Frozen Fleets: Driving EVs in Winter

Posted: January 31, 2018
Tagged As: Electric Vehicles, Fleet Management

Cold weather has the ability to slow down the best of us, and modern conveniences are no exception. Both conventional and electric vehicles behave differently in a Canadian cold snap than a balmy summer day, but exactly how that impact shakes out in everyday use varies.

Winter range is a key concern for municipalities looking to replace a petroleum-powered vehicle with a battery electric equivalent. For an internal combustion engine (ICE), the majority of the energy contained in the fuel is converted to heat, with a minority (20-35%) actually being used to propel the vehicle. This waste heat comes in handy, allowing us to keep vehicle interiors at t-shirt friendly temperatures even in the dead of winter.

Because electric vehicles are much more efficient at turning electricity into motion (~90%), heat needs to be created independently of the drivetrain. This FleetCarma article looks at energy demands from the HVAC system in a Nissan Leaf and Chevrolet Volt. At the freezing point, the Volt uses around 4kW for its systems, whereas the Leaf uses about half as much. When compared to the Leaf, the Volt has a much more powerful battery heater (1800W versus 300W), which explains a big part of the difference. The Volt also runs its gas engine below -4°C to produce heat, making it less reliant on electrons to keep occupants cozy.

The impact of temperature on range is significantly impacted by driver behaviour – a driver that sets the climate control at 27°C so they can show off their Bermuda shorts while driving in a blizzard will have much more of an impact on range than one who is mindful of energy use and is willing to keep their jacket on. Seat and steering wheel heaters are much more efficient in electric vehicles than the forced-air systems we’re accustomed to, as they focus energy on the person in the seat rather than heating up the entire car.

Preconditioning, where a cold car is warmed up while plugged in to the charger, has a significant positive effect on range. Electric vehicles stored in enclosed but unheated spaces have a major added perk – no concern when ‘remote starting’ the car with the garage door closed! By giving the vehicle time to warm up before unplugging, driving range and driver comfort are significantly improved. For best results, the vehicle should be plugged into a Level 2 charger (220V), as cabin heaters often use more energy than a Level 1 (110V) plug can provide. An EV kept in a heated garage will see a significantly reduced range drop; it takes much less energy to maintain a warm car than to defrost a frozen one, and batteries are generally most efficient at similar temperatures to what their human drivers prefer.

Electric vehicle ranges are affected by temperature, and this is something fleet managers need to keep in mind as they select vehicles. FleetCarma found that a Nissan Leaf’s range would peak at ~120km at 20°C, and drop to a low of ~75km at -15°C. Range loss depends on the individual vehicle, but battery-only EVs can expect a ~30% range drop during the depths of winter, whereas a plug-in hybrid may experience a slightly larger drop.

If you’re looking for more specific information than what’s above, consider the continued use of a telematics platform / device post EV purchase.  The LAS Fleet Management service uses telematics to assist in choosing the most appropriate EV to replace its ICE counterpart, but continued use of telematics after the purchase can provide a more accurate analysis on the impact of temperature and duty cycle on your EV fleet. 

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