My personal best is 17 miles, but I can only do that if I ride a certain way and have my board configured in a certain way.
As the battery level dips, it gets increasingly difficult to stay foiling or to restart.
And no brand, none of them actually live up to their marketed ride times because it's so highly variate.
I get the need for alternative fuel sources, but I really don't want to have to figure these dynamics out in an automobile and am staying away from full electric cars for now.