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If you’ve already integrated Flex Lite and want to unlock higher revenue and full schedule optimisation, this guide covers exactly what changes when upgrading to Smart Charging.

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Why upgrade?

Flex LiteSmart Charging
Scheduling modelInserts pauses into your scheduleAxle generates the entire schedule
Optimisation windowSingle 30-min pauseFull charging session
Re-schedulingOne-shot (at plug-in)Continuous — Axle re-optimises as prices change
Revenue potentialLowerHigher — more flexible capacity to sell
Smart Charging maximises flexibility revenue because Axle controls the full charging window, not just a single pause.

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What changes

  • Tariff data — send the user’s energy tariff so Axle can cost-optimise charging
  • Intent — send the user’s energy requirement (kWh) and ready-by time, which sets the minimum requirements for the schedule Axle will build
  • Separate plug-in / plug-out events — replace the combined plug-in-schedule call so Axle knows the charging window
  • Schedule endpoint — Axle calls your API with an OCPP schedule payload whenever a new schedule is generated
  • Half-hourly readings — report consumption so Axle can verify delivery and calculate rewards
  • plug-in-schedule endpoint — replaced by separate plug-in event + async schedule delivery
  • Schedule in API response — schedules arrive via a call to your API with an OCPP schedule payload, not in the plug-in response
  • Authentication — same OAuth token flow
  • Site & asset model — same entities, same IDs
  • Onboarding — same onboard-site-and-asset (or advanced initialise / enrol) flow, though Smart Charging uses the full_asset_schedule_control proposition instead of limited_pause
  • Offboarding — same offboard-site-and-assets endpoint
  • Payments — same rewards and transaction endpoints

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Integration steps

These are the changes you need to make on top of your existing Flex Lite integration. For full detail on each step, see the Smart Charging integration guide.

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1. Send tariff data

Axle needs the user’s energy tariff to optimise charging cost. Send it once at enrolment time, then update whenever the tariff changes.

Send tariff

Send or update a user’s tariff

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2. Collect and send intent

Collect the user’s charging requirement and deadline:
  • kWh — how much energy to add
  • Ready-by time — when the vehicle needs to be ready
Send intent once at enrolment time, then update whenever it changes.

Send intent

Send or update a user’s charging intent

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3. Replace plug-in-schedule with separate events

Instead of a single plug-in-schedule call that returns a schedule synchronously, send separate plug-in and plug-out events. Schedules are delivered asynchronously in OCPP format via an API call to your endpoint.

Plug-in event

Notify Axle when a vehicle plugs in

Plug-out event

Notify Axle when a vehicle unplugs
You should also send a plug event when a user is first enrolled to inform Axle of the initial plug state.

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4. Set up schedule endpoint

Axle sends charging schedules to your platform in OCPP format via an API call. You need to expose an endpoint that can receive and apply these schedules to the charger. Axle will send a schedule:
  • When the user plugs in
  • When the user is already plugged in and one of the following events happens:
    • The user’s tariff is updated
    • The user’s intent changes
    • Axle reoptimises in response to changes in the wider market

Example OCPP charging profile

See the format of schedule pushes from Axle

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5. Report half-hourly readings

Send consumption readings so Axle can verify delivery and calculate rewards.

Send readings

Report asset consumption readings

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6. Enrol users in Smart Charging

Once the above integration work is complete, you can start enabling users. Enrol them in the full_asset_schedule_control proposition via the enrol endpoint: 
{
  "proposition": "full_asset_schedule_control"
}
Sites can be enrolled in multiple propositions simultaneously, so this won’t affect the existing Flex Lite enrolment. Once you’ve verified Smart Charging is working, unenrol from limited_pause via the unenrol endpoint to keep things clean and avoid ambiguity.

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Sequence diagram

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Migration checklist

Use this to track your migration progress:
1

Send tariff data

Send each user’s tariff to Axle.
2

Collect and send intent

Add UI to collect kWh requirement and ready-by time, and send via the intent endpoint.
3

Replace plug-in-schedule with separate events

Switch from plug-in-schedule to separate plug-in and plug-out event calls.
4

Set up schedule endpoint

Expose an endpoint to receive and apply OCPP charging profiles from Axle.
5

Report half-hourly readings

Report consumption data via the readings endpoint.
6

Test end-to-end

Run a full charging session through the sandbox to verify the integration.
7

Enrol users in Smart Charging

Enrol each user in full_asset_schedule_control. Once verified, unenrol from limited_pause.

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Next steps

Smart Charging integration guide

Full integration walkthrough

Smart Charging API Reference

Complete API documentation

OCPP example

Example charging profile payload