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Why EV winter range loss is both fact and fiction

RMI

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In late 2014, as the last days of fall were giving way to the earliest days of winter, my family and I were walking back into the parking lot of a local Nissan dealership here in Colorado. We’d parked our LEAF there to charge while we visited a nearby shopping center to run a few quick errands. As we returned to our car, another family was standing next to another LEAF parked adjacent to ours, a dealership salesperson at their side.

As my wife and I buckled our kids into the back seat, the woman spoke up, a look of mild concern on her face. “Does it really only get 50 miles of range in the winter?” she asked. Clearly she was looking for an honest answer from a real-world LEAF driver. Did the LEAF’s EPA-rated 85 miles of range really take a severe hit when the mercury dipped?

“No, not at all,” I told her honestly and confidently. Even in very cold weather, I was consistently getting 70+ miles out of a charge, and frequently closer to 80.

Yet her concern was entirely reasonable. Fair-weather driving in an EV is one thing, but over the past two or three winters there’s also been no shortage of coverage about winter EV range in the likes of The Charging Point, the Kicking Tires blog at Cars.com, AutoBlogInside EVs, and Plugin Cars, to name but a few. Perhaps the most widely distributed piece I’ve seen is a piece by Green Car Reports with graphs based on Fleet Carma data that conveniently plot average and best-case range estimates for the Nissan LEAF and Chevy Volt across a 100-degree temperature range.

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The long and short of it all is that you can maintain range or curtail it severely, with your range ultimately less dependent on outside temperature and more dependent on how you use the car. That includes how you choose to maintain your own personal thermal comfort while driving in cold weather. Let me put that more bluntly: if you use the cabin heater, kiss a significant percent of your range goodbye. If, on the other hand, you choose other strategies to stay comfortable, you’ll make only a tiny dent in your estimated range.

This simple strategy has proven true even when I’ve driven my LEAF to Rocky Mountain Institute’s offices on multiple consecutive days when my morning drive takes place in literally zero degree Fahrenheit temps and the daytime high never climbs out of the single digits. Wearing a light jacket and using both the heated steering wheel and heated seats keeps me more than comfortable for the duration of the drive.

Some might read that and thus accuse me of making a substantial compromise, of making a hefty sacrifice in the name of maintaining my EV’s range. I’d argue, though, that this is instead about a paradigm shift in both expectations and how we maintain our own comfort while driving our cars.

rsz_blog_2015_01_29-3For decades internal combustion engine (ICE) cars have tricked us into thinking our vehicle cabins should be the equivalent of sweltering saunas on wheels, even in the depths of winter. I have a right to comfortably drive in a short-sleeved shirt even when snow is falling!

ICE’s comparatively inefficient powertrains have more than enough heat to spare, which is useful for cabin heat in winter but which risks overheating our cars in summer, hence the need for liquid coolants, engine fans, front grills that permit open airflow over the engine block, etc. Factories have combined heat and power—industrial heat processes that can put their heat to dual use and generate power. The internal combustion engines in our cars are the flip side. They’re combined power and heat—they generate horsepower and torque for vehicle propulsion, with a side effect of generating waste heat that can be harnessed for cabin heat.

Yet there are other equally valid—and frankly, more energy-efficient—ways of maintaining personal thermal comfort, from my aforementioned light jacket, heated steering wheel, and heated seats, to wearable technologies like Wristify, to even turning down my home’s thermostat at night and sleeping snugly beneath warm covers. It largely comes down to conditioning the person for comfort, rather than the space that person occupies … including the cabin of my EV.

Trust me: I’m no masochist. Banish any visions you might have of me shivering in the driver’s seat as I drive to work in the morning. I truly am comfortable, and you need not take my word for it. I have three young children, ages six, four, and one. They’re all in either rear-facing child seats or full-back booster seats. As such, they don’t benefit from our LEAF’s rear heated seats. When I drive them to school on certain weekday mornings, I always ask: “Are you comfortable? Are you too cold? Too warm?” They almost always say they’re comfortable, and if they’re cold, I run the cabin heat enough so everyone’s warm. But a rolling, electrified version of the Caribbean climate we are not.

Any EV driver has already made an automotive paradigm shift from internal combustion engine to electrified powertrains. Why then cling to the old way of staying warm in a car during winter? It’s time for a paradigm shift there as well. If you can make that leap, as others and I have, then you can have your winter range and heat it too. EV winter range loss can be fact, but it can also be fiction. The choice is yours.

Source: RMI. Reproduced with permission.

Comments

6 responses to “Why EV winter range loss is both fact and fiction”

  1. Ron Horgan Avatar
    Ron Horgan

    Is the cabin heating in the Leaf reverse AC?.
    VW Passat uses this rather than waste heat. Seems to be simpler and more reliable than plumbing hot coolant into the cabin.
    What about demisting?

    1. Peter Campbell Avatar
      Peter Campbell

      Demisting is quicker and more effective with the air-con used to dehumidify and that takes less from the battery. In my home-converted car I have the aircon wired so that it can optionally come on controlled by the brake pedal – the switch for the brake lights is wired so it can also pull in a relay to do the same as pushing the aircon button. The aircon on the converted car runs on a pulley from the traction motor just as it did on the original petrol engine so it is a drag that slows the car down. Whether for demisting or intermittent summer cooling it costs me nothing to have it run when I would want to slow down anyway so I am touching the brake pedal.
      In the commercial iMiEV the aircon runs from a separate small electric motor.
      In either case, having some heating also is rarely a problem even though range takes a hit because neither car is used to the limit of its range on cold frosty nights.

    2. JeffJL Avatar
      JeffJL

      Not in Oz Ron. Australia has the 2012 version. The newer model in the
      rest of the world (except NZ) uses a heat pump. They also use the heated
      seats and steering wheels.

      Demisting uses the AC.

  2. Peter Campbell Avatar
    Peter Campbell

    The newer Leaf has a reverce cycle AC; the original was a direct resistance heater.

    I live in reasonably chilly Canberra and have been driving a home converted electric car for 6 years and an iMiEV for one winter so far. In both cabin heating with a direct resistance heater sucks a lot of battery. Of course it is hard to heat an uninsulated glass and metal box moving at speed through sub-zero air. It is only possible in a petrol car because of the prodigious amount of waste heat from an internal combustion engine. I have on occasions considered a fossil fuel burning cabin heater like this: http://www.ebay.com.au/itm/Webasto-Diesel-Heater-Single-Outlet-Vehicle-Kit-12v-/280887944338
    However, for much less money I got a heated car seat kit. In my converted car, 45W applied directly to the bottoms and backs of the driver and passenger is more effective than almost a kilowatt applied to space heating. The iMiEV came with a heated seat only for the driver which was a bit mean. I might add a kit for the passenger some time. The iMiEV’s space heating is very effective but range takes a hit (say, 100km down to 70km). More often than not we have ample range anyway since 70km is more than all our routine, around town trips.

    1. David Osmond Avatar
      David Osmond

      Thanks for the interesting info Peter

  3. Malcolm Scott Avatar
    Malcolm Scott

    My experience with the Holden Volt is that range does decrease a little in winter, but more night time driving, and more likely use of the wipers all goes to reduce the range. My winter real world typical winter range drops about 10km. In summer the need to cool the cabin affects range also, but that is A/C not a resistance heater. I seem to be getting good results from starting the car 10 min before I leave with it still connected to the EVSE. Getting to operating temperatures for some parts of the car, cabin and heated seats is better from house power rather than from the battery if range is what you are after. Range reduction is all a moot point if you have charging capabilities at work, or at your destination. For me the public charging network helps greatly in winter and on steamy hot summer days. I can use the heater and A/C without a second thought. That charging network is the key for success. I wish more businesses realised that charging stations are honey pots for some new clients. Many of my trips are at the limit of the Volt’s battery electric range and so I do change my behaviour to use businesses that have charging stations or have charging stations near by.

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