Alfen
How an Alfen charger connects to Joulo over OCPP 1.6J, and why the first 24 to 48 hours look different.
Alfen has no cloud API for owners. Alfen chargers connect straight to Joulo over OCPP 1.6J, which gives live meter values while the car charges.
At a glance
| Property | Value |
|---|---|
| Route | OCPP 1.6J |
| Endpoint | wss://ocpp.joulo.nl/{chargePointId} |
| Authentication | OCPP basic auth, or ?auth=<secret> |
| Sync | Live, over the WebSocket |
| MID detection | From the boot notification. Alfen builds a MID meter in as standard |
| Backfill | Alfen pushes its stored history after the first connection |
How the connection works
You set the Joulo endpoint and credentials in the Alfen configuration tool, ACE Service Installer. The charger then opens a WebSocket to wss://ocpp.joulo.nl and keeps it open.
Joulo runs one Cloudflare Durable Object per charge point, so your charger has its own connection, its own outbox and its own frame archive. Every OCPP frame in and out is archived, which is what support reads back when a session is disputed.
If an installer, a CPO or an energy supplier already operates this charger, changing the backoffice URL cuts their services. Confirm you are allowed to change it before you do.
The first 24 to 48 hours
Alfen buffers transactions locally and pushes stored history after it connects to a new backoffice. That push can take 24 to 48 hours to complete. During that window your dashboard fills in backwards, which is expected and not a fault.
Live sessions started after the connection appear immediately.
What Joulo reads
Joulo stores start and stop transactions and the Energy.Active.Import.Register meter samples. Other measurands are archived but not persisted as meter values, because the register is the number an ERE registration stands on.
Charging keeps working without internet
Connecting to Joulo never makes charging depend on the connection. On every boot Joulo pushes a configuration that keeps the charger autonomous, including local authorisation and offline transaction handling. Sessions started while offline are delivered when the WebSocket reconnects.
MID certification
Alfen builds a MID meter into its Eve line as standard. Joulo confirms it from the boot notification rather than assuming it from the model name.
Limitations
- History before the first connection arrives on Alfen's schedule, not on ours.
- A charger that an operator manages cannot use this route without cutting that operator off.