Availability is a reliability metric that describes how often an EV charger or charging network is operational and usable for drivers. It is usually expressed as a percentage of time a charger is ready to deliver charging, and it is a key KPI for CPOs, site owners, fleets, and public infrastructure programs.
What Is Availability?
Availability measures whether a charger is in a state where a customer can successfully start and complete a charging session. A charger is considered available when it is:
– Powered on and functioning
– Communicating correctly (where network connectivity is required)
– Able to authenticate users (RFID/app/QR)
– Able to deliver energy without faults
– Not blocked by critical errors (connector faults, isolation errors, safety trips)
Availability is different from “uptime” in casual usage, because a charger can be powered on but still not usable due to software, payment, communication, or hardware issues.
Why Availability Matters in EV Infrastructure
High availability is essential for user trust and network growth. If chargers are frequently offline or failing, drivers avoid the location and the operator loses revenue.
Availability impacts:
– Customer satisfaction and station reputation
– Revenue and utilization for CPOs and hosts
– Compliance with public funding requirements and SLAs
– Fleet operational planning and depot readiness
– Maintenance workload and operational costs
For public charging especially, availability is a core measure of service quality and is often required in tenders and government programs.
How Availability Is Measured
Availability is typically calculated over a defined period (daily, monthly, yearly):
– Availability (%) = (Time charger is operational and usable ÷ Total time in period) × 100
Operators may track availability at different levels:
– Per connector (most precise)
– Per charger (single or dual outlet)
– Per site (aggregated across multiple charge points)
– Network-wide (portfolio KPI)
Many systems determine availability using charger status signals via OCPP, combined with operational rules defining which states count as “available.”
Common Causes of Low Availability
– Grid power outages or unstable supply
– Hardware failures (contactors, relays, connector wear, cable damage)
– Software crashes or misconfigurations
– Communication failures (SIM, router, backend downtime)
– Payment or authentication issues (RFID, app, QR payment flow)
– Safety-related faults (RCD trips, insulation monitoring alarms, overheating)
– Poor maintenance (blocked connectors, vandalism, environmental damage)
How to Improve Availability
Typical strategies used by CPOs and site owners include:
– Remote monitoring and proactive fault detection
– Preventive maintenance schedules and spare parts strategy
– Robust installation quality (earthing, protection devices, correct cabling)
– Redundant connectivity options (e.g., Ethernet + cellular)
– Clear fault-handling workflows and fast service response
– Load management that prevents overload trips and nuisance shutdowns
– Firmware management and controlled updates across fleets
Key Benefits of High Availability
– More charging sessions and higher revenue per charger
– Stronger driver trust and better public reviews
– Improved ROI and faster network growth
– Easier compliance with SLAs, funding programs, and corporate standards
– Lower total cost of operation through proactive service rather than emergency repairs
Limitations to Consider
– Availability definitions can differ between operators (what counts as “available”)
– A charger can be technically available but practically unusable if bays are blocked or signage is poor
– Measuring only backend status can miss real user issues (e.g., payment failures, intermittent faults)
– Public sites face higher risks from vandalism, misuse, and environmental exposure
Related Glossary Terms
Uptime
Service Level Agreement (SLA)
Remote Monitoring
Preventive Maintenance
Fault Diagnostics
OCPP
Mean Time Between Failures (MTBF)
Mean Time To Repair (MTTR)
Charging Session Failure Rate
Charger Status Notifications