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Vehicle Interoperability Best Practices to Enhance the EV Customer Experience 

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By Jeremy Bibeau, EVSE System Engineer
Feb 6, 2024

2023 was a record year for the electric vehicle (EV) industry. Over 1.4 million EVs were sold in the U.S., a 50% increase in one year.1 With more than 50 EV models on the road featuring unique software and communications protocols, it is more important than ever to focus on the interoperability between EVs and charging infrastructure. In the EV charging industry, interoperability refers to the ability of different EVs to seamlessly charge with any charger, otherwise known as the complex “handshake” between the vehicle and charger. During this handshake, EVs and chargers bilaterally communicate with each other, which introduces complexities and multiple potential friction points. To ensure a consistently seamless charging experience, the EV and the charging infrastructure must harmoniously work together.  

As a part of EVgo’s commitment to enhancing the customer experience, a team of engineers, including myself, perform extensive interoperability testing at the EVgo Innovation Lab in collaboration with industry stakeholders such as automakers and equipment manufacturers. We invite all automakers to visit our Lab for this testing at no charge to not only help bolster One & Done success rates on the EVgo network but also to support the advancement of the entire EV charging industry.  

Based on the expertise and testing performed at our Lab, we identified and shared nine best practices for vehicle interoperability with the Connect the Watts™ community to increase the efficiency, accessibility and experience of EV charging. If implemented industry-wide, these best practices will support the continued adoption of EVs across the U.S. and ultimately aid the achievement of the country’s electrification goals. EVgo highly encourages automakers to incorporate these best practices to ensure a seamless handshake between the vehicle and charger.  

  1. Allow Ample Time for Charging Session Authentication Before Time Out 

    EV drivers, especially first-time EV drivers, often take a few minutes to plug in, pay for and initiate a charging session. Public fast charging is different than filling up a gas tank as you can choose between using an app, finding a program/RFID card or swiping your credit card to begin a session. The current standard authentication time after plugging in a connector can be as short as 60 seconds, which doesn’t always allow enough time for new or existing drivers to start a charge before having to unplug and plug in the connector again. A short authentication time often leads to unsuccessful charging attempts for customers. 

    However, this type of unsuccessful charging attempt can be avoided if automakers and charging equipment manufacturers extend authentication to at least 150 seconds (two and a half minutes) before triggering session timeout. With this best practice widely implemented, EV drivers will have enough time to successfully initiate a charging session on the first try – what EVgo refers to as One & Done success – which will improve satisfaction with public EV charging infrastructure. As part of our Reliability Solutions best practices, EVgo recommends that this longer time-out be included in both the vehicle and the charger, and ultimately that codes and standards be adopted to facilitate this otherwise significant barrier to One & Done success. 

  2. Initiate Seamless Retry of Charge Session Set Up to Ensure First-Plug Success  

    In addition to extending authentication time, the seamless retry of charging sessions by the charger is a built-in redundancy to help ensure One & Done success. Before the session times out, it would be best for the vehicle to be capable of following a specific state change sequence at least five times without unplugging the connector from the EV. This best practice not only improves session authentication but also corrects other potential errors such as cable check and pre-charge failures, leading to higher One & Done success rates.  

  3. Match the EV Communication Controller ID (EVCCID) and MAC Address 

    Ever wonder how EVgo implemented Autocharge+ across our network? A key component to this functionality is the MAC address of your EV, which is a unique identifier (similar to your EVgo program card). It enables EVgo’s network to recognize your unique EV model, associate it with your customer account and initiate a charging session by simply plugging in. When the EVCCID doesn’t match the MAC address or MAC addresses are duplicated, we’re unable to provide proper Autocharge+ functionality to an EV model. To enable this seamless experience for even more EV drivers, it is best practice for EV manufacturers to match the EVCCID to the MAC address and never duplicate MAC addresses across vehicles. 

    In addition to Autocharge+ compatibility, EVgo encourages EV manufacturers to support ISO 15118-2. This will allow for Plug & Charge technology to be used in the future, which is another secure method for authorizing payment by simply plugging in.

    autocharge shot

  4. Standardize Vehicle Port Locations 

    There are over 50 different EV models available in the U.S. and the charging port location on each model varies from center front, back driver side, front driver side, front passenger side, and back passenger side. With five possible locations across EVs of various lengths, EV charging stations must be equipped with longer cables to reach all charging port locations, increasing the probability of strain on the cable. This also requires the cables to include more materials often resulting in heavier cables, which can introduce customer experience issues, decrease efficiency of charging and increase the likelihood of unintentional damage from usage. By standardizing EV port locations, just like gas fuel fill inlets on ICE vehicles, the industry can simplify station design and customer experience. This best practice would have the added benefit of supporting those with disabilities or other EV drivers who may currently experience difficulty maneuvering heavier charging cables. 

Regardless of what EV you drive, EVgo is committed to providing a best-in-class customer experience. That is why we engage partners across the EV ecosystem and develop best practices to help ensure drivers have a seamless experience from the beginning of their EV journey. It is also why we attend the CharIN Testival North America, participate in industry groups such as CharIN and the ChargeX Consortium, as well as lend our voice to and endorse international standards including SAE, ISO and DIN. The customer experience is pivotal to the continued adoption of EVs and we’re on a mission to expedite the transition by delivering reliable and accessible public fast charging for everyone.  

Interested in learning more? Dive into the full vehicle interoperability best practices that were specifically created for EV manufacturers.