At this point, we all know that the future of road transportation — at least in the near term — lies in electric vehicles. In fact, plug-in vehicles are predicted to make up 23% of new passenger vehicle sales globally in 2025, up from just under 10% in 2021, as per Bloomberg NEF’s Electric Vehicle Outlook 2022.
Despite the growing trends and increasingly insistent predictions, though, there are still some major hurdles that need to be cleared before EVs become fully adopted and replace internal combustion engine vehicles. Arguably, the biggest one of these hurdles is electric vehicle routing.
Though it may not initially seem all that different, you’ll see that routing for EVs is far more convoluted than for traditional vehicles, once you get into the details of it. There are a number of complex dynamic factors and mechanics that come into play and interact with each other in various ways to influence EV battery life and performance — and therefore, routing. Let’s take a look at some of them.
1. Charging stations
There’s a plethora of considerations to take heed of with regards to EV charging stations. Most obviously, there’s distribution and coverage — the sheer number of charging stations, where they’re situated and how accessible they are to EV owners across any given region or route.
Then, there’s the matter of charger compatibility, power levels and connector types. For electric cars, most Level 1 (120V) and Level 2 (240V) chargers come with an industry standard connector that can be used interchangeably — though not all. When it comes to Level 3 chargers or DC fast chargers, compatibility can become much more of an issue, as there’s no industry standard at the moment. It’s also worth noting that there are differences between regions; for instance, in North America, the electricity supply is usually one phase or split phase, while in Europe, three-phase electricity is much more common.
One often overlooked detail about EV charging stations in routing algorithms is the availability of various payment methods. Contactless payments, debit or credit cards, mobile apps, websites, registered RFID cards… the options are many, and customers may prefer one over the other, so a user-centric routing software would do well to give the driver this additional filter for charging stations. The software should also get frequent updates on the operational status of charging stations. After all, the last thing you’d want in the middle of a journey is to be stranded at an out-of-service charging station and nothing else within range.
All of this factors into when, where and for how long you need to charge your EV across your trip. And there’s more! We haven’t even scratched the surface of how speed of charging factors into routing decisions, or how certain routing software might promote specific partner charging outlets at the expense of user convenience. EV routing is a complex problem, and it only makes sense that charging stations are at the center of it all.
2. Vehicle and driving characteristics
It’ll come as no surprise that the characteristics of the EV itself and how it’s being driven can have major consequences on battery life and range, and thus on routing.
The weight of the vehicle, and by extension, number of passengers and amount of luggage, are big factors when it comes to routing. Any extra weight is additional load that needs to be carried around, and this takes a heavier toll on the battery. Speed of travel, rate of acceleration, tire quality, air conditioning and traffic conditions also have their own roles to play in battery consumption. Some vehicles come with battery-saving modes and sport modes which further complicate calculations.
As you can see, the variables are numerous. And, of course, these parameters are dynamic — most of them are constantly changing from one drive to the next, or even within a single trip. A comprehensive understanding of these parameters can be used in conjunction with information on road characteristics (discussed below) obtained from map data to get a reasonably accurate estimation of battery consumption and range.
3. Road characteristics
The type of road that you’re driving on comes with its own set of implications for EV battery consumption. Higher quality map data will enable more accurate predictions on EV range and battery consumption.
As you might imagine, it takes more battery power to traverse uphill roads than level ones; the steeper the incline, the more power required. Interestingly, some EVs can actually harness energy while going downhill and use that energy to recharge the battery to some extent. In these cases, the routing software must know the vehicle’s downhill efficiency as well as the gradient of the slope to account for energy recovery and project accurate range information accordingly.
Various road features like sharp turns, junctions, traffic lights and speed bumps, which cause changes in speed and acceleration, must be considered as well, as these are tied to consumption patterns. Road surface conditions and friction also come into play to a degree. Data on speed profiles, current and historical traffic flow patterns, etc. can be harnessed to further improve the accuracy of range predictions.
4. Battery characteristics
EV battery performance can be influenced by a spectrum of factors, from battery age, capacity and temperature to internal resistance, chemical composition and state of charge. All of these have their own effects on how the battery attains, retains and drains charge, and must be accounted for in an accurate EV routing system.
In terms of recharging EV batteries, power tends to be highest when the battery holds no charge, and it gradually drops off as the battery fills up. This means that typically, during the early stages of charging, the battery level rises rather quickly, and the rate of charging slows as it continues.
This adds even further to the complexity of optimal routing for a long-distance journey. As a result of the variance in charging power, the permutations and combinations of feasible charging strategies and sequences on a well-connected route are nearly infinite.
EV batteries don’t hold up well in extreme weather conditions, neither hot nor cold. In particularly cold environments, the vehicle runs a number of auxiliary systems, such as cabin heating, that wouldn’t otherwise be necessary. According to research by AAA, just the use of air conditioning for cabin heating alone can lower EV range by as much as 41%. Depending on its chemical composition, the cold may affect the internal resistance of the battery to varying extents and thus alter its performance. Extreme cold also has the potential to permanently lower maximum battery capacity and worse still, sometimes render the battery broken, unusable and beyond repair.
High temperatures can be just as bad, if not worse, for EV batteries. Again, depending on the battery’s chemical composition, heat can degrade performance to differing degrees. Most dangerously, extreme heat can even set off undesirable chemical reactions within the battery, which can produce gasses that build up and eventually disfigure the battery structure to the point of failure. In the most catastrophic cases, this can result in explosions.
Ignoring the extreme cases where batteries fail completely, EV routing software should, ideally, be able to account for the effects of current and historical ambient temperatures on range and battery life expectancy.
At first glance to the layman, EV routing may not seem like much of a departure from routing for traditional vehicles powered by internal combustion engines — it likely appears largely the same, with the single added complication of calculating which charging stations to stop at and for how long.
While this is true on some level, it is vastly oversimplified, and few appreciate the true complexity and intricacy of EV routing. The list of contributing factors covered in this piece is far from exhaustive; however, it should serve as a good starting point to help understand just how nuanced the EV routing problem is.