When a driver in another country taps a card at your charger, two identifiers must be understood by every system in between: the identifier of the charging point and the identifier of the driver's contract. In e-mobility these are the EVSE ID and the EMAID. They look like simple strings, but wrong formats are one of the most common reasons roaming partners reject data.
- An EVSE ID identifies a charging point publicly and uniquely, e.g. a country code, an operator ID and an outlet ID.
- An EMAID (contract ID) identifies a driver's charging contract with an e-mobility provider.
- Operator and provider IDs are issued by national registration bodies.
- The public EVSE ID is not the same as the numeric EVSE id used inside OCPP 2.0.1.
What is an EVSE ID?
EVSE stands for electric vehicle supply equipment. In roaming, the EVSE is the unit that can charge one vehicle at a time, even if it has several connectors. The EVSE ID is its public, globally unique identifier. It appears in apps, in roaming data, in charge detail records and in national access point data required by regulations such as AFIR.
EVSE ID structure
The widely used format, based on the eMI3 work and ISO 15118, has three parts:
| Part | Format | Example |
|---|---|---|
| Country code | ISO 3166-1 alpha-2, two letters | DE |
| Operator ID | Three alphanumeric characters issued to the CPO | ABC |
| ID type and outlet ID | The letter E followed by up to 30 alphanumeric characters chosen by the operator | E1234567 |
Written with the optional asterisk separator, the example becomes DE*ABC*E1234567; without separators it is DEABCE1234567. Partners should treat both forms as the same identifier, so normalise them before comparing.
What is an EMAID?
The EMAID (e-mobility account identifier), also called contract ID, identifies the charging contract a driver has with an eMSP. It is what the CPO ultimately bills against in roaming and the identifier carried in Plug & Charge certificates.
| Part | Format |
|---|---|
| Country code | Two letters, ISO 3166-1 alpha-2 |
| Provider ID | Three alphanumeric characters issued to the eMSP |
| eMA instance | Nine alphanumeric characters chosen by the provider |
| Check digit | Optional single character to catch typing errors |
A pattern such as DE-8AA-1A2B3C4D5 followed by an optional check digit is typical. The eMSP also maps RFID card UIDs to EMAIDs, which is why your platform must store both. See RFID charging authorisation for how cards are validated.
Who issues operator and provider IDs?
Operator and provider IDs are allocated by national ID registration organisations, for example BDEW in Germany and AFIREV in France. Some countries have no dedicated body yet, and some hubs can assist with registration. Register before going live with roaming: partners will reject locations or tokens with unregistered or borrowed prefixes.
EVSE ID in OCPP vs OCPI
| Context | Identifier | Meaning |
|---|---|---|
| OCPP 1.6J | connectorId (integer) | Local number of a connector on the charger, 0 for the whole station |
| OCPP 2.0.1 | evseId (integer) and connectorId | Local number of the EVSE on that charger, not globally unique |
| OCPI | evse_id (string) | Public EVSE ID such as DE*ABC*E1234567 |
| OCPI | uid | Internal unique ID of the EVSE object in your system |
Your CSMS must map each charger's local EVSE numbers to the public EVSE IDs. Errors in this mapping lead to sessions billed to the wrong point or statuses shown on the wrong connector. For the OCPP side, read StatusNotification and connector statuses.
Designing your EVSE ID scheme
- Keep it stable: an EVSE ID should not change when you replace hardware at the same location, or when a charger is moved between projects.
- Keep it meaningful but private: encoding site numbers helps support teams, but avoid personal data or customer names.
- Avoid reuse: never assign a retired EVSE ID to another point, because old CDRs and reviews still refer to it.
- Print it on the charger: drivers quote it to support; a sticker with the EVSE ID and a QR code speeds up help and payment, see QR code payment.
Common mistakes
- Using a station serial number or OCPP charge point ID as EVSE ID.
- Mixing separators or lower case between systems without normalisation.
- Giving every connector its own EVSE ID when they share one power unit that charges only one vehicle at a time.
- Using a test operator ID in production after a pilot.
- Forgetting that EMAIDs and RFID UIDs are different things in CDRs.
Frequently asked questions
Is the asterisk required in an EVSE ID?
No. The asterisk is an optional separator. Systems should accept both forms and compare normalised values.
Can a private charger have an EVSE ID?
Yes, but it is mainly needed for public charging, roaming and regulatory reporting. Private sites often use only internal identifiers.
Do I need an EMAID if I am only a CPO?
No. EMAIDs are issued by eMSPs. As a CPO you receive and store them in sessions and CDRs, but you only need an operator ID.
Üreticy maps OCPP connectors to public EVSE IDs and publishes them correctly to roaming partners. See the platform or contact our team.