The geography of EV charging: How regional climates impact charging and driving behavior

Published on January 6, 2021

Introduction

It is commonly understood that temperature, particularly the cold, impacts electric vehicles. More energy is used to maintain a comfortable cabin temperature and there are various forms of built-in battery conditioning. This results in reduced range for the vehicles in colder climates. However, studies have shown that higher temperatures also impact the range of an EV for the same reason maintaining comfortable temperatures, but in this case the energy is used for cooling.

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Why is temperature important for those managing EV charging load?

Utilities can benefit from knowing how temperature-related impacts to the range fundamentally alter the charging and driving behavior of the EV owner. It can influence when they charge, how often they charge and the overall distance they drive.

Utilities should take their service territories’ climates into consideration when establishing a load management program, to help account for the impact of temperature.

There are multiple factors to consider when managing an EV charging load regardless of location, including: commuting patterns, vehicle market share and existing EV charging infrastructure. However, what this report will show is that understanding how climate and temperature influence driver behavior plays an important role in creating an effective strategy for managing EV charging load.

“Utilities can benefit from knowing how temperature-related impacts to range fundamentally change the charging and driving behavior of the EV owner.”

Further analysis from the world’s largest electric vehicle dataset

The groundbreaking data-driven study titled EV Growing Pains was released in May 2020. This was one of the largest studies of EV charging load ever conducted and included an analysis of data from over 3,900 electric vehicles from across North America. This report is based on the same dataset and further examines real-world data in order to showcase the role that temperature and seasonal climate play in influencing charging and driving behavior.

The original dataset, which contained a full year’s worth of information (from 1 January through 31 December 2019), has been broken down to reflect the summer and winter months in North America. The vehicles have also been sorted by geographic location into a group representing the North and the South. It includes 40 EV makes and models, as well as home and away charging from various EV charging stations.

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The impact of temperature and climate on EV range and battery health

Before examining the changes in driving and charging behavior, it is important to understand the impact temperature and climate have on the electric vehicle itself. Geotab has created two online tools that allow users to calculate the implications to an EV’s range and battery state-of-health. With both of these tools, temperature plays a significant role.

Summary of findings:

  • The data shows that on average EVs will maximize their range, exceeding their rated range, when operating in 70°F (21°C) weather.
  • As external temperature either increases or decreases the overall range is reduced.
  • Maintaining a comfortable temperature for the occupants and for the battery accounts for the majority of this loss of range.

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Figure 2. Real-world versus rated EV range.

Another factor that will impact an EVs range is its battery’s state-of-health (SOH) or how much the battery has degraded. Like all batteries, an EV will start to lose its ability to hold a charge over time. Their tool shows that prolonged exposure to high temperatures will accelerate the rate of degradation.

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Figure 3. Battery state-of-health (%) versus time (months) for varying climates.

Why is this information important to utilities?

Firstly, it is important for customers. Potential EV owners are looking for more education about electric vehicles, particularly their range and what it means. Someone who lives in a colder climate may be deterred from buying an EV when they see that in the winter the range of their vehicle could be cut in half. The reality is that even at 50% of the range of today’s most popular vehicles, long-range battery electric vehicles (BEV), far exceeds their average daily driving distance. Utilities looking to grow EV adoption in their service territory can help their customers overcome these types of objections through awareness campaigns.

Secondly, a vehicle's range will ultimately shape the owner’s charging behavior. Do they charge every day? Is this behavior different when the seasons change? How does the average driving distance change and when are drivers more likely to use public charging infrastructure? All of these questions need to be examined to adequately plan for infrastructure needs and to create an effective EV load management program.

“Utilities looking to grow EV adoption in their service territory need to know how to help their customers overcome these types of objections.”

Average daily driving distances by region and by season

In general, EVs are driven less during the winter months than in the summer, and this was true for both the North and South group. EVs in the southern group drove more on average in both respective months. However the difference between the seasons is less extreme than with the northern group.

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Figure 4. Average daily driving distance (total miles) for all vehicle types by season.

When reviewing driving data, it is important to note that it includes plug-in hybrid electric vehicles (PHEV), which operate on gasoline as well as electricity. In fact, during this study it was shown that approximately 60% of the miles driven by PHEVs were powered by electricity and this number drops to only 56% in northern-regions during winter.

Looking at electric-only miles reveals an average distance drop in daily driving for all vehicle types. That being said, PHEVs are declining in popularity. In 2019, PHEVs accounted for 26% of all new EV sales, down from 46% in 2014.

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Figure 5. Average daily driving distance (electric miles) for all vehicle types by season.

The fastest growing vehicle type is the long-range BEV, which made up 66% of new EVs sold in 2019. These electric vehicles not only have a larger impact on the grid, due to their larger battery capacities and higher power draws, but they are also driven more. When looked at on their own, long-range BEVs are driven more than the overall averages in both seasons and vehicle groups.

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Figure 6. Average daily driving distance (long-range BEV electric miles) for all vehicle types by season.

Overall, this data reveals that not only do daily driving patterns vary from one area to another, but that they may differ throughout the year depending on the seasonal temperature. Another consideration is that both of these groups consist of multiple service territories and averaged data. A territory that is predominantly suburban will typically have longer daily commutes than those in urban or rural areas. In order to accurately forecast driving distances territory-specific data should be used.

“Overall, this data reveals that not only do daily driving patterns vary from one area to another, but that they may differ throughout the year depending on the seasonal temperature.”

More miles doesn’t necessarily mean more energy (kWh)

One of the more interesting discoveries during this study was that the vehicle group that drove the most miles did not use the most charging energy. Although the North group drove the fewest miles in the winter, they used the most energy per vehicle.

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Figure 7 and 8. Average monthly charging energy (all vehicle types versus long-range BEVs).

Both groups drew more energy in the winter months compared to the summer, with the North group experiencing the most drastic increase. This is a result of more energy being required to keep the cabin at a comfortable temperature. This fact is less pronounced for long-range BEVs, where the seasonal difference in energy use was not as drastic between the North and South groups. Per-vehicle averages for BEVs are higher overall. This appears to be the result of PHEVs relying more on gasoline during the colder winter.

So while it is important to understand how far an EV travels in a territory, it is only one of the factors that will contribute to its charging load. As temperature changes, so does the amount of energy being used.

“Although the North group in the winter drove the fewest miles, they used the most energy per vehicle.”

Region, season and vehicle type will determine an EV’s charging pattern

One of the main lessons from the EV Growing Pains study was that long-range BEVs are gamechangers for utilities. Their larger battery capacities allow them to charge less frequently while still meeting their daily driving needs. This was proven again in this study as EVs on average did not charge every day regardless of season or location. However, EVs in the North were charged less frequently than those in the South.

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Figure 9. Average vehicle charge sessions by season (North and South regions).

It is unclear exactly why there is less frequent charging in the North. One theory is that there was an earlier adoption of EVs in the South, as a result of the limited range of earlier EVs and the range reduction caused by cold weather. This would mean that those in the South were conditioned to charge every day, which has carried over even though their capabilities have changed. While this is purely speculative, it is worth noting that even when you compare the charging frequency by individual vehicle type the results are the same – the Southern group charges more often.

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Figure 10. Comparison of average charge sessions for all vehicle types.

The frequency of charging in all three vehicle groups is higher during the winter, with more significant differences in the North. The data also shows that long-range BEVs are the only vehicles that consistently do not charge every day. In fact, in both regions short-range BEVs and PHEVs tend to charge more than once per day, which makes sense given their small battery capacity.

On average, EVs spent roughly three to four hours charging per session. The length of charging sessions were shorter in the South, which would align with the fact that they charge more frequently.

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Figure 11. Average number of hours charging per session by season and region.

Unlike other forms of residential load, such as air conditioning, EV charging is much less predictable. Not only does every vehicle behave differently, every driver has their own set of unique circumstances that will define how they charge.

“Unlike other forms of residential load, such as air conditioning, EV charging is much less predictable.”

Regardless of where home is, it is still the most desirable place for drivers to charge

Regardless of season or region, the majority of EV charging occurs at home. However, multiple Geotab Energy studies have shown the percentage to be less than the often quoted 80%. This study showed that when reviewing charging by energy use, roughly 70% of charging occurred at home, with Level 2 charging accounting for the majority.

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In both regions, direct-current fast charger (DCFC) usage increased during the summer months, while home Level 2 charging decreased and Level 1 charging remained the same. This would indicate that it is most likely the result of drivers traveling and not having access to their Level 2 home charger.

Figure 12. Comparison of home versus away charging levels by season.
When reviewing the charging data by number of sessions you see additional differences between the North and South groups. In general, there is a higher level of at home charging, closer to the standard 80%. However, in the North there is a much higher percentage of Level 1 charging in winter and double the amount of DCFC charging in the summer.

Both of these are indications that charging behavior is affected by differences in seasonal temperature. In the cold winter, drivers are more inclined to use home chargers, even if they don’t have a Level 2 charger, to ensure they have the range they require. In the warmer summer months, drivers are more likely to travel out of town for vacationing, which makes them more likely to use DCFC.

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Figure 13. Comparison of home versus away charging sessions by season.

Although it is important for utilities to ensure there are enough public charging stations in their territory, for those without access to home charging or for drivers who are from out of town, residential infrastructure should still take precedence. Regardless of where the home is, it is still the most desirable place for drivers to charge.

“In the cold winter drivers are more inclined to use home chargers, even if they don’t have a Level 2 charger, to ensure they have the range they require.”

The impact of vehicle type on charging power

When looking at the per vehicle average power per charging session there was little difference between the North and South regions. Both groups had a slightly lower average power in the winter months, but as a whole they stayed the same with an average of roughly 9 kW in the winter and 11 kW in the summer.

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Figure 14 and 15. Average power per session with and without direct-current fast charger (DCFC) usage.

Average power includes DCFC, which charges at a higher power. When DCFC charge sessions are removed, the average for all regions is between 5 and 6 kW. This further illustrates that DCFC plays a larger role in the summer months, most likely the result of people traveling away from home.

The most significant factor when reviewing the average power per vehicle relies more on the type of EV. Long-range BEVs charge at a significantly higher power, roughly three times as high as short-range BEVs and up to six times as high as PHEVs.

As well, while the average power for the short-range BEVs and PHEVs stayed relatively the same for both seasons, there was more of a difference in the long-range BEVs. Lastly, when you remove DCFC, long-range BEVs are the only vehicle group where the average power changes, meaning these charging stations are rarely being used by short-range BEVs or PHEVs.

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Figure 16-21. Average power per session by vehicle type.

When it comes to EV charging loads, long-range BEVs are revolutionary. In order to accommodate their larger batteries their charging capabilities have significantly increased. This is also the fastest growing segment of EVs and they are continuing to evolve. With larger vehicles entering the market, including SUVs and pickup trucks, we will continue to see an increase in charging power.

“Long-range BEVs charge at a significantly higher power, roughly 3 times as high as short-range BEVs and up to 6 times as high as a PHEV.”

The differences in peak load

In a comparison of load curves, there is a clear difference in average peak load between the North and South groups. It should be noted that these curves represent the average load over a month, January for winter and July for summer, and that daily peaks may be higher. Also this load is strictly EV charging load and does not include any electricity transmission and distribution (T&D) losses, which could add an average of about 5% to the overall demand.

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Figure 22. Comparison of average load curves (kW) by region and season.

The most significant difference between the North and South group is that the load is spread out differently during the day. The northern group has a peak in the morning, which is a result of the vehicle being preconditioned before the work day with a higher peak during the winter. This earlier peak also appears to result in the evening peak being lower. Southern roads are relatively the same for both seasons, with peaks occurring at the end of the traditional workday.

The ability to shift EV charging load

To showcase the ability to shift EV charging load, vehicles from the North were split in two groups. The first group was being intensified by a Time-of-Use (TOU) rate or reward program, encouraging off-peak charging, and the second group was left unmanaged.

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Figure 23. Comparison of average load curves with and without incentives.

When left unmanaged, peaks appeared leading up to the beginning of the workday, a result of preconditioning, and at the end of the work day for both summer and winter months. In areas where incentives were provided, the load was shifted off-peak to the middle of the night.

The impact that EVs have on the grid is evolving and if left unmanaged they pose a significant risk, particularly to distribution assets. Fortunately the EV charging load can be shifted and when managed properly it becomes an incredibly valuable asset as it can help support clean energy initiatives while boosting profitability.

Conclusion

A key takeaway from this study is that the EV charging load is very nuanced. The vehicles in this report were simply grouped by North or South, and there were significant differences in the averaged data. Each individual service territory is going to have its own unique factors that will influence how EV owners will charge and drive.

Commuting patterns, vehicle-specific market share, and pre-existing load management initiatives, in conjunction with seasonal temperatures, will all contribute to a one-of-a-kind load profile.


About Geotab

Geotab is advancing security, connecting commercial vehicles to the internet and providing web-based analytics to help customers better manage their fleets. Geotab’s open platform and Marketplace, offering hundreds of third-party solution options, allows both small and large businesses to automate operations by integrating vehicle data with their other data assets. As an IoT hub, the in-vehicle device provides additional functionality through IOX Add-Ons. Processing billions of data points a day, Geotab leverages data analytics and machine learning to help customers improve productivity, optimize fleets through the reduction of fuel consumption, enhance driver safety, and achieve strong compliance to regulatory changes. Geotab’s products are represented and sold worldwide through Authorized Geotab Resellers.

To learn more, please visit www.geotab.com and follow us @GEOTAB and on LinkedIn.


© 2021 Geotab Inc.All Rights Reserved.

This white paper is intended to provide information and encourage discussion on topics of interest to the telematics community. Geotab is not providing technical, professional or legal advice through this white paper. While every effort has been made to ensure that the information in this white paper is timely and accurate, errors and omissions may occur, and the information presented here may become out-of-date with the passage of time.

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