Cold Weather Complicates Electric Vehicle Deployment
By Bill Franklin
The Electric Vehicle revolution is everywhere, featured in news headlines, YouTube EV Road reviews, endlessly analyzed in business publications, pursued and promoted by politicians. This amazing sea change after 120 years of the internal combustion engine (ICE) has inspired city councils to mandate fleet services switch to electric. Alas, this is where the rubber hits the road, and reality and reason collide with aspirations.
The City of Saskatoon’s Parking management is a client of our company and approached us to evaluate the feasibility of switching their LPR vehicles to all electric. We already had installed autoChalk LPR on electric vehicles elsewhere and it had minimal impact. But cold temperatures significantly impact battery performance and increase a vehicle’s energy consumption. We were intrigued to join them as part of
Since the internal combustion engine has been around for over a century, engineers and manufacturers have improved both the 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.
What then should be expected of an electric vehicle?
• Operates in temperatures from -50°C to +40°C.
• 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, 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.
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 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.
Examples of EPA1 range at 25°C
All use Lithium-Ion batteries
EPA driving range is rated at 25°C, but Saskatoon and the rest of Canada do not enjoy such a temperate climate for a sizeable part of the year, hence we need to look at the impact of cold weather.
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)
- Seat heater
- Air conditioner (for drying the air and defrosting)
- Cabin heater
- Rear window heater/defroster
- Windshield wipers (front and rear windows)
- Windshield fluid pump
- Light bar
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.
- In theory, driving the Leaf at a steady 40 km/h on a smooth flat paved road with little 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)
- 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 seemed that the likelihood of the electric vehicle running all day was slim, and more likely to be about half of
- 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.
Consumer Reports and the American Automotive Association also performed 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.
Our recommendations to the city were to pilot only one or two units, to get the appropriate charging equipment (e.g., level 2 charger) and to be realistic about their EV expectations.
After considering the above constraints, Saskatoon purchased two Chevrolet Bolts and tested them over the winter months.
The Cold Winter Experience
It would be fair to say that Saskatoon experienced a barrage of EV challenges in the winter:
- The range of the Bolt was abysmal. The Bolt would be operational for about four hours then needed recharging.
- The Bolt would not recharge if the temperature was too cold.
- The charging station has a software component that the Fleet services could monitor and see if the Bolt was fully charged. The city staff would get into the Bolt and it would not start. The charging application indicated the Bolt’s battery was fully charged. The Bolt then sat for days until the problem was resolved.
- The cabin did not warm sufficiently when it was very cold.
- It often got stuck in the snow.
- It hampered the productivity of the city staff.
Chevrolet Bolt at charging station
EV Infrastructure Impact
In addition to winter challenges, electric vehicles also have demanding infrastructure upgrades and associated costs for both city and utilities:
- Level 2 charging stations and dedicated parking stalls and potentially rewiring of the electrical feed to the building or even from the local electric utility distribution substation.
- Upgrade in infrastructure requires qualified electricians and contractors to install the equipment and upgrades to the city’s facilities.
- Each level 2 charger needs around 50 amps at 240 volts so if you are deploying 30 electric vehicles and concurrently charging them overnight, the current draw will be considerable at some 1500 amps at 240 volts (360 kwatts).
- This power draw will draw the interest of the local electric utility as it may exceed local capacity. One notes that the cumulative demand for public and private EVs and their charging needs are likely to reach back to the capacity of the province’s power generation stations and the power grid.
- The charging stations will be susceptible to power outages in winter storms.
In summary, our recommendation to cities is to do your research, choose carefully and pick quality. Performing a pilot with a couple of vehicles is prudent as the experience will be useful to gain hands-on experience, shape future acquisitions and influence infrastructure. Forecasting energy needs and discussing power demands with your power utility will facilitate future EV expansion.
Electric Vehicles are definitely the shape of the future. But it seems that when EVs collide with cold temperatures, the future may have to wait. In the meantime, we can identify the obstacles and figure out solutions.
About the author:
Bill Franklin, P.Eng. President, Tannery Creek Systems