AC versus DC EV charging: speed, losses and cost
AC and DC describe different ways of supplying power to an electric car. AC charging uses the vehicle’s onboard converter; DC charging supplies converted power directly through a compatible fast-charging system. Neither label guarantees a fixed charging time.
AC is common where you park longer
Home and many destination points supply alternating current. The car's onboard AC charger sets an upper limit alongside the station and electrical supply. Charging can be slower, yet time is less important overnight or at work.
DC speed changes through a session
At a rapid DC station, available station power, battery temperature, state of charge and vehicle limits influence the actual charging curve. A headline peak such as 150 kW does not mean that power is sustained from empty to full. Charging often slows substantially at high battery percentages.
Compare costs on energy delivered
Operators may bill by kWh, time, a connection fee or a combination. Read the displayed tariff and any idle fees before starting. When comparing offers, distinguish energy entering the battery from energy billed at the charger; charging losses and time-based fees affect the result.
Choose a practical charging stop
For a trip, compare the time to reach a useful charge level, connector compatibility, station reliability and the next viable stop. A slower charger nearby may be more convenient than a faster charger requiring a detour. In cold weather, preconditioning may help if supported by your car.
Worked example with explicit assumptions
If a car accepts 60 kW on average over part of a session, adding 30 kWh takes approximately 30 minutes before other limits. A charger advertised at 150 kW does not change that average. The same 30 kWh at an illustrative price of 0.60 per kWh costs 18 in that currency, excluding extra fees.
Check current pricing in the charging operator's app; the example is not a live tariff.