A Factory Acceptance Test (FAT) is a formal set of inspections and functional tests performed at the manufacturer’s facility to verify that equipment meets the agreed technical specification before it is shipped to the site. In EV charging projects, FAT reduces commissioning risk by confirming hardware quality, safety functions, software configuration, and integration readiness in a controlled environment.
What Is a Factory Acceptance Test (FAT)?
FAT is a pre-shipment verification step used for chargers and related electrical systems.
– Confirms the product is built to the correct configuration (model, options, accessories)
– Validates key electrical safety and functional performance before delivery
– Documents test results and deviations, creating an auditable record
– Reduces on-site troubleshooting time and prevents costly returns
FAT is commonly required for large deployments, public tenders, fleet depots, or projects with strict compliance needs.
Why FAT Matters for EV Charging Infrastructure
– Catches build issues early (wiring errors, missing parts, incorrect configuration)
– Reduces site commissioning failures and prevents schedule delays
– Improves reliability by validating protective functions and control behavior
– Ensures the charger is ready for backend onboarding and remote management
– Provides evidence for procurement, QA, and warranty baseline documentation
– Reduces total project risk when deploying multiple units across many sites
What a Typical FAT Covers for EV Chargers
Visual and Documentation Checks
– Correct model, serial number, and configuration against the bill of materials
– Labeling, rating plates, and documentation pack completeness
– Assembly quality: seals, cable routing, torque markings, ingress protection features
– Mechanical fit and finish: doors, locks, connectors, displays, buttons
Electrical Safety Tests
– Protective earth continuity and bonding verification
– Insulation resistance tests on power circuits
– Dielectric withstand test (hipot) where required by the test plan
– Verification of protective device behavior (RCD/RCBO logic if integrated)
– Touch-safe checks and enclosure integrity
Functional Charging Tests
– Power-up sequence and self-diagnostics
– Connector detection and lock/unlock behavior (socket shutters where applicable)
– Start/stop charging under controlled load (simulated EV or test bench)
– Verification of output limits and current control
– Fault handling: emergency stop, ground fault, overcurrent, overtemperature responses
– Recovery behavior after faults and safe restart logic
Software and Communication Tests
– Firmware version verification and secure update readiness
– Charger configuration parameters (power limits, phase settings, load management inputs)
– Connectivity validation (Ethernet/cellular, where supported)
– Protocol readiness: OCPP connectivity to a test CPMS environment
– Time sync, logs, remote commands (start/stop, reboot, configuration push)
– Cybersecurity basics: credential policy, disabled services, certificate readiness (project-dependent)
Metering and Billing-Related Tests (Where Applicable)
– Correct meter installation and data reporting (kWh, timestamps)
– Accuracy verification approach per specification (spot checks or calibration evidence)
– Receipt and transaction data completeness for backend systems
– Tamper indicators and seal points where required
FAT Documentation and Outputs
A good FAT produces a clear test record that can be reused in commissioning and warranty workflows.
– FAT checklist and pass/fail results
– Measurement values (insulation, earth continuity, functional steps)
– Firmware/configuration snapshot
– Non-conformity list and corrective actions (with photos if needed)
– Final sign-off by manufacturer and customer/inspector (if attended)
– Reference to applicable standards and internal procedures
FAT vs Site Acceptance Test (SAT)
– FAT: done at the factory to verify build quality and core functionality before shipping
– SAT: done on-site to verify correct installation, grid compatibility, connectivity, and real-world operation
Both are complementary: FAT reduces risk before shipment; SAT validates the full system in its real environment.
When FAT Is Especially Valuable
– Multi-site rollouts with tight deadlines and standardized configurations
– High-volume orders where repeating errors would be expensive
– Projects requiring strict documentation packs and tender compliance
– Complex integrations (payment terminals, load management, EMS, metering)
– Remote or hard-to-service sites where rework is costly
Limitations to Consider
– FAT cannot fully replicate site conditions (grid quality, grounding, network/firewalls, physical layout)
– Some issues only appear under real EV behavior, local vehicle mix, or extreme weather
– If the FAT scope is too narrow, critical integration risks can still move to the site
– FAT adds time and cost, so the test plan should focus on the highest-risk functions and customer requirements
Related Glossary Terms
Site Acceptance Test (SAT)
Electrical Commissioning
Conformity Assessment
Dielectric Withstand Test
OCPP
MID Metering
Charger Diagnostics
Secure Update Pipeline