Guide
How much does a 7 kW wallbox cost to run?
A 7 kW wallbox can move a lot of energy in a short session, so the true cost depends less on the charger label and more on how often and when you charge.
Short answer
The charger itself is not what makes the bill large. The pattern that matters is how many kWh you put into the car each week and whether you shift that demand into cheaper off-peak hours.