Calculate maximum flight time

If you know your average cruise current you can estimate maximum flight time from any battery.

Assuming you only want to use 80% of the battery capacity the equation is:

Battery mAH divided by Cruise Current Amps multiplied by 0.048 = Flight Time Minutes

Example using 2200mAH Lipo and 3Amp cruise current 

2200mAH / 3A X 0.048 = 35min

Note that battery cell count is not required for the calculation