EV Charging Basics

Electric vehicle charging is broken down into the following “levels”:

Level 1: 120V connection – plugs into wall in a standard 120V AC outlet

Level 2: 240V connection – utilizes 240V AC outlet or electrician installs in existing breaker in panel.

Level 3 (DC Fast Charge – DFCF): 480V DC direct connection to onboard charging port

This posts focuses on Level 2 charging, or the most popular for residential, workplace, and hotels. Basically, anywhere that long charging periods (ie at work or overnight) are the main charging methods for an EV. Level 2 charging is the primary type that we install at Mr. Car Charger.

Level 2 chargers can be wired directly to a circuit breaker by an electrician or they can utilize a plug to plug into an existing 240V receptacle that an electrician has installed. If utilizing a 240V receptacle there are two types of plugs:

  • NEMA 6-50P (welder plug)
  • NEMA 14-50P (stove plug)

If a 240V receptacle is not available you may need to hire an electrician to install the EV charger in an existing breaker.

The charging speed of EV’s plugged into Level 2 charging stations operating at 240V depends on:

  • The amperage of the charger (usually 16, 30, 32 or 40 amps)
  • The car’s acceptance rate in kW

The maximum power you can get from 16 amps, 30 amps, 32 amps and 40 amps chargers are the following EV power ratings at 240 V from PGE EV Fleet Guide. Keep in mind that the maximum continuous draw of the breaker is 80% of its full load amperage.

Energy (kWh) that is added to the EV battery is a function of the power rating (kW) and time plugged in (hours, h):

Energy (kWh) = Power (kW) * Time (h)

EV’s have a max power acceptance for Level 2 and DCFC. For instance, if an EV has a max charging power acceptance of 7.7 kW for Level 2 and it is plugged in for 1 hour, it will add 7.7 kWh of energy to the battery. If plugged in for 2 hours it will add 15.4 kWh of energy to the battery.

Connector Type:

SAE J1772 – Most electric cars use this connection type

Tesla SAE J1772 Charging Adapter – needed if you have a Tesla and want to use an EV Charger that has a J1772 connector

ChargeHub maintains an excellent page for EV charging station information, both for home and public charging.

Mounting:

Level 2 chargers will typically mount on a wall if inside of a residence (garage) or utilize a pedestal/bollard mount if at a commercial property (as shown in the image with the ChargePoint EV charger). If mounting at a commercial property, other considerations include:

  • Concrete work
  • Bollards to ensure EV’s do not hit the charging infrastructure
  • Americans with Disability Act (ADA) accessibility
  • Cord management.

An example of a Level 2 charger on a pedestal with cord management from Chargepoint is shown on the right.

Communication Capability:

Many chargers now have Wi-Fi connectivity.  Your EV may already have Wi-Fi capability and if so, you’ll need to decide if you want to use the EV’s or the charger’s Wi-Fi.  The advantage of having this is:

  • Remote Control – enabling which EV can connect to the charger
  • Data Monitoring – feedback on charging performance
  • Utility integration (if utility offers Time of Use (TOU) charging rates and other charging programs)

Other Considerations:

  • Access/Interface for commercial customers: How will they engage with the EV Charger
  • Utility incentives – ChargePoint maintains a useful database of EV charger incentives
  • Charging Cable Length
  • Outside or Inside – If outside, you’ll want to know the EV charger’s enclosure NEMA rating
  • Locking system – If installed outside using a plug (ie not hardwired)
  • Warranty – often overlooked but very important for such an important piece of equipment. Make sure the company you are purchasing from is reputable and has been in business long enough that you feel comfortable they could honor the warranty!
  • Holster to hold the cable/connector?

Below is a great graphic from Alternative Fuels Data Center on Electric Vehicles Charging Infrastructure:

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