Why might a car charge below the power printed on an AC charger?

A charging point’s power rating is not a promise that every connected car will receive that power. On AC charging, check the car’s onboard charging capability as well as the supply and charging equipment.

Use documentation for the exact variant. Keep AC capability separate from DC rapid-charging figures, and check whether the installation shares available power or applies a current limit.

For a time estimate, use a supported average rate and the energy that needs to be added. A short observation at one power level does not prove that the same rate will continue throughout the session.