@TomL65 … this post gives you the answer… no need to look anywhere else … your car is charging correctly at full speed. (This is an easy confusion to make … yup, I did myself a few years ago)You are looking at the usage over only half an hour. 3.9kwh in 30 minutes equals a usage of 7.8kw in an hour or 7.8kwh. So that means its working fine.
You are mixing up KW and KWH. an energy usage of 3.9kwh over 30 minutes requires a charge rate of 7.8kw of power.