Electric Vehicle Performance in Extreme Winter Conditions

By Wayne Sum and Bill Franklin

Introduction

Few denizens of Canadian cities give thought to the sophisticated and robust civic infrastructure and organization that enables a safe and enjoyable life whether uptown, downtown or in suburbia. Clean, well lit, well built and maintained streets, effective policing, parking, garbage collection, water and sewage, libraries, parades, medical centers among a multitude of other services all directly impact the satisfaction and safety of city residents.

Management of a dynamic and resilient city will consider key factors that can be employed in an emergency, whether it be political protests, rampant homelessness to fires, flooding or intense cold and blinding snow.

As the fires in California vividly attest, global warming and drought has intensified the desire to reduce reliance on internal combustion engines in favour of electric vehicles  that get their energy for locomotion directly from the sun, wind or water (hydroelectric). In this article, we look at the challenges of achieving an all-electric fleet while retaining the resilience required from municipal services.

Massive fires in Ventura county California, seen by author driving on Highway 101 from LA to Santa Barbara on November 6, 2024.

Consideration of EV’s touch on the following topics:

• Saskatoon’s Electric Vehicle goals
• Electric Vehicle (EV) performance in general
• A closer look: Nissan Leaf
• Winter Driving Conditions and impact on EV driving range
• Theoretical look at
  • Impact of cold on battery performance
  • Impact of cold on power consumption
• Real World Tests: Consumer Reports, American Automobile Association
• City of Saskatoon’s pilot EV experience
• Recommendations to advance electrical vehicle utilization

The road to reducing Saskatoon’s carbon footprint starts here…

In July 2021, Saskatoon began its Electrical Vehicle (EV) Adoption Roadmap. The objective was ambitious: all municipal & transit fleet to be fully electric by 2030. This would include buses, utility vehicles, snow clearance, garbage trucks among other equipment.

The objectives were:

• Re-evaluate corporate fleet in context of EV
• Determine costs & savings associated with EVs
• Assess durability, viability & required infrastructure change
• Ability to purchase electric vehicles in a normal purchasing process (RFP)
• Assess real world EV performance: pilot 4 EVs in 3 departments (Chevrolet Bolts)

Although electric vehicles are having substantial success such as in California where the percentage of EV’s (especially Tesla) is amazingly high, locations where winter conditions are harsh and long significantly impact EV performance. Cold temperatures sharply diminish battery capacity and significantly increase energy consumption.

Since the internal combustion engine has been around for over a century, engineers and manufacturers have improved both engines and vehicles to face extreme cold. At times Saskatoon dips to minus 50 C yet their diesel and gas powered vehicles, trucks, tractors, snowplows, SUVs are out in the field doing their job and indeed are expected to perform.

What then should be expected of an electric vehicle?

• Operates in temperatures from -50C to +40C
• Runs all day on a tank of fuel or an electric charge
• Starts up reliability every morning and runs all day, month after month
• Is comfortable to drive (e.g. warm interior in cold weather), has storage space, can have equipment mounted to it (e.g. License Plate Recognition equipment)
• Fleet services can maintain it and get parts
• Purchase price of CAD$40,000 or less for an EV SUV
• Maintenance cost is reasonable
• Infrastructure cost is affordable
• Replacement of an ICE vehicle with electric vehicle is a 1 for 1 exchange

Tesla and Nissan have been producing electric cars and SUVs for fifteen years and Toyota has sold the very successful Prius hybrid since 2000. It seems reasonable to conclude that electric and hybrid vehicles already fit the bill. However, unlike hybrids, EVs store their fuel in the form of electrons and in batteries, and these  devices differ radically from the internal combustion engines and their fuel system.

In short the City wanted to pilot test electric vehicles to see if:

• Too cold on occasion to operate vehicle?
• Will it run 14 hours continuous? Is 24/7 operation possible?
• Is it reliable? Day after day, month after month in same conditions as an ICE vehicle?
• Able to operate ancillary equipment e.g. LPR?
• Does it have the same productivity?
• Which vehicles can be an EV?
  • Equipment where waste energy can be easily recovered and converted to stored electrical energy is good.
  • An SUV has considerable kinetic energy that can be recovered and stored in a battery and is a good choice
  • A bulldozer or grader does not have readily available convertible energy hence bad choice
• Bottom line: can we simply replace an ICE vehicle with an EV?

An Engineering Assessment

In our analysis, we looked most closely at the very popular and reasonably priced Nissan Leaf, as there was more data to work with, the price range attractive to cities and its similarity to the Chevrolet Bolt, a domestic EV that some of our clients have bought.

The Nissan Leaf and the Chevrolet Bolt driving range fall in the middle of the pack as the table shows.

EPA driving range is a mix of highway and city driving at a temperature of 25 C, a temperature admirably suited for southern California. Alas, Saskatoon, most of Canada and the northern American states do not enjoy such a mild climate for a sizeable part of the year, hence we need to look at the impact of cold weather.

Impact of Cold on Battery Performance and Energy Consumption

Cold temperatures bring energy sapping challenges such as:

• Snow covered roads significantly increase rolling resistance
• Rolling resistance increases as grease and oil become stiffer
• More equipment is used such as:
  • Head lamps and running lights
  • Windshield defroster (heat and fan)
  • Air conditioner (for drying the air and defrosting)
  • Seat heater
  • Cabin heater
  • Rear window heater/defroster
  • Windshield wipers (front and rear windows)
  • Windshield fluid pump
  • Vehicle emergency lighting platform

The cumulative impact of these energy demands significantly diminishes rated range of gasoline or electric powered vehicles. However, a tank of gas will retain its energy capacity, i.e. it is not diminished by the cold. Batteries, on the other hand, do not fare as well. Their energy capacity is significantly reduced by cold temperatures.

Lithium-Ion batteries demonstrate these characteristics:

• Full charge typically rated at 25 C
• As temperature drops both voltage and amp hour capacity decline so total stored energy declines significantly
• Stored energy at -40 C in battery is roughly 65% of that at 25 C
• Results in one-third loss of operation time and/or distance
• The pictured graph is a Panasonic Li-ion battery which is similar to that in a Tesla or Nissan Leaf

The following table shows the power consumed to propel a vehicle at 40 km/h and the load of typically used auxiliary equipment. The target vehicle is a Nissan Leaf which has a standard 40 kilowatt hour (kWh) Lithium Ion battery pack and an optional 60 kWh battery. In this analysis, the 60 kWh battery is used (216 mega-joules).

Notes:

1. Defrost (and hence air conditioner) on intermittently (20%)
2. Vehicle driven with defrost always on, hence AC continuously on (i.e. 100%)
3. Battery capacity (60 kWh @25C) degrades about 30% at -30 C to 42 kWh
4. Typical power consumed to move a vehicle at 40 km/h on a smooth dry road
5. Power in watts (W)
6. Battery capacity is in kilowatt hours (kWh)
7. Approximate and to the closest half hour or 50 km

Observations:

• In theory, driving the Leaf at a steady 40 km/h on a smooth flat paved dry road with no wind and a temperature of 25 C should see it go very far, close to 600 km.
• In practice, it all depends on the equipment being used (e.g. air conditioning), wind conditions, traffic and terrain
• Cold weather performance drops the distance and time by about 50%
• Running defrost continually will drop it further to about 30% of ideal range
• Snow greatly increases rolling resistance, decreasing range even more
• autoChalk (an LPR system) consumes 100 watts on average, which is about 1 to 2% of the total energy consumed by the Leaf at 40 km/h hence has little impact on the vehicle’s battery life.
• Hence it seems the likelihood of an electric vehicle running all day is slim, and more likely to be about half of one day. For example ensuring about 20% battery capacity is left at the end of the use of the vehicle (to avoid getting stranded) would reduce 5 hour operation time to 4 hours.

Moreover there are operational problems with the Leaf at cold temperatures:

• the vehicle cannot be charged if the temperature is -20 C or colder
• the vehicle is not recommended to be stored outside at temperatures of -25 C as the Lithium-ion battery can freeze and malfunction

Here’s an example from the Nissan user’s manual:

Other reputable organizations tested electric vehicle range in cold weather and include Consumer Reports and the American Automotive Association. Their winter testing and the degradation was similar to the predicted impact that we had calculated, for example at minus 20 C all vehicles’ range dropped to about 50% of that measured at 25 C.

A Brief Look at the Power Grid for a Fleet of Electric Vehicles

The City of Saskatoon has 170 buses. Batteries range from 300 kWh to 500 kWh. Let’s pick 400 kWh. Let’s suppose the buses are recharged between midnight and 6 am.

Hence the total capacity of all buses is 170 * 400 kWh or about 68,000 kWh.

Since the batteries take 6 hours to charge, the average charging per hour is about 11,000 kWh. At 240 volts that’s a current of 47,000 amps which is the equivalent of 470 homes (100 amp service). Explore the electrical demands with your electric utility.

Saskatoon’s Experience with Chevrolet Bolts

Fill it up with electrons please!

Saskatoon “The Winter City”

Saskatoon is a City of extremes and winters are long and cold:

• Winter weather is typically 5C to -30C
• 4 months a year with visible snow
• Mid-winter snow averages 20 cm
• Coldest in 2024 was -39.5C, windchill -53C
• Average coldest temperature since 1893 is -39.6C²
• Average in last 5 years -39.4 C

² Source ExtremeWeatherWatch.com

Notice cold extremes have continued to occur despite climate change and have remained quite similar for the last 130 years.
The city must work with actual data and plan around this reality.

A reality check in 2024:

• City experienced two major snowstorms
• Record breaking snowfall (~40 cm in 24 hours) & high winds
• City-wide “snow day” declared with civic services shut down.
• Chev Bolt charging stations
• No palm trees here!

Here’s a summary of Saskatoon’s winter experience with Chevrolet Bolts:

• Depleted battery reduced range (down ~20 to 30%)
• Constantly getting stuck in snow
• Cabin temperature was hard to heat
• Battery recall forced outdoor parking
• Charging station issues and long recharge times reduce vehicle availability
• This means one ICE vehicle may have to be replaced by two or even three EVs
• This fiscal reality raises difficult questions
• The quantity of the charging may strain the grid and require very expensive upgrades

However, it was not all bad. During the warmer months the Bolts performed well:

• Excellent range & mileage
• Positive reduction in overall fuel costs
• Reduction in overall corporate GHG emissions

Reviewing the ICE/EV Scorecard

Let’s review again what should be expected from an ICE or EV vehicle?

Regrettably the No list is pretty long. Perhaps this is why EV’s are getting a frosty reception in Saskatoon:

• Only 100 Battery EV’s registered in Saskatchewan
• City of Saskatoon built 4 free public charging stations
• Collectively used only 3 times a day
• Tepid interest has raised considerable debate
• Some public questioning expense
• Does the city lead or follow public adoption?

Ideas for Piloting EV’s and alternatives

Here are ideas to begin piloting EV’s.

• Pilot EVs with demands that are not critical
  • equipment that will not be missed if not working
  • e.g. SUVs used for staff
• Mission critical transport not advisable
  • Police, ambulance, fire
  • Snowplows, service vehicles (e.g. grid support)

Explore pragmatic alternatives such as hybrids. For instance, the Toyota Rav4 plug-in
EV provides electric-only range of about 60 km (likely 40 km in deep freeze season).

Other advantages of hybrids:

• Hybrids & Plug hybrid alternatives can run all day
• Significantly reduce carbon fuel consumption for short haul trips
• Work reliably in bitter cold
• Makes a big step to carbon reduction
• A reliable solution for cold climates
• Does not need huge electrical infrastructure changes

In conclusion, EVs have a future in cold climates, but cities need to pick and choose the most appropriate solutions that meet their reliability, resiliency and performance goals.

About the authors:

Bill Franklin, P.Eng. President, Tannery Creek Systems, bfranklin@tannerycreeksystems.com

Wayne Sum, MBA, City of Saskatoon, wayne.Sum@saskatoon.ca