Charging Session Integration
Topics in this document:
- Session Start Timeout
- Driver Authorization
- Offline Sessions
- Meter Values Reporting
- Session Event Retry
Session Start Timeout
Please ensure to configure the session start timeout period on charger side. It covers the time available to start the session, since the acceptance of remote start request or driver authorization.
Remote session start and authorization timeout on charger side represents the time since OCPP
RemoteStartTransaction/Authorization acceptance, after which session must be started. If this time is breached, the charger should prevent any session start without the next OCPP RemoteStartTransaction or Authorization operation acceptance.
To avoid fraudulent usage, we suggest using preventive measures by configuring the charger’s timeout period in which the session is expected to start. OCPP 1.6 has a
ConnectionTimeOut setting, which can be used, as described below.
Charger may also have other settings which are not part of OCPP 1.6 to handle other preventive scenarios - to tackle those, please check the charger’s specific manual or consult with the manufacturer.
OCPP 1.6 requires support for
ConnectionTimeOut setting: Interval in seconds from beginning of status: ‘Preparing’ until incipient Transaction is automatically canceled, due to failure of EV driver to (correctly) insert the charging cable connector(s) into the appropriate socket(s). The Charge Point SHALL go back to the original state, probably: ‘Available’.
Session timeout section is related to ready-session-expiration settings of the central system, as it closes inactive sessions based on the expiration settings and idle job configuration. Make sure to use the consistent ready-session-expiration time on the central system, so it works aligned with the charger.
Example:The EV driver plugs the connector with the vehicle. Then the driver presses the session start request button on the mobile application, and at this point, session is ready. Ready session expiration time of 30 seconds starts ticking. If it reaches 30 seconds and session did not start yet, then the session gets closed on the central system side and is not being tracked anymore.
Note:If you experience the session without a customer reference, you need to make sure to configure the suitable timeout settings in dependence with ready-session-expiration settings.
As the drivers/customers who intend to charge the vehicle may use the payment types of prepaid, postpaid or pay-now, each session charging needs to be first authorized by the Tridens EV Charge’s central system to verify the driver’s fund sufficiency for beginning the charging session. Thus, charger’s local and offline authorizations lists and caches need to be disabled, to propagate all the authorizations to the central system.
Below is the list of OCPP 1.6 and OCPP 2.0.1 standardized authorization settings. Note that the chargers may have their own customized list of configuration settings, out of standardized scope. As a CPO, please review the charger specific implementation for any additional settings that need to be managed.
Configuration Attribute Name
OCPP 1.6 Variable Name
OCPP 2.0.1 Variable Name
|Authorize Remote Session Requests
|Indicates whether remote start requests need to be authorized by the charger before proceeding to charge.
|Set to true, to ensure that the session is still authorized to start.
|Authorization Cache Enabled
|Indicates whether the charger supports the authorization cache for the driver’s identifiers.
|Set to false, to prevent using charger’s local authorization caches.
|Local Offline Authorization
|Indicates whether the charger, when offline, will start a transaction for locally authorized identifiers.
|Set to false, to prevent using charger’s local authorization caches.
|Allow Offline Session of Unknown Driver
|Indicates whether the charger allows authorizing any unknown identifiers that cannot be authorized by local authorization list or authorization cache.
|Set to false, to prevent any unverified sessions.
|Central Contract Validation
|Indicates whether the Charge Point can provide a contract certificate that it cannot validate to the Central System for validation as part of the authorization.Used in the scope of ISO 15118’s Plug & Charge.
|Set to true, so the central system’s verification is used.
|Offline Contract Validation
|Indicates whether the charge point will try to validate a contract certificate when it is offline (not connected to the central system).Used in the scope of ISO 15118’s Plug & Charge.
|Set to false, so the central system’s verification is used.
Table: List of authorization settings to manage in OCPP 1.6 and 2.0.1.
Disable the charger to start the charging sessions without allowance of the central system, as it would result in non-customer public sessions.
Make sure to disable
AllowOfflineTxForUnknownId settings of OCPP 1.6 on the charger side.
CPO needs to review the charger specific implementation and configuration, as other settings out of standardized scope may apply.
Meter Values Reporting
Configure session meter values report interval on the charger, so the session’s progress will show up. We advise using a 15 seconds interval. You can usually configure this on the charger’s own dashboard, or use EV Charge dashboard, which can do it by OCPP.
To access this section in EV Charge, from the Menu, click Stations. A paginated list of all stations is shown in a tabular format. Click Actions for the specific station. On the station’s page, click Configuration on the top right corner to access Configuration page, the click Custom tab.
Figure: OCPP 1.6 example of setting the interval in the Station’s Configuration form on Tridens EV Charge dashboard.
Note:The settings can be set by the central system to the charger only when charger is connected to the central system and communicating by OCPP protocol.
To show active power measurement in mobile app, CPO needs to configure the charger to send the certain measurements in scope of the charging session (usually at least kW for power and kWh for energy). Once again, this is usually doable by the charger’s dashboard or EV Charge dashboard, where OCPP’s
MeterValuesSampledData setting can be used.
To navigate to this area in EV Charge, go to the Menu and select Stations. You’ll see a paginated list of all stations in a tabular format. Click on Actions for the specific station. Once on the station’s page, access the Configuration page by clicking on Configuration at the top right corner, then navigate to the Custom tab.
Figure: OCPP 1.6 example of setting measurands in the Station’s Configuration form on Tridens EV Charge dashboard.
Note:The settings can only be configured by the central system to the charger when the charger is connected to the central system and actively communicating via the OCPP protocol.
Important measurands to cope with:
|OCPP 1.6 Name
|OCPP 2.0.1 Name
|Instantaneous imported energy (Wh or kWh) to the vehicle.
|Instantaneous power (W or kW) import to the EV.
|Instantaneous current (A) import to the EV.
|Instantaneous voltage (V) supply between grid and EV.
|Battery State of Charge
|Percentage representing the vehicle’s battery state of charge.
Table: List of measurands settings in OCPP 1.6 and 2.0.1.
Session Related Meter Values
Meter values which are related to the specific charging session and representing measurands related to it.
Session Meter Values Interval
Interval in seconds, by which the charger will send the meter value reports to the central system during the charging session. Suggested interval is 10-15 seconds.
MeterValueSampleInterval of OCPP 1.6 and
SampledDataTxUpdatedInterval of OCPP 2.0.1.
Session Meter Values Measurands
Measurands which the charger will send on ‘Session meter values interval’. Suggested: power, energy, state of charge, voltage, current.
MeterValuesSampledData of OCPP 1.6 and
SampledDataTxUpdatedMeasurands of OCPP 2.0.1.
General Meter Values
General meter values are reported independent of the session and may be required in the scenarios of the sessions which are being terminated by the final parking.
General Meter Values Interval
Interval in seconds, by which the charger will send regular meter value reports to the central system during the charging session.
ClockAlignedDataInterval of OCPP 1.6 and
AlignedDataInterval of OCPP 2.0.1.
General Meter Values Measurands
Measurands which the charger will send on ‘General meter values interval’. Suggested: power offered.
MeterValuesAlignedData of OCPP 1.6 and
AlignedDataMeasurands of OCPP 2.0.1.
Session Event Retry
Retry to send the event in case of failure. Suggested value is 3.
TransactionMessageRetryInterval of OCPP 1.6.