Charging speed query

[Tigger]

i'm only getting 3.27kw charging power, i would have expected around 7kw - battery was at 69% when i started charging, am i missing something obvious here?

How many other cars are charging on that circuit? On the free chargers outside my local Sainsbury's in Charlton I sometimes get 7kw, sometimes 3.5kw. I think this depends on how many other cars are charging at the same time - load spreading algorithm?