Originally Posted by Anthony Yuen
If the average voltage keeps the same, but runtime has extra 20-30 seconds that means the IB4200 cell discharge profile is still higher than the IB3800s. I hope you can understand the mathematics behind.
I understand were you are coming from and it makes sense, however I doubt the voltage will be higher even though you are averaging over time (dv/dt).
If you look at a discharge curve the only thing that needs to change to maintain the same average voltage without an increase in overall cell voltage is the slope of the curve. IB cells have two critical slopes, one during the first 2300mah (+/-) and then the remaining (for IB3800s).
The difference between these two slopes is the rate of change.
Besides, most of the IB3800 cells that we are matching at Axxis Racing are in the 4150 mahr range, with about 5% of them above 4200mahr. That is very close to the nominal 4200mah.
Danny stated that the IB4200s have around 430 seconds at 35 amps, that equates to 4180mahr...that is within limits of what we are seeing in the best IB3800.
Untill I test the cells and see the actual discharge curves I will not speculate or pass erroneous information, but I am going under the assumption that the two cells will be very similar in their discharge and voltage characteristics.
This is based on the results that I have seen on the last few thousand IB cells that we have matched.