juice in the battery? Might be true, but if you look at my nearby comment – I lost plenty of range in my BOLT ev, with no deliberate battery heating AT ALL. The purpose of the battery heater seems to be battery longevity in the BOLT anyway.

My Roadster would ‘usually’ discharge (except in -10 deg F, where it would preheat for minute or so before allowing driving), but would not charge AT ALL until the battery got to at least 34 deg f.

Not at all simple thermodynamics.

It would be interesting to see a thermodynamic analysis. But as Counterpoint says, the issue with a cold battery is that it loses capacity; it literally can’t hold as much energy as it can at room temperature.

Warming up the battery would, as I understand it, use far less energy than the loss due to cold. It’s not a simple matter of 3 – 1 = 2.

For those who want to do a deep dive into the data related to range loss due to cold weather in a Tesla car, there is a lot of info in this article, if you’re willing to wade thru the chaff to find the wheat:

http://www.duckware.com/blog/tesla-elon-musk-nytimes-john-broder-feud/index.html

* * * * *

@Bill: Dude, I’ve never claimed to be an expert on any subject related to EVs or engineering. But then, neither I nor anyone else needs to be an “expert” on a subject to understand it much better than you do.

Well my comment here was tongue in cheek obviously – but we’ll see if that stops you bragging about it in the future – but since you apparently don’t know what it is you are talking about (no offense) – to say you understand it more than me, is a bit of a stretch, after all I received an “A” in the subject during my University studies. Employers would take the documentation much more seriously than your proclamations. If youre worried that Ben doesn’t know anything because he calls fast charging L3, that’s silly. I call fast charging L3 and so do some manufacturers. The Sae’s new system is so disjointed and incomplete and arbitrary that their OLD way of demarcating charging is used since it was more clearcut. The standards organizations aren’t what they used to be. By ‘modern standards’ Tesla’s home charging at 80 amps and 250 volts (the voltage they use in their brouchure) – i.e. 20kw IS NOT EVEN LEVEL II, when it is obviously the exact kind of thing a 72 ampere charger would be, other than just a bit more powerful – therefore I’m sure Ben calls a dual charger tesla ‘L2’ and so… Read more »

Yup, I used the TESLA GRAPHS mentioned in the duckware article to calculate that the loss Broder experienced overnight was at a rate of 1840 watts. Since this was larger than the 1400 watts conceivable ‘plugging in’ with the occassional use travel adapter, he would have STILL lost range overnight, even if he had plugged into the motel.

As your article just stated, Broder charged EXACTLY as Tesla said to – heeding warnings NOT to charge up each time 100% at the Supercharger Locations – the article explicitly states Broder is not at fault in what he was accused of, namely not ‘charging to 100% each time’, he can’t be accused of it since he was told not to do it.

Slightly after this time, a Minnesota woman, on a field trip in a new “S”, proved my calculation that you indeed DO lose more than you gain when plugging into 120 volts during cold weather.

“…If you already own an EV, you know that your rated range, that is how far you can travel on a single charge, never is as advertised…”. HAHA! If you define “EV” as only a Tesla – his statement applies. I can’t remember the last time my ELR ‘got less than 100% efficiency’ (rated 37 miles). When I drive it I get around 50, my nephew gets around 42, but he’s got a lead foot. Now I’m curious about cold weather operation – apparently this guy considers 50 cold. I noticed in the Bolt when driving between 10 and 20 deg F the range drops around 40%, and that is with the HEATER OFF (seat heaters only) 98% of the time. I turn it on in short bursts to keep the windshield clear. The times I’ve done this the battery was either discharging, or charging, so the ‘battery heater’ never came on – at least the ‘dayfile’ screen said there was “0% battery conditioning”. The current constantly through the battery kept its temp within specs. So, where did the juice go if the battery was constantly warm? My friend Brian states, Physicist that he is, that the colder air is… Read more »

Besides the effects of colder temperatures on the energy efficiency of all vehicles due to denser air and more viscous lubricants, both of which increase drag, EV’s suffer from electrochemical reaction dependencies on temperature.

First, the rate of the electrochemical reactions in a battery cell is proportional to temperature, so that the rate decreases with decreasing temperature. This limits the maximum charging and discharging rates.

Second, the electrochemical potentials of electrochemical reactions in a battery cell decrease as the temperature decreases. So the maximum cell voltage decreases as the temperature decreases. This reduces the usable capacity of a battery cell because the power that it can produce is less at lower voltages.

Third, the internal resistance of a battery cell might increase as the temperature decreases, but I’m not certain about this. If true, some of the power produced by the cell would be converted to heat rather than being used to propel the car.

True on all count.
Cold affect charge rate, alter internal resistance of the battery, and this one can’t store as much energy.
Cold air is more dense and harder to move around.
So, you have less energy to begin with.
You need more to move your car in denser medium.
You can’t regen as much, and sometime not at all.
And there is more resistance to get the energy out of the battery.
If you run snow tire, they are also harder to spin.
Put some snow or anything slippy on the road
and you lose more there also.
This is not counting any heating.

Simply put, cold drain more energy.

Reading Comprehension Alohart.

FIRST, I stated the battery was warm, remained warm, and finished warm at the beginning, duration, and end of the trip. So not a factor.

That would be some pretty tough lubricant to use up a huge amount of battery capacity, and if the frictional losses were from that the lube would heat up.

Ditto Djoni..

In this particular case the battery started warm, and ended warm with no wasteful heating outside of the ordinary. SO it must be something else.

Yeah, things like cold air being denser, and lubricants being less fluid at lower temperatures, certainly are not going to give a 40% hit to range, or anywhere close to that.

The question you raise, Bill, doesn’t appear to have an obvious answer. Common sense would suggest the various heaters, for the battery pack, and the cabin, used a lot more energy than your comments suggest. But that’s only an “armchair engineer” guess on my part; I wasn’t there, and you were.

I do question your claim that charging the battery pack is sufficient to keep it warm, if you’re talking about L1 or L2 charging. My understanding is that some or most BEVs, if plugged in, will automatically run the battery heater as necessary to keep it within normal operating temperatures. Perhaps — again, this is just a guess — perhaps the car reports “0% conditioning” only as an indication that it hasn’t used any of the battery’s stored energy to run the heater; it’s running off external power.

Nice to see some discussion about cold air and EV range. We always see these reviews of drivers in California who don’t know the concept of cold and have never used an ice scraper or even know what it is! Now that we are getting into colder temps, I’m regularly seeing my Bolt range go from 240 miles fully charged down to 170 miles fully charged. A Bolt owner in the warmer temps would never experience this.

How can your efficiency drop? In the winter, my LEAF specifically tells me that I’ll lose 20 km of range if I turn on cabin heating. Then it shows me its revised range estimate.

Doesn’t the vehicle always take into account outside temperature and HVAC settings to give you the best estimate of range?

“Doesn’t the vehicle always take into account outside temperature and HVAC settings to give you the best estimate of range?”

Heck no. This is one area where EV makers have really lagged behind on development.

As I recall, even Tesla finally implemented temperature adjustment for its in-car range estimator only a few months ago. Even there, I think the car just reads the outside temperature wherever it is. So if your car spends its nights in a garage, it’s going to read warmer than the ambient outside temperature.

What EV makers really need is for the car to automatically get up the outside temperature from a local weather station via internet connection, and use that for range estimation.

Maybe there’s an app for that?

The Volt uses historical data. So when it gets cold, and your range starts dropping, it remembers. (or if you are a lead foot)

His advice about parking out of the wind is only true if the air temperature is already below that at which the battery heater would come on. Then the wind would increase convective heat loss and the heater will come on more often. However, the wind will never create a temperature below ambient. Wind chill isn’t a real measure of temperature.

The advice given is about as good as I would expect from someone whose knowledge is so outdated he’s still using the term “level 3 charger”.

That’s why a long range plugin hybrid with manual mode override is so much better.

50 degrees is not cold. I want to hear reports from people driving a 200+ mile BEV in negative temps. I need to hear some worse-case-scenario stories.

Yeah, during the COLD (around 10 degrees F), “S”‘s USED to lose 1840 watts constantly, at least Broder’s “S” did. (see my comment above).

I’d be interested to see if this loss has decreased somewhat with more modern “S”‘s, under similar conditions.

Pushy seems to think he’s more familiar with the characteristics of a newer Tesla “S” than Ben Sullins. And this AFTER Mr. Sullins went to a Lab to get proof.

The EPA test cycle already somewhat accounts for this. Not completely, and definitely not worst case, but they do somewhat factor this into the numbers ever since they revamped the EPA numbers about a decade ago.

So something that might cut real world range by 20% might actually only cut range by 10 or 15 percent vs. EPA numbers.

Slowing down for bad weather would also help mitigate the losses. And since everybody should already be slowing down for bad weather anyways…..

It is definitely something that folks need to be aware of though, so it is good to have stories like this. Especially as we go into winter.

This article from Car and Driver explains the history of the EPA fuel economy test cycles. The five-cycle test includes, “the SC03, or “A/C,” cycle, which is very similar to the city cycle but run in 95-degree heat with the vehicle’s air conditioning filching fuel; and the cold FTP test, which is exactly the same as the city cycle but run at a frigid 20 degrees.”

This explains why the NRCan fuel economy rating of 18.6 kWh/100 mile is so close to my LEAF’s winter efficiency of 5 km/kWh. (In temperate BC)

https://www.caranddriver.com/features/the-truth-about-epa-city-highway-mpg-estimates-measuring-fuel-economy-page-2

I purchased a Model 3 a few months ago and live in the Seattle area. The car has been charging up at around 268 miles reported on the main screen. I went on a trip of a 110 miles and returned. I charged my car and it only charged to 247 miles reported on the main screen. What has caused this?