KPIs for Charging Networks: Uptime, Utilization, Session Success and More

Short answer: run a charging network on four groups of KPIs: availability (uptime, repair time), driver experience (session success rate), commercial performance (utilization, energy and revenue per connector) and cost (cost per kWh delivered). Define each precisely, measure it per connector and per site in your CPMS, and review the worst sites every month.

The KPI set

KPI	Formula	What it tells you	Benchmark or target
Uptime	Time the connector can charge ÷ total time	Is the hardware available?	> 97 % per connector (US NEVI requirement)
Session success rate	Successful sessions ÷ attempted sessions	Can drivers actually charge?	As close to 100 % as possible; track failures by cause
Utilization	Charging time ÷ available time	Is the site busy enough?	US DC average 16.4 % in 2025 (Paren); compare with your break-even
Energy per connector per day	kWh delivered ÷ connectors ÷ days	Commercial output	Site-specific
Energy per session	kWh ÷ sessions	Dwell and vehicle mix	Highway DC typically higher than urban
Revenue per connector	Revenue ÷ connectors	Commercial result	Against your business plan
Mean time to repair (MTTR)	Total repair time ÷ number of faults	Service performance	Agree in the service contract
Faults per connector per month	Faults ÷ connectors	Hardware reliability	Trend down over time
Cost per kWh delivered	All site costs ÷ kWh	Efficiency	Below your price per kWh
Peak demand vs installed power	Highest site kW ÷ installed kW	Demand-charge exposure	Managed by load limits

Define before you measure

Small definition differences change the numbers a lot:

Question	Options
Per connector or per site?	Per connector is stricter and more useful
Base time	24 hours a day, or the site’s opening hours
Planned maintenance	Counted as downtime or excluded
Grid outages and vandalism	Counted or excluded (NEVI excludes some causes outside the operator’s control)
Utilization	Charging time, or plugged-in time including idle
Session success	From the first authorisation attempt, or from plug-in

Write the definitions down and keep them the same, so that months and sites can be compared.

Session success: the KPI drivers feel

A connector can be online and still fail drivers: a payment terminal that times out, a cable that will not unlock, a car model whose handshake fails. J.D. Power’s 2026 US study found 12 % of public charging visits ended without a charge. Track failed sessions by cause in the CPMS:

Failure cause	Typical action
Authorisation or payment errors	Payment provider, CPMS settings
Communication timeouts	Network connection, local authorisation list
Vehicle communication errors with specific models	Firmware update from the charger supplier
Connector or cable faults	Replace; check cable management
Power module or internal faults	Repair; check modules and spares

Turning KPIs into action

1. Rank sites each month by uptime, session success and utilization.
2. Investigate the bottom five: a few sites usually cause most lost revenue.
3. Separate hardware, software and site causes — and take hardware issues to the supplier with logs.
4. Feed utilization into decisions: price changes at busy times, more chargers at full sites, marketing at quiet ones.
5. Report to partners: site hosts and funders often require uptime and usage reports.

Data you need from the charger

Data	Why
Connector status changes with timestamps	Uptime
Session start, stop and energy	Utilization, energy, revenue
Detailed error codes	Failure causes, repair time
Meter values during sessions	Power profiles, demand management
Firmware version	Linking faults to versions

VULTAE chargers report status, meter values and detailed error codes over OCPP 1.6J / 2.0.1 to the CPMS you choose — see charge point management software and uptime.