Are you running 3S in a monster truck? It seems like that may be what is killing your run time. If you ran 4S or 5S then you would get TONS more run time since you would drawing much less amps to get the same power.
I can only imagine what kind of amps are being pulled on 3S...
Probably high average, but it wouldn't be able to pull a whole lot for power, because you need more voltage to get more amperage... that's why you get exponentially more power available when increasing the voltage.
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens