A home EV charger does not actually charge the battery. It is a smart safety switch, technically called electric vehicle supply equipment (EVSE), that connects your home’s AC supply to the car only when it is safe and tells the car how much current it may draw. The car’s own on-board charger converts the AC power into DC to charge the battery.
Step by Step
- 1. Plug in. The connector has power pins and a small signal pin (the control pilot).
- 2. Handshake. The charger sends a signal on the pilot pin. The car responds by changing the signal, confirming it is connected and ready.
- 3. Current limit. The charger communicates the maximum current, for example 40 A, through the signal.
- 4. Safety checks. The charger confirms ground continuity and checks for leakage current.
- 5. Power on. A relay closes and AC power flows to the car’s on-board charger.
- 6. Monitoring. The charger watches for faults, over-temperature and leakage throughout, and opens the relay instantly if anything goes wrong.
- 7. Stop. When the car is full or you unlock it, the car signals the end of the session and the relay opens before the connector can be removed.
Why AC Home Chargers Have a Speed Limit
Because the conversion to DC happens in the car, the speed is limited by the smaller of the charger’s rating and the car’s on-board charger. DC fast chargers do the conversion inside the station and feed DC directly to the battery, which is why they are much larger and faster. See are EV chargers AC or DC.
Built-In Protection
US chargers include a charge circuit interrupting device to detect ground faults, as required by the National Electrical Code; European chargers use RCD protection with DC fault detection. See RCD protection for EV chargers.
EVDANCE home chargers such as the EVDANCE EV-ACT5006T 48A Level 2 wall charger and portable units such as the EVDANCE EV-ACS4005T 40A NACS portable charger follow this design, with over-current, over-temperature and ground-fault protection.
Frequently Asked Questions
Is a home EV charger really a charger?
Technically it is supply equipment; the real charger is inside the car.
Why is the connector safe to touch?
It carries no power until the handshake is complete and the relay closes.
Can a charger overcharge my car?
No. The car controls charging and stops when full.
Related Reading
- What Does a Home EV Charger Look Like?
- Mode 2 vs Mode 3 Charging
- Level 1 vs Level 2 vs DC Fast Charging
Key Takeaways
- A home charger is a smart safety switch; the car’s on-board charger charges the battery.
- A pilot-signal handshake sets the current and confirms safety.
- Ground-fault protection cuts power if leakage is detected.