Real Time Session Power Management

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Introduction

If your smart charging application wants to manage the power available to the EV during a session, eDRV gives you a set of tools to do so easily in near real-time.

Your application can read the power and current on an ongoing session in near real-time (approximately 30 seconds) via session metrics, see Webhooks and Real Time Session Energy Reports. Your application can then act intelligently to vary the power and current delivered to the EV in the session via the sessions/{id}/manage_power API endpoint.

Use Cases

Some possible use cases for Session Power Management are:

  • Solar powered EV charging where the delivered power varies throughout the day due to weather
  • Battery assisted EV charging. If your application uses on site batteries, you may want to manage the delivered power to a bank of EVs depending on the battery state of charge
  • Utility Demand Response. If there is an upstream power congestion event, your application may want to manage the delivered power to chargestation(s) instantly.

Receiving Session Power Reports

You can receive the latest Power and Current delivered in a charging session as reported by the charging station via Webhook events. See Show Charging Metrics in Real Time

session.energy_report.power and session.energy_report.current report instantaneous power and current being consumed by the EV.

(We will be updating these shortly for DC session reports)

Set the Power or Current Delivered in a Session

Your application can alter the maximum power or current available in an ongoing Session. You can do this via eDRV's sessions/{id}/manage_power endpoint.

Example 1
The following example limits the power available to the EV to 3.7kW.

{
  session: '5eafcdaf9e7760a2646be432',
    unit: 'power',
    limit: 3700
}

Example 2
The following example limits the current available to the EV to 26 Amperes for the lifetime of this session.

{
  session: '5eafcdaf9e7760a2646be432',
    unit: 'current',
    limit: 26
}

Expected Response
If the chargestation accepts the power limit request, the API call response should return an ID. Your application must store this ID, in case you want to cancel the power limits on this session.

{
  id : 19675644
}

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EV Response to a sessions/{id}/manage_power command

The chargestation responds to a sessions/{id}/manage_power command by changing the maximum current available to the EV via an (analog) Control Pilot signal. The EV's on board charging controller will take this new limit into account and adjust accordingly. The response time to a new command varies by EV OEM.

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On IDs

Your application must save this ID. Please note that power limits are only valid until the end of the session. You must send a new sessions/{id}/manage_power command if you want to manage a new transaction.

Clear the Power Limits on a Session

If your application wants to remove the power / current limits on a transaction you can do so via the DELETE sessions/{id}/manage_power endpoint.

{
    id : 19675644
}

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Do you need help with Smart Charging?

Do reach out to the eDRV team via chat or email for help for your specific Smart Charging use case.