No of course you don't. No really. You don't. At all. Have to.Assume 25 watts/mile @ 25mph so that gives 12.6 miles - subtract 20% for "good battery practice" and you have 10.08 miles - so you're bob on.
Of course, you don't "have" to go everywhere at 25mph ;-) And you could carry a spare battery.
Very nice bike though but direct drive hubs aren't for me.