Originally Posted by
POUNDITRACING
The cell # has nothing to do with length of time. The capacity is still 4200. The differance is that they are on the throtle more.
How is that? It would be true if the cars were slower. But they are faster. To be fast they need watts. watts come from the product of volts x amps.(in simple terms)
For example if you have a car with 1500gr and 375w with 7,2v you will put out from the batteries 52A (375w/7,2v=52A)
If you would like to have a car with 5 cells that is as fast you will need the same power to weight ratio as the other (250w/kg). So for a 1430gr car you will need 357,5watts. this time with 6v you will need to pull from batteries 59,5A
(357,5w/6v=59,5A).
That is why with the same batteries you will have less time to drive. With 6 cells you pull 52A with 5 you will pull 59,5A.
If you aply the formula that relates time with the batteries capacity and currente drawn you have Time(minutes)= Capacity(in amp)x60/discharge rate(amp)
That makes T=4,2(4200mah)x60/52 that makes T=4,84minutes (for 6 cells)
With 5 cells, T=4,2x60/59,5 that makes T=4,23minutes.
These are just invented numbers this is not the real thing but I hpoe I can help understand the stupidity of using 5 cells, at least at big tracks.