How Does EV Charging Work?


EV charging works by supplying electricity from a charging station to a car’s battery via a cable, with charging speed varying based on the charger type and battery capacity.

As electric vehicles become increasingly prominent on the roads, charging stations are starting to pop up everywhere. There is a high chance you know someone with a home EV charging station installed. But how does the process work?

In this article, I will discuss, in detail, the process involved in charging an EV. I suggest reading through this article to understand the basics of EV charging better.

At a Glance:

1️⃣ EV chargers come in different levels: Level 1 charging, level 2 charging and level 3 charging / DC charging.

2️⃣ The charging speed of an electric vehicle depends on the charger level, battery capacity, and other factors.

3️⃣ A rectifier converts AC to DC power.

4️⃣ EVs use a battery management system that oversees the entire charging process.

When charging your vehicle, there are six things to look out for. If you know these, you should understand how EV charging works. So, let’s jump into it.

AC Is Converted To DC within the Charging Station

An EV’s onboard charger oversees converting the AC power from a charging station or outlet into the DC power (direct current) required to charge the battery.

In this process, the AC power is rectified into a steady DC voltage appropriate for the charging profile of the battery.

Electricity must go through several processes, from the charging station to the battery. One of these processes includes going through something called a bridge rectifier. Its sole job is to convert electricity.

DC fast chargers bypass this step, and thus, they are able to charge the battery a lot faster than conventional chargers.

The comparison between AC and DC EV charging can further your understanding of how EV charging operates.

Charging Rate

The charging rate (not to be confused with charging time) refers to the amount of electricity that can be fed to the car in a single moment. Several factors determine the charge rate of an electric vehicle:

Charger TypeLevel 1: 120V, slowest charge rate
Level 2: 240V, faster charge rate
DC Fast: Direct DC power, fastest charge rate
Vehicle Charge ControllerRegulates power, converts AC to DC for battery
Other FactorsTemperature and charge state can influence charge rate

Regarding the charge rate, the charger being used is more of a factor than the battery’s capacity. Yes, the size of the battery will determine the time it takes to charge, but it does not affect how much electricity is passed through to the battery from the charger.

EV Charging Time

You can give yourself a rough idea of how long it will take to charge your EV. To do so, you need to know the battery capacity and your charger’s capacity. Once you have this information, here’s how to divide it:

Estimated Charge Time = (EV Battery Capacity) / (Charger Rate)

For example. If your battery capacity is 100Khw and your charger is 15Khw, then 100 / 15 = 6.6 hours. That said, how long it takes an EV to charge is highly important.

Sometimes, you are going to need to get somewhere and need the vehicle to be charged. However, the time it takes for the battery to charge depends on various factors, these include:

  • The charger being used
  • The battery capacity
  • The temperature
  • The state of charge

Another important factor is the battery management system. For example, if the battery is running hot, the management system will adjust the rate at which the charges. This will prolong the battery’s lifespan.

Charge Monitoring

EVs typically come with a battery management system. It starts with sensors that monitor your battery.

The sensors can track the state of charge (SOC), temperature, and much more. The sensors then send signals to software designed to interpret the data.

If the battery is overheating, the software can halt the charging process or at least alert the owner. Also, the battery management system prevents overcharging and undercharging.

All of this monitoring keeps the battery protected, increasing its lifespan. Monitoring is also involved in keeping track of how many miles your battery has left.

Charging Completion

If you decide to charge your vehicle overnight, which is pretty much the best way to do it, you do not have to worry about the battery being overcharged. Electric vehicles have an intricate battery management system (BMS) that utilizes hardware and software.

The BMS constantly monitors the battery and will prevent it from overcharging or overheating. Some vehicles also let you adjust how long the car can charge for. Doing this helps protect your battery as well as help you stay within TOU rates.

If not for the BMS, your battery would be at risk. Some of these risks include:

  • Overheating
  • Natural degradation occurs faster
  • The battery may lose capacity
  • The battery may become unstable

With that said, it is perfectly fine to leave your electric vehicle plugged in overnight. Remember, it will automatically stop charging when necessary. It is far more detrimental to charge your vehicle more often than it is to have it plugged in for longer periods.

Charging Notifications

Again, the battery management system plays a significant role in the notifications we get from our cars.

It gathers information about the battery and sends it to you, the user. There are various ways that you can receive notifications; these include:

  • Dashboard Display: The most common method of receiving notifications is through the dashboard. However, this only works when you are sitting in the car.
  • Mobile App: Most Electric cars come with mobile apps. Through these apps, you can check the status of your car, adjust the charge limit and, best of all, track how much charging your car needs and how much mileage the battery currently holds.
  • Audio alerts: When all else fails, audio alerts can notify you when your battery is full or completely discharged. These notifications are particularly useful while driving.

So, what kind of notifications can you expect? Well, it depends. From the dashboard and mobile app, you can expect the following:

  • Battery health
  • State of charge
  • Any issues
  • Expected mileage
  • Alert to charge

Audio alerts are a little bit different. Your vehicle will only typically give you an audio alert for more important things, such as how much time or miles your battery has left and if there are any issues with the battery.


How Long Does It Take To Fully Charge An Electric Car?

Various factors affect how long it takes to charge an electric car; However, you can work out roughly how long yours will take.

According to information provided by the US Department of Transportation, on average, a level 2 charger will get an electric vehicle from zero to 100% and five to 10 hours. That time is drastically increased for level 1 chargers. While DC fast chargers can take your car from zero to 100% in an hour.

Key Takeaways

Learning about the different levels of EV charging can enhance your understanding of how it works. But to recap what we have discussed:

1️⃣ Charging rate depends on the charger type, vehicle charge controller, and other factors like temperature and charge state.

2️⃣ EV battery capacity and charger rate determine the estimated charge time.

3️⃣ Battery management systems monitor the charging process, preventing overcharging, overheating, and prolonging battery life.

Charging an electric vehicle is simple. Most cars have a guide, and you just need to connect the car to a charging spot. But, there are many steps the electricity goes through before reaching the battery.

Next, I recommend learning the best way to use EV charging stations to further your grasp on the topic.