How does EV charging work?

On the surface, the question of how EV charging works has a pretty simple answer: you open the charge port on your car and plug the charging connector in. In actuality, there is a whole production going on behind the scenes that sends energy as possible from the charger into your car as quickly and efficiently as possible. But first, let’s hit the basics.

If you’ve never had to plug an electric car in before, doing so for the first time can be a little confusing or even intimidating because you’re dealing with potentially lethal amounts of electricity. The good thing is that EV charging is totally safe, even in the rain, unless you’re dealing with severely damaged equipment.

The first step in charging your EV is figuring out where you will charge your car. The steps are mostly the same whether you’re using a public charging station or the charger that came with your car that plugs into your wall. Public charging can have a few extra choices you need to consider.

Next, you need to know what kind of charging port your car has. This is less complicated than it sounds. If you have a Tesla, you can go to a Tesla charging station and plug right in. If you have another brand of EV, you likely have what’s called a J1772 port, which is broadly standard across US EVs.

If you’re using a DC fast charger, you will probably use the Combined Charging System (CCS) connector. Some Japanese manufacturers like Nissan and Mitsubishi use what’s called the CHAdeMO connector, but it’s pretty easy to see the difference when you look at the plug.

Once you know which plug you have, you need to know where your charge door is on your vehicle so you can park in a way that offers the easiest reach to the charger. Now that you’re parked, open the charge door for your car, and if you’re at a public charger, follow the on-screen instructions for payment.

Now is the big moment. It’s time to plug your car in.

EV charging cables, especially fast chargers, are bulky and heavier than you might expect if you’re used to filling a car with gas. They’re also less flexible, so parking orientation is so important. If you’re using a DC fast charger on a car with a CCS plug, you might need to open a separate flap over the bottom part of the plug meant to keep dust out. From there, orient the charging handle to the plug and push it in until you hear a click.

Congratulations, you’re charging. You might even hear a beep and/or see some lighting come on in your car to let you know the juice is flowing.

Once you’re done, you’ll sometimes need to stop the charger before the car will let you remove the plug. Push the release button, give the plug a firm tug, and it should slide free. Replace the handle on the charger, close your charge door and you’re all set.

If you plan on doing most of your vehicle charging at home – which you should, if only for the cost savings – you’ve got a lot less to worry about, particularly if you’ve made the smart decision and had a Level 2 charging system installed.

Modern Level 2 chargers not only replenish your car’s range much more quickly than the Level 1 charger that might have come with your car, but many of them can also help save money by charging your car when electricity prices are lowest. Some can even let you send your car’s electricity to your home (this is called "bi-directional charging") during a power outage if your vehicle allows it.

Now that you’re actively adding electricity to your car’s battery, you might wonder how long this whole process will take. Manufacturers like to advertise charging times like “10 percent to 80 percent in 20 minutes,” but you can’t always expect that kind of performance because there are a lot of factors that contribute to how fast your car can accept energy and how much energy a plug can provide – especially if you’re at a public charger.

Some factors that can affect charge speed include the ambient outside temperature. If it’s very hot or cold, your car won’t be able to transfer energy as efficiently. Another factor is how busy the public charger is. If many people are charging at once, the amount of electricity available to each plug might be lessened, increasing charge time.

Other factors that you have control over can affect your charging, too. For example, if you’re in the car with the stereo or the climate control on, the car will charge slower than if you left it off entirely and went to get a coffee. Something else to consider is what kind of charger you’ve plugged into. If your brand new Porsche Taycan – which can charge at up to 225 kilowatts – is plugged into a 150-kilowatt charger, it can’t charge at its full advertised speed.

At the beginning of this whole thing, we talked about a whole production going on behind the scenes when you plug in your EV to charge, and that’s true. Plugging the car into the wall is only the beginning. To truly understand everything, you’d need an electrical engineering degree (and maybe a chemistry degree on the side); we’ll give you a broad overview.

Once the car detects incoming voltage, the car’s onboard charger starts to work with the charge controller to distribute electricity to the various battery modules that make up your car’s battery pack. Each module comprises many individual cells – some look like big versions of the AA batteries you’re used to seeing at home, others are pouch cells that look more like something you’d microwave for dinner – and all of those cells need to be carefully balanced and monitored.

This balancing and monitoring are critical because the chemicals that make up those cells and give them the ability to store energy are volatile. If they get too hot or see too much (or too little) voltage, they can become inoperable at best or catch fire at worst, and there are usually hundreds or even thousands of cells to manage.

Many modern EVs use a liquid cooling system for the battery pack, which can help with temperature regulation and ensures more consistent charging. Some cars, like the Lucid Air, have an option to “pre-condition” the battery pack so when you plug it into a super fast 350-kilowatt DC charger, it can take full advantage of it.

Proper charge management also greatly affects the longevity of your EV’s battery. If the pack is kept within its specified parameters and all its cells are balanced correctly and not over or undercharged, your pack will last longer. If you run your battery to fully dead or regularly DC fast charge to 100 percent, you could get less life from the most expensive part of your EV. 

Follow your vehicle’s owner’s manual when it comes to suggested charging practices, and you’ll be just fine.