EVSE calibration and legal metrology
EVSE Calibration and Energy Measurement Verification
Compare the energy recorded by a charging station with a traceable reference. Control the load, measure the deviation and document the result.
Energy measurement at the charging point
Measure the energy your customer receives.
A charging station can complete a session and still record the delivered energy incorrectly. Calibration compares its energy reading with a traceable reference at defined operating points. The result connects the deviation with the conditions under which it was measured.
Controlled operating points
Set voltage, current and dwell time so the same measurement can be repeated after an adjustment, repair or software change.
The installed charging path
Measure at the charging connection with real energy flowing. This includes the cable path and the effects present during the charging event.
Comparable results
Record station and reference values together. A documented campaign makes differences between stations and repeated tests easier to evaluate.
Beyond a single power rating
Cover the voltage and current combinations that matter.
Test in the relevant 400 V and 800 V charging bands and at the boundaries of the station's operating range. A headline power rating alone does not show whether a calibration load can reach every required point.
| Example operating point | What it reveals |
|---|---|
| 150 V × 500 A = 75 kW | A demanding high-current point at low voltage. The load must reach the current even though the total power is below its headline rating. |
| 1,000 V × 10 A = 10 kW | A high-voltage point at low current. Stable control and a suitable reference range matter here. |
Select the campaign for the station's supported range and the applicable procedure.
Prepare. Measure. Report.
Take a repeatable campaign from the office to the station.
- Prepare the campaign. Define operating points, dwell times and the information needed for the report in comframe.
- Connect at the station. Establish the charging communication and connect the reference measurement and controlled load.
- Run and review. Follow voltage and current during the measurement; compare the station's energy value with the reference.
- Keep the result. Store the measured values and campaign data and prepare the measurement report for review.
Controlled real-load calibration
Measure the complete charging event with a controlled real load.
Real-load testing operates the charging station during actual energy transfer. The reference and station meter observe the same charging event, including the selected operating point and the installed measurement path. Easy Chester Calimera provides a controlled load for repeatable work at installed stations.
This makes load stability, charging communication and thermal behaviour part of the measurement context. Plan the voltage, current, duration and synchronization needed for the applicable verification procedure.
Compact meter-circuit setups have a narrower test boundary: stimulating selected conditions does not reproduce the complete station under charging load. The selected method must therefore match the required EVSE verification scope.
Understand real-load calibration and measurement-scope limits →
Requirements and product capability
A practical route from requirement to measurement.
We configure the test system around the operating points, charging interfaces and measurement records your task requires.
| Reference | What it addresses | How Calimera supports the work |
|---|---|---|
| VDE-AR-E 2418-3-100 | Measurement systems for AC and DC charging under German legal metrology. | Controlled energy comparison and documented measurement campaigns. |
| OIML G 22:2022 | International guidance for EVSE metrological requirements and tests. | A repeatable load and reference measurement for the selected points. |
| NIST Handbook 44, §3.40 (2026) | EVSE test procedures, including separate DC type-evaluation and field-verification methods. | Configurable charging conditions and recorded station/reference values. |
| GM-P 6.8 Elektromobilität (20 February 2026) | German procedures for verification and in-service investigation of EVSE metering systems. | Reproducible test conditions and documented reference comparisons for the applicable procedure and selected configuration. |
Calibration provides a measurement result. Formal verification follows the applicable national procedure and authorization.
Easy Chester Calimera
Bring the calibration system to the station.
Calimera combines charging communication, reference measurement, controlled load and comframe in a mobile setup. Prepare the campaign once and bring the measurement equipment to the installed charging station.
A 150 kW configuration supports voltage up to 1,000 V and current up to 500 A; higher-power expansion options extend the available test range. Voltage, current and power limits apply together: these maxima are not available simultaneously at every operating point.
Our calibration experience also comes from the laboratory at comemso eMobility Services GmbH. Its published ISO/IEC 17025 accreditation documents describe the accredited scope. View the laboratory accreditation.
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Practical questions
EVSE calibration: what customers ask.
Why use a controlled load instead of a vehicle?
A normal electric vehicle controls its charging demand according to its battery state, temperature and charging curve. You cannot freely select and reliably repeat all the voltage and current operating points required for a complete metrological test with a vehicle and adapter. A controlled load makes those operating points reproducible within the configured test range.
The PTB presentation explains this limitation and states: “Benötigen ein voll-ausgestattetes Labor an der Ladeeinrichtung”. .
The permitted method depends on the task: calibration, formal verification (Eichung) and an in-service investigation (Befundprüfung) have different purposes. GM-P 6.8 includes procedure-specific vehicle use for a Befundprüfung; this is not a universal ban on vehicle-based checks. The applicable procedure determines the required test points and any permitted exceptions.
Does a successful charging session prove energy accuracy?
No. Functional charging and energy accuracy answer different questions. Calibration compares the recorded energy with a suitable reference at known conditions.
Can one setup cover every charging station?
The required interfaces, voltage/current range, continuous load capacity and reference uncertainty determine the configuration. Share the station data and required test points so we can match the system to the campaign.
Plan your EVSE calibration system.
Tell us the charging interface and required measurement range.