Back 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.