The distance was probably shortened due to ambient temperature. When you ride e-boards in colder weather the battery loses energy much quicker, def recommend retrying in the summer time. Also the 15 mile range is most likely determined by completely flat terrain and a constant speed the whole time. When you accelerate really hard you use more energy from the battery. Either way 8.5 miles is kinda short comparing to 15 mile range... im def sure you will gain some miles back in 60+ F weather. Good luck riding man, really like your channel!!! I stoke on boards alot too and have recently been getting into biking and noticed you get the same adrenaline rush and the workout it great. Def recommend checking out some NYC fixie biking videos, soooo sick.
*Try somethin like an Exway, the X1 line of models* if you like "stealthy, no battery" style of eBoards. ⚡🤙🏼⚡ usually much better build quality and controls than brands like Outdoor Master
