I took my one son to the NASCAR theme park just north of Toronto and found it rather humorous that the fast karts were electric. The gas powered outdoor karts were over governed and idled nearly all day long with fumes that would make a car from the 50s seem right at home.
In comparison, there were electric go-karts inside on an under over figure 8 track. They used a very large starter motor - forgot the details of the motor - sorry - connected by a toothed rubber belt to the axle. The back tires were fairly skinny for a gokart and just behind the front tires and in front of the rear tires were 12 volt deep cycle batteries - the ones that look like enclosed 6-packs.
The cool part was the charger. When the cars come back from the pit, the center surface between the tires was a raised surface and they stop the cars so that they are strategically placed above two flush metal plates beside one other measuring about 6" wide and a foot long that charge the batteries between races. The races would run around 6 minutes and you could feel them depleting by then. Great torque though... I'm over 230 and had no problems keeping the far lighter weight competitors humble!
