Originally Posted by
6376vette
Only true assuming your system can pull that higher c rating. example. if a motor can only pull 25c then the runtime on a 5000mah 40c battery will last as long as a 65c 5000mah battery. If that motor can pull over the 40c rating on the same two packs the runtime would decrease. I doubt the difference would be a whole lot in racing though. How often are our motors pulling their max capacity? Not much or we would be melting wires and speed controls.
Not true. C rating and Internal resistance are not the same thing. You will get a lower internal resistance with a higher C rating however C rating has nothing to do with the power the battery puts out. It is the value that the battery can handle before it CAN'T put out.
The internal resistance allows the battery to output higher voltage at a regular rate compared to nominal voltage. It would be like having a thicker guage wire. The motor is drawing the same current however the wire loses X amount during that draw. C rating would be like the same example except when the motor draws the current the wire can't handle the current and would melt or fail.
Hopefully that explains it. We are talking about a very small difference here and it is all on the assumption that a 90C battery is rated the identical way to a 50C battery.
Internal resistance was the number one value we looked at for matched batteries racing stock classes. It gave more power however drained your battery more so it wasn't as important in modified where run time was the most important.