from the threads I've seen, it is much faster to charge from empty than 1/2 full, but does it cost less to charge (due to shorter time) ? scenario 1 charging from 0 miles to 100 miles - 30 minutes. scenario 2 charging from 150 miles to 250 miles - 60 minutes. does scenario 2 cost more ? due to longer charge. or it costs the same, because it will charge at slower amperage ? thanks.