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What is a DC fast charger?

What is a DC fast charger?

If you're like most EV drivers, you probably rely on home charging the most.

And I can't blame you. Just the convenience of overnight charging alone is enough for me to stick to my good ol' Level 2 charger.

But, we may be missing out on one important feature of modern electric vehicles: fast charging.

Our trusty Level 1 and Level 2 chargers use the same Alternating Current just like household appliances.

AC power is the simplest form of electric current found in most residential areas, shopping centers, and offices.

That's why AC charging speed is limited to just 3kW up to 22kW.

Then comes DC charging.

What is DC fast charging?

As the name suggests, DC fast charging uses Direct Current (DC power) to provide power directly to your vehicle's battery.

With AC chargers, your EV's on board charger is tasked to convert AC power to DC power before it enters the battery.

This slows down the charging process significantly, as acceptance rate of on board chargers varies by brand, therefore, limiting the amount of power it can convert.

DC chargers bypass this process to directly supply power to your car battery.

On average, a DC fast charging station is capable of 50 kW to 350 kW of charging output.

Depending on the battery size and the output of the dispenser of your electric vehicle, you're looking at an 80% charge in about an hour.

How does DC fast charging work?

There are three types of DC fast chargers available today: the Combined Charging System (CCS), Tesla Superchargers, and the Japanese "CHAdeMO" (CHArge de MOve).

These chargers use different ports, with the CCS being the most common.

CHAdeMO is not as common, but is still the standard for a few Japanese automakers.

Meanwhile, Tesla Superchargers can only be used by Tesla vehicles, but the company is slowly opening its Supercharger network to non-Tesla EVs.

Tesla owners can enjoy CCS and CHAdeMO chargers using charger adapters.

EV batteries have an acceptance rate, or maximum power rating, which limits them to a specific number of kilowatts they can accept.

This varies widely from vehicle to vehicle, but most EVs in the market have an acceptance rate range of 50 kW to up to 270 kW.

And with the emergence of newer EV with bigger battery capacities, DC chargers have also been increasing in power output, with some reaching up to 350 kW.

Now, it's easy to get confused with the power ratings of EVs and EV chargers, but don't fret, the limits of your EV don't have to match the limits of the charger.

So, even if your electric vehicle is only capable of charging at 150 kW, you're perfectly fine using a 200 kW-rated charger with it.

The charger and the EV will "communicate", and the charger will deliver only what your car can accept.

In the same sense, a higher-rated car will slow down its charging speed when using a lower-rated charger.

When and how to use DC fast charging

Check your car and connector type

DC chargers use a different type of connector from your J1772 Level 2 charger. Fast charging standards are the SAE Combo (CCS1 in the US and CCS2 in Europe), Tesla, and CHAdeMO. Check your electric car's port before plugging in a DC charger.

Here's what some common connectors look like:

Save fast charging for when you need it most 

Because DC fast charging generates so much heat and increases battery temperature, frequent trips to DC fast charging stations is not advised as this could take a toll on your EV's battery life.

So, save fast charging for when you need it most, like when you're on a long road trip needing a fast recharge.

With the DC fast charging cost, it's not the most cost-effective way of charging your electric vehicle's battery. Add to that, with how much power it generates, frequent usage of DC fast charging connectors could reduce your battery’s efficiency and lifespan.

Follow the 80% rule

In using DC fast chargers, it's best to unplug your EV when it reaches 80%. Charging speed dramatically decreases when battery level is at 80%, and it could take just as long to fill the remaining 20%.

This is known as DC fast charging curve, which is when charging starts slow while monitoring different factors, speeds up to peak performance, and then slows down again to prolong battery life.

What are the different levels of EV charging?

Level 1 EV charging

Level 1 EV charging is the simplest and has the slowest charging speed of the three. Most EVs come with a Level 1 electric car charger which you can simply plug into your standard outlet.

While convenient and low-cost, the bad news is this charging cable uses 110-120-volt AC power, so expect slow charging. However, with an added 4 to 6 miles of range per hour, it will likely be enough for your daily commute. If you have an EV with 200 miles of range, it will take around 35 to 50 hours to fully charge.

Level 2 EV charging

Level 2 charging uses connectors that are plugged into 220-240-volt outlets that are typically used for RVs, washing machines, dryers, and other major appliances. The Tesla wall connector and Lectron V-BOX are an example of Level 2 chargers.

There are portable ones which you can just plug directly into a three-pronged outlet. You probably have the outlet and circuit in your laundry room, but unplugging your washing machine every time your vehicle’s battery needs a recharge could be inconvenient.

Because of this, many EV drivers opt to install a Level 2 home EV charging station in their garage. You’ll need the service of a professional electrician to install a 240-volt dedicated circuit to supply electrical current in your garage.

These chargers are very reliable and can give your electric vehicles up to 200 miles of driving range in under 10 hours, so you’re likely to save money in the long run.

DC fast charging

DC fast charging uses direct current instead of alternating current (AC). DC Fast charging bypasses the onboard charger to deliver DC power directly to your car, with up to 400-900V of maximum power. This can charge your unit from zero to 80% in just under 30 minutes!

What is the difference between AC and DC fast charging?

The main difference between AC charging and DC fast charging is how they deliver power to your EV battery.

AC chargers deliver power to your car's on board charger, which then converts DC to AC, before delivering the converted power to the battery.

DC fast chargers delivers DC power directly to your car's battery, significantly increasing your EV's charging speed.


How fast are DC fast chargers?

Generally speaking, DC fast chargers can charge EVs to 80 percent in 20-30 minutes.

Can I install a DC fast charger at home?

Because they require large amount of power, DC fast chargers cannot be installed in residential areas.

What cars support DC fast charging?

Some of the cars that support DC fast charging are:

  • Audi e-tron

  • BMW i3

  • Chevrolet Bolt

  • Honda Clarity EV

  • Hyundai Ioniq EV

  • Nissan LEAF

  • Tesla Model 3

  • Tesla Model S

  • Tesla Model X

Is DC fast charging worth it?

It depends on your charging needs. If you're only driving within the national average of around 40 miles a day for daily commutes, then spending on DC fast charging may not be the most cost-effective solution. But if you drive long ranges, frequent trips to DC fast charging stations may be the most viable option.

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