Today, there are three primary types of EV (Electric Vehicle) charging stations with a fourth under development. Charging equipment is classified by the speed, or rate, at which the vehicle batteries are charged. The rate of charge is a function both of the supply voltage and amperes. Higher voltages and/or higher amperes supply more power and therefore speed up charging. Each type of charging station require different levels of voltage, amperes, and in some cases phases of electricity, hence the three different types of charging stations. Another factor that must be considered is the rate at which an electric vehicle can safely receive charge. Nearly all new EVs come equipped with BMS (Battery Management Systems). These onboard systems optimize both service life and capacity range of electric vehicle batteries. Optimization is accomplished by thermal control of the battery as well as the charging rate. Every electric car is different and therefore the charging rate, or speed of battery charge, is different even if the charging station is the exact same. Of course charge time is also a function of level of battery depletion, total capacity of the vehicle batteries, physical and chemical composition of the battery, and ambient temperature. Cold batteries take more time to charge than warm batteries. Which charging station is right for you? Let’s explore the different types below.
Types of EV Charging Stations
Nearly all new electric vehicles come standard with a Level 1 AC (Alternating Current) car charger, or slow charger. A level one cordset receives power from a standard 120-volt, 15 or 20 amp receptacle. The cordset comes with a vehicle connector, generally an SAE J1772 charge port on one end, and a NEMA (National Electrical Manufacturers Association) 120-volt standard receptacle plug on the other. These types of EV charging stations provide a power rate around 3kW, or 3,000 watts. The charge time for a level one charger generally ranges from 10 to 14 hours and is well suited for overnight charging at home.
As a second option offered by most electric vehicle manufacturers, and various third-party suppliers, is a Level 2 AC electric car charging station, or fast charger. The output connection is the same as a level one charger using the J1772 charge port that connects the charging unit to the electric vehicle. Some newer level 2 chargers provide vehicle charging without any physical connection to the vehicle. These are wireless, or untethered, charging technologies that use inductive charging through an electromagnetic field. A level two unit obtains electricity from a multi-wire 240-volt, 40 or 50 amp receptacle or alternatively a permanent wire configuration. Many residential garages and carports do not have an existing 240-volt electrical circuit already in place, therefore a level 2 charger often requires installation of a new dedicated branch circuit. A level two unit provides power charging between 7 to 22kW, 22,000 watts. The level two charge times typically range from 2 to 6 hours, more than two times faster than a level one slow charger.
A third option is public Level 3 DC (Direct Current) fast charging. This type of unit fast charges the first 80% of the EV battery typically in 20 to 40 minutes, then tapers off reducing the charge speed during the final 20% to protect the batteries from excessive heat. There are three distinct connectors used with level three DC chargers, differentiated primarily based on EV country of origin. Most models built in Asia use a CHAdeMO connector, while German and American car makers rely on SAE Combo plug. Tesla is the only manufacturer with a proprietary connector. A level three unit can provide up to 100kW, 100,000 watts of power delivery. The key difference with a level three fast charger is how electricity is fed to the electric vehicle. With level one and two charging, alternating current is supplied to the electric vehicle which then converts the power onboard to direct current through the vehicle BMS. Alternatively, a level three charger converts AC from the power source to direct current and then feeds DC power directly to the EV batteries which significantly improves charging speed. Because DC fast charging typically require higher voltages such as 208 or 477 volts to properly operate, these units need a three-phase power supply. Nearly all residential service is single phase electrical supplying 120/240 volts as compared to commercial and industrial buildings which generally use three phase electrical service capable of 208/477 volts. The primary difference is the quantity of power delivered. Three phase service delivers both higher voltages and total power. Therefore, without significant electrical infrastructure upgrades to a home, which may not be available by the local utility, or financially feasible for the homeowner, DC fast charging is generally not a viable option for individual homes. This type of charging station is most common in heavy traffic locations, such as shopping areas, highways, rest areas and the like. According to the DOE (U.S. Department of Energy) over 15% of public EV charging stations are DC fast charging. Most plug-in hybrids, defined as an electric vehicle with an ICE (Internal Combustion Engine) do not have the ability to fast charge at all. There is some research suggesting DC fast charging may reduce the lifespan of certain types of batteries, although the degradation has found to be nominal. The initial research was completed by INL (Idaho National Laboratory) in 2011 with further assessment by Geotab a web-based analytics platform that integrates electric vehicle data. They found heat, high ambient temperatures, and frequent DC fast-charging combined to degrade batteries about 10% over six years. This degradation is not significant as all batteries lose some capacity over time.
XFC (Extreme Fast Chargers) is the newest EV charging technology currently being developed in the United States. This type of car charger is capable of power outputs of up to 350 kW and higher. The U.S. Department of Energy’s Vehicle Technologies Office is working to employ this technology at scale. A challenge with this type of charging are most electric vehicles today are only capable of accepting a maximum charge rate of 50kW with some notable exceptions such as Tesla reaching 125kW. This limit is determined by the EV battery voltage and maximum amperes the wire and components can safely accept. As Level 3 and XFC charging become more ubiquitous, manufacturers will undoubtedly engineer electric vehicles to accept faster and higher kW charges further reducing charge times.
For in-home charging, the best all-around EV charging station is a level 2 unit. The level two charger is a financially feasible option maximizing charging speed with minimal electrical upgrades to a home.
Incentives for a Fast Level Two Charger at Home
The Taxpayer Certainty and Disaster Tax Relief Act of 2020 extended property tax credit for alternative refueling systems installed before 31 December 2021. For the purposes of this federal tax incentive, the IRS considers electricity as an alternative fuel. Therefore, electric vehicle chargers, if installed in a home, qualify for a 30% credit not to exceed $1,000. See IRS form 8911 rev. February 2021.
Home Performance Group EV Charger Installation in Kansas City
Interested in a level 2 AC electric vehicle charger, consider hiring an electrical professional with expert knowledge to properly design, size and install your charger and power circuit. A small upfront investment in careful design can save thousands in future repairs and mitigate the chance of a home fire.
At Home Performance Group, we continue to invest in technical training so we can correctly design, specify, size, and install electrical branch and feeder circuits. We have performed numerous EV charging station installations for our clients. If you are interested in a no cost in-home consultation, schedule with a Solutions Advisor today.
If you are interested in a no-cost in-home consultation, schedule with a Solutions Advisor today.
Article by Larry L. Motley Jr., 2 August 2021
Larry is a graduate of both Wentworth Military Academy and Missouri Western State University earning a double bachelor’s degree in Economics and Finance. Additionally, he maintains six professional tradesman licenses in two states and advanced credentialing in green technology, project and program management, and process improvement. Larry is a three-time combat veteran having served in Operation Iraqi Freedom, Operation New Dawn, and Operation Inherent Resolve. He continues to serve through a value-based building science company focused on providing clients the best design, highest quality installation, and most honest repair services in the community.
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