LOL! I have one of those, except it's yellow instead of blue!
The book on the thing says it will go 20 miles on a charge, but I can guarantee you that they really meant 20 BLOCKS!!!
Anyway... I took the body off of mine a while back, to see how everything worked, and promptly added two batteries to the two already there, for more range.
I tried to wire it up with 48 volts instead of 24 (MORE POWER!!!) but the controller cut power to the motor instead. I added a 6-volt battery to make 30 volts for a while, and it had more power, but things started smelling funny, so I just did the two strings of batteries for the 24 volts with more range, and the voltage doesn't drop so bad when you gun it!