Only a few years ago, it would be rare for me to see a plug-in electric vehicle (EV) on the streets of Durham, North Carolina. Yesterday, I saw 12 on the 10-minute drive to my child's school. That's a good thing in terms of climate and air quality. But as electric cars become more popular, we will have to navigate some new and occasionally challenging questions around electric vehicle etiquette. Below are some examples, along with my own suggestions for how to handle them.

Is it OK to leave your car plugged in after it's charged?

Nissan Leaf It can take several hours to go from empty to full with electric vehicles, which sometimes leads to a fully charged car occupying a spot while someone else has to wait. (Photo: Puget Sound Energy/flickr)

Electric vehicle charging isn't like filling up at the gas station. Even on a Level 2 charger, it can take several hours to go from empty to full. So folks (quite reasonably) leave their car plugged in and head out to do whatever it is that they need to do. This sometimes leads to a problem: A fully charged car using up a spot while someone else waits to charge.

Sami's answer: Among most electric vehicle owners I speak to, the consensus appears to be that you should unplug and move on as soon as your charge is complete. EV charge points shouldn't be treated as "priority parking spots," and staying plugged in deprives someone else of a charge.

At risk of upsetting some folks, however, I'd like to suggest there's some ambiguity here — if you're heading to a movie or an important meeting, for example, is it really reasonable to expect someone to step out halfway through to unplug? My opinion — which admittedly is shaped by living in a community with a fairly large number of chargers that often sit idle — is that folks should move their vehicle as soon as practically possible after their charge is done. Consider leaving your phone number on your dashboard so someone can reach you should they need a charge more urgently.

Of course, the case is entirely different for fast chargers or Tesla's superchargers — which are intended for long-distance travel and emergency top-ups. Hogging these facilities does feel like an imposition on drivers who may need them more.

Is it OK to use a public charger to top up a battery?

Alongside the spread of electric vehicles, EV charging points have been popping up in many cities, too. For some drivers, they are seen as a nice perk — especially if charging is free. For others, they are a use-in-case-of-emergency lifeline if you find yourself stranded. So is it OK to top up your battery when you don't really need to, or should you save the spot for someone who finds themselves in trouble?

Sami's answer: EV charging stations are there to be used. If we save them only for times of emergency, I suspect we may soon see them begin to disappear as other drivers question their utility. That said, some drivers suggest not taking the last available spot if you're just getting a little top up — or at least leaving your phone number on your dashboard.

Should plug-in hybrids use public chargers?

Electric cars charging As public charging infrastructure gets built, operators would do well to clarify usage rules and to build in communications technology to ease social tensions. (Photo: Scharfsinn/Shutterstock)

Because plug-in hybrids have a gas engine to fall back on, some EV owners have argued that they shouldn't take up public charging spots when pure battery electric vehicles may need them more. Others argue, however, that we all benefit from plug-ins using less gas so, as long as they don't hog the infrastructure, they should feel free to use it.

Sami's answer: I've previously expressed skepticism at the idea that chargers are for pure battery electrics only. After all, they are public infrastructure — often paid for with our tax dollars. And when a plug-in hybrid uses a public charge point, that driver is helping us all breathe easier by reducing gas consumption. That said, if there's high demand for a particular charge point — for example, if there's a "drive electric" rally going on — folks might want to give priority to pure electric vehicles. And again, leaving your number on your dashboard can't hurt, in case someone needs you to unplug.

The other solution, of course, would be for charge point owners to specify the rules: If some charge points are intended for emergency use only, then they should be left free for those who really need them.

Is it OK to plug into a charger without asking the owner?

Back in 2013, a Georgia man was arrested when he plugged into a local school's outlet. He had not, apparently, asked permission from the school, so he was technically stealing power that was intended for other purposes.

Sami's answer: You should ask permission before plugging into someone else's power supply. That said, the same would be true if you were charging your cellphone or laptop — neither of which would get you arrested. And while I agree that you should ask before plugging in, I get more upset at the idea of taxpayer dollars being used to prosecute folks for such a tiny infringement. Much better to spend that money on educating people about proper etiquette or (gasp!) installing some public charge points and helping clean up our air.

Is it OK to park a gas car in an electric-only spot?

Electric vehicle parking spot Electric vehicle-only parking spots are usually located in prime real estate, such as at the front parking lots or close to store entrances. (Photo: J.D.S/Shutterstock)

In many parking lots, electric vehicle charging is located in prime locations — close to the parking lot entrance. That leads some Internal Combustion Engine (ICE) drivers to be tempted to pull into a spot, especially if they rarely see it in use. Is this OK?

Sami's answer: No. Just no. This is something we can all agree on. If a spot is reserved for electric vehicles, then you shouldn't take it up with your non-electric vehicle. It's as simple as that. For similar reasons, you should never take up an electric-only parking spot if you have no intention of charging. That's just rude.

Is it OK to charge at peak times?

Tesla Model 3 As long-range vehicles like the Tesla Model 3 become more commonplace, demand for chargers will change. (Photo: Tesla Motors)

While the fear of imminent disruption has largely been overblown, electric vehicles will put a larger strain on our grid as they become more popular. That's why many electric vehicles have an option to charge on a timer — displacing your charge until times of low demand. Should you feel obligated to use it?

Sami's answer: Like many of these questions, I think it's a problem best viewed through the lens of system design — not individual responsibility. If charging during peak hours is becoming a problem, then utilities should use pricing mechanisms or other incentives to move demand elsewhere. That said, I do use the charge timer on my used Nissan Leaf whenever it's practical to do so, even though I don't benefit from off-peak pricing. Do what you can. Don't sweat it too much. At some point, we'll have to solve such issues as a society.

Is it OK to drive below the speed limit to maintain a charge?

This one isn't related to charging, but it drives my wife crazy. I have a habit of driving at 60 miles per hour on the highway because I hate to waste my charge. (To be fair, I often drive 60 mph in our gas car, too, for the very same reason.) I've occasionally been tailgated by irate drivers who clearly feel I am in their way. So what's the socially acceptable practice?

Sami's answer: Speed limits are posted as a "maximum" safe speed, and it is perfectly legal to drive 10 or 15 mph below the speed limit as long as you are not impeding traffic. You just need to use common sense. If your dawdling is creating dangerous situations, then you probably need to speed up. I would also argue, however, that other drivers are usually going too fast. Just watch what happened when a group of students decided to drive at the speed limit a few years ago:

Ultimately, as with so many things, the answer to these questions will get clearer over time. In the same way that many of us are learning to navigate cellphone etiquette at dinner, for example, we'll figure this out together. As electric vehicles get more commonplace, as charging infrastructure gets built out, and as charge point owners get clearer about their policies, I suspect we'll start to see a more nuanced approach to what is, and what is not, socially acceptable. And we'll also find drivers putting pressure on decision makers to build the types of charge points that we actually need.

What if malls, cinemas or offices, for example, had some chargers dedicated to longer-term charging — where an immediate unplugging would not be necessary — and other chargers reserved for an emergency charge only? What if charge points incorporated communication technology like many restaurants do when you're waiting for a table — allowing waiting drivers to ping owners and ask them to unplug?

Of course as 2,300-mile-range electric vehicles start becoming more commonplace, and as semi- or fully-autonomous cars start rolling out, we may find technical solutions to some of the thornier problems. After all, if my car can drop me off at work and go charge by itself, it would eliminate the need for me to sit waiting for a charge point to open up.