I think your cost calculations are slightly out mate –
To work out how long an EV will take to charge you can use either of these calculations.
Battery capacity (kWh) x 1000 / EVSE power (kW) x 1000
(65 kWh x 1000 / 7 kW x 1000 = 9.3 hours)
or simply Battery capacity (kWh) / EVSE power (kW)
(65kWh / 7kw = 9,3 hours)
To work out the cost (£) based on unit rate of electricity.
Battery capacity (kWh) x unit rate of electricity
(65 kWh x 0.075p = £4.87)
The aove calculations are based on charging your EV to 100% battery capacity, which you would only do if you were going on a long journey! For everyday running around its best keeping the battery within optimum range and keeping the charge between 20 – 80% or 10 – 80%.
To work this out, keeping the battery capacity between 20 – 80% which is 60% of the battery capacity – you would do the folling to work out what 60% of the battery capacity is in kWh –
60% (as a decimal) x total battery capacity (kWh)
(0.6 x 65 kWh = 39kWh)
To work out the cost to charge 39 Kwh you can follow the above exampe.
(39 kWh x 0.075p = £2.93)
* You would also need to add 5% VAT on the above charging costs, which is peanuts.
There is another calculaion based on efficiency and charging time required, (which is not difficult) that may be useful if you were to plan journeys but, were look at that when the time comes 🙂
Hope this helps!