Communication protocols
IEC 61851, ISO 15118, DIN 70121 and OCPP.
You'll learn
- Explain communication protocols clearly and accurately
- Read the numbers that define the behaviour
- Apply the idea to a real charging session
Overview
Four standards cover the whole chain: car to charger, charger to network, and network to roaming platform.
In depth
| Standard | Covers | Why it matters |
|---|---|---|
| IEC 61851 | Basic pilot signalling | Sets the AC current limit via a PWM duty cycle |
| DIN 70121 | Early DC digital communication | Still the fallback on many posts |
| ISO 15118 | Modern DC and Plug & Charge | Certificates, automatic billing, smart charging |
| OCPP | Charger to back office | Remote start, tariffs, firmware, diagnostics |
| OCPI | Network to network | Roaming and shared availability data |
Plug and Charge
ISO 15118 lets the vehicle present a signed certificate over the charging cable. The post authorises the session against the driver's contract with no card and no app — the connector is the identity.
Key takeaways
Remember this
- IEC 61851 handles the analogue pilot; ISO 15118 the digital layer.
- OCPP connects posts to their operator.
- Plug & Charge removes cards and apps.
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