Originally Posted by beemerfan

I mounted an amp meter in a VTA car once to evaluate the need for higher "C" rating on batteries. I did dead stop burn outs on the street and also had it in the car for practice laps. Result was about 12 amp average draw on the track and about 22 amp draw peak for hard acceleration from a dead stop. I don't remember my gearing at the time but it was probably between 3.3 and 3.8 FDR. Figure about 15% more draw for a 21.5 and you would be under 14 amps average on the track and just over 25 amps peak. So no need for a higher rated speed control based on amperage.

HOWEVER, higher rated speed controls tend to have lower internal resistance and less voltage drop. So basing your decision on a lower voltage drop rather than the amperage rating makes more sense. I doubt there is any sort of industry standard for the numbers manufacturers publish about their products. You can use them as guidelines but you would have to setup some sort of controlled experiment to actually compare different speed controls.