OCPP Common Smart Charging Use Cases

Overview

Smart Charging in OCPP allows you to dynamically influence charging behavior without stopping a transaction.
A common use case is to pause charging temporarily and later resume charging without ending the session.

This is typically achieved by:

• Applying a TxProfile
• Using chargingProfileKind: Relative
• Setting the current limit to 0 A to pause
• Setting a value greater than 6 A to resume charging

Key Concepts

TxProfile

A TxProfile applies only to the currently active transaction on a connector.

Relative Charging Profile Kind

When using chargingProfileKind: Relative, all schedule periods are interpreted relative to the start of the transaction (t = 0).

This makes it ideal for session-based control such as pausing or resuming charging.

Use Case: Pause an Active Charging Session

To pause an ongoing charging session without stopping the transaction, apply a TxProfile with a current limit of 0 A.

Example: Pause Charging (0 A)

{
  "chargingProfileId": 1001,
  "stackLevel": 1,
  "chargingProfilePurpose": "TxProfile",
  "chargingProfileKind": "Relative",
  "chargingSchedule": {
    "chargingRateUnit": "A",
    "chargingSchedulePeriod": [
      {
        "startPeriod": 0,
        "limit": 0
      }
    ]
  }
}

Expected behavior

• Charging current is reduced to 0 A.
• The transaction remains active.
• The EV and charge point enter a paused or suspended state.
• Charging may resume automatically once a new profile is applied.

Use Case: Resume Charging After a Pause

To resume charging, apply a new TxProfile with a current limit greater than 6 A.

Most EVs require a minimum current (typically 6 A) to resume charging.

Example: Resume Charging (e.g. 16 A)

{
  "chargingProfileId": 1002,
  "stackLevel": 10,
  "chargingProfilePurpose": "TxProfile",
  "chargingProfileKind": "Relative",
  "chargingSchedule": {
    "chargingRateUnit": "A",
    "chargingSchedulePeriod": [
      {
        "startPeriod": 0,
        "limit": 16
      }
    ]
  }
}

Expected behavior

• Charging resumes within a few seconds.
• The transaction continues normally.
• Power is delivered according to the new limit.

Use Case: Explicitly Set the Number of Phases

In OCPP 1.6J, the number of phases is configured per chargingSchedulePeriod using the optional numberPhases field.

This can be used when the CSMS wants to explicitly request single-phase or three-phase charging as part of a TxProfile.

If numberPhases is omitted, the charge point decides which phase mode to use based on its local configuration, available installation capacity, EV behaviour, and current charging state.

Example: Resume Charging with 3 Phases

{
  "chargingProfileId": 1003,
  "stackLevel": 10,
  "chargingProfilePurpose": "TxProfile",
  "chargingProfileKind": "Relative",
  "chargingSchedule": {
    "chargingRateUnit": "A",
    "chargingSchedulePeriod": [
      {
        "startPeriod": 0,
        "limit": 16,
        "numberPhases": 3
      }
    ]
  }
}

Example: Resume Charging with 1 Phase

{
  "chargingProfileId": 1004,
  "stackLevel": 10,
  "chargingProfilePurpose": "TxProfile",
  "chargingProfileKind": "Relative",
  "chargingSchedule": {
    "chargingRateUnit": "A",
    "chargingSchedulePeriod": [
      {
        "startPeriod": 0,
        "limit": 16,
        "numberPhases": 1
      }
    ]
  }
}

Expected behavior

When numberPhases is set to 3, the charge point should apply the profile as a three-phase charging limit, if supported by the charge point, installation, and EV.

When numberPhases is set to 1, the charge point should apply the profile as a single-phase charging limit, if supported by the charge point and installation.

If the EV or charge point cannot apply the requested phase mode, the actual charging behaviour may differ.

Phase Switching Considerations

Changing between one-phase and three-phase charging may require a short interruption in energy transfer. Depending on the charge point and EV behaviour, the charge point may briefly pause charging before applying the new phase configuration.

For this reason, phase changes should not be sent too frequently.

Recommended approach:

• Include numberPhases in each relevant chargingSchedulePeriod if your integration needs explicit phase control.
• Use numberPhases: 1 for single-phase charging.
• Use numberPhases: 3 for three-phase charging.
• Avoid switching between one-phase and three-phase charging repeatedly within a short period.
• If no explicit phase control is needed, omit numberPhases and allow the charge point to decide.