How Far Does A Solowheel EXTREME Go On A Full Charge?

Recently acquired a Solowheel Extreme and I wanted to see the minimum distance (Riding at full speed, never stopping so regenerative braking can't add power back into the wheel) it could go so I'd never be stranded. Because I was wearing new shoes, I cheated and had to stop once during my test. Since the Extreme has a bigger tire than the Original Solowheel I just assumed it would go farther on a charge. I signed the waiver to have this Extreme "boosted" to have it's top speed maxed at 15mph. Not sure if Inventist remembered to do this for me. Not only did my Extreme end up going slower than my Original...it died sooner. Was not expecting that. Have to admit, it is a more comfortable ride though.