EVSEs provide power to charge EV batteries at Level 1 and Level 2 voltage ratings.
Electric vehicle (EV) owners rely on electric vehicle supply equipment (EVSE) to charge their batteries efficiently. Often referred to as charging stations or docks, EVSEs provide a reliable and safe connection between EVs, the electric grid, and other energy sources.
This FAQ explores the various components housed in EVSE enclosures, describes the differences between residential and commercial installations, and previews emerging EVSE trends.
A look inside EVSE enclosures
EVSE enclosures (Figure 1, left) protect sensitive electronics from environmental hazards such as rain, snow, and extreme temperatures. These enclosures also ensure the safety of drivers and passengers during charging cycles.
Designs range from compact wall-mounted units and bollard-style stations (short, stout, cylindrical units typically standing at waist height) to pedestal-mounted setups, pole-mounted variants, and standalone structures resembling gas station pumps. Advanced EVSEs support real-time monitoring, adjustable power output, and mobile apps.
Key components housed within EVSE enclosures include:
- Main relay: Functioning as the primary switch, the main relay safely and efficiently directs the flow of power to an EV.
- Control module: This component regulates and optimizes power delivery by analyzing key metrics from the main relay. The control module also protects both the EV and EVSE from potential electrical spikes and anomalies.
- Power Supply: Commonly a 12 VDC unit, this component provides energy to EVSE control modules and internal electronics.
- Plug connectors: Varying by geography and manufacturer-specific standards, plug connectors establish a physical link between vehicles and charging stations.
Understanding the charging capabilities of residential EVSEs
Residential EVSEs primarily support Level 1 and Level 2 AC charging. Level 1 stations operate at 120-VAC, drawing approximately 10 A, with a power capacity of 1 kW. Additionally, these stations often use National Electrical Manufacturers Association (NEMA) connectors, which are standardized for household electrical outlets. Increasingly popular due to faster charging rates, Level 2 stations operate at 240 VAC (often drawing more than 32 A) with power delivery exceeding 7 kW.
Many homeowners opt for Level 1 charging, which seamlessly integrates with existing wiring. Although they require a dedicated circuit, Level 2 chargers are preferred for quickly charging EVs with larger batteries. While residential EVSE connector standards vary, the most prevalent connectors for EVs in the US include the J1772 (Type 1) and Tesla’s proprietary design. See Figure 2.
Residential EVSEs often incorporate features such as Wi-Fi for remote monitoring via smartphone apps. Some even offer adjustable power settings, helping homeowners easily modify charging speeds based on energy consumption. For safety, features such as ground-fault circuit interrupters (GFCIs) and durable casing are common, ensuring EVSEs operate reliably in all conditions.
Residential hardwired EVSEs are favored for their integrated and polished look. Although appreciated for cost-effectiveness and portability, plug-ins are more vulnerable to theft due to their detachable design. While hardwired systems offer a more permanent setup, homeowner choice is typically made based on specific factors, such as installation location, budget, and frequency of use.
Exploring public and commercial EVSEs
Public and commercial EVSE designs span sleek wall-mounted units to extensive multi-port complexes. These stations predominantly offer AC (Level 2) and Level 3 DC Fast Charger (DCFC) configurations, support grid synchronization, efficient load distribution, and individualized billing.
Public and commercial EVSE stations offer multiple connectors to accommodate a wide range of EVs. For example, the J1772 Type 1 connector is common in North America and Japan, while Type 2 is favored in Europe. Originating in Japan, the CHAdeMO fast-charging system is also gaining global traction. In North America, the J1772 Combo (Type 1 CCS) is common, whereas the Type 2 Combo (Type 2 CCS) dominates in Europe. As mentioned earlier, Tesla’s proprietary connector is widely adopted in North America, with J1772-to-Tesla adapters being widely available.
A look ahead: Emerging EVSE trends
The EVSE industry continuously refines technologies and standards such as the Open Charge Point Protocol (OCPP) and Open Charge Point Interface (OCPI) to meet the evolving requirements of current and future EVs. OCPP provides a unified communication framework for EVSEs to ensure seamless interoperability for different EVs. At the same time, OCPI facilitates efficient data exchange with charging networks and delivers consistent service across various providers and regions.
Additional evolving EVSE standards and technologies include:
- Vehicle-to-grid (V2G): Assists EV owners in offsetting energy demand during peak times by redistributing excess power back to the grid.
- Wireless charging: Offers a tether-free charging experience using electromagnetic fields.
- AI-enhanced smart charging: Integrates artificial intelligence (AI) and machine learning (ML) to intelligently allocate energy.
- Solar-power panels: Complements electric grids during peak solar output, reducing reliance on conventional power sources.
- Integrated payment systems: Modernizes global EV charging by facilitating seamless payment options and integrating with apps from various automakers.
Summary
EVSEs serve as an essential interface between EVs, electric grids, and other energy sources. They include software and communications protocols and house crucial components to facilitate efficient power transfer, including the main relay, control module, and connectors. EVSEs are designed to accommodate different EVs with configurations available for residential, public, and commercial settings.
References
Inside the EVSE Infrastructure, Mouser
What is EVSE?, Lectron
Charging Electric Vehicles at Home, US Department of Energy
What is Electric Vehicle Supply Equipment?, EVConnect
OCPI vs OCPP, ChargeLab