Stop 02 of 08 · The idea

How do car and charger talk to each other?

About 7 min · 3 questions ·

Friday
The situation

In the second after plugging in, car and charger find each other on the cable, agree on an address and open an encrypted connection.

Then they exchange what each can do, and the car presents its contract.

The questionHow can a charging cable carry a conversation?

The first seconds after plugging inFrom a cable to a conversation
01
Step 01Signal

The control pilot line in the cable signals that a car is connected and that high-level communication is possible.

Select each step to see what happens.

A protocol for two controllers

ISO 15118-2 details the communication between the car and the charging equipment: it detects a vehicle in a communication network and enables IP-based communication between the car's controller and the charger's. It defines messages, a data model, the XML/EXI data format and the use of TLS, TCP and IPv6; the data link and physical layer are described in ISO 15118-3.

More than identification

The same conversation carries more than the contract. The car can report how much energy it needs and when it plans to leave, so the operator can plan the session. 2.0.1 supports this input from the car in full. How such plans become limits is the subject of Load management, stop 03.

Check your understanding

3 questions. Answer all of them to complete this stop. Each answer explains itself.

01Question 1 of 3

Over which medium do car and charger communicate in ISO 15118?

02Question 2 of 3

What does ISO 15118-2 define?

03Question 3 of 3

What can the car report besides its contract?

Further in other paths

  1. Charging hardware · Stop 03What do connector types tell you?Type 2 for AC, Combo 2 for DC: which connectors EU law requires, how one car inlet takes both plugs, and why public DC chargers have a fixed cable.
  2. Bidirectional charging · Stop 04Which standards make it work?ISO 15118-20 between car and charger, OCPP 2.1 between charger and backend, and the EU rules around them: the stack behind a bidirectional session.
  1. ISO: ISO 15118-2:2014, Vehicle-to-Grid Communication Interface, Part 2: Network and application protocol requirements. https://www.iso.org/standard/55366.html. Checked 09 Oct 2026.
  2. ISO: ISO 15118-2:2014, Vehicle-to-Grid Communication Interface, Part 2: Network and application protocol requirements. https://www.iso.org/standard/55366.html. Checked 09 Oct 2026.
  3. 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.
  4. 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.
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