E-TWOW Booster 9s vs 12s battery HD

The first part shows the original battery 9s (36.8V fully charged). The second part, adds a 3s battery 6200mAh (around 43 euro at http://www.hobbyking.com) in series with the original battery for a total of 12s (49.2V fully charged). No other modifications were needed to the scooter. This gives much more torque and at my 90kg weight, I am able to ride on flat terrain at 38km/h using the rear rubber wheel. The autonomy in 12s is 15km instead of 20km on 9s.