An EV charging station display is the primary user interface for electric vehicle charging — guiding the driver through connector selection, authentication, charging session monitoring, and payment — across a range of environmental conditions that impose hard constraints on display technology, touch interface, and GUI architecture. From compact AC wall boxes in parking garages to high-power DC fast chargers on motorway corridors, the display is the critical touchpoint between the charging network and the driver. Designing it well requires balancing outdoor durability, payment UX standards, real-time session data, and cost-optimised hardware. This guide covers each dimension.
Types of EV Charging Displays
EV charging stations span a wide range of form factors, each with different display requirements:
- AC slow chargers (Level 1/2, 3.7–22 kW): Compact wall-mounted units in parking garages, residential complexes, and workplaces. Displays range from minimal LED status indicators to 4–7 inch touchscreens. Interaction: tap RFID card or scan QR code, receive confirmation. No complex UX required.
- DC fast chargers (Level 3, 50–150 kW): Standalone kiosk units in petrol station forecourts, motorways, retail car parks. 7–10 inch touchscreens, payment terminal integration (NFC, card reader), multi-connector selection (CCS, CHAdeMO, Type 2). Complex UX flow with authentication, session monitoring, and receipt.
- Ultra-fast chargers (HPC, 150–350 kW): Premium kiosk units at dedicated charging hubs. 10–15 inch displays, advertising screens, loyalty program integration. Higher display quality expectations — customer-facing in high-visibility locations.
Outdoor Display Requirements: What Makes EV Charger Displays Different
Outdoor EV charging displays operate in conditions that indoor consumer electronics never experience:
- Sunlight readability: Direct sunlight produces ambient illuminance of 100,000 lux. Standard indoor displays become unreadable above 10,000 lux. Outdoor displays require minimum 1000 nit brightness (preferably 1500–2000 nit) with optical bonding to eliminate internal reflections. Optical bonding (filling the air gap between the cover glass and LCD panel with optically clear adhesive) reduces reflective glare by 70–80% and is non-negotiable for outdoor display legibility.
- Temperature range: Operating from -30°C to +70°C in direct sun. Display controllers, MCUs, and touch controllers must all be rated for the full operating range. LCD panels have known issues below -20°C (slow pixel response); wide-temperature-rated panels or heater elements may be required in cold-climate deployments.
- Ingress protection: IP54 minimum (protected against dust and water spray from all directions) for most deployments; IP65 or IP66 for exposed locations. The display, touch controller interface, and any front-panel openings must all maintain the rated IP class.
- Vandalism resistance: Public-facing displays are subject to physical impact. Minimum 4mm tempered glass or polycarbonate cover lens. IK08 impact rating (5 joule impact) is a common specification for public charger displays.
- Touch with rain and gloves: Projected capacitive touch (PCT/PCAP) with a cover glass > 4mm loses sensitivity for standard tuning. Touch controller firmware must be configured for thick-glass operation. Rain detection and rejection is critical — outdoor touchscreens must distinguish rainfall (which should not generate touch events) from deliberate finger touches.
UX Workflow Design: The EV Charging User Journey
The EV charging station UX has a defined sequential workflow that the GUI must guide the user through without ambiguity:
- Idle/attract state: Display is visible from distance, showing availability status (free/occupied/out of service), charger power level, and pricing. Animation or motion on the idle screen draws attention to the charger. Must be sunlight-readable from 3–5 metres.
- Connector selection: If multiple connector types are available (CCS + CHAdeMO + Type 2), the user selects their connector type. Clear iconography — IEC connector symbols are standardised — with large touch targets (minimum 20mm × 20mm for outdoor gloved operation).
- Authentication: RFID/NFC card tap, QR code scan, or app-linked session (ISO 15118 Plug & Charge). The GUI must provide clear feedback during the authentication phase — RFID tap confirmation animation, QR code scanning guide, or network authentication progress indicator.
- Session start: Clear confirmation that charging has begun. EV connection detection feedback. Initial State of Charge (SoC) from OCPP communication (if available).
- Charging progress monitoring: Real-time display of: kWh delivered, session duration, current power (kW), estimated time to target SoC, estimated cost. Progress bar or circular arc visualisation. Must update at least once per 5 seconds — drivers actively monitor session progress.
- Session end: Automatic display when charging stops (SoC target reached, user stop request, cable unplug). Total kWh, total time, total cost summary with itemisation.
- Receipt: Print receipt option (if printer fitted), email receipt (via QR code to web portal), or app receipt if mobile-linked session.
Hardware Platform Selection
EV charging station MCU selection is driven by display resolution, connectivity requirements (4G/LTE modem, OCPP over Ethernet, RFID reader, payment terminal interface), and cost.
- STM32H7 series: Suitable for compact AC chargers and basic DC fast chargers with 4–7 inch displays at 800×480. DMA2D hardware acceleration provides smooth progress animations. Low cost, wide availability, and STM32's Cube ecosystem make it a common choice for cost-sensitive charger designs.
- NXP i.MX RT1170: For DC fast chargers with 10-inch displays, multi-connector UX, and higher animation quality. Dual Cortex-M7+M4 enables separating the connectivity stack from the GUI rendering task. 2D/3D GPU supports richer visual design.
- Renesas RA6M3 / RA8D1: Good balance of graphics performance and connectivity peripheral integration. RA8D1 with Mali GPU handles complex progress visualisations at full resolution smoothly.
Real-Time Data Display: Connecting OCPP to the GUI
The OCPP (Open Charge Point Protocol) communication stack runs on the charger's connectivity module, exchanging charging session data with the central management system. The GUI must consume OCPP-derived data — SoC, power, kWh delivered, session status — and display it in real time without blocking the OCPP stack or dropping data.
Design the data pipeline as a shared memory model: the OCPP task writes session data to a shared structure with RTOS mutex protection; the GUI rendering task reads from this structure at the display frame rate. Never read directly from the network stack in the rendering path. Use a watchdog or timeout to detect OCPP communication loss and display a connectivity warning in the GUI.
Visual Design Considerations for EV Charger Displays
- High contrast for outdoor readability: White or very light text on dark backgrounds performs better in sunlight than dark text on white (backlight-dependent). Test all screen states in direct simulated sunlight before finalising colour palette.
- Large, glove-friendly targets: All primary touch targets (connector selection, authentication confirmation, stop charging) must be minimum 20×20mm on the physical display surface — not just in the GUI layout coordinates.
- Multi-language support: Public charging infrastructure serves international users. Plan for dynamic language switching based on user preference or network locale. Sparklet's Unicode rendering engine supports dynamic language switching without UI rebuild.
- Accessibility: High contrast mode, large text option, and screen reader integration may be required for public-use kiosk compliance in certain markets.
Developing EV Charger UIs with Sparklet
Sparklet's architecture maps directly to EV charger GUI requirements: the OCPP data pipeline connects to Sparklet's widget data binding, real-time progress bars and animated arcs render via hardware acceleration, and the charging session state machine is modelled visually in Flint UI Designer. The Windows simulator enables full EV charger UX development — including simulated OCPP data — before target hardware is available.
Explore Sparklet's features and supported hardware platforms for EV charging applications, or request the evaluation package to begin your charger UI development.