Batteries in cold weather

Batteries in cold weather

I withdrew from ordering myself Tesla S model just because of poor batteries behavior in cold weather.
Is it true that productivity of Tesla car batteries could go down about 30% in winter time when temperature goes below -20*C? We have long and cold winters out here. And this question was bowering me for almost a two years now :)
I would be happy if you shear some information about your Tesla roadster behavior in cold weather conditions.
Thank You :)

Kevin Sharpe | March 14, 2011

I didn't notice any impact on Roadster range after several days at -6*C

ggr | March 14, 2011

The roadster uses battery power to keep the battery itself warm. So it uses up slightly more power but still has full capacity, if you know what I mean. However, it will use this power continuously, even when just sitting there, so in really cold climates it is important to keep it plugged in in "storage mode" if you're away for even a few days (at least that's what they suggest).


Douglas3 | March 14, 2011

The Roadster does not heat the battery when switched off and unplugged. If the battery is below freezing when you first start driving, regenerative braking will be disabled and the battery will be a bit less efficient. But it will warm up in 10-15 minutes of driving. I don't know if they actively heat the battery when the car is running, but it is probably not necessary. Simply drawing power from the battery will cause it to self-heat.

If you leave the car plugged in (but not in storage mode) it will heat the battery to keep it above freezing. This allows you to use regen as soon as you drive the car.

Bryan Larsen | March 20, 2011

-6C isn't cold, that's spring or fall weather. I'm not super concerned about short-term cold weather performance -- what about long term performance sitting unplugged at work every day for 8 hours in -35C weather? Before I buy a Tesla I'll be looking very closely at the battery warranty: I'd love to see them match the GM/Nissan 8 year/100,000 mile warranty.

Tom A | March 21, 2011

From what I've read, Tesla guarantees down to -20C. Below that, to paraphrase from a recent Lexus commercial, you don't need an EV - you need a new place to live. :)

Timo | March 21, 2011

That's a bit insulting to someone that lives in places where temperatures go below -20C.

Douglas3 | March 21, 2011

Despite the -20C thing, I've driven my Roadster at -26C. Worked just fine.

Tom A | March 22, 2011

Sorry, Timo, was meant in jest only.

William13 | March 22, 2011

I decided to install a regular 110 outlet at my office so that I won't need to worry about a few days of -30C weather every year. I hope that this is not actually needed. I hope I just need to deal with slow acceleration etc. when very cold. The batteries start out solid after all and are in antifreeze.

Anyone besides Doulas 3 with a roadster sitting at work in very cold weather?

Ad van der Meer | March 28, 2011

Maybe this guy:

2 Roadsters above the Artic circle

Brian H | March 28, 2011

That's "Arctic"... and he got another one for his daughter at university in Denmark! Probably the 1st 3-Tesla family anywhere?

msiano17 | April 11, 2011

What about batteries in hot temperatures. I know it has a temperature control system, how does it keep it at optimal temperature when it is around 100'F?

Sudre | April 11, 2011

It's cools the batteries when they are too hot and heats the batteries when they are too cold.... I'm guessing since I don't have the schematics in front of me :-)

Volker.Berlin | April 12, 2011

msiano17, nobody knows exactly, because "battery pampering" is Tesla's secret sauce. It's Tesla's key to deliver EV's with unmatched range at an unmatched price.

What we know, though, is that battery temperature control is fluid based. So some heat-conducting fluid is cooled or heated as required (probably sharing some of the car's HVAC components that also serve to keep the cabin at comfortable temperatures) and then circulated between the battery cells. Obviously, this process requires some energy, but it pays off many times because at sub-optimal conditions the capacity and life span of those batteries suffer significantly. Compared to the energy required to propel the car, the amount of energy required to heating or cooling is practically negligible.

Actually, batteries need cooling rather than heating most of the time because they get warm by themselves when current is drawn. Here is another advantage of placing the batteries in the bottom of the car, besides low center of gravity/handling and accessibility: The bottom of the car is a fairly large surface exposed to air flow while driving, so quite a bit of excessive warmth from the batteries can be disposed that way.

Tiebreaker | April 12, 2011

And your feet don't get cold. :-P

Vawlkus | April 12, 2011

Fringe benefit :p

msiano17 | April 12, 2011

Do you all figure it may have a set up like an engine cooling system just a bit more high tech and monitored?

Volker.Berlin | April 13, 2011

msiano17, sure it must be at least remotely similar to an engine cooling system. What's your point? Sounds to me like you are worried about some specific detail, but from your very general way of asking the question it is very hard to tell, which is it?

msiano17 | April 13, 2011

Actually to be honest I am just ignorant on the topic. I was chatting with some friends about the car and battery system, and they were asking about how it gets cooled. So just plugging the forums on the topic to see what you all know.

I feel very confident in Tesla's ability so not too worried, but it is nice to know answers to questions others ask me.

neroden | April 25, 2011

Thinking about it, I would not be comfortable leaving a Tesla unplugged for 8 hours at -35C, although it would most likely be just fine. But if it's at work, surely there's some way to arrange for an outdoor power socket to plug into? An ordinary low-amperage 110V socket would be fine for keeping the battery heater running, and then you'd have no problems.

Jaffray | April 26, 2011

Neroden, this is exactly what I have done...standard charge at night to (usually) 302 kms...drop my daughter off at school & park at work (about 3 kms).

I installed a 110 plug at work (not to recoup range) just to keep the pack warm and not lose the regen.

Driving without regen is simply just not as much fun imo.

@ Evaldas...there are lots of Roadsters in Canada, Norway, Germany...I've not read of anyone having a battery problem due to cold weather or experiencing anywhere near the 30% loss you use in your example...

Evaldas Čepulevičius | May 26, 2011

I live in Vilnius, capital of Lithuania. Over here we have public transport running on electricity since '70s and a very cold winters every second year or so. From my life experience, I could tell that car battery, as any other battery, is very sensitive to cold temperatures. Performance of battery reduces drastically if operated under -20C and especially if process of operation is started in cold environment and without preheating.
If Tesla Motors is building model S battery similar to the ones we have in "laptops", then bigger part of the world would be left uncovered bye their insurance.

@Tom A - there must be a reason why Tesla Motors wouldn't agree to guarantee on battery performance if temperature drops below -20C. I would expect performance of battery life time to be reduced by one third.

@Jaffray - near the 30% loss is a minimum you would expect living in the countries with cold winters. Germany is below us and they don't have such a harsh winters, but Scandinavia, Russia or Canada are way too great markets to be ignored, so my question is oriented to Tesla car owners who live in these countries.

@Ad van der Meer - I'd love to have his opinion after another year or so.

I could be a happy Tesla S owner, but I want to know, as I don't want to be disappointed.
Nokia, Apple and mostly all other electronic suppliers don't recommend to use their gadgets outside in winter time, as they don't cover insurance due to faults that could happen from drastic temperature changes as one is entering in or out of heated facilities. Everyone is used to change their phone here every second year not because of new models on the market, but because of their performance reduces dramatically.
Now who would like to find out that his car is no good anymore due to the cold weather conditions of this one season, and insurance is not covering his loses?
I am very enthusiastic if we talk about renewable energy and I wan't to take a part in reducing humanities influence on global warming or exploitation of pressures of our earth - this is the reason I like Tesla Motors and their idea of efficiency.
There's so many more questions that originate from that point but they need to be asked and answered.

Volker.Berlin | May 26, 2011

Evaldas, it's the same battery cell, but you cannot compare the Tesla battery pack with that of electronic gadgets. Tesla's "magic sauce" is in the way they treat their batteries. The battery pack is liquid cooled (or heated, if need be), charging rate as well as charging level are meticulously monitored and adjusted to make the battery feel good.

It seems to work: One of the largest Roadster populations outside the US is in Norway, which should be approximately in line with Lithuania temperature-wise. Experience from the recent winters did not show significant degradation of the battery in practical use, according to some blog posts and reviews that can be found in the web.

Timo | May 26, 2011

Norway is colder. And there are mountains.

William13 | May 26, 2011

Panasonic battery lithium ion NCR-18650A spec sheet shows graphs comparing different temperatures.

45deg.C 3.7V. 3.15Ah max capacity

-10deg.C 3.4V. 2.5 Ah max capacity

There are no graphs below -10deg.C

These graphs only apply at these temperatures. The battery pack is heated and cooled actively when plugged in or while driving. Thus maximizing results. Certainly there are concerns if your pack rating is very close to you driving distance. Thus I will get the 300 mile pack to cover round trip drives to Chicago at 90 miles each way. This should cover both cold and degradation of the pack until enough charge stations are conveniently located for me.

Although the graphs do not go to -20 or -30deg.C the listed temps seem very closely clumped.

If there is a problem a 110V (household) plug is more than sufficient to keep the pack warm at work or play.

mhubb | June 4, 2011

I live in Canmore near Calgary where the Model S road show rolled through just a week or so ago.

I was not able to attend due to working up north. But I wrote an email with a question about the battery performance in the cold weather that we get in Calgary, (a cold snap can be two weeks of -25'c to -35'c with sub -40'c not unheard of)...

Steve Warren replied with the following

"In answer to your question: yes! out batteries have been cold weather tested and perform quite well. We both heat and cool each cell to ensure the highest performance and longest life."

I think I will be waiting to see how the first generation of these cars survive a couple of Alberta winters before buying. As i don't have the luxury of buying a Summer car.

Ramon123 | June 4, 2011

GM did quite a bit of Volt testing in both a lab cold room and real life driving in a cold northern climate (it might have been Canada) to ensure that the battery pack worked OK. On cold mornings, the car automatically starts the range extender engine
to get the battery pack up to best operating temperature (probably 72 degrees F). Probably because their battery pack is so tiny compared to the Tesla vehicles, it doesn't have the power to get the car moving when the cold reduces the battery packs's output.
The Fisker Karma has the same problem when the driver demands "sport high performance driving" - in that case the Karma turns on the range extender engine and draws power from both its
generator output and that from the battery at the same time. These are some of the deficiencies of tiny battery packs, in addition to limited range.

ncn | June 6, 2011

Since people seem to be repeating their questions, the crucial point is, again, that Tesla's batteries are "temperature managed": insulated and surrounded by a heating/cooling fluid (I believe it's operated much like a heat pump, which is like an air conditioner which can either heat or cool). While plugged in or turned on, they stay in a constant temperature range. When unplugged and turned off, the insulation means that they stay in that temperature range for quite a while longer. Only if you leave the car unplugged and turned off for long periods will the batteries ever BE at ambient outdoor temperature.

Even *then* the batteries are guaranteed to work (well enough to warm themselves up) at -20 C. If you're going to be routinely leaving a Tesla parked for more than a few hours in a climate colder than that, do what Jaffray did and find an outdoor electrical outlet; it can just be an ordinary outlet, as the heating/cooling system uses a very small amount of energy. It'll probably be fine unplugged at -35 C for 8 hours, but the small cost of installing a single outdoor socket should be well worth the peace of mind. And in fact there's likely to already *BE* an outdoor socket; all new construction has them.

Frankly, gasoline cars routinely don't start if left out for 8 hours at -35C; that's why, in that kind of climate, there are block heaters which you plug in. If you're in that kind of climate, you are already going to have the facilities you need.

Nicu | June 7, 2011

I think the battery pack will use a bit of energy to maintain the temperature in a suitable range even when not plugged in (too lazy to search for a link). Unless you leave your car in the cold for a month, it should always be ready to start in optimal conditions at any moment.

Vawlkus | June 7, 2011

Correct, the battery will start using charge to maintain itself at the temperature the batteries require.

William13 | June 7, 2011

Although having the battery keep itself warm would be fairly simple for the s and might just be a firmware decision, Tesla has never indicated they would do this. The Roadster does not currently. They may be concerned about loss of range if left on accidentally. I would think this could be negated by an adjustable timer for around ten hours normally before it would shut itself off. It could alternatively be set to turn on half an hour before the expected next drive.

DartLady S77 | June 7, 2011

Canadian office buildings have installed block heater plugs for employee use for years - problem solved. At most, have your employer designate a spot for you (though that makes the space a taxable benefit)

Fellow Canadian and Signature reservation holder #77

forsakendemogorgon | June 19, 2011

But does the roadster use the energy being provided for temp control while charging? Without the firmware (software updates) it wont know if it has to or not.

cablechewer | June 19, 2011

DartLady - I have never seen block heater plugs at company offices in Southern Ontario. I have heard they are common in Alberta, Saskatchewan and Manitoba, but haven't headed out there to look for them :)

forsakendemogorgon - I have been told by a Tesla rep that the battery will draw energy while plugged in to handle its internal thermal management. I didn't find solid backup in the blogs, but you might still be interested in reading this old blog about the battery: