Electric Vehicles

Electric Vehicles

Questions and answers from EC&M webinar on how electrical systems will be modified for new electric vehicles (EVs)

On June 9, 2010, EC&M hosted a free webinar titled, “Electric Vehicles are Coming — Is Our Electrical Infrastructure Ready to Accept Them?” The 1-hr event was sponsored by GE Energy — Industrial Solutions, which provides energy solutions for commercial, industrial, and residential use in more than 100 countries. The 45-min. presentation was delivered by Michael Mahan, global product manager electric vehicle supply equipment, and Keith Brock, senior specifications engineer — both of GE Energy — Industrial Solutions. For those of you who may have missed the webinar but still want to listen in on it, check out the archived session.

Automakers have started to launch new electric vehicles (EVs) or plug-in hybrid electric vehicles (PHEVs) into the U.S. marketplace. A key factor in the successful introduction and adoption of EVs will be the ease and convenience of access to refueling points by the vehicle owner. This can only be accomplished by designing and constructing a widely distributed network of EV charging stations. In addition to installation of the charging stations themselves, the development of this network will require enhancements to the U.S. electrical grid and power distribution system, as well as end-user facilities. This new “charging infrastructure” will need to be built in the home, at work, at coffee shops, near shopping malls, hotels and all around town — virtually anywhere we drive, stop, and park our vehicles.

This webinar addressed the types of customers and buildings that will require EV infrastructure equipment and the estimated size of the potential market opportunity for new business. It also offered a glimpse of EV charging station product specifications and their associated codes and standards — and showed examples of electrical infrastructure designs for residential and commercial applications. The live presentation drew more than 750 participants as well as an impressive number of questions submitted by attendees throughout the live event. As a follow-up to this webinar, we thought it would be worthwhile to present a summary of some of the most pressing Q&A items generated from this event.

Q. Will smart meters make it cheaper to charge the car at night as opposed to peak daytime hours?

A. Yes. Every utility’s time-of-use hours are different. Off-peak hours are generally from 8 p.m. to 6 a.m. Monday through Friday and all day Saturday and Sunday.

Q. What impact will an EV have on an electrical bill in a regular household with at least one car used daily?

A. While we cannot predict all geographic utility costs for charging, we believe it will be around $2 a charge or $10 per week using our company’s charging station and a car with a battery capacity of 24kW.

Q. For public charging stations, is there a standard for billing the hookups?

A. No.

Q. How long is it projected to take for EVs to hit the streets in Midwestern cities?

A. We would expect EVs to be in most parts of the United States by early 2011.

Q. Is the SAE J1772 connector standardized across all levels of charging? I have been told by a couple of fast charging manufacturers that it is for Levels I and II, but is being disputed by one car manufacturer for Level III?

A. It’s currently the standard for Levels I and II, but not for Level III.

Q. Where in Art. 625 of the 2008 NEC does it require that the cable be permanently connected to the charging station?

A. Section 625.13 (Electric Vehicle Supply Equipment) of the 2008 NEC reads as follows: “Electric vehicle supply equipment rated at 125V, single phase, 15A and 20A or part of a system identified and listed as suitable for the purpose and meeting the requirements of 625.18, 625.19, and 625.29 shall be permitted to be cord-and plug-connected. All other electric vehicle supply equipment shall be permanently connected and fastened in place. This equipment shall have no exposed live parts.”

Q. Is our current power grid sufficient to accommodate mass EV usage?

A. It depends on what you mean by “mass vehicle usage.” In general, the electric grid is sufficient for off-peak charging. On-peak charging capability depends on individual utilities.

Q. How would the energy rate be determined at public charging station locations?

A. This is still to be decided. We know there are a couple of methods that can be used. In some states, you cannot resell electricity. Therefore, it will be more of a convenience charge. For example, a public parking lot or structure may impose a fee (say $5 or $10) to park and charge your vehicle at the same time.

Q. As electric utility engineers, we are concerned about the quantity of harmonic current generated by these new vehicles.

A. FCC 15 sets the level of harmonic distortion for automotive manufacturers to meet when filtering their rectifiers. Most of them are publishing total harmonic distortion (THD) levels between 5% to 10%.

Q. What about making the chargers 3-phase? Wouldn’t that take care of balancing the distribution loads between single-phase chargers?

A. Yes, but the expense between single- and 3-phase chargers would be very high. As long as the electrician or engineer distributes the loads equally in the panelboard, the real consumption should be very close and should not be an issue.

Q. How would I get into providing design services and/or installation services in my area?

A. Your first step should be to get educated. View the EC&M webinar, if you haven’t already done so, and study the installation examples provided in this session. Then decide where your services would fit within the proposed infrastructure. Another good resource for you to check out is ElectricDrive.org.
The Electric Drive Transportation Association (EDTA) is the industry association dedicated to advancing electric drive as a core technology on the road to sustainable mobility. As an advocate for the adoption of electric drive technologies, EDTA serves as the unified voice for the industry and is the primary source of information and education related to electric drive.

Q. When an EV is fully charged, does the charging station shut down and stop supplying power to the vehicle?

A. Yes, the car protects the battery from overcharging by telling the charger to shut down.

Q. You said Level II charging would take 4 hr to 8 hr with charging current up to 80A. How long will charging take if you limit the charge to 32A?

A. This was not said during the presentation. Level II charging stations are rated for a 40A circuit and charge at 32A. The charging time depends on the car and the battery. For example, an EV with a 24kW battery will take 4 hr to 8 hr to charge with a 32A supply.

Q. Do you think there will be any demand factor adopted by the NEC for multiple charging stations?

A. We expect the NEC to provide guidelines on this issue in the near future. For now, we think assuming 100% is the safe bet.

Q. What precautions must be taken when charging an EV in inclement weather?

A. None. The charging stations are equipped with GFCI protection.

Q. Will the first generation of EVs support Level II charging?

A. It depends on the vehicle manufacturer, but typically the answer is yes.

Q. Do EVs have a standard battery voltage, or will the charger be able to determine the battery voltage of the EV that is connected to it?

A. This issue will be addressed by the vehicle manufacturer rather than the charge station manufacturer. We recommend you check out the various EV car manufacturers’ websites for this type of information.

Q. Will EVs come equipped for Level III charging?

A. We are not sure about all makes and models, but at least one EV will come with a Level III option.

Q. Let’s assume you’re installing a new charging station in an existing building. If you need to upgrade the panelboard, run additional conduit, and cut paths in the concrete sidewalk, how you do explain the return on investment (ROI) to the customer (i.e., store owner)?

A. We feel retail outlets or store owners will install and make available EV charging stations for two reasons. First, they will do it because it’s the “right thing to do” for the environment, or they want to be seen as a green leader in the retail industry. Secondly, some of them will view the charging stations as a competitive advantage. The incentive would exist for their customer to choose a charging-station-equipped store over its competitor’s non-equipped charging station store.

Q. Is the electric utility always the power seller down to the charging station, or will the hotel owner (as an example) be able to add surcharges to the retail price of electricity?

A. Most electric utilities have a defined and exclusive service territory. Adding surcharges to the retail price of electricity is typically prohibited by the governing Public Service Commission (PSC). For example, in Baltimore, the electric utility is only allowed to charge a $1 surcharge to render the bill.

Q. Can you speak briefly about the DC option for charging?

A. There is a rectifier in the vehicle that will typically allow DC charging, but you have to consult each vehicle manufacturer to be certain this will work for its specific vehicle. Because the auto manufacturer designs the rectifier, which could be designed in any number of ways, you would have to check with the specific automobile maker to see if the electronics would be damaged or not produce the correct DC level if the charging voltage is DC rather than AC.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.