Saturday, February 14, 2015

Driving An Electric Car In Winter

VoltBack in September I wrote a series of three articles about the efficacy of driving electric cars (EV’s) in the Adirondacks. My overall conclusion was that electric cars had a definite, practical future in the Adirondacks.

All of my driving experience however, was in summer and early fall, which accounts for only about a quarter of an Adirondack year. The $64,000 question then, was how would an electric car perform under real winter conditions? With the January we’ve had in Wisconsin I’m ready to report.

The bottom line?   I find that the standard critique of electric cars in the winter, namely that the battery range plummets, is greatly overstated and basically not true. Electric cars are just fine in the winter and even offer some advantages.

As in the Adirondacks, Wisconsin has so far seen a winter of unusually cold temperatures including several doses of extreme cold. I drove my Volt for about an hour one morning when it was -17, and many times when it was below zero. We recently got a good foot of snow which also allowed me to test handling in deeper snow. We’ve also gone through the range of winter conditions.

I do have two caveats. First, I’ve only driven a Volt, but many of its characteristics are more or less common to all EV’s. Second, my car had the same low-resistance “all-season” tires it came with last summer. In the Adirondacks I’d have snow tires for sure.

One big question is whether an EV battery can hold a charge long enough in a cold winter to provide sufficient range. I made a clean comparison to summer driving by measuring battery use in a variety of temperature conditions without changing other parameters attributable to winter, such as using the heater and driving with poor road conditions or visibility. That way driving style and cabin comfort did not skew the results.

Physics dictates that a battery will lose some efficiency due to colder temperatures. How bad was this loss? For my Volt if the temperature was in the mid-twenties or higher the drop in battery range was negligible, usually not more than 5%. If the temperature was colder the drop in range was more noticeable, but not all that much worse, maybe more like 12%. The biggest drop I registered was about 15%.

With an average range loss of around 8-10% I concluded that battery range was not a big winter issue. That’s especially true because gas engines become less efficient too. According to a study by the US Department of Energy the average gas vehicle loses about 12% efficiency at 20 degrees versus summer conditions (the DOE also reports that Hybrids fare worse and I found that to be true in my Volt; when the gas engine was operating to charge the battery, efficiency dropped by a good third).

So far so good, but the elephant in the room is not intrinsic battery loss due to cold; it’s battery loss due to cabin comfort. A gas engine heats the cabin with excess heat that would only goes to waste anyhow, thus the net additional cost to heat the cabin is zilch. An electric car has to use the battery. If it’s a cold day and you want a warm cabin you will brutalize the battery, at least until the heater has caught up to your settings and shifts to maintaining them. Once that threshold has been reached the loss is more like a grave wound you’ve stemmed: not life threatening any more but pretty ugly.

I tried comfort settings in my Volt in various conditions and the results were never short of alarming. While the electric heater was warming everything up battery loss looked to clock up to 70% or so. Five minutes of that would easily cut my total range by as much as a fourth. After the heat was stabilized the loss in range settled more into the 25-30% range.

Since the real blow to battery range is the initial warming, EV manufacturers have developed ways to mitigate the effect. First, all major EV’s have some version of pre-warm. For instance in the Volt you can program it to pre-warm while plugged in. You can also run the gas engine briefly to “get you over” the the warming hump (in the Volt, if the temperature drops below 15 degrees you have no choice – it runs the engine in an idle mode to warm battery fluid in order to protect the battery, in which case the warming hump is much less of an issue).   The electric pre-warming feature is one of the advantages EV’s have. There is no problem with over-idling and there are no emissions. It’s a great winter feature and a definite advantage over internal combustion cars.

Next, EV’s rely upon more efficient methods to give you comfort, most notably heated seats. The Volt has boffo heated seats and even when you have two of them going full bore it only takes 3 or 4% of your battery. I learned early on to wear warm socks (heated seats do nothing for your feet, obviously), keep the cabin heat off and rely entirely upon the heated seats. That works great; I stay perfectly cozy and the cabin, which holds heated especially well due to the car’s quality and superior aerodynamic efficiency, is plenty warm.

But there’s a big catch: the same warm, dry air that heats a cabin also clears your winter windshield. Depending upon the weather you may have no choice but to run the cabin heater.  If I had weather where I had a fight on my hands to keep the windshield clear my battery charge drained a good 20% to 30% faster than summer driving. The only mitigating factor is that there are not that many days where the problem is acute. Still, this is the Achilles’ heel of the electric car in my opinion. It occurs to me that the typical forced air defrost is inefficient – I wonder if engineers are looking at alternatives.

In terms of handling the situation is more straightforward. My Volt’ behavior on winter roads is definitely above average because of two more advantages EV’s have over most conventional cars: size-to-weight ratio and a low profile coupled with a low center of gravity. The low-resistance tires are pretty lousy in snow and ice but that aside the feel of the car is nearly as sure-footed as my Subaru WRX. The concentrated, low weight of the Volt is obvious and delivers a grip on the road that feels consistently confident. One especially nice feature is the flat profile which along with the weight makes the effect of crosswinds almost nil. I was somewhat concerned about the low road clearance in deeper snow but I could not tell any difference versus a regular car.   Overall handling is a plus over a typical car, but definitely get snow tires.

Meanwhile the goal of a Park-wide charging network is clearly being achieved by natural evolution.  In September 2014 the Wild Center had the only charging station publicly announced and available in the park. Now, a mere four months later, I count eight around the region including Lake George, Lake Placid and Old Forge. At least four of these are 240 volt sources for faster charging, adding to the practicality of operating an EV in the Adirondacks. That’s a good thing, because every reduction in emissions is both a statistical and symbolic benefit.

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Pete Nelson is a teacher, writer, essayist and activist whose work has appeared in a variety of Adirondack publications, and regularly in the Adirondack Almanack since 2005. Pete is also a founder and current Coordinator of the Adirondack Diversity Advisory Council, which is working to make the Park more welcoming and inclusive.When not writing or teaching mathematics at North Country Community College, Pete can be found in the back country, making music or even walking on stilts, which he and his wife Amy have done professionally throughout the United States for nearly two decades.Pete is a proud resident of Keene, and along with Amy and his dog Henderson owns Lost Brook Tract, a forty-acre inholding deep in the High Peaks Wilderness.

30 Responses

  1. John Jongen says:

    Your excellent report will certainly move the needle on the use of hybrid EV’s in the ADK. A win for us all.

  2. Dave Mason says:

    We drive a Prius (and a gas guzzling 4wd truck). In winter, with snow tires and cooler temps Prius mileage drops from 50 or so to around 44 mpg. We use AC in the summer and heat in the winter so I’ve no idea how changing that might impact mpg but I am sure it has an impact.

    Does AC use in the Volt cause range to drop like heat does?

    Another question: You say “in the Volt, if the temperature drops below 15 degrees you have no choice – it runs the engine in an idle mode to warm battery fluid in order to protect the battery” Which engine does it run, electric or gas. Does it do this automatically?

    The issue I wonder about is storage. Suppose you leave it parked for a month in winter? Does someone need to start it once in a while? Or you just leave it plugged in? For the Prius, we have someone come and start it every 2 weeks or so.

    • Pete Nelson says:


      It sounds like your Prius drop is less than what the government reports.

      A/C use definitely affects battery range but I have not measured it.

      The Volt runs the gas engine at idle if the temperature is below 15 degrees. This is automatic

      It is recommended that the Volt not be left in extreme cold for an extended time unless it is plugged in (while plugged in the current is used to circulate fluid through the battery and keep it from getting too cold). However with the Volt if it is a cold start in weather below 15 degrees it’s going to start the gas engine anyhow. You can also choose a gas prewarm/start if you like.


      • Dave Mason says:

        Would leaving it plugged in mean the gas engine will not start at 15 degrees? I would not want the gas engine running inside a garage, for example.

        • Pete Nelson says:

          No, when the Volt is plugged in the gas engine does not start. The engine starts is only when you are actually driving, in temps below 15 degrees. Even then it is only sporadic – when the internal temp drops below a certain threshold. On a trip of more than a couple miles much if not most of my driving in really cold weather is still pure electric as the gas engine does not need to idle all the time in order to keep the battery fluid warm enough.

  3. Christine says:

    Good grief Pete… Why don’t you first spend a full winter or two in the Adirondacks and then get back to us… in the meantime we will keep back seats passengers warm and hope when driving 40 minutes away as it is often the case we can make it back safely.

    • Pete Nelson says:


      A full winter or two in the Adirondacks, eh? Happily, that will happen soon. But in the mean time my different location is not relevant. That’s because I’m reporting from Madison, Wisconsin, not Florida. The average January temperature in Lake Placid is 27 degrees; Old Forge 25 degrees; Madison 26 degrees. Wisconsin is North Woods country too.

      By the way, my daily commute happens to be 40 minutes one way. With a gas backup EV like a Volt that 40 minute drive is no sweat and my overall emissions are much lower. I’ve driven more than 4,000 winter miles already in the Volt, this during an unusually cold winter. I’m not lacking for a real test.

      With an EV you have the option to warm the cabin as much as you like. I’m just reporting the trade-offs. We haven’t frozen anyone in the car yet, we’ve used some gas. But our aggregate mileage in our winter Wisconsin driving has been right around 100 mpg. How does that compare to yours? That’s the point.

      My “good grief” is US aggregate carbon emissions, not worries over who has the coldest winter.


      • Christine says:

        …and where does much of the electricty comes from?

      • EE says:

        “But in the mean time my different location is not relevant.”

        Temperatures might be near the same, on average*, but driving conditions with respect to terrain are not comparable. Are there mountains in WI? Elevation changes eat battery, much more work being done. It also sounds like your doing mostly interstate driving, which wouldn’t be true in the Adirondacks.

        *average low and average high would be a better measure than a simple “average”. As you point out, battery performance drops off very quickly below 30 degrees. 5-10 degrees lower at night will affect the performance.

  4. George Morrow says:

    Very interesting and informative article. I don’t have an electric car yet, but find many things about them very attractive. This article answers some important questions for those of us who head for the Adirondacks at all times of the year. Good job, Pete.

  5. Hawthorn says:

    I’ll assume you have been measuring battery capacity via the instrumentation, but it would take some independent measuring system/testing to measure capacity accurately. Possibly have you compared the amount of charge going into the car in winter vs. summer? Have you tried a cold-soak overnight to see what happens?

  6. John Tiernan says:

    While I appreciate this report, it’s just as confusing as others about EV versus hybrid versus gasoline. Your Volt, apparently, is not an electric vehicle, but a gasoline/electric vehicle; so in essence it’s a hybrid like my Prius. It baffles me that the manufacturers can’t make it clear to us consumers which are purely electric or hybrid.
    Next, what about diesels? My VW diesel seems to do the job well and get good fuel mileage, so what’s the comparative experience?

  7. EE says:

    Where is the vehicle being stored overnight? Outdoors vs. Garage is going to make a huge difference. You never mentioned that.

    It will affect both the temperature of the cabin and temperature of the battery, which, as you point out, both play into the range of the battery.

    Try parking it outside overnight and see how it does vs inside. I’d bet there is a huge difference during winter, This does affect its practicality. Not everyone has a garage.

    In general, I think the volt is the best route to take- gas powered generator feeding a battery bank, driving an all electric motor/drive train, much like “diesel” locomotives. I’d be most interested in a diesel volt.

    The dual drive trains (electric and gas) of most “hybrids” have Henry Ford trying to claw his way out of his grave. “you want two engines and drive trains? How about 3 or 4?” Much more complicated and expensive.

    “I’d give the cars away for free if I had a monopoly on the parts.” Henry Ford

    • Paul says:

      I think where the car is being stored is an excellent question. In my experience with off grid solar you have to keep the batteries where it is warm to keep them in good shape. I keep both of my cars outside all winter (no plug in) can you do this with a Volt and get good results. I should note that one of my cars is a Civic Hybrid. It seems to do fine in the very cold weather. Perhaps it isn’t very efficient when it is cold and I just don’t pay attention, but it seems like it does as well as it does in the summer. Eight years old and 140K now on that car and zero problems (knock on something!). That is a big open question can Chevy make a dependable car, especially one as complex as this machine? Best of luck Pete.

  8. Nate Gilbraith says:


    Thanks for the very well thought out and written discussion of PHEV use in the winter. I appreciate your point by point discussion of the individual strengths and drawbacks.

    One qualm I have, being somebody who does energy systems research, is your terminology. To me and many other researchers the Volt is at Plug-in Hybrid Electric Vehicle (PHEV) and not an Electric Vehicle (EV). The distinction being the gas engine, which as you note helped overcome many of the cold-related shortcomings of battery based vehicle energy storage.

    I also have a couple of questions 🙂
    – How did your energy consumption change (kWh and gallons) between summer and winter? You provided percentage changes, but the change in energy consumption wasn’t clear to me. Do you use more kWh but the same amount of gasoline? Vice versa?
    – Have you remained committed to maintaining a cooler cabin temperature in order to save gasoline? My girlfriend and I always keep the house in the upper 50s in the early winter to save energy, but the temperature tends to creep up as the winter drags on!

    Thanks again!


  9. Nate Gilbraith says:

    Also, for anybody interesting in learning about the pros/cons of driving hybrid vehicles with smaller battery packs (think the normal Prius) versus larger battery packs (such as the Volt):

    This paper was published in the Proceedings of the National Academy of Sciences, one of the top academic journals in the U.S.

  10. Hawthorn says:

    Can you park the Volt overnight, or maybe for a couple of nights, with below-zero temperatures and not plugged in and will it start? I’m thinking parked at a trailhead in the Adks while on a winter trip or even parked at say the Adk Loj for a few nights. Early Volts had a warning that the batteries could not be used below a certain temperature and it was not possible to use them until they warmed up again, therefore even the gas engine was prevented from starting if the batteries were below a certain temperature. Any information on that in the handbook? Thanks!

    • Paul says:

      I think he already addressed this question. The car is fully capable of working just as a gas powered gar and it could start (or not start!) under the same conditions as any car. I think, like with my hybrid, the batteries that propel the car have nothing to do with the regular battery that starts the engine.

      • Paul says:

        Sorry “car” not the funny looking pointed fish “gar”!

      • Michael Cerkowski says:

        Actually, the EV pack is what actually starts the engine in most hybrids, including the Prius. The 12 volt battery just closes a relay that engages the starter/generator.

        • Paul says:

          On the Civic Hybrid I have I think it can work either way? If the engine starts from the 12V battery you hear it turn over like a regular car (which it sometimes does if very cold like this morning for example about 5 below where I am). If it starts just the electric engine, I would assume from the IMA batteries, it will just quietly turn on.

  11. Lou says:

    Good read. I’ve had similar experiences with my Model S in the cold.

  12. Michael Cerkowski says:

    I can offer more pertinent observations on driving an (actual) EV in frigid Winter weather in Upstate NY. I am in the second Winter of my lease on a 2013 Leaf SV. I’m retired now, but I drove it all last Winter to commute from Mechanicville to Albany and back, at night, in all weather, including sub-zero nights with very low wind chill temps. The commute was about 43 miles, round trip. I always made it back with charge to spare, although I did reduce the heat to 68F in the worst weather, relying on the heated seat and wheel, and a fleece lap blanket to help keep my elderly legs warm. I could have set the heat to 71 or so in Eco Mode then, I now realize. In typical Winter weather I set the climate control to 76F. The car’s effective range, in mixed driving (hills and flats, with speed limits from 30 to 65MPH, although I rarely drive faster than 55-60 in Winter), in frigid weather, is about 50 miles. This is using some, but not all, of the “reserve” range below the first Low Battery warning but before the second, more urgent alert, something that can seem alarming at first but is perfectly safe. Given more hills or higher speeds, I’d expect the range to drop to 40 miles.The car is always parked outdoors, a few yards from the Hudson River, with both the North and West winds striking it directly. It has never so much as shuddered at the cold.

    My Leaf has two Winter advantages over typical EVs: it has a heat pump as well as the usual resistance heater, and it has remote access to the climate control via the Nissan “Carwings” website. (It also has a battery pack warmer that comes on near 0 F, which is a mixed blessing: it keeps the battery pack from getting dangerously cold, but it also uses charge to do so.)The heat pump extracts heat from the air instead of generating it, and this saves substantial power, at least in the operating range of the unit, which is technically from +5F on up, but is realistically from about +14F and up. Below that temp the resistance heater is doing all the work, and using charge at the usual high rate. The remote access feature lets me turn on the climate control from my bedroom (or from an android phone) while the car is still plugged into my charging station or even it’s not plugged in, anywhere there is cell reception for the car’s 2GHZ cell transceiver. The heated seat(s) and steering wheel are also activated. This lets me get into a car that is at least “mild” and if I choose, “warm” even in sub-zero weather. The Leaf also has a built-in timer for the climate control, which can be set inside the car.

    Both the mid-range SV model and the high-end SL have these features, but the Base “S” model Leaf has only the resistance heater, heated seats and wheel, and a more basic on-board timer. For this reason I would not recommend the Leaf S for year-round driving in this part of the country, only the SV or SL. The exception would be in cases where the car will only be used for 20-30 mile trips, in which case the S’s resistance heater alone should be adequate even in the worst cold.

    In conclusion, the Leaf makes a great car for those who don’t need the range of an ICE or hybrid, and who don’t want to burn gas or spend lots on money on maintenance. It climbs mountains with ease, using substantial extra power to do so. Where the Leaf and other similar EVs like the Volkswagen e-Golf really shine is as a second car for shorter trips and commutes, even in Winter.

    • Hawthorn says:

      Michael, thanks for the additional useful information. Does your manual say anything about what happens if the car is left parked and not plugged in so that the batteries drop below zero in temperature? I have read in numerous places that lithium batteries can’t be recharged if they are below a certain temperature–you have to wait for the temperature to increase inside the batteries before they can be safely charged. Does your battery pack heater come on even if not plugged in? I wonder how the Volt deals with that issue.

      • Paul says:

        “I have read in numerous places that lithium batteries can’t be recharged if they are below a certain temperature–you have to wait for the temperature to increase inside the batteries before they can be safely charged.”

        How is this possible if I keep my Hybrid outside all winter? They would never warm up enough to charge. Mine appear to be charging as soon as I start driving on a cold day?

        • Paul says:

          Might effect the performance or the longevity but they do seem to function even when stored below zero.

      • Michael Cerkowski says:

        The battery pack heater comes on when the pack temp (not the air temp) is near 0 F whether the car is plugged in or not, using about 300 watts of power. Once the pack charge falls to 30% it shuts off, and if it gets too cold after that, the car “hibernates” – it won’t charge again until the pack is warm enough. It doesn’t run that much in Winter, even this Winter, because driving the car raises the pack temp, charging raises it, and whenever the air temp rises well above zero, that also warms the pack, relatively speaking. It has to get down to just above zero or colder, and then *stay there* for a long time (days, not hours), for this to become an issue.

  13. Curt Austin says:

    At least you don’t have range anxiety. I know someone with a Leaf; in the summer they can make it to the big city, but not in the winter. Another factor in winter is the increased drag from the colder, denser air (with its unfortunate cubic relationship to power). It may also be relevant to mention that winter gas has less energy content.

    I’m waiting for the Apple Car. I’ll just have to whisper into my Apple Watch “Bring the car around, James.”

    • Michael Cerkowski says:

      Range anxiety is something that all EV owners experience at first, but those of us who take the time to get familiar with how our vehicle performs under various conditions don’t usually worry about it. I know that I can do at least 35 miles in Winter from an 80% charge (an option only on the 2013 Leaf) or 50 miles from a 100% charge. I also know how to increase range while driving, by simply slowing down, lowering the heat a bit, or both. I agree that driving a current generation EV in Winter isn’t for those who both want a carefree driving experience *and* regularly drive more than 25 miles at a time.

      For those who want to use much less gas, and experience EV driving with no range anxiety, there are two cars that stand out: the Volt and the Prius PHEV (aka “Plugin-In Prius” or “PIP”). The Volt is great for those who want a fairly large EV range and don’t mind charging the car like an EV. The Prius PHEV is unique in that while it gets fantastic – near unbelievable, actually – fuel economy when charged, it also gets even better MPG than the regular Prius, *even if you don’t charge it*. My housemate drives a 2013 PIP, and the transition from her last Prius (also a Gen III) was seamless, as the cars drive virtually the same. She doesn’t mind plugging it in regularly to get 70+ MPG, but even if she didn’t she could expect 55-60 average (not highway, *average*) MPG. The reason is that the PIP’s larger battery pack is also used for Hybrid mode, and provides more electric-drive range than the regular Prius, by storing more energy recovered while braking. As it is, her car’s “lifetime” fuel economy average stands at 68MPG. Typically she gets 70+ MPG in all but the most frigid weather. For those of you who want to avoid sitting at traffic lights enveloped in your own exhaust fumes while wasting gas idling, or who want to use the least amount of gasoline possible, the Prius PHEV and Volt (improved for 2016) are the cars to test drive.

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