Originally Posted by Sangesf

It doesn't say the AH of the battery.

Here is the calculations you need...

Volts times Amp Hours = Watt/Hours
More volts = more speed.
More AHs = more distance.
Wattage of motor = Pulling Power (torque)

So everything hinges on those calc...

Example....
36v 10ah = 360 w/h
36v 20ah = 720 w/h = more distance
48v 10ah = 480 w/h (compared to 36v 10ah) = more speed and distance
48v 20ah = 960 w/h (compared to 48v 10ah) = more distance.

Given equal batteries(lets say 36v 20ah), a 250w motor will use up all the battery in ~3 hrs. (720wh / 250w)
A 500 watt motor will give much better torque, but can use up twice as much power as the 250w one will. (720wh / 500w)

Given different voltages, it gets a little trickier...
A 36v 20ah running a 250w motor = a little less than 3 hours. (see above calc)
A 48v 20ah running a 250w motor = more speed and a little less than FOUR hours. (960wh \ 250w)
You'll notice the batteries have the same "AH" but you'll see that the 48v will give you more speed and distance.
A 48v 20ah running a 500w motor = even more speed, more torque, and less time (960wh / 500w = a little less than TWO hours.

Hope this helps.