Onboard charger

The converter in the car that turns AC from a wallbox or public AC charger into DC for the battery; its rating limits AC charging power.

Explained in

eMobility and EV basics · Stop 04What do kWh and kW mean for a car?Kilowatt-hours are the amount, kilowatts the rate. With both units, battery size, consumption, motor power and charging time all fall into place.

At an AC wallbox, the car converts the current itself with its onboard charger, so the onboard charger sets the limit. At a DC fast charger, the charger converts the current and the battery sets the limit.

From “Where each limit sits”, stop 04

Also in

  1. eMobility and EV basics · Stop 03How does an electric motor drive the wheels?Few parts, little loss
  2. eMobility and EV basics · Stop 07Where do electric cars charge?AC where cars park, DC where they travel
  3. Charging hardware · Stop 01Why are there AC and DC chargers?The converter moved out of the car
  4. Load management · Stop 05Why do the three phases matter?Why some cars use one phase
  5. Bidirectional charging · Stop 03Where is the energy converted: in the car or in the charger?Two paths, two trade-offs
  1. U.S. Department of Energy, Alternative Fuels Data Center: How do all-electric cars work?. https://afdc.energy.gov/vehicles/how-do-all-electric-cars-work. Checked 09 Oct 2026.