XXII.5 September-October 2015
Page: 22
Digital Citation

Ending charge anxiety

Jonathan Bean

back to top 

Who would think that electric vehicle charging stations—relatively simple technology compared with, say, facial recognition—could be so hard to use?

It's not the interface on the device itself; that part is fairly simple. Tap a card, insert a plug, walk away. The problem lies in how the chargers are used. Often the problem is attributed to "range anxiety," which refers to the fear that an undercharged or insufficiently capacious electric car battery will strand its driver. From this perspective, one can understand why drivers of electric vehicles, and especially plug-in hybrid electric vehicles (PHEVs), which typically have limited all-electric range, plug in at every chance they get. But these PHEVs also have small batteries compared with, say, a Nissan Leaf or a Tesla Model S, which means they charge in less time. The result is that a lot of PHEVs spend time parked at chargers that they aren't actively using.

So far, the solution has been to attempt to change the behavior of PHEV owners. In 2012, Ford issued a cutesy guide to EV etiquette [1]. Among the suggestions for owners of PHEVs: When the battery is full, move your car to another spot. Sounds great, and framing this desired behavior as good manners was a sound strategic move, given the largely upper-middle-class, environmentally conscious buyers of PHEVs, including the author of this column, who imagines himself to be fairly considerate. So let's walk through the reality: You drive 15 miles to work at a professional job. Upon arrival your car has five miles of range left, so you need to charge if you're going to get home on electricity. You plug in, walk 10 minutes to your desk, and get started on a project. In about two hours you get a text message saying your car's battery is full. It's 11 AM. You've just gotten immersed in the flow of the workday. You have a meeting in a few minutes. You'll have lunch at your desk in about an hour. Do you leave your desk for 20 to 30 minutes to walk back to your car, unplug, and find another parking spot? The stragglers have arrived and the parking lot is jammed, so it's no easy task. Or do you leave your car in the spot until lunch, or even until the end of the day?

PHEVs hog charging stations, but not because of range anxiety or lack of consideration for others. There are at least four interconnected reasons:

  • The car is linked to freedom and identity. The very idea of automobility, especially in American culture, is inextricably linked with the removal of restriction. Furthermore, many PHEV owners derive a special sense of satisfaction in operating their vehicles on electric power as often as possible. Ford has recognized and encouraged this feeling of accomplishment through the design of the user interface in its plug-in cars, which reports the total electric and gasoline energy consumed after every trip. If you don't plug in, you negate the reason you bought a PHEV.
  • PHEV batteries aren't big enough to handle an average day's driving. Most plug-in cars can't travel 25 miles—the average number of miles driven per capita in the U.S. in 2014—before the electric battery gives up and the gasoline engine kicks on. The Prius Plug-In can go up to 11 miles on a charge; the Ford C-Max Energi can go 21. Even the champ, the current model of the Chevrolet Volt, can go only 38 miles under ideal conditions before its battery is depleted and it starts to burn gasoline. These figures can fall by as much as half in cold weather, when the battery does not operate efficiently and the climate-control system slurps energy to warm the cabin.
  • Chargers are not placed by the people who use them. Chargers are often placed in visually prominent locations, but they end up in places that are not always the most convenient. Say you're going to the mall: In a regular car, you'd scope out the spot closest to your destination. If you want to plug in your car, however, you're stuck parking wherever the charger is, even if that means a 15-minute walk. Because vehicle chargers are underused in some areas, but often placed close to building entry points, they are sometimes occupied by cars left by drivers thinking they're not likely to inconvenience anyone else.
  • Plug-in cars take different amounts of time to charge, depending on the charger, model of car, and level of battery depletion. Furthermore, because the range estimate is dependent on the weather, it's hard to judge how much charge is really needed. If a battery is 25 percent depleted from the outbound leg of your journey, it may take significantly more energy to get back home, especially if you're heading uphill or if there's a cold snap.

The result of these four factors is manifest in charging-station use that is perfectly logical at the individual level. PHEV owners like to charge their cars to full capacity as often as possible. When lots of people are trying to do this, it creates problems: too many cars, not enough chargers. More specifically, there are too many cars with full batteries parked at chargers that could otherwise be used to charge other cars. Think charging for the time, electricity, or both will solve this problem? It just makes it worse, because paying for a service makes one feel entitled to use what's being paid for. Of course, the most surefire solution would be to increase the number of chargers. But this is difficult because curbside EV chargers cost money—$5,000 to $10,000 each—and installation is no trivial task.


So if a plugged-in car isn't going to be moved, then another solution is for others to know that it's okay to unplug it. To solve this problem, one can buy smartly designed Take Charge and Go hangers for the charge plug that are similar in principle to a Do Not Disturb hangtag for a hotel-room door. The hangers clearly identify the time a car will move from necessity to opportunity charging. The idea is that if another EV driver knows that you are merely opportunity charging, then it's okay to unplug your car. Sounds great, but even this seemingly simple solution requires additional parking spots adjacent to the charger and either a new or modified charging station. Attaching multiple cords to a single station and moving the station to the middle of parking lots, where it could serve more spots, would also help increase accessibility, but this solution raises liability concerns about trip hazards compared with a location against a wall, where people are unlikely to walk. The second problem is that your conscientious plug-in-driving coworkers are likely to arrive to work at the same time as you; someone will still need to go out to switch the cord from one car to another. Even if this process is automated, who decides which car gets to be charged first?

Rather than trying to change user behavior—always an uphill battle—we might look to airports. Ten years ago, it was a challenge to find a place to plug in a laptop computer or phone charger, but that's changed; there is now a proliferation of outlets and USB ports. This was a market-led shift resulting from consumer demand, catalyzed perhaps by the threat of liability should someone trip on a power cord snaking across the gate area. But if electric cars are going to offer the same level of freedom and unfettered movement that gasoline-powered cars do now, government incentives currently aimed at encouraging consumers to buy electric cars might be better spent on changing the built environment so that it's as easy to charge an electric car as it is to fill it up with gasoline.

back to top  References


back to top  Author

Jonathan Bean is an assistant professor of markets, innovation, and design at Bucknell University. His research deals with domestic consumption, technology, and taste.

back to top 

Copyright held by author

The Digital Library is published by the Association for Computing Machinery. Copyright © 2015 ACM, Inc.

Post Comment

No Comments Found