Welcome to EV101: Electric Vehicle Charging Basics
Whether you own an EV, or you’re EV-curious, this page will answer all your electric vehicle related questions. We’ll cover a range of topics, from the basics — What is an electric vehicle? — to the nitty-gritty variables that affect your charging speeds. Scroll at your leisure! Your curiosity is welcome.
What is an Electric Vehicle?
There are actually three types of electric vehicles. The type most people associate with “EVs,” is called a “Battery Electric Vehicle” — or “BEV.” However, there are also “Hybrid Electric Vehicles” and “Plug-in Electric Vehicles,” which we’ll discuss below.
Battery Electric Vehicle – BEV
A Battery Electric Vehicle has no gasoline engine. All the car’s energy comes from the battery, which powers an electric motor. BEVs have zero emissions, and they’re quiet—quiet as a cucumber. The “range” (or distance you can travel on a charge) varies between models and years, but most BEVs can get anywhere from 75 – 402 miles on a single charge. (And that number is growing — and fast!).
Examples of BEVs include the Tesla Model 3, the Chevy Bolt, and the Nissan LEAF. Different models have different “charge ports” (the socket through which you connect a charger to the car). We’ll discuss these later. Just know that BEVs are charged by electricity alone.
Plug-in Hybrid Electric Vehicle – PHEV
For those who like living in both worlds, a second type of EV is called a “Plug-in Hybrid Electric Vehicle” — or “PHEV.” PHEVs have both a gasoline engine and tank, and they also have a charging port to recharge an electric battery. For most Americans, the average daily commute is about 15 miles. A typical electric range of a PHEV is about 10-40 miles, which is perfect for a commuter who can recharge at home or on-the-go. Once the electric range is depleted, the vehicle reverts to hybrid mode and relies on its gasoline engine.
Examples of PHEVs include the Chevrolet Volt, Toyota Prius Plug-in, and the Kia Optima Plug-in. Unlike HEVs, PHEVs can recharge at AC Level 2 EVgo stations, and some can even accept a DC Fast Charge.
Hybrid Electric Vehicle – HEV
For those not quite ready to take the “all electric plunge,” there’s another type of EV called a “Hybrid Electric Vehicle” — or “HEV.” HEVs are powered by an internal combustion gasoline engine (or ICE). In some HEVs, the ICE both recharges the electric battery and drives the transmission, while in others the ICE only recharges the battery (which drives the electric motor). In both cases, HEVs are gasoline powered cars that emits much lower pollutants than a typical gasoline car. They’re excellent for environmentally conscious people (or people looking to save money on gas!). As you can see in the diagram, an HEV has both an electric motor and a gasoline engine. And in back, you’ll see both an electric battery and a gas tank.
Examples include the Toyota Prius, the Honda Insight, and the Ford Fusion Hybrid. Because HEVs cannot plug in, they will not charge at EVgo (or at any public charging station).
4 Ways Charging Your EV is Different from Filling Up Your Car
Charging your EV is a lot like… charging your phone. Yes! Just like how people have different habits for charging their phones, EV drivers have different habits for charging their vehicles. Some people charge their phones at night while they sleep. Some charge at work at their desk. And others take advantage of chargers everywhere – in their car, at home, at the airport — wherever they can. So, the good news is that there are several options for how to charge your EV, just like there are for charging your phone.
As of now, charging an electric vehicle from near empty to full takes more time than refilling a gasoline powered car. However, that time difference is shrinking. The EV world is versatile – and evolving. At first, the majority of people with EVs charged at home or at work over a period of several hours. Now, as thousands of fast chargers are deployed across the country, EV drivers have the option to “charge on-the-go” — as they shop for groceries, pick up a prescription, or grab a coffee — all in about 15-45 minutes.
EVs are better for the environment
The “end of oil” is closer than people think. Fossil fuels – including gasoline – are not permanent resources. And fossil fuel consumption produces smog, greenhouse gases, and other pollutants harmful to human health.
All battery-electric vehicles (BEVs) produce zero local emissions. And because PHEVs and HEVs are more efficient than gasoline-only powered vehicles, they produce much less tailpipe emissions, even when running only on gasoline.
There’s a common misconception that the production of electric vehicles — and the energy electricity generated to charge them — creates as much harmful pollutants as gas powered vehicles. That’s simply not true. Electric vehicle emissions are lower. And the grids that power them continue to increase their sourcing from renewable energies, electric vehicles will continue to get cleaner. On our end, EVgo powers all of our chargers with 100% renewable electricity from wind and solar.
NOTE: The Union of Concerned Scientists has an excellent visual graph to show the estimated emissions for various areas across the US – some with over 100MPGe!
Charging an electric vehicle costs less money than filling up a gasoline car (on average, about 35% less). The price of gasoline depends on several factors – the cost of crude oil, taxes, and world supply & demand. The price of electricity depends primarily on how many other people are using electricity. When a lot of people are using electricity, it adds strain to the grid. And this strain increases the cost of a charge. Because the electric vehicle and charging industries are evolving simultaneously, new innovations are being created to make charging faster and less expensive.
If you’re interested in learning more, check out this calculator from the US Department of Energy to see the long-term differences in cost between an EV and a gasoline-powered car:
4 Types of Connectors
When we travel to different countries, sometimes the outlet types are different. Electric vehicles are a lot like that. Because so many manufacturers around the world design EVs, they install different connector compatibilities in their vehicles. Thankfully, EVgo is compatible with nearly all of them. But it’s still important to know which “connector” is inside your EV to charge correctly.
Standing for “Charge de Move,” CHAdeMO was designed by a collection of carmakers industry groups, primarily in Japan. Manufacturers like Nissan, Toyota, and Mitsubishi tend to use the CHAdeMO standard.
Designed as an “open industry standard,” vehicle manufacturers around the world use the Combined Charging System or CCS connector, but they are most often associated with North American and European automakers. In North America, all newly manufactured passenger EVs (except Tesla) will use the CCS connector.
Tesla connectors are found exclusively in… (you guessed it) Tesla cars. EVgo is the first public fast charging network to offer native compatibility with Tesla vehicles at our chargers, which means you do not need to use an adapter to plug in. Because Tesla was one of the first EVs to market with fast charging, they designed their own connector. Tesla sells adaptors for their EVs that allow Tesla drivers to charge their EVs on non-Tesla chargers. Tesla includes with the vehicle an adaptor for AC Level 1 and 2 (J1772) and offer for sale a CHAdeMO to Tesla Adaptor for DC charging.
L2 – J1772
This connector is used for “Level 1” and “Level 2” AC charging. Level 1 and Level 2 charging are considerably slower than DC Fast Charging, and are primarily meant for charging over a few hours (like at home or at work). The SAE J1772 connector (also known as “J Plug”) is used by all EVs except Tesla for AC charging (Tesla vehicles come with an adapter to use this connector).
Adapters are devices that enables charging with one standard to another. Although there are several standards existing in the industry, there are few adapters in the market. The use of adapters is not recommended because adaptors add an additional part in the electric connection between EV and Electric Vehicle Supply Equipment (EVSE), which increases the probability of faults and affects the functional safety.
There are two adapter types that are tested and validated. One Is the Level 2 AC adapter that can be used for L2 J1772 to Tesla, and the other Is CHAdeMO to Tesla adapter. Any Tesla adapters not made by Tesla are not approved for use by EVgo and can cause damage to the EVSE or vehicle.
A common mistake is to mis-apply the Tesla AC adapter to the DC charging connector. When it is forced into a DC CCS1 plug it won't enable the charge to Tesla, and causes damage to the DC connector.
How Long Does It Take to Charge Your Electric Vehicle?
Most non-electric vehicle drivers think charging takes forever. However, electricity is everywhere, and some drivers will do the bulk of their charging at home or at work, where their car is able to "fill up" while sitting all day or all night. Also, most non-EV drivers are not aware of DC fast charging — where drivers can now typically charge in 15-45 minutes. And when you find an EVgo charger that aligns with your grocery shopping or trip to the park, it only takes a minute or two for you to plug in and tap on the app to start your session, and then the car and the charger do the work while you go run your errand for those 15-45 minutes!
AC Level 1
When a driver plugs their car into a standard wall outlet, that’s Level 1 charging. It’s the most basic type of charging. And it’s the slowest. But for people who don’t drive a lot each day, and are able to charge at home, Level 1 charging is a convenient way to charge because it doesn't require installing an AC Level 2 charger.
AC Level 2
Level 2 charging utilizes a 208-240 volt circuit (like the kind used for electric dryers). They charge faster than Level 1 chargers — about 5-6 hours instead of 20+ hours. Level 2 chargers are most often found where vehicles are parked for a significant amount of time where charge speed does not matter as much (like at home or at work). You can also find Level 2 charging stations in public, such as malls and shopping centers.
DC Fast Charging
If AC Level 1 and Level 2 chargers are like “dial-up Internet,” then DC Fast Charging is like “fiber internet.” When charging on Level 1 or 2, electric vehicles convert AC power from the grid to DC power to recharge the battery. DC Fast Chargers do this conversion internally, using a much larger grid connection, and deliver DC power directly to the vehicle— resulting in a much faster and more powerful charge.
As the industry has evolved, EV battery sizes have increased to provide greater driving range. The power of fast chargers has also evolved and increased to fill these batteries in the fastest possible times. Fast chargers today are available from 25kW to 350kW for passenger EVs—with even higher-powered chargers for heavy duty electric vehicles like semis-trucks. It is important to understand the maximum power at which your EV can be charged and the power of the charger you plug into for the best charging experience.
Fast Charge Your EV in 3 Easy Steps
EV Chargers Available in EVgo's Network
EVgo has a multitude of chargers to choose from. Our “bread and butter” is DC Fast Charging, and we currently have over 850 fast charging stations across the country. And because of our “Partner Roaming” capabilities, a membership with EVgo gives you access to thousands of fast chargers across the country!
DC Fast Charging
Most Battery Electric Vehicles (BEVs) are capable of fast charging. And our fast chargers have power levels from 50 kW all the way to 350 kW. The speed at which vehicles charge is usually decided by the vehicle’s Battery Management System (or BMS — it’s sort of like the vehicle’s “brain”).
Click here to see a map of all our fast chargers and find one that’s right for your vehicle.
Level 2 Chargers
All Battery Electric Vehicles (BEVs) and Plug-in Hybrid Electric Vehicles (PHEVs) are capable of AC Level 2 charging. Because AC Level 2 charging is done at a slower rate, it’s best for people who don’t mind waiting a few hours for their cars to recharge. Many workplaces and homes are equipped with AC Level 2 chargers, and EVgo has a network of public AC Level 2 stations available as well.
Click here to see a map of all our AC Level 2 chargers and find one that’s nearby.
NOTE: DC fast charging is best for charging vehicles “up to 80% full.” Afterwards, the charging rate slows down, and it’s generally a better use of time to switch to an AC Level 2 charger.
EV Charging Terms Explained
It’s helpful to think of charging an electric vehicle like water flowing through a pipe.
Voltage refers to the tension — or potential — of energy. Using the analogy above, “water pressure” is equivalent to “voltage.” The higher the pressure, the more water can push through. The same applies for voltage — higher voltage means each bit of electricity can provide more power.
Amps refer to the flow of electrons through a conductor (called a “current”). Using the water pipe analogy, this describes the volume of water flowing. The wider the pipe, the more water can flow.
Watts are units of power. They describe the rate at which energy is transferred. Using our water pipe analogy, we find that rate by multiplying the voltage (the water pipe pressure) by the amps (the flow rate or water). W=V*A
Kilowatt-hours are a measurement of energy. It equals the amount of energy transferred over one hour. Using the water pipe analogy, it refers to how much water — or energy — flows out of the pipe over one hour.
Drivers on Pay As You Go and EVgo Membership plans both currently pay by time spent charging, with EVgo members having access to a lower rate. Because charging rates slow down dramatically after 80%, it’s more cost-effective to switch to an AC Level 2 charger--and helpful to the next EV driver hoping to fast charge.
SOC (State of Charge)
State of Charge describes how full your battery is, in terms of percentage. Think of it like a fuel gauge.
What Affects Charging Speed?
There are a lot of variables that affect each vehicle’s charging speed. When a battery is more depleted, the charging speed is typically faster. However, batteries don’t like to charge quickly when they’re too hot or too cold, so charging may be slower in extreme temperatures.
Different vehicle manufacturers design different batteries. And because the battery is usually the single most expensive “thing” inside a vehicle, it’s in everyone’s best interest to maximize the battery’s longevity, health, and safety. As a result, when a vehicle charges, the vehicle decides the power it draws from the charger in a way that maximizes longevity.
The charging system
Different electric vehicles have different capacities for charging speeds; charging stations also have different capacities, and the maximum rate of your charging session is determined by whichever is lower, the capability of the car or the charger. For example, a 50 kW capable EV would not charge any faster at a 350 kW station. Also, it is worth noting that higher capable vehicles can charge at lower capable stations, they are just limited to what the station can provide.
Electric vehicle batteries don't like to be too hot or too cold. The charging of a battery generates heat (check your mobile phone when its charging), and the battery management system will protect a battery from overheating, so when the battery gets too hot the battery management system will slow down charging (and if the ambient temperature is high or you've been driving your EV for a long time then this might happen earlier as the battery temperature is already elevated).
How Does the Vehicle Decide Your Charging Rate?
The vehicle’s Battery Management System (BMS — or “brain”) considers all of the factors explained above in order to maximize the longevity of the battery. Is the battery hot right now? Is it cold outside? Is the battery old and deteriorated? How full is the battery? Given all of this information, the vehicle tells the charger the voltage and current it can accept - the product of which determines the charge rate.
When the vehicle starts charging, it may reach (or get close to) the maximum charging rate (i.e. 50 kW). But as the charge continues — and the battery gets hotter and its cells start to fill — the vehicle will slow the charging rate to reduce the strain on the battery. When the battery is about 80% full, the charge rate can slow rapidly, as shown in the example below:
Why Does My Charging Speed Slow Down as I Charge?
To answer that question, we first have to understand the vehicle’s battery. When most people imagine a car battery, they might imagine one big block sitting inside the car. In reality, inside a “battery pack” are hundreds — and often thousands — of smaller “battery cells.” (The Tesla Model S has up to 7,104 battery cells!) As a result, when a battery charges, those thousands of cells are actually what’s being charged.
A helpful analogy might be to imagine sitting in a movie theater. When the theater is empty, it’s easy to find a seat right away. But as the theater fills up, we have to take a few moments to find a seat — and climb over people (without knocking over their popcorn). That’s what happens with battery cells at the molecular level. When the battery cells are nearly empty, it’s easy to “find a seat” to charge. But as the battery cells fill up, it takes more time to find (and navigate) the empty cells. Generally, above 80% full is when it’s hardest for electrons to find a seat in your battery’s movie theater.
NOTE: Your charging speed will slow down throughout the course of your charge. And every vehicle decides that “slow down rate” differently. Every manufacturer determines this in order to keep your vehicle’s battery healthy and increase longevity.
Why Am I Not Getting the Maximum Charge Rate on My Car’s Nameplate?
There are several reasons for this. When a car advertises a maximum charging rate of 50 kW, that doesn’t mean it can consistently charge at that rate.
When a vehicle connects to a charger, a conversation takes place between the charger and the vehicle — and it’s dominated by the vehicle. The charger tells the vehicle both the voltage and current rates it can accept, and the charger provides only what the vehicle can accommodate. As a result, the vehicle manages its battery to provide the longest useful life by not overcharging it. Here are some examples of things that affect your charging speed: