How does a backend tell a charger how much power to use?
The controller decides: 80 kW for fourteen cars. Within seconds, every charge point receives a new limit.
The cars' onboard chargers follow, and the total at the connection falls back below 80 kW.
The questionHow does a limit travel from the controller to the car?
A meter at the connection reports the building's current load, every few seconds.
Select each step to see what happens.
Profiles at three levels
has carried since version 1.6 of 2015. In OCPP 2.0.1 it is a functional block of its own: functionality that lets the operator, or indirectly a third party, influence the current or power of a session, or limit what a charging station offers. Limits can be set:
- for the whole station, as a ceiling for everything behind it,
- as a default for every new session,
- for one session, for example to follow a schedule until the car leaves.
When the connection drops
A charger that loses its backend can no longer receive new limits. That is why sites keep a safe default in every charger: a limit that applies to new sessions whenever nothing else is known. that runs on site, in a local controller, keeps working even when the internet does not.
Since 13 April 2024, new public charge points in the EU must be capable of smart recharging.
The car can talk too
With , the car can report its energy need and planned departure time, so the backend can build an accurate profile for the session. OCPP 2.0.1 supports this exchange in full. More on that conversation in Plug & Charge.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
How does a charge point tell the car how much current it may draw?
The charging cable carries a control signal that sets the maximum current for the onboard charger.
Since which version has OCPP supported smart charging?
OCPP 1.6 introduced smart charging; 2.0.1 made it a functional block of its own.
Why do chargers keep a default limit for new sessions?
Without a backend, no new profiles arrive. A safe default keeps the site below its limit.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- Load management Shares a site's grid connection between the cars charging at the same time. EV charging fundamentals, stop 04 Glossary
- ISO 15118 International standard for the digital communication between car and charger, the basis of Plug & Charge. EV charging fundamentals, stop 08 Glossary
- Smart charging Charging whose power is adjusted in real time, based on information received electronically, for example from the grid operator or a price signal; EU law calls it smart recharging. Bidirectional charging, stop 01 Glossary
- Open Charge Alliance: What is new in OCPP 2.0.1? Whitepaper, version 1.0, March 2023. https://openchargealliance.org/wp-content/uploads/2024/01/new_in_ocpp_201-v10.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- Open Charge Alliance: What is new in OCPP 2.0.1? Whitepaper, version 1.0, March 2023. https://openchargealliance.org/wp-content/uploads/2024/01/new_in_ocpp_201-v10.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Article 5(8). https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- Open Charge Alliance: What is new in OCPP 2.0.1? Whitepaper, version 1.0, March 2023. https://openchargealliance.org/wp-content/uploads/2024/01/new_in_ocpp_201-v10.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.