Just to be pedantic... there is no way you will use 12kWh to charge it.
between 9 and 10, maybe. More likely less than 9.
The battery generally discharges to around 30%, sometimes a bit lower, but never less than 26% in normal use.
So, from 30% charge (3.6kWh) back to 12 would take 8.4 (without...