EV Charging FAQs: What You Need to Know to Charge Your Electric Car

As the electric vehicle (EV) market expands, new information continues to roll in. This can overwhelm potential yet unfamiliar buyers. If you're thinking about purchasing an EV, the how, when, and where of charging your vehicle might be confusing.

This guide will answer some of the most common questions about charging an electric vehicle, including how it's done, the differences between charging at home and at a public charging station, what to do in a power outage, and more.

The Basics

How does electric vehicle charging work?

An electric vehicle motor runs on AC electricity, the same alternating current that comes into your home. Like a laptop or phone, however, the electricity stored in the battery is direct current (DC), so between the car's battery and the motor is an inverter that converts DC electricity to AC.

The inverse happens when you charge your EV. Just as the charger for your phone or laptop has a little brick that converts AC to DC, there's an inverter between your AC outlet and the car that converts the electricity to DC.

How often do I need to charge an EV?

How often you charge your electric car depends on the battery size of the vehicle, how energy-efficient your vehicle is, and, of course, your driving habits.

Recent electric vehicles have ranges of more than 400 miles, with batteries that can store from 50 to 200 or more kilowatt-hours (kWh). EVs get, on average, two to six miles per kWh, so a 50 kWh battery has a range of somewhere between 100 and 300 miles, depending on how efficient the car is at using energy. (As in a gasoline vehicle, how efficient your EV is depends on your driving habits.)

Do I have to charge my EV 100% every time?

No. EV manufacturers recommend you keep your battery charged between 20% and 80% of charge, which extends the lifetime of the battery. Only charge your battery up to 100% when you plan on going on a long trip.

It's also recommended that you leave your vehicle plugged in if you're going away for an extended period of time.

Charging at Home

How long does it take to charge an EV at home?

Charging using a standard 120-volt outlet will give your battery about five miles of range per hour. That would mean charging for at least six hours daily if you commute 30 miles per day. Considering this, most EV drivers charge their vehicles overnight at home, while they're sleeping. Note that charging speeds are slower in cold weather.

Should I install a high-speed charger at home?

Many EV owners get by with just a standard household 120-volt outlet. Even if a Level 1 “trickle charge” takes seven to 10 hours to fully recharge your vehicle, it can be ready for you in the morning.

A Level 2 charging station might be convenient if you need a quicker charge because you drive more miles on a daily basis. The purchase and installation of a Level 2 charger can cost $1,000 or more. If the need for fast charging is infrequent, it may be less expensive to use a high-speed public charging station for the few times you need it.

Can I power my home off of my EV's battery?

An electric vehicle is itself a large battery backup, and recent innovations in EV technology allow you to supply power to your home in an emergency. Not every EV is capable of vehicle-to-home charging, however.

Public Charging

Where can I find a public charging station?

If you don't have access to a home charger or you're traveling, you will have to rely on public charging stations around the country. Tesla has the widest network of charging stations, but all other electric vehicles can be charged at every other network's charging stations.

There are a number of apps to help you find the nearest charging stations or map out a longer journey. PlugShare, A Better Route Planner, Google Maps, and AAA's mobile app all have extensive, frequently updated EV charging station maps.

How long does it take to charge at a public charging station?

Public EV charging stations with Level 3 chargers (also known as a DC Fast Charger) can sometimes charge an electric vehicle fully in as few as 30 minutes, depending on the car. Either way, it takes longer than it does to refuel a gas tank. The good news is that you don't always need to refuel your EV to 100%. Many EV drivers refuel at public charging stations only enough to get them to their destination if they have the ability to charge overnight at home or at a hotel.

Home charging is far cheaper than public charging anyway, and many accommodations offer free EV charging, so it's worth waiting to fully charge until you get there.

Can I charge my EV at any public charging station?

Unlike gas stations, there is no universal charging port shared by all electric vehicles and all charging stations. Every EV has a J1772 port, which is good for Level 1 and Level 2 charging speeds. Most but not all charging stations have J1772 chargers.

Not all stations will have high-speed, Level 3 charging. For Level 3 charging, there are two types of connectors, CHAdeMo and CCS, which are incompatible with each other. Most EVs have multiple charging ports, so it's likely that you'll be able to plug something in.

There are also a variety of networks of public charging stations. To use their charging services, you are required to either have a RFID card or an app installed on your phone that's tied to your credit card. See what charging networks are in your area, and sign up for their (usually free) membership.

Miscellaneous

Is it cheaper to charge an EV than to fuel a gasoline car?

Even if you only charge at the more expensive DC fast chargers, electricity is always cheaper than gasoline. And it's also cleaner nearly everywhere.

The cheapest place to charge your vehicle is at businesses or workplaces that offer free charging. Second to that is charging at home, where electricity on average costs $0.14/kWh. Over the course of the car's lifetime, the cost savings can make owning an EV cheaper than a gas-powered car, even if the purchase price is significantly higher.

What happens if my battery runs out of charge?

Most electric vehicles will give you a warning when your battery is running low, and their navigation system can identify the nearest charging stations. When your charge gets dangerously low, your EV is likely to shift into economy mode. This reduces the maximum speed you can drive and sets regenerative braking to its highest level.

When your EV's display says your battery is down to zero, it's not really down to no electrons. It's down to zero usable battery capacity. Your EV's battery management system maintains a reserve supply of electrons to protect the battery from degradation.

In short, if you've never run out of gas, you're not likely to run out of electricity either.

Can I charge my car while the power's out?

If you are expecting extreme weather that might threaten your power supply, it's a good idea to fully charge your vehicle beforehand. That should give you two or three days of electricity to run your vehicle. For longer outages, you may have to drive some distance to find a public charging station that still has power. Charging your EV with solar panels on your roof, especially with a battery backup, will also help you weather any outage.