What is inside a DC charger?
Overnight, DC charger 2 reported a fault in one of its power modules. It has kept charging, at reduced power.
The technician now opens it, with the replacement module on the trolley.
The questionWhat sits inside a DC charger, and why does one fault not stop all of it?
Breakers and protection devices connect the charger to the site's supply and disconnect it safely in case of a fault.
Select each part to see what it does.
Modules, not one block
Many DC chargers are built from identical . That has two consequences:
- A failed module lowers the charger's maximum power, but the other modules keep charging.
- A module can be replaced on site in a single visit, without changing the charger.
The same modules make power sharing between outlets possible, the subject of stop 05.
Connected by law
A charger is a networked device. Since 14 October 2024, every public charge point in the EU must be digitally connected: able to send and receive data in real time and to be monitored and controlled remotely. Points built since 13 April 2024 must also be capable of , so their power can follow signals from the grid or the operator.
The backend side of this connection is , introduced in EV charging fundamentals, stop 08.
and above: a card reader or contactless device at points deployed since 13 April 2024
every public point since 14 October 2024
points built after 13 April 2024 or renovated after 14 October 2024
at every public DC point since 14 April 2025
All from Article 5 of AFIR. Below 50 kW, an internet-based payment such as a QR code is also allowed.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
What happens when one power module of a modular charger fails?
The remaining modules keep working. That is one reason why chargers are built from modules.
What does the controller of a DC charger talk to?
Two conversations at once: limits and status with the car, authorisation and data with the operator's backend via OCPP.
Since when must every public charge point in the EU be digitally connected?
AFIR set 14 October 2024 for digital connection. 13 April 2024 applies to smart recharging at new points, 14 April 2025 to fixed DC cables.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- Power module One of several identical conversion units in a DC charger; together they set its power, and one can fail or be replaced without the others. 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
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Articles 2, 5 and 20 and Annex II. https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Articles 2, 5 and 20 and Annex II. https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Articles 2, 5 and 20 and Annex II. https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.