RFID Cards vs. Smartphone Authentication: Which is Best for EV Charging?

More than one million electric vehicles are registered in the U.S.—and they all have to plug in somewhere. As EV charging stations pop up across the country, one of the top questions will be how charging station users are identified, authenticated and connected with membership or payment systems. Radio‐frequency identification (RFID) cards and tokens and smartphone authentication apps have emerged as two viable options for EV charging authentication. Which is best? It may depend on the user base you plan to serve.

User Authentication for EV Charging

Most electric vehicle owners have a spot to plug in at home, either in their own garage or carport or in a designated charging spot in a tenant parking garage. But electric vehicles also need places to charge while owners are out and about. The EV charging market is broadly divided into two tiers:

• Level 2 charging stations, which operate at 208-240 V and use AC power. These stations will add 20-25 miles of range in about an hour of charging. The U.S. Department of Transportation listed more than 22,800 public Level 2 EV charging stations across the nation as of mid-2020. They are commonly found in public parking lots and garages, hotels, grocery stores, malls and other commercial areas. They may also be installed in private parking garages and business parking lots for tenants, employees or fleet drivers. 
• Direct Current Fast Chargers (DCFS) are designed to charge an EV battery to about 80% in 20-30 minutes. There are currently about 15,000 DCFC stations across the U.S., but their numbers are expected to explode as more people start taking EVs on longer road trips. They are commonly found along major interstate highways.

As the market evolves, user authentication requirements for EV charging stations are likely to vary by type, location and user base.

• Some commercial locations may provide Level 2 EV charging as a free amenity to shoppers, guests or employees. If there is no charge for the service, there may be no need to authenticate users at all—people can park and plug at any available spot. However, there may be a benefit to collecting membership data (e.g., shopper reward club).
• Public, for-profit EV charging stations, like gas stations, need a method to collect payment for their services. In some cases (especially at roadside DCFS stations), users may pay for the minutes used with a credit card—just like at the gas station pump. However, many EV charging station users are already accustomed to identifying themselves with an RFID membership card or a smartphone app. Charging networks like ChargePoint and Blink enable members to access any EV charging station within their networks with a card or smartphone app, which connects to their membership, account and payment information.
• Private charging stations—such as those offered to tenants, employees, or fleet drivers—may not require payment but need to ensure that only authorized drivers access power and take up valuable parking spots. An RFID card or smartphone app can identify authorized drivers and track charging behaviors.

Moving forward, many EV charging stations may find that they need a mix of options for users, including membership cards, smartphone apps and a credit card payment option for out-of-network drivers.

Choosing Between RFID and Smartphone Apps for EV Charging

When user identification and authentication are desirable, which is the better option: RFID cards or smartphone authentication? Both have their uses in the EV charging market. In the long run, the answer may be “both.”

RFID cards are economical and easy to issue. And for some users bases, you may not have to issue a new card at all—you can take advantage of an RFID card they already carry. In many cases, it is possible to leverage existing employee IDs and membership cards for access to privately controlled EV charging stations. RFID membership cards may be a good bet for:

• Fleet drivers who already carry an RFID card for vehicle access.
• Employee parking lots and garages where people already use a card for entry.
• EV charging parking spots at gyms or other locations where you want to limit charging access to active members.

On the other hand, public charging stations may find that consumers prefer to use a smartphone app rather than receive another membership card to carry in a physical wallet. Many consumers prefer to carry only their phone and one or two essential cards (such as a driver’s license and a single credit or debit card). As more retailers enable consumers to pay via a digital wallet app on their smartphones, some don’t even carry a physical credit card anymore. Most consumers would prefer not to carry a physical membership card for every retail outlet they visit, including EV charging stations.

Smartphone apps for user authentication are simple to set up and highly secure. Instead of RFID, they typically use either Bluetooth® Low Energy (BLE) or Near-field Communication (NFC) protocols. For the user, the experience is almost identical to RFID authentication, except they wave a smartphone over the reader instead of a card. Apps have other user benefits, too. A custom app for EV charging can be configured to help users locate or reserve charging stations, check their balance and usage history, and change their payment options right on their phones. These features make smartphone authentication ideal for consumers accessing a public charging station network.

However, EV charging network managers should keep in mind that some users may still want a physical membership card. There are still some user populations, such as older consumers and those from lower-income brackets, where smartphone ownership is not ubiquitous. If users primarily use EV charging for a fleet vehicle, they may not want to download an application for work on their personal cell phone. Other users may find smartphone apps confusing or prefer to have a card for different reasons.

The answer for both public EV charging networks and private charging station owners is to have an RFID reader that is capable of both card-based and smartphone-based authentication. This will provide maximum flexibility as user preferences change.

Finding the Right RFID Reader for EV Charging

The best RFID reader for EV charging is one that is flexible enough to meet the needs of all user populations and evolve as requirements change. The ELATEC TWN4 MultiTech family of readers is ideal for authentication at EV charging stations.

• The reader supports 60+ RFID transponder technologies and BLE and NFC smartphone authentication. This means that one reader can support all technologies already in use across the entire user base—both nationally and internationally. This capability becomes essential for applications where you want to enable drivers to use an existing RFID card (such as their employee or fleet ID card or an access card for a tenant parking garage) for access to charging locations. It also provides more flexibility as technologies or preferences change in the future.
• TWN4 MultiTech supports advanced encryption and security configurations for highly secure transactions between the card or smartphone and the reader. This is important for EV charging applications tied to payment or employee/driver identification.
• ELATEC readers are mobile-ready. The ELATEC Mobile Badge BLE NFC App offers simple and practical components for building or extending a mobile application for EV charging networks. Non-managed mobile credentialing using the ELATEC app is free. TWN4 MultiTech readers also work with multiple existing third-party managed credential systems, such as KleverKey, Safetrust and Transact.
• The TWN4 MultiTech is easy to customize with the powerful Software Development Kit (DevPack) and App Blaster and Director utilities. Readers can be easily configured to support custom functionality (such as LED light flashing sequences or sounds for user feedback) and integration with backend software for easier member management. The DevPack tools make the TWN4 family the most powerful, versatile and sustainable readers on the market.  

As electric vehicles move from niche to mainstream, EV charging infrastructure will need to grow and evolve to accommodate millions more drivers—both in the consumer market and in commercial fleets. With TWN4 MultiTech readers, EV charging station managers will be ready.

Interested in learning more about technical considerations for RFID in EV charging? Download 14 Considerations for RFID Readers in EV Charging for additional advice, including operating power and consumption requirements, antenna placement, hardware communication interfaces and more.

Sean Houchin is the product manager for ELATEC Inc in Palm City, Florida, and part of the global ELATEC GmbH product management team. He has more than 20 years of experience in product development, management and applications engineering. Sean is an expert in RFID technology, optoelectronic and fiber optic video, audio, and data transmission equipment for military and commercial applications and is a veteran of the United States Navy.