Signed meter value

A meter reading signed by the meter itself, so drivers and operators can check that it is authentic and unaltered.

Explained in

OCPP in depth · Stop 05How do status and meter values travel?Connector status, periodic and clock-aligned meter values, and signed readings for measuring law: the data a charger sends while nothing seems to happen.

Where measuring law requires it, as in Germany, the meter signs its readings. OCPP transports these signed meter values from the charger to the backend; at minimum, a signed start and a signed end value are needed. The meter's public key belongs to the meter itself and changes only when the meter is replaced, so a driver or operator can check the readings against it.

From “Readings a driver can check”, stop 05

Also in

  1. OCPI and roaming · Stop 06How does a CDR settle a session?Push or pull
  2. Payments and billing · Stop 07What belongs on a charging invoice?Session details that help
  3. Regulations and compliance · Stop 04What does measuring law require?Until then: national rules
  4. Regulations and compliance · Stop 07How do national rules add to EU law?Two German examples
  1. OCPPOpen Charge Point Protocol: the open protocol between a charger and its operator's backend.
  1. Open Charge Alliance: Signed Meter Values (Eichrecht paper), version 1.0, February 2025. https://openchargealliance.org/wp-content/uploads/2025/05/signed_meter_values-v10-1.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
  2. Open Charge Alliance: Signed Meter Values (Eichrecht paper), version 1.0, February 2025. https://openchargealliance.org/wp-content/uploads/2025/05/signed_meter_values-v10-1.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.