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How Do Level 3 EV Chargers Charge An EV in <30 Minutes?!

September 25, 2022

When you hear EV (electric vehicle) charging, and DC (direct current) fast charging, maybe they sound like two completely different things. 

DC fast charging is just the fastest “level” of EV charging. It's also called Level 3 EV charging, and it’s the only level that uses direct current (DC) power, instead of alternating current (AC) power. In this article, first we’ll quickly go over the differences between the 3 levels, then we’ll dive into the technical reasons why DC fast charging is so much faster, and why it’s also more efficient. 

There are three levels to EV charging:

Level 1: 120 Volts AC Power 

Level 2: 240 Volts AC Power

Level 3 EV Charging (DC Fast Charging): 480+ Volts DC Power

Level 1: 120 Volts AC Power

If you’re charging your EV with a Level 1 charger, you can simply plug in the portable cord that came with the EV into a standard electrical wall outlet. All EVs come with a portable cord for Level 1 charging. These outlets are also used for things like phone chargers, toasters, lamps, etc. As you can imagine, this method of EV charging requires the least amount of capital investment, and is the easiest to implement in a home or building. You just need a wall outlet close enough to where you park your car for it to work. The disadvantage of this method is that it’s (by far) the slowest Level of EV charging, charging at about 6 - 8 km per hour.

Even though Level 1 chargers are the slowest, speed isn't everything. The affordability of Level 1 chargers, make charging an EV or hybrid vehicle overnight possible if you don't want to spring for a Level 2 charger. In this way, Level 1 chargers suit the consumer market for EV chargers just fine.

120 volt AC wall outlet
120 Volt AC wall outlet

Level 2: 240 Volts AC Power

Level 2 chargers uses a 240 V AC wall outlet. This outlet might be used for things like ovens or clothes dryers, and they charge at about 30 km per hour. However, they also require much more capital investment for installation than Level 1 chargers. Level 2 chargers have their place in the consumer market for people who prioritize EV charging speed and efficiency. Level 2 chargers are more efficient than Level 1 chargers because they distribute a higher voltage. If you review the formula for power/wattage, you'll see that when voltage increases, current decreases. When current decreases, less heat is emitted, and less heat lost means less energy lost.

240 volt ac outlet
Image Source

As for the costs associated with purchasing and installing Level 2 EV chargers, here's a breakdown: 

  • A level 2 charger (the actual device) costs between $500 - $1300 USD
  • There are also a number of contractors you might have to hire in order to install a level 2 charger. First off, you will need an electrician to determine if you have enough capacity, and figure out where the conduit would need to go, and how much of it you would need. For example, if your panel is in the garage, the project would be much more simple and cheap than if your electrical panel were in a separate building, or at the opposite end of the building. The further away your electrical panel is from your level 2 charger, the more expensive and complicated the project could be. 
  • Finally, there’s the question of red tape when it comes to installing a level 2 charger. For example, you might have to go through a condo association, or get a permit in some cases (especially if you’re doing any digging). You will also most likely require an electrical permit for the work to be completed.
  • Other factors that could affect cost include if the charger is an indoor or outdoor charger, and if it’s networked or non-networked.

power plugs

Level 3 EV Charging (DC Fast Charging): 480+ Volts DC Power

Finally, there’s Level 3 EV charging, which is also called DC fast charging. These chargers supply 480 Volts DC or more, and supply DC electricity rather than AC. These are often used in urban centers so that the drivers of EVs can charge up quickly if they’re travelling long distances. This, along with their steep cost, means that they are not typically purchased by everyday consumers; more often they are purchased by businesses, building owners, towns and cities (for example). They can typically charge at about 178 miles of electric drive per hour, or about 286 km of electric drive per hour (for all my fellow Canadians out there). This is obviously much faster than Level 1 or 2 chargers. The disadvantage of Level 3 EV chargers is their cost; it costs between $28,000 - $140,000 USD to install a DC fast charging station, remember that’s including the cost of electricians, labour, permits, and anything else associated with the cost of installing a DC fast charging station. Check out this article for a detailed breakdown of EV charging costs. This is a big reason why level 3 chargers are primarily found in public locations; they are typically just too expensive for an individual homeowner and, frankly, it’s usually overkill for a homeowner to install a level 3 charger if they can charge their EV overnight with a level 2 charger.

level 3 ev charger

Example with a Tesla Model 3: How much faster are Level 3 EV chargers, really?

EV Charging Level Time to Charge a Tesla Model 3
Level 1 charger 1.9 kW Up to 35 hours
Level 2 charger – 11-22 kW Between 3 to 6 hours
Level 3 (DC Fast Charging) - 50 - 350 kW Less than 30 minutes

Table Source: Tesla Model 3 Charging Time

tesla charging
Image Source
tesla model 3 charges in 35 hours on level 1 station and in 30 mins in level 3 station

Why are Level 3 EV Chargers so much faster?

You might hear that one of the main reasons EVs haven’t surpassed internal combustion cars in the market is because they’re too slow to charge. This is true, but it’s actually a simplification of the problem. The problem is really when Level 1 or 2 EV chargers are used as the range extenders of choice in public spaces. They’re the slowest option for charging EVs, so if they’re installed in lieu of Level 3 EV chargers in buildings or along travel routes, they make it difficult for EVs to proliferate the roadways. Basically, EV drivers need to be able to charge their cars quickly in the middle of long drives but, as you can see from the table above, it takes far too long for even a Level 2 charger to charge an EV if you want to get back on the road quickly. Level 1 and 2 chargers have their place in the consumer market for people who want to charge their EVs at home, overnight. You can compare Level 3 chargers to gas stations in the way that, you wouldn't put one on your property, but you sure do need to use one sometimes in order to use your car.

There are two things that make Level 1 and 2 chargers slower than Level 3 EV chargers:

Reason 1: Level 1 and 2 chargers charge at lower voltages than DC fast chargers

According to the formula we use to calculate power (see image below), when voltage is increased, current can be decreased. More current also means more heat, and heat is actually wasted electricity. So, sending higher voltages not only means more total power is sent to a load, but also that less energy is wasted along the way.

power formula is power= current x voltage
Power Formula

Reason 2: Level 1 and 2 chargers supply AC power to EV batteries that need DC power

You can’t charge EV batteries (or any battery for that matter) with AC power, so the AC electricity flowing into an EV must be converted into DC power to charge the battery. This AC to DC conversion is done by a device called an “onboard charger” that’s built into EVs.  

Remember, when AC power with a lower voltage (and therefore higher current) is sent to a battery, more heat is generated, as we covered above. This heats up the AC to DC converter (onboard charger), so it can only convert at a rate where it’s not overheating. This means that, the lower the voltage, the higher the current, and the slower the onboard charger is able to convert from AC to DC power. Therefore, needing to convert AC to DC power intrinsically slows down the charging process for EVs. 

DC fast charging is faster because it supplies DC power directly to an EV’s battery, and so bypasses the EVs onboard charger. When the onboard charger is not necessary, it doesn’t slow down the charging process, and this makes DC fast charging much faster than any charger that supplies EVs with AC power.  

level 1 or 2 charger diagram showing how they are slow
level 3 ev charger, diagram showing why it's faster

And there you have it, the two reasons why Level 3 EV charging is so much faster! But did you know that DC power distribution not only makes EV charging more fast and efficient, but also can be implemented in buildings to save energy and operational expenses?

According to the USGBC, DC consumption currently makes up about 74% of total energy loads in buildings that have EV charging stations, and HVAC equipment with DC motors. When AC power is distributed to buildings (which it usually is, unless a building has a DC microgrid), then all of these DC loads need to convert AC to DC power. Making these conversions at an individual level, every time a DC powered device is turned on, can waste a lot of energy. If you’re a building owner or manager that’s interested in saving energy and operational costs, contact the team of engineers here at Cence Power to get the answers to all your questions related to DC power. 

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Erin Law

Erin is the Creative Director at Cence Power. She has a New Media degree from the University of Toronto and 5 years of experience in the communications field. She has also done digital content creation for dozens of clients through her own business called Story Unlocked. Erin loves technology, especially when it makes the world a better place.

Cence Brings Buildings Into The Future

We improve the value of commercial and multifamily buildings with an intelligent DC power distribution system that's pain-free to install. It combines the benefits of low-voltage wiring practices with voltage capabilities of up to 450 Volts DC.

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