When (and How) Should You Use a DC EV Charger?
According to the Alternative Fuels Data Center, there are 36,366 DC Fast charging stations available in the United States. Should you use one of them to charge your Electric Vehicle (EV)? Before you plug in, take a moment to learn the difference between AC and DC charging, how much time it will take, and whether there are any consequences for your route planning or battery maintenance.
The Difference Between AC and DC Current
Electrical current comes in two forms: alternating current (AC) and direct current (DC). AC is the type of electricity that flows through power grids and into homes and businesses, including to power EV chargers. DC is the type stored in batteries. AC can be thought of as "low and slow" charging, while DC is very fast and powerful.
The key difference between AC and DC for EV charging is the power level. AC EV chargers operate at lower power levels, usually 7-22kW, which enables slower charging. DC EV chargers can provide much faster charging, with power levels over 50kW or up to 100kW and beyond. This makes DC ideal for rapid charging stations.
While AC dominates inside homes and businesses for slower overnight charging, and DC is best for rapid highway charging, both AC and DC chargers can be found in various locations. The power level capabilities are the primary distinguishing factor between AC and DC chargers, not necessarily just the location type. With DC's ultra-fast charging, and AC's slower but cheaper and more widespread infrastructure, both technologies have an important role for EV charging.
Which Do I Need?
Let’s say you have an hour to spare. Based on Department of Transport figures, your Level 1 charger at home will be able to deliver enough charge for 2 to 5 miles of driving. An hour of Level 2 charging will give you 10 to 20 miles. But an hour of DC charging can give you 180 to 240 miles of driving, and you could be ready to go again with as little as a 20-minute charge.
That’s why you’ll see the term DCFC or DC Fast Charge. Clearly, drivers or fleets who are already on the road with considerable mileage to cover cannot interrupt their journey for several hours just to travel a few more miles. They need the sustainable, electrical equivalent of a fully refilled gas tank, with similar speed and convenience.
What Do You Need for DC Charging?
Before you set out, it’s important to check what type of EV plug you’ll need for fast charging. DC chargers require a Combined Charging System (CCS1), CHAdeMo or Tesla Supercharger plug because they deliver current directly into the car battery, whereas AC chargers pass the current first through the car’s onboard charger.
In North America, you’ll be able to fast-charge with a CCS plug, which now allows you to connect to Tesla Superchargers even if you’re not driving a Tesla.
Some models (typically from Japan or South Korea) might use a CHAeMo plug.
Not every vehicle is compatible with DC fast charging. For example, plug-in hybrid electric vehicles (PHEV) cannot connect to DC stations.
Check your manual for the recommended plug and ask your dealership if adaptors are possible as an upgrade.
Pros and Cons of DC Charging
If you’re a recent EV convert from internal combustion engine driving, DC charging feels most similar to topping off the gas tank at a roadside station. It’s fast, and you’ll usually find amenities and refreshments to keep you busy while you wait.
However, DC is premium charging. If you want to know how much it costs to ‘fill up’ at a DC station, the total cost will then depend on the time of day and location.
A word on battery health
While research shows that fast charging does put an extra strain on your battery, the effect on battery health is very minor. In fact, DC charging only increases battery deterioration by about 0.1 percent on average.
Your EV’s battery life has more to do with temperature management than anything else, as lithium-ion (Li-ion) batteries are sensitive to high temperatures. Luckily, most modern EVs have built-in temperature management systems to protect the battery, even while fast charging.
Where to Find a DC Charging Station
Availability of DC charging options varies enormously by location. Those that are taking the lead on alternative fuels, such as California, Texas and New York, have plenty of options to choose from in the more heavily populated areas. But if you’re planning a road trip in Idaho, Wyoming or North and South Dakota, for example, check where you can recharge in advance. Coverage is sparse for now.
Luckily, you no longer need a screen full of apps to plan a single journey. The EV Connect Driver App allows you to easily find, access, and securely pay for EV charging. EV drivers can search for and locate stations based on location, station ID, availability, power level provided, and accessibility.
In this blog, we took a deep dive into DCFC stations. We encourage you to explore our other related blog posts, such as our coverage of plug types and the difference between AC and DC power.
To locate the nearest charger, check your charging status, easily make payments, and stay up to date on your account, download the EV Connect Driver App.
Sources
Department of Transport - Charger Types and Speeds | US Department of Transportation
Alternative Fuels Data Center - Alternative Fueling Station Counts by State