One charging session, fully understood
The motorway service station. Same driver, same charger, same tap.
After eight stops, the two seconds and the twenty minutes look different: you know who is involved and what flows.
The questionCan you describe the whole session: who acts, what flows, and why each part exists?
Guess firstThe display shows “Preparing…” for a few seconds. What comes to mind now?RevealHide
Safety check, negotiation, precharge, all normal. If that comes to mind right away, the model is in place. Knowing what lies behind each pause, each price and each status light is the aim of this path.
Data: every step of the authorisation.
The charger reads the RFID card and sends an OCPP Authorize message to its backend.
Energy: from the grid to the cells.
The connection was planned when the site was built. All chargers on site share it through load management.
Money: opposite to the energy, with a share at each step.
The eMSP's price, not the operator's. The visitor paying ad hoc pays the operator's own price, the subscriber pays less.
Switch the flow, then select each step. Prices are an illustrative example.
The 22 minutes, narrated properly
The tap. to the operator's backend, to the card provider's side, the approval back within about two seconds.
Stop 03Energy flows after the safety check, with the station converting and the battery setting the pace.
Stop 04The power falls. The driver knows the charging curve and unplugs at 80%.
Stop 04A is created, travels the route and becomes one line on next month's invoice, margin included.
Stop 05Had something gone wrong, a control room would first have checked it remotely.
Stop 06
Three flows. Many companies. Four standards. One tap.
Energy and data run while the car charges. The session closes with the CDR, and only then do settlement and the invoice follow. Power values follow the example session.
Where to go from here
You have the map now. Further learning paths go deeper into each part of this journey: the hardware itself, OCPP in depth, OCPI and roaming, payments and billing and the grid. Each of them builds on the session you now know. See all learning paths.
Check your understanding
4 questions. Answer all of them to complete this stop. Each answer explains itself.
The session's authorisation crossed company borders. Which protocols carried it, in order?
Towards the own backend first, then between companies: the pattern of every roaming session.
The power fell at 80% and the driver unplugged. Why was that a sensible choice?
On a journey, knowing the charging curve saves time.
Leaving VAT aside, the 0.64 €/kWh the driver pays and the wholesale rate the CPO receives differ. That difference is…
Money flows from the driver to the eMSP, possibly through a hub, to the CPO. Each step has its share.
What is the most durable thing this path taught?
Details change, the model stays. Each new term has a place in it.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. Stop 03 Glossary
- OCPI Open Charge Point Interface: an open protocol for roaming between operators and e-mobility service providers. Stop 03 Glossary
- Roaming Charging in another company's network with your own card or app. Stop 03 Glossary
- CPO Charge point operator: runs the chargers, keeps them available and sells the charging service. Stop 02 Glossary
- eMSP E-mobility service provider: issues the charging card or app, sets the driver's price and sends the invoice. Stop 02 Glossary
- Site host The owner of the location, who provides the parking spaces for the chargers. Stop 02 Glossary
- CDR Charge detail record: the digital receipt of a session, with energy, duration and tariff. Stop 05 Glossary