AC Charging
AC charging supplies alternating current to the vehicle, where the Onboard Charger converts it to direct current for the traction battery. The vehicle controls battery charging while the external equipment provides the electrical connection, protection, and signalling.
What limits AC charging power
The usable power is limited by the lowest applicable limit in the complete path:
- The building supply and circuit
- The Electric Vehicle Supply Equipment (EVSE)
- The cable and connector
- The vehicle's inlet and onboard charger
- Battery temperature and charging limits
A wall unit rated for more power than the vehicle's onboard charger can accept will not make that vehicle charge at the wall unit's full rating. Likewise, a high-capacity onboard charger cannot exceed the available supply or EVSE limit.
AC charging is not synonymous with one voltage, connector, phase count, or regional charging level. Terms such as Level 1 and Level 2 belong to particular regional classifications, while IEC charging modes describe how conductive charging equipment is connected and controlled. Single-phase and three-phase supplies can also produce different power limits.
During DC fast charging, the main AC-to-DC conversion occurs outside the vehicle and controlled DC reaches the battery system. For the wider relationship between supply, equipment, vehicle, and battery, see EV Charging: The Complete System.