Hi @Menorca Mike
These are my figures just substitute your own electricity rate.
Kona battery is 64 kWh
Costs:
My Electricity rate is £0.1831 / kWh
So to charge from 0% to 100% costs: 64 x 0.1831 = £11.72
Range 300 miles = £11.72 divide 300 = just under 4 pence per mile.
Charging;
BP Home charge point 7.2 kWh ( ish )
Kona battery 64 kWh
So to charge from 0% to 100% : 64kWh divide 7.2 kWh = just under 9 hours
In reality you rarely if ever get to 0% figures shown for extremes.